OAR-2002-0009

National Emission Standards for Hazardous Air Pollutants:  Halogenated
Solvent Cleaning

Summary of Public Comments and Responses

To the Proposed Rule

U. S. Environmental Protection Agency

OAQPS/Sector Policies and Programs Division

National Resources and Commerce Group (C504-04)

Research Triangle Park, North Carolina  27711

April 2007

	Disclaimer

This report has been reviewed by the Sector Policies and Programs
Division of the Office of Air Quality Planning and Standards, and EPA,
and approved for publication.  Mention of trade names or commercial
products is not intended to constitute endorsement or recommendation for
use.

TABLE OF CONTENTS

Chapter                          	Page

  TOC \o "2-2" \h \z \t "Heading 1,1"    HYPERLINK \l "_Toc135645670"
Introduction	  PAGEREF _Toc135645670 \h  1

  HYPERLINK \l "_Toc135645672"  I.	Background	  PAGEREF _Toc135645672 \h
 3

  HYPERLINK \l "_Toc135645673"  I.A.	What is the statutory authority for
regulating hazardous air pollutants (HAP)?	  PAGEREF _Toc135645673 \h  8

  HYPERLINK \l "_Toc135645674"  I.B.	What is halogenated solvent
cleaning?	  PAGEREF _Toc135645674 \h  12

  HYPERLINK \l "_Toc135645675"  I.C.  	What are the health effects of
halogenated solvents?	  PAGEREF _Toc135645675 \h  19

  HYPERLINK \l "_Toc135645677"  II.  General Comments on the proposed
rule	  PAGEREF _Toc135645677 \h  23

  HYPERLINK \l "_Toc135645678"  II.A.	Co-proposal of Option 1 versus
Option 2	  PAGEREF _Toc135645678 \h  23

  HYPERLINK \l "_Toc135645679"  II. B.	Suitability of using CalEPA URE
versus OPPTS URE for PCE	  PAGEREF _Toc135645679 \h  30

  HYPERLINK \l "_Toc135645681"  III. Rationale for the Proposed Rule
PAGEREF _Toc135645681 \h  39

  HYPERLINK \l "_Toc135645682"  III.A.	What is our approach for
developing residual risk standards?	  PAGEREF _Toc135645682 \h  39

  HYPERLINK \l "_Toc135645683"  III.B.	How did we estimate residual
risk?	  PAGEREF _Toc135645683 \h  46

  HYPERLINK \l "_Toc135645684"  III.B.1	How did we estimate the emssion
and stack parameters for these sources?	  PAGEREF _Toc135645684 \h  53

  HYPERLINK \l "_Toc135645685"  III.C	What are the results of the
baseline risk assessment?	  PAGEREF _Toc135645685 \h  57

  HYPERLINK \l "_Toc135645686"  III.D	What is our proposed decision on
acceptable risk? 	  PAGEREF _Toc135645686 \h  60

  HYPERLINK \l "_Toc135645687"  III.E	What is our proposed decision on
ample margin of safety?	  PAGEREF _Toc135645687 \h  61

  HYPERLINK \l "_Toc135645688"  III.F.	What is EPA proposing pursuant to
CAA Section 112(d)(6)?	  PAGEREF _Toc135645688 \h  78

  HYPERLINK \l "_Toc135645689"  III.G	What is the Rationale for the
Proposed Compliance Schedule?	  PAGEREF _Toc135645689 \h  79

  HYPERLINK \l "_Toc135645701"  IV.  Solicitation of Public Comments	83

  HYPERLINK \l "_Toc135645702"  IV.A.	Introduction and General
Solicitation	83

  HYPERLINK \l "_Toc135645707"  V. Statutory and Executive Order Reviews
110

  LIST OF TABLES

Table	Page

1.	List of Commenters	2

Introduction

	The Environmental Protection Agency (EPA) is revising the national
emission standards for hazardous air pollutants (NESHAP) for halogenated
solvent cleaning (HSC) (40 Code of Federal Regulations (CFR) 63, subpart
T).  In 1994, EPA promulgated technology-based emission standards to
control emissions from HSC.  As required by section 112(d)(6) of the
Clean Air Act (CAA), EPA has reviewed the NESHAP for major and area
sources and determined that, taking into account developments in
practices, processes, and control technologies, no further action is
necessary at this time.  In addition, pursuant to Clean Air Act (CAA)
section 112(f), EPA has evaluated the remaining risk to public health
and the environment following implementation of the technology-based
rule and is publishing more stringent standards for major sources and
some area sources to protect public health with an ample margin of
safety.  The revised standards are expected to provide further
reductions of halogenated solvent emissions based on application of
equipment, switching of solvents and work practice standards.

	In response to the proposal, we received about 24 unique comment
letters on the proposed rule amendments.  A majority of sixteen comments
were received from industrial sources representing the narrow tube
manufacturing industry, solvent distributors, the aerospace industry and
the continuous web cleaning industry.  We received four comments from
industry associations representing aerospace, narrow tube manufacturing,
the chemical industry and solvent manufacturers.  Two comments from
regulated Federally-owned facilities were received.  One State and one
local municipality provided comments.  A major association of state air
pollution program administrators provided comments.  No comments were
received from environmental groups.  These comments included one set of
mass comments, for which more than 5 individual companies were
signatories to the comment submission.  A list of commenters, their
affiliations, and the EPA docket item number assigned to their
correspondence is provided in Table 1.  To achieve an organized
presentation, we have grouped the comments by topic in Chapters I
through V of this document.  These chapters are organized according to
the preamble sections in the proposed rule (71 Federal Register (FR)
47670, August 17, 2006).

Table 1.  National Emission Standards for Hazardous Air Pollutants:

Halogenated Solvent Cleaning – List of Commenters

Docket ID	Commenter Name

2002-0009-0088	Ali Mirzakhalili, Administrator, State of Delaware
Department of Natural Resources and Environmental Control (DNREC)

2002-0009-0089	David R. Crandall, Parts Cleaning Technologies, LLC

2002-0009-0090	Fiona M. Allen, Office of Deputy City Manager, City of
Arlington, Texas

2002-0009-0091	Jeffrey M. Farina, Accellent Endoscopy, Incorporated

2002-0009-0092	Wayne H. Jochmann, Alcoa, Incorporated

2002-0009-0093	Tracy Grable, Delta Air Lines

2002-0009-0094	Donald R. Schregardus, Deputy Assistant Secretary of the
Navy, Clean Air Act Services Steering Committee

2002-0009-0095	Steven P. Risotto, Halogenated Solvents Industry Alliance

2002-0009-0096	Albert V. Hartman, Ultra-Kool, Incorporated

2002-0009-0097	Hoai B. Huynh, Aerospace Industries Association of
America

2002-0009-0098	Plymouth Tube Company

2002-0009-0099	Venson Hellwig, State and Territorial Air Pollution
Program Administrators and

Robert Colby, Association of Local Air Pollution Control Officials
(ALAPCO)

2002-0009-0100	Timothy R. Henderson, American Safety Razor Company

2002-0009-0101	Elizabeth McMeekin, PPG Industries, Incorporated

2002-0009-0102	Frederick J. Prossen, Salem Tube, Incorporated

2002-0009-0104	Charles G. Valeska, Eastman Kodak Company

2002-0009-0105	Phillip Bell, Fehr-Graham & Associates

2002-0009-0106	Douglas I. Greenhaus, National Automobile Dealers
Association

2002-0009-0107	Tara L. Flynn, Drinker, Biddle & Reath, LLP on behalf of
the Narrow Tube Industry Collective Comments

2002-0009-0108	Thelma Norman, American Airlines

2002-0009-0109	Laurie A. Miller, American Chemical Council

2002-0009-0110	Tod J. Wawzysko, Spirit Aerosystems, Incorporated

2002-0009-0111	Andrew C. Lawrence, Department of Energy

07455-C44-01	Confidential Business Information:  Anthony J. Jost,
Superior Tube Company, Inc.

I.	Background

Comment:  One commenter (OAR-2002-0009-0088), a state regulating agency,
indicates that an important tool in writing permits, providing
compliance assurance and interpreting regulatory language for the
various maximum achievable control technology (MACT) standards has been
the “General Provisions Applicability” table that is included in
virtually every MACT standard.  The commenter finds that no changes have
been proposed to the “General Provisions Applicability” table
[Appendix B to Subpart T] as a result of proposed residual risk
additions to the MACT standard.  The commenter further states that by
not having changed or updated Appendix B, incorrect information is being
provided in Appendix B, for example:

Appendix B indicates that 63.6(c)(2) applies to Subpart T.  Yet, the
proposed paragraph 63.460(i) specifies contradictory compliance date
timing (2 years from promulgation) for existing sources.  Past EPA
practices would have noted the non-applicability of the specific general
provision and defined the specific difference in the Comment column of
the table.  Please refer to treatment of 63.5(b)(3) in Appendix B as an
example.

Appendix B indicates that 63.9(h), Notification of Compliance Status,
does not apply to Subpart T and provides an explanation of the
requirements in the “Comment” column.  Paragraph 63.471(f) of the
proposed Subpart T residual risk rule provides requirements that are
different than those in the Appendix B “Comment” column.  The
appropriate Subpart A applicability and the “Comment” column of
Appendix B need to be revised to reflect this and other changes made in
the proposed Subpart R residual risk rule.

There have been a number of changes to the General Provisions since 40
CFR Part 63 Subpart T was initially promulgated.  Whether any of those
changes would have resulted in Appendix B should be evaluated and
Appendix B should be revised as appropriate.

The commenter states that these few examples illustrate what they view
as a disturbing trend.  They contend that if the accuracy of the General
Provisions Applicability table is not going to be maintained; then, its
value as a tool is lost and it will become a point of confusion, rather
than a help.  The commenter strongly recommended that EPA update the
General Provision Applicability table [Appendix B] before issuing the
final Subpart T residual risk rule and that the EPA should  incorporate
this practice in future proposed residual risk rulemakings.

Response:  CAA section 112(d)(6) requires that  we review our previously
adopted MACT and GACT standards and to revise them as necessary meeting
the criteria stated therein.  Section 112(f) requires that we ensure our
rules protect public health with an ample margin of safety, and in this
final rule, we have concluded that certain revisions to the pre-existing
MACT standard are required.  For the section 112(d)(6) review required
for major and area sources, we have determined that certain revisions
are not necessary, after considering technological developments and
other relevant factors such as the qualitative degree of risks posed by
HSC emissions.  In particular, EPA  SEQ CHAPTER \h \r 1  identified that
batch cold cleaning machines are well controlled at baseline and by
themselves are area sources, which is why GACT rather than MACT was
applied to these area sources.  However, if a machine is located at, and
contributing to HAP emissions at a major source, it is classified as
part of that major source.  Therefore the EPA has classified these
sources as area and major sources.

Comment:  Commenter (OAR-2002-0009-0091) stated that EPA failed to
engage industry stakeholders in its development of the proposed rule in
contravention of its own policy and stated intention.  As a result, the
commenter asserted that EPA’s proposed “one-size fits all”
approach was technically and economically infeasible for narrow-tubing
manufacturers.

Response:  Halogenated solvent cleaning is conducted across many
industries and is often co-located with numerous source categories and
EPA attempted to involve as many industry representatives as possible
during the risk assessment phase.  Additionally,   SEQ CHAPTER \h \r 1
EPA does not have provisions for industry to serve on internal EPA
workgroups.  The Agency, however, does contact commenters to inform them
of any industry symposium that may be planned on solvent cleaning where
their input could be used.  Further, in response to the comment that we
proposed a “one-size fits all” approach,  and certain comments
discussed below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to
gather more information pertinent to the halogenated solvent machines
used by the aerospace industry, narrow tubing manufacturing industry,
and the facilities that use continuous web cleaning machines.  EPA also
subsequently met with a cross segment of industry that would be affected
by this final rule.  Responses to the NODA provided significant data and
information that have led EPA to determine that it is both
technologically infeasible and not cost effective for these industries
to implement any further emission controls or requirements.
Consequently, as stated in Section III.A.3., of the Preamble to this
final rule, we are not promulgating any facility-wide emission limits
for halogenated solvent cleaning machines used by the aerospace
manufacturing and maintenance industry, the narrow tubing manufacturing
industry and for continuous web cleaning machines.

Comment:  Commenter (OAR-2002-0009-0091) stated that if EPA must
promulgate a rule at this time to meet its consent order obligations by
the Federal court-ordered deadline, the rule should be applicable only
to small degreasers with a surface area less than 1.21 square meters (13
square feet).  The commenter also suggests that EPA establish a tubing
industry working group to assist in the development of potentially
feasible technologies to support any necessary rulemaking for degreasers
larger that 13 ft2 and for degreasers that process specialty metal
tubing.

	Response:  In response to this comment and certain comments discussed
below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to gather
more information pertinent to the halogenated solvent machines used by
the aerospace industry, narrow tubing manufacturing industry, and the
facilities that use continuous web cleaning machines.  Responses to the
NODA provided significant data and information that have led EPA to
determine that it is both technologically infeasible and not cost
effective for these industries to implement any further emission
controls or requirements.  Consequently, as stated in Section III.A.3.,
of the Preamble, we are not promulgating any facility-wide emission
limits for halogenated solvent cleaning machines used by the aerospace
manufacturing and maintenance industry, the narrow tubing manufacturing
industry and for continuous web cleaning machines.

As also indicated in the earlier response,   SEQ CHAPTER \h \r 1 EPA
does not have provisions for industry to serve on internal EPA
workgroups, the Agency will contact (and did subsequently hold various
meetings with industries that are affected by this final rule), to
inform them of any industry symposium that may be planned on solvent
cleaning where their input could be used.

Comment:  Commenters (OAR-2002-0009-0091, OAR-2002-0009-0093,
OAR-2002-0009-0095, OAR-2002-0009-0098, OAR-2002-0009-0102,
OAR-2002-0009-0107, OAR-2002-0009-0108 and OAR-2002-0009-0110) feel that
the 45-day review and comment period provided insufficient time for
facilities to understand and evaluate the underlying risk analysis,
adequately assess the potential economic and production impact of the
rule to their operations and consider their realistic ability to achieve
compliance.

Response:  EPA is currently under a Federal court-ordered consent decree
ordering EPA to complete the requirements of §112(f) and §112(d) and
if needed, promulgate necessary amendments to Subpart T no later than
December 15, 2006.  The proposed rule, proposing to amend Subpart T, was
published in 71 FR 47670 on August 17, 2006.  In the preamble to the
proposed rule, we provided 45 days in which the public could submit
written comments to the agency.   We did subsequently issue a NODA (71
FR 75184, (December 14, 2006)) in order to gather more information
pertinent to the halogenated solvent machines used by the aerospace
industry, narrow tubing manufacturing industry, and the facilities that
use continuous web cleaning machines.  We also sought and obtained an
extension of time to promulgate this final rule from December 15, 2006
to April 16, 2007.

Comment:  Commenters (OAR-2002-0009-0107), a group of five narrow tube
manufacturing industries, stated that their industry produces highly
engineered, small diameter tubes that are used in extreme applications
in the aerospace, nuclear and medical device industries.  The commenters
also indicated that the products the manufacture for the Department of
Defense are “mission critical” components of national defense
systems, that these products have extremely demanding requirements for
product cleanliness and overall surface condition.  They further
indicated that qualification conditions are imposed on certain products
by the Department of Defense, the Food and Drug Administration and the
Nuclear Regulatory Commission.  These qualification require that a
manufacturer satisfy customer and regulatory agency requirements and
that changes in manufacturing process must not adversely affect product
quality.  The commenters pointed out that the narrow tube industry uses
specialized lubricants during the manufacturing process and that these
lubricants and coatings are highly specialized and often proprietary and
are designed as part of a full-cycle system that includes the degreasing
solvent.  The commenters indicated that TCE is the only effective
cleaning solvent for removing lubricants and coatings for many
applications.  They also indicated that they degrease tubes that range
from forty to one hundred feet long with extremely small diameters, some
as small as 0.0005 inches.  Because of the small diameter, they
indicated that it is often difficult to remove all of the cleaning
solvent and contamination carried by the solvent from the tube.  They
indicated that the dominant issues for the narrow tube industry is the
combination of great length and small diameter, the extreme cleanliness
required and the manufacturing processes involved.  They indicated that
emission levels of TCE from cleaning operations at narrow tube industry
facilities often exceed 40 tons per year, and in some cases 50 tons per
year, The commenter disagreed with EPA calculations of residual risks
and EPA’s approach and results in establishing an ample margin of
safety.  The commenters stated that they understand that EPA is under a
court-ordered consent decree compelling promulgation of the residual
risk rules, but that this consent decree neither trumps the clear
language of the Clean Air Act and nor relieves EPA of the obligation to
comply properly with each step in the rulemaking process.

Response:	In response to this comment and certain comments discussed
below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to gather
more information pertinent to the halogenated solvent machines used by
the aerospace industry, narrow tubing manufacturing industry, and the
facilities that use continuous web cleaning machines.  Responses to the
NODA provided significant data and information that have led EPA to
determine that it is both technologically infeasible and not cost
effective for these industries to implement any further emission
controls or requirements.  Consequently, as stated in Section III.A.3.,
of the Preamble to this final rule, we are not promulgating any
facility-wide emission limits for halogenated solvent cleaning machines
used by the aerospace manufacturing and maintenance industry, the narrow
tubing manufacturing industry and for continuous web cleaning machines.
Additionally, we are concluding that the current level of control for
the above-noted facilities’ cleaning machines called for by the
existing NESHAP reduces HAP emissions to levels that present an
acceptable risk, protects public health with an ample margin of safety,
and prevents adverse environmental effects.

Also, as stated in Section III.B of the Preamble to this final rule,
based on comments and data received on both the proposal and the NODA,
we re-evaluated the risk, the technical feasibility, the costs of the
proposed options, and the compliance time needed to implement the
proposed options.  This re-analysis focused especially on the four
industry sectors discussed above.  Additionally, in response to public
comments we updated the risk assessment for the entire source category
using the 2002 National Emissions Inventory (NEI) database, which was
not available for the proposal. The resulting re-analysis of risk at the
baseline emission level (i.e., the level of emissions allowed by the
1994 MACT) indicated that the maximum individual cancer risk (MIR)
associated with this source category is 100-in-a-million with an annual
cancer incidence of 0.55.  This is as compared to the 200-in-a-million
MIR and 0.40 annual cancer incidence level that we presented at
proposal, which was based on the 1999 NEI database.  We consider both
MIR values to be acceptable levels of maximum individual risk
considering the number of people exposed at these levels and the absence
of other adverse human and environmental health effects.  We note that
the MIR of 100-in-a-million  (calculated using the 2002 NEI data) is the
same regardless of the URE for PCE chosen for the risk analysis (i.e.,
the CalEPA value or the OPPTS value, which results were contrasted at
proposal).  This is because PCE is not the only driver of the MIR risk
level for the highest risk facilities.

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

The revised population risk distribution at baseline emission levels
shows that about 25 people are exposed to the MIR risk level, about
22,000 people are at estimated risks of ≥ 10-in-a-million risk level,
and about 4,000,000 people are at estimated risks of ≥ 1-in-a-million.
 This is compared to approximately 90 people exposed to risks at the MIR
level (200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

I.A.	What is the statutory authority for regulating hazardous air
pollutants (HAP)?

Comment:  Commenter (OAR-2002-0009-0100) states that EPA established a
MACT standard for the continuous web subcategory in December 1999 and
therefore, Section 112(f) risk analysis for the subcategory is not
required until December 2007.  The commenter states that the continuous
web subcategory was established five years after the standard for the
other halogenated solvent machines.  EPA proposed rule fails to
recognize that under this requirement EPA has eight years from December
3, 1999 (Or by December 3, 2007) to conduct the residual risk evaluation
for the continuous web subcategory.

A commenter, from a facility with a continuous web cleaning machine,
points out that the proposed rule fails to account for or respond to the
information which led EPA to adopt the alternative MACT standard for
continuous web facilities in 1999.  The commenter submits that
information provided to EPA, led to EPA’s recognition that the
individual machine approach of the 1994 MACT standard for HSC machines
does not work for continuous web systems.  The commenter referenced a
number of Federal Register Notices in their comment.  The commenter
requests that EPA re-evaluate the proposed Section 112(f) standard as it
applies to the facilities in the continuous web subcategory separately
from the other solvent cleaning machines in light of the information in
the rulemaking docket for the subcategory.   The commenter also points
out where EPA explained that “the inability of some continuous web
cleaning machines and the cleaning machines used as the bases for the
HSC NESHAP promulgated in 1994.”

Response:  Section 112(f)(2)(A) requires the Administrator to promulgate
applicable standards “within 8 years after promulgation of
standards,” under section 112(d).  We read this provision as allowing
for our promulgation of standards, under section 112(f), within 8 years
of the effective date of section 112(d) requirements, rather than within
8 years of the compliance date of the section 112(d) requirements.  (See
for example, section 112(f)(3) (“the Administrator shall establish a
compliance date or dates . . . which shall provide for compliance as
expeditiously as practicable but in no event later than three years
after the effective date of such standard.” (Emphasis added)). The
effective date of the Halogenated Solvent Cleaning NESHAP is December 2,
1994, and not December 3, 1999, as suggested by the commenter, although
we subsequently made certain clarifications and amendments to these
requirements. Our obligation to promulgate residual risk standards for
this source category is therefore past, and we are now operating under a
consent decree that required our promulgation of today’s rule on or
before December 15, 2006, subsequently extended to April 16, 2007.  We
also believe that there is nothing in the Act that precludes our
completion of the residual risk review prior to 8 years after
promulgation of section 112(d) standards.

	Comment:  Commenter (OAR-2002-0009-0098) is concerned if the proposed
regulation become final, it will detrimentally affect operations, as
well as those of the narrow tube industry within the United States.  The
commenter fully supports the directive of the Clean Air Act to reduce
residual risk.  To this end, the company wishes to participate in
discussions that will lead to rules governing use and emissions of
halogenated solvents.  The commenter believes that costs and other
effects of the proposed rule have not been considered in light of the
special factors involved in the narrow tubing industry.  With this in
mind, the commenter requests the following actions by EPA: 1) that EPA
suspend promulgation of the proposed rule as to the narrow tube
industry; namely, the industry sector “Tubing, mechanical and
hypodermic sizes, cold-drawn stainless steel, made from purchased
steel” subset of NAICS classification 331210, until EPA has an
opportunity to examine the special circumstances applicable to that
industry; 2) that if the consent order regarding this rulemaking, as
noted in EPA’s letter refusing requests for an extension of time to
develop and submit comments, prevents EPA from suspending promulgation
of any portion of the proposed rule, then in following earlier size
distinctions, the rule should be applicable only to small degreasers
with a surface area less than 1.21 square meters (13 square feet);  3)
Establish an advisory group made up of companies representative of the
narrow tube industry and charge that group with the responsibility to
work with EPA and advise EPA as to the feasibility of existing and
developing technology that could be proven to allow compliance with
residual risk rules; and 4) defer promulgating emissions standards based
on residual risk of TCE until EPA has completed the pending
re-evaluation of the carcinogenicity of TCE.

	Response:   In response to this comment and certain comments discussed
below, EPA issued a NODA (71 FR 75184, (December 14, 2006)) to gather
more information pertinent to the halogenated solvent machines used by
the aerospace industry, narrow tubing manufacturing industry, and the
facilities that use continuous web cleaning machines.  Responses to the
NODA provided significant data and information that have led EPA to
determine that it is both technologically infeasible and not cost
effective for these industries to implement any further emission
controls or requirements.  Consequently, as stated in Section III.A.3.,
of the Preamble to this final rule, we are not promulgating any
facility-wide emission limits for halogenated solvent cleaning machines
used by the aerospace manufacturing and maintenance industry, the narrow
tubing manufacturing industry and for continuous web cleaning machines.
Additionally, we are concluding that the current level of control for
the above-noted facilities’ cleaning machines called for by the
existing NESHAP reduces HAP emissions to levels that present an
acceptable risk, protects public health with an ample margin of safety,
and prevents adverse environmental effects.

	Concerning comment 3 from the commenter, as stated in earlier response,
  SEQ CHAPTER \h \r 1 EPA does not have provisions for industry to serve
on internal EPA workgroups.  The Agency will, however, contact the
commenters to inform them of any industry symposium that may be planned
on solvent cleaning where their input could be used.

Concerning the commenter’s request that we “defer promulgating
emissions standards based on residual risk of TCE until EPA has
completed the pending re-evaluation of the carcinogenicity of TCE, we
have the authority to revisit (and revise, if necessary) any rulemaking
if sufficient evidence becomes available that changes within the
affected industry or significant improvements to the underlying science
suggest that the public is exposed to significantly more or less risk
than estimated in the risk assessment prepared for this rulemaking (See
CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  Thus, it may become necessary at some time in the future to
revise the facility emission limits if the pending Agency's Integrated
Risk Information System’s(IRIS) assessments result in significant
changes to the UREs for PCE, TCE, or MC.

	Comment:  Commenter (OAR-2002-0009-0098) states that EPA has not
complied with the CAA section 112(f)(2) requirements to give appropriate
consideration to the cost, energy, safety and other relevant factors
when developing residual risk standards for this category or
subcategory.  The commenter further states that EPA’s proposed rule
was offered as a vehicle for allowing the regulated community to save
money while also lowering emissions of halogenated solvents and reducing
residual risk.  Regardless of whether the residual risks would be
lowered, or whether the air emissions of halogenated solvents would
diminish, the commenter states that the facts are clear that neither
factor would happen at any cost savings to any of the parties affected
by the proposed rule.  The information entered in the Docket by EPA,
combined with the information obtained by the commenter, indicates
directly the opposite of the conclusion presented in the Federal
Register notice supporting the proposed rule.  The proposed rule is
based on conclusions which, themselves, are based on incorrect
assumptions.

	Response:  In response to public comments received on our proposal and
subsequent NODA, we re-examined the data and assumptions used to
estimate the risk and compliance costs presented in the Preamble to our
proposed rule.  We determined that certain significant data and
assumptions that we used to develop our cost estimates at proposal were
either no longer relevant, not reflective of more recent inventory data,
or not valid.  As a result, we re-evaluated risks using the more recent
inventory data and modified our cost estimates in response to public
comment.  The most important change we made is that we re-analyzed the
risk metrics and costs using the halogenated solvent cleaning facilities
in the finalized 2002 NEI, but removing facilities in four specific
industry sectors -- aerospace manufacture and maintenance facilities,
narrow tube manufacturing facilities, facilities using continuous web
cleaning machines, and military equipment maintenance facilities -- from
the database for the purpose of estimating the risks and compliance
costs associated with the remaining facilities (Sections III.A.3 and
III.B.3 of the Preamble to this final rule explain our rationale for
removing the facilities in these industry sectors from this analysis).

Other changes we made to our cost estimates in response to public
comment are as follows:

We used the finalized 2002 NEI database containing facility and
emissions data as the source of our baseline emissions estimates.  We
removed aerospace manufacture and maintenance facilities, narrow tube
manufacturing facilities, facilities using continuous web cleaning
machines, and military equipment maintenance facilities from the
database for the purpose of estimating the compliance costs for the
remaining facilities. (Sections III.A.3 and III.B.3 explain our
rationale for removing these facilities from this analysis.)

We changed our assumptions about the percent reductions in emissions
that can be achieved by vacuum-to-vacuum machines from 97 percent to 95
percent.

In the proposal, we assigned no operation and maintenance cost to
vacuum-to-vacuum machines.  Based on public comment, our cost estimates
for this final rule incorporate annual operation and maintenance costs
of $18,832 for each machine.

We updated the cost per gallon of PCE and TCE based on information
provided by commenters representing manufacturers of solvents and the
narrow tube manufacturing industry.

We added a carbon adsorption device (CAD) option that assumes a 30
percent control in emissions.  We did not have this option in the cost
assumptions we made at proposal.  We received comments that this option
may be available for some industries but that it is at least ten times
more expensive than the retrofit options we costed for the proposal.

We reduced the number of units for which solvent switching could be a
compliance option from 30 percent, used in the proposal, to 15 percent.
We also corrected our method for calculating the emission reduction
impacts and solvent savings associated with solvent switching.

After re-assessing the risk and calculating revised cost estimates, we
re-examined our decision as to what level of control is necessary to
provide an ample margin of safety to protect human health and to prevent
adverse environmental effects, as required by the second step of the
residual risk process under CAA section 112(f)(2).  We considered the
re-assessed risk estimates and the other health information along with
additional factors consistent with the 1989 Benzene NESHAP (54 FR 38044,
September 14, 1989), such as cost, technological feasibility,
uncertainties and other relevant factors as discussed at proposal.  We
re-analyzed the risk metrics using the halogenated solvent cleaning
facilities in the 2002 NEI, but removing aerospace manufacture and
maintenance facilities, narrow tube manufacturing facilities, facilities
using continuous web cleaning machines, and military depot maintenance
facilities.

Because we estimated that the cost of achieving the 25,000 kg/yr and
40,000 kg/yr emissions limits would be considerably greater than what we
had projected for this rulemaking at proposal, we additionally evaluated
the next less stringent emission limit that was considered and presented
in the proposal, but not selected as one of our two proposed options for
limiting emissions from the entire category -- a 60,000 kg/yr MC
equivalent facility-wide emission limit.  For the subset of the category
that excludes the four specific industry sectors, we estimated that the
60,000 kg/yr level reduces the MIR to between 20-in-a million and
50-in-a million and reduces cancer incidence by about 0.19 cases/yr.
These risk reductions are estimated to be achieved at total annualized
cost savings of just over $1.3 million, or a savings of $832/ton of HAP
reduced (we estimate 1,594 tons HAP reduced at this level).

	Comment:  Commenter (OAR-2002-0009-0109), The American Chemistry
Council, states that EPA has the authority to limit the applicability of
additional control requirements to specific sources in a category.  The
commenter believe that a number of EPA approaches taken to date strongly
suggest it has this authority.  The commenter states that EPA has
demonstrated that it has the authority to apply requirements only to a
subset of sources or specific emission points in the Hazardous Organic
NESHAP (HON) rule.

	The commenter provided a copy of comments they submitted for the
proposed rule on the Hazardous Organic NESHAP (HON).  In those comments,
most of which are applicable to the HON source category, they cite
comments that are applicable to the EPA’s residual risk program in
general and in turn, applicable to the proposed rule on HSC.  In those
comments, the commenter details how EPA can limit residual risk rule
applicability and allow low-risk sources to demonstrate
non-applicability.  The commenter suggests that EPA could incorporate
existing regulatory language drawn from the HON NESHAP.  The commenter
also provides risk level criteria that could apply for any further
emission reductions required by §112(f) and (d)(6), a framework for
assessing site-specific source emissions and risks and permit
requirements for applicability demonstrations.

	Response:  EPA agrees with the commenter that EPA has authority to
limit applicability of additional control requirements to specific
sources in a source category if such limits are  not warranted after
considering the cost, energy, safety and other relevant factors. This is
in order to ensure that the existing NESHAP reduces HAP emissions to
levels that present an acceptable risk, protects public health with an
ample margin of safety and prevents adverse environmental effects.
Further, as stated in earlier responses, in this final rule, we are not
setting any emissions limits for facilities that use continuous web
cleaners, and halogenated solvent cleaning machines that are used by
narrow-tubing manufacturing and aerospace manufacturing and maintenance
facilities.  We have concluded that due to the costs associated with
compliance, technical feasibility, and other factors, the current NESHAP
requirements provided for continuous web cleaning machines and
halogenated solvent cleaning machines that are used by narrow-tubing
manufacturing and aerospace manufacturing and maintenance facilities
reduce HAP emissions to levels that both pose acceptable risk and
protect public health with an ample margin of safety and prevents
adverse environmental effects..

Comment:  Commenter (OAR-2002-0009-0107) requests that EPA suspend
promulgation of the proposed rule as it directly relates to the narrow
tube industry, namely, the industry sector “tubing, mechanical and
hypodermic sizes, cold-drawn stainless steel, made from purchased steel:
subset of NAICS classification 331210, until EPA has an opportunity to
examine the special circumstances applicable to that industry.  The
commenter also requests that EPA initiate a separate rulemaking to
address the unique issues of the narrow tube industry and to identify
feasible technologies and risk control strategies to support the
rulemaking effort.

Response:  As stated in earlier responses, in this final rule, we are
not setting any emissions limits for facilities that use continuous web
cleaners, and halogenated solvent cleaning machines that are used by
narrow-tubing manufacturing and aerospace manufacturing and maintenance
facilities.  We have concluded that due to the costs associated with
compliance, technical feasibility, and other factors, the current NESHAP
requirements provided for continuous web cleaning machines and
halogenated solvent cleaning machines that are used by narrow-tubing
manufacturing and aerospace manufacturing and maintenance facilities
reduce HAP emissions to levels that both pose acceptable risk and
protect public health with an ample margin of safety and prevents
adverse environmental effects..

I.B.	What is halogenated solvent cleaning?

Comment:  One commenter (OAR-2002-0009-0106) who represents 20,000
franchised automobile and truck dealers nationwide who engage in
service, repair and parts sales and employees in excess of 1,3000,000
people stated that only MC was ever used as a batch solvent in
maintenance facilities.  While still a component of some vehicle
maintenance commercial consumer products, MC essential is no longer
present in batch cold cleaners (e.g., carburetor cleaners).  The
commenter states that since HCS is no longer an integral part of
automobile or truck dealership operations, it would be inappropriate for
the NESHAP rule to regulate the batch cold cleaners found in their
facilities.

Response:  The CAA provides us with the discretion to regulate area
sources based on GACT in lieu of MACT or residual risk.  We exercised
this discretion in the original NESHAP because of the potential for an
adverse economic impact on a large number of small businesses.  In the
current rulemaking, we decided not to regulate area sources based on
GACT and did not conduct a rulemaking under section 112(d)(6) that
updates the current standards.  Our final standards result in an
adequate level of protection of the public, and this goal has influenced
our determination of what amendments to the pre-existing GACT standards
are “necessary” under section 112(d)(6). On October 5, 2006, a
Control Techniques Guidance document was published for HSC area source
facilities using batch cold cleaners.

Comment:  Commenter (OAR-2002-0009-0111) suggested EPA establish an
exempt emissions threshold (e.g., less than 200 pounds per year) as an
incentive that would encourage owners and operators of these facilities
to implement processes and controls to further reduce emissions from
HSC.  The commenter asserts that if HSC emissions are below this
threshold, the facility would not be subject to 40 CFR 63 Subpart T
emission standards.

Response:   SEQ CHAPTER \h \r 1 EPA established in the definition of
solvent cleaning machine, under Section 63.461 to clarify that vessels
(buckets, pails, and beakers) containing more than 7.6 liters (2
gallons) of solvent are considered solvent cleaning machines for
purposes of Subpart T.  This size limit was included to ensure that
larger vessels, not specifically designed to carry out cleaning or
drying, remain subject to the MACT rule.  EPA appreciates the
commenter’s suggestion but feels it would be unsuitable to amend the
applicability threshold already established in the MACT.

EPA believes the commenter may also be referring to de minimis levels
established under section 112(g) of the CAA.  These levels were
established for the specific intent of 112(g) and are not applicable to
any other standard.  As discussed above, a minimum halogenated HAP
solvent content was added to ensure that only those solvents intended
for regulation are covered by the final MACT standards..

Comment:  Commenter (OAR-2002-0009-0104) states that Subpart T, Section
63.467 (recordkeeping for solvent content, solvent consumption, monthly
and 3-month rolling average emissions calculations) and Section
63.468(f-g) (annual reports) do not currently apply to batch cold
cleaning machines.  The proposed solvent emission methodology in Section
63.471 may not be suitable for all batch cold cleaning machines.  The
commenter recommends that EPA change rule language to allow for
flexibility in calculating emissions as long as the alternate
methodology is scientifically sound and documented.

Response:   SEQ CHAPTER \h \r 1  EPA wants to provide each owner or
operator the flexibility to choose the emission estimation method that
is the most effective for their operations.  In this case, the batch
cold cleaning machines at area sources are not subject to the proposed
requirements.

	Comment:  Commenter (OAR-2002-0009-0088) indicated that in paragraph
63.471(a), EPA proposed to exempt the owner or operator of “cold batch
area source cleaning machines” from the requirements of “paragraphs
(1) and (2) of this section.”  The commenter finds this subcategory
“cold batch area source cleaning machines” confusing and
inconsistent with the regulatory language typically used in other Part
63 MACT standards.  By way of example, the commenter suggests following
two scenarios that might fit the “cold batch area source cleaning
machines” subcategory exemption.

The exemption would apply to all cold batch solvent cleaning machines
but only if 1) the facility was an area source and 2) only cold batch
solvent cleaning machines were located at the facility.  In other words,
if a facility is an area source and only has cold batch solvent cleaning
machines, the facility is exempt from the requirements of 63.471(a).

Inherent in the above interpretation is that a facility that is area
sources and has both cold batch solvent cleaning machines and a batch
vapor or inline cleaning machine must include ALL solvent cleaning
machines in the requirements of 63.471(a).

As an alternative interpretation, the exemption would apply to cold
batch solvent cleaning machines located at a facility that is an area
source, whether there are also batch vapor or in-line solvent cleaning
machines at the facility.  In other words, if the facility is an area
source, the cold batch solvent cleaning machines would be excluded from
the requirements of 63.471(a); however, all batch vapor or inline
cleaning machines must be included in the requirements of 63.471(a).

The commenter recommends that EPA revise paragraph 63.471(a) in the
final Subpart T residual risk rule to more clearly identify or define
the solvent cleaning machine subcategory that it intends to exempt.
Instead of “cold batch area source cleaning machines,” language such
as “any cold batch cleaning machine located at an area source” would
clarify EPA’s intend, if that was EPA’s intent.  The commenter
refers to similar area source exemptions in the recently proposed
Stationary RICE rule [71 FR 33804, June 12, 2006].

Response:  EPA agrees with the commenter.  On October 5, 2006, a Control
Techniques Guidance document was published for HSC area source
facilities using batch cold cleaners.  EPA stated that cold batch
cleaning machines located at an area source using halogenated solvents
were not included in the MACT but were covered by GACT.  On October 5,
2006, a Control Techniques Guidance document was published for HSC area
source facilities using batch cold cleaners.

Comment:  Commenter (OAR-2002-0009-0097), an aerospace industry
association, states their belief that the proposed rule does not
recognize the varying nature of solvent cleaning among different
industries and the inability of many affected facilities to switch
solvents.  They express their concern that the residual risks to human
health and the environment potentially posed by the degreasing
operations today at aerospace facilities may not justify the potential
safety and performance risks for aerospace operations under the proposed
rule’s requirements.  The commenter contends that the emissions data
and related information used by EPA did not sufficiently take into
consideration the decreases in emissions already resulting from the MACT
standards on HSC at aerospace facilities and as a result, overestimates
the exposure risks.  The commenter supports a facility-specific approach
to risk evaluation and emissions limit for HSC operations.

	Response:  We state in the risk report supporting this proposal that
overall we believe our assessment may overstate the risks, but this
conclusion is based on a variety of factors, not solely on database
differences.  We agree with the commenter that changes in the industry
have occurred since 1999 as evidenced by the differences seen between
the 1999 and 2002 NEI databases for these sources  In this final rule,
we used the 2002 NEI inventory to re-analyze the risk from this source
category.  The resulting re-analysis of risk at the baseline emission
level (i.e., the level of emissions allowed by the 1994 MACT) indicated
that the maximum individual cancer risk (MIR) associated with this
source category is 100-in-a-million with an annual cancer incidence of
0.55.  This is as compared to the 200-in-a-million MIR and 0.40 annual
cancer incidence level that we presented at proposal, which was based on
the 1999 NEI database.  We consider both MIR values to be acceptable
levels of maximum individual risk considering the number of people
exposed at these levels and the absence of other adverse human and
environmental health effects.  We note that the MIR of 100-in-a-million
(calculated using the 2002 NEI data) is the same regardless of the URE
for PCE chosen for the risk analysis (i.e., the CalEPA value or the
OPPTS value, which results were contrasted at proposal).  This is
because PCE is not the only driver of the MIR risk level for the highest
risk facilities.

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

The revised population risk distribution at baseline emission levels
shows that about 25 people are exposed to the MIR risk level, about
22,000 people are at estimated risks of ≥ 10-in-a-million risk level,
and about 4,000,000 people are at estimated risks of ≥ 1-in-a-million.
 This is compared to approximately 90 people exposed to risks at the MIR
level (200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

	Finally, we did not reassess the environmental risks using the 2002 NEI
inventory but believe that no "adverse environmental effects," as
defined in CAA section 112(a)(7), would occur given the similarities of
the human health risk results between the 1999 NEI data and 2002 NEI
data and the fact that we showed in the proposal that no adverse
environmental effects would likely occur using the 1999 NEI inventory.

Comment:  Commenter (OAR-2002-0009-0100) states their belief that the
proposed rule proposes a standard which would require facilities to
demonstrate compliance on a machine by machine basis.  The commenter
states that the standard directs measurements of solvent additions and
deletions at fill lines in each machine.  The commenter further adds
that the standard is a machine-specific standard masquerading as a
facility-wide standard.  The commenter states that this is the type of
compliance determination in the 1994 MACT that the 1999 MACT amendments
for continuous web cleaning acknowledged would not work for continuous
web machines.  The commenter states that EPA explained in 1998,
“without any action by the EPA to the contrary, individual
case-by-case equivalency determinations would be required to ensure that
each machine is applying alternative control measures that achieve the
same or better emission reduction as the NESHAP-required controls.  Such
a case by case approach would be unduly burdensome for both the affected
sources and the EPA.  Therefore, the EPA is conducting an evaluation of
methods of control for all web cleaning machines to determine which
emission control measures would be equivalent to the NESHAP.”  The
commenter states that the cap-only control approach has no logical or
rational basis.  While EPA’s cost assessment study supporting the
emission cap options explains that, “establishing the control options
on a facility-wide basis allows each facility the flexibility to comply
in the most cost effective manner.  This is because each facility can
choose which units to control, which controls to apply, and which
solvent to control so long as the limit is met.”  The commenter states
that its two facilities have a carbon adsorption system, which exceeds
the TCE reductions required by the Halogenated Solvent Cleaning NESHAP
requirements for continuous web cleaners.  Each has a state of the art
control system which was installed at great expense.  Yet even an
upgrade of the systems likely will not allow the facilities to achieve
either cap options proposed by EPA.  The commenter suggests that for
continuous web facilities, EPA should evaluate a range of more stringent
percent reduction limits.  That would have been consistent with the
alternative standard set by the continuous web MACT.

	Response:  In this final rule, EPA recognizes that continuous web
machines are designed differently from general halogenated solvent
cleaning machines, i.e., batch and in-line cleaning machines.  As
explained in earlier responses, we have determined that it is both
technologically infeasible and not cost effective for continuous web
cleaning machines to comply with our final promulgated emissions limit.
As also stated in Section III.A.3. of the Preamble, in this final rule,
we are not setting any emissions limits for facilities that use
continuous web cleaners.  As also explained earlier, we are concluding
that the current level of control for continuous web cleaning machines
called for by the existing NESHAP reduces HAP emissions to levels that
present an acceptable risk, protects public health with an ample margin
of safety, and prevents adverse environmental effects.  Based on new
information they provided in response to the NODA, including new cost
information, we re-analyzed the costs for facilities that use continuous
web cleaners and estimated the annual cost effectiveness of complying
with emission limits they provided in comments.  For the continuous web
cleaners, we estimated a baseline MIR risk level of about
30-in-a-million with an annual cancer incidence of 0.03 cases.  Comments
from this industry suggested they could achieve an 80 percent overall
control efficiency compared to their current emission levels, within a
three-year compliance period.   The current NESHAP limit requires a 70
percent overall control efficiency.  To achieve the 80 percent overall
efficiency, facilities would be required to reduce emissions by 33
percent ((1-70%)-(1-80%)/(1-70%) = 33%).  We developed risk and cost
estimates for that level of reduction.  We have estimated that under
this scenario, the MIR would decrease to approximately 20-in-a-million
with and the annual cancer incidence would decrease to 0.02 cases
annually.  The annual cost effectiveness of complying with the 80
percent overall emission control efficiency rate is over $3,400/ton with
a total annualized costs of over $600,000.

Comment:  Commenter (OAR-2002-0009-0098) stated that EPA did not
consider the special circumstances surrounding the cleaning of narrow,
small-diameter, specialty-use, long stainless steel tubes.  The
commenter also stated that EPA did not give due consideration to the
cost-effectiveness of the proposed rule on the six percent of companies
who are the only ones that must make changes in response to the proposed
rule, EPA developed an emission standard based on an average of
“all” machines.

Response:  At proposal, we explained that we acting under the purview of
CAA section 112(f), we had collected data on the emissions of the HSC
source category and assessed the possibility of residual adverse health
risks existing as a result of routine emissions of HAP following
implementation of the MACT standards.  According to CAA §112(f)(2) and
the Benzene NESHAP test, we identified a level of acceptable risk.  The
Benzene NESHAP also establishes that it is permissible to use the
acceptable risk level in deciding at what level to further control
emissions beyond the level of acceptable risk to protect public health
with an ample margin of safety for us to consider the economic impacts
of various options.  In this consideration of costs, it is reasonable
for us to evaluate the scope of impacts across subject source
categories, and nothing in section 112(f)(2) precludes us from noting
whether further controls are feasible for a few, some, or all sources in
that category.  Similarly, under section 112(d)(6), while we are not
required to demonstrate that revised standards are economically feasible
for all sources in the category, in assessing what further controls are
“necessary” we are permitted to evaluate the extent to which any
subject sources would be able to incur the direct costs of the
regulation.    Based on new information that narrow-tubing manufacturing
facilities provided in response to the NODA, including new cost
information, we re-analyzed the costs for halogenated solvent cleaning
machines used by narrow-tubing manufacturing facilities. In this final
rule we estimated an MIR of 70-in-a-million with an annual cancer
incidence of 0.08 at their baseline level of emissions.  Based on
comments received from this industry, on the NODA, indicating that they
could reasonably accomplish a 10 percent reduction in their current
emission levels within a three-year compliance time, we developed risk
and cost estimates for that level of reduction.  We have estimated that
the MIR would decrease to approximately 60-in-a-million with very little
change expected in the annual cancer incidence.  The annual cost
effectiveness for complying with an overall 10 percent reduction in
total emissions limit would be a cost of over $3,600/ton with total
annualized costs of nearly $700,000.  The final rule requirements are
inapplicable to this industry due to the calculated costs of compliance.

I.C.  What are the health effects of halogenated solvent cleaning?

Comment:  Commenters (OAR-2002-0009-0104) suggests that EPA should not
set new residual risk standards prior to completion of the IRIS
assessments for the affected solvents.  Commenter (OAR-2002-0009-0104)
notes their understanding that the toxicity values for each of the four
chemicals included in the proposal are scheduled for revisions that are
expected to be completed in 2007 or 2008.  The commenter contends that
the current proposal is based on outdated toxicity information.  For
example, several recent publications indicate that the current unit risk
factor for methylene chloride is overly conservative.  This would affect
the allowable emission quantities proposed in this rule.

Response:  Commenter 0104, states that more recent information on
methylene chloride indicate that “the current unit risk factor is
overly conservative”.  No information was sent that would support that
claim or that we could evaluate.  As stated in Section III.D. of the
Preamble to this final rule, for those situations where a particular
chemical does not have a cancer potency value in IRIS, we have
established a prioritization process for accessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as the California
Environmental Protection Agency (CalEPA).  Further, as stated earlier,
we have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  Thus, it may become necessary at some time in the future to
revise the facility emission limits if the pending Agency's Integrated
Risk Information System’s(IRIS) assessments result in significant
changes to the UREs for PCE, TCE, or MC.

Comment:  Commenter (OAR-2002-0009-0089), a distributor of cleaning
chemicals, including chlorinated solvents and a supplier of vapor
degreasing equipment, stated that they represent approximately 40% of
the vapor degreasing metal cleaning market in the United States.  The
commenter stated that based on a review of  437 companies impacted by
the proposed regulations they noted the following:  1)  approximately
15% of the companies representing 40% of the estimated emitted tons no
longer use a chlorinated solvent in their process.  This information is
based on commenter’s knowledge.  The commenter further asserted that
the actual number of companies no longer using a chlorinated solvent is
much higher.  Secondly, the commenter estimates that there are less than
50 companies in the entire United States emitting more the 50 tons per
year.  Thirdly, the commenter stated that EPA’s study assumes the
majority of the large users will install vacuum airless equipment to
meet proposed emission requirements.  The commenter stated that
vacuum-to-vacuum machines have had a positive impact on the industry and
that small to medium machines are reliable and are a good alternative
for companies that have small parts and limited volume.  However, the
commenter stated that vacuum-to-vacuum machines for companies with large
parts and heavy volume have been mostly unsuccessful in the industry.
The commenter adds that seals for vacuum pumps have been unreliable and
that cleaning batch cycles are significantly longer for vacuum machines.
 Production requirements are met by designing a cleaning chamber up to 4
times larger than the existing machine, resulting in quadrupling floor
space, (which most companies don’t have), significantly increasing the
price of the equipment above that estimated in the study.  Most of the
large users do not view vacuum machines as a viable alternative.

The commenter stated that EPA assumes medium size users of
trichloroethylene (TCE) will switch to methylene chloride (MC).  The
commenter stated that most companies in their customer base would not
switch to MC based on OSHA worker exposure limits and the fact that MC
has a lower boiling point and is harder to keep in the machine.

The commenter stated that a review of the large users in the customer
data base revealed that approximately 20 companies emitted more than 10
tons per year, that eighteen of the companies were at least ½ of a mile
from the closest resident, that 12 of the companies had a single large
machine, that a majority of these companies are in the tube
manufacturing and heat exchanger industry, that the majority of the
companies stated vacuum machines were not a viable option, citing floor
space, cost and reliability as the main factors.  The commenter
concludes that the actual number of companies using a chlorinated
solvent and the actual amount of tons emitted in the metal cleaning
market is significantly lower than the amounts estimated in the EPA
study.  Also the commenter states that the actual number of residents
within a block of the emitting facility is significantly lower than
estimated in the EPA study.  Finally, the commenter states that
alternative cleaning processes are not a viable alternative for the
limited number of small businesses that are emitting in excess of 10
tons per year.  The commenter recommends EPA allow more time for the
industry to obtain factual information regarding actual tons emitted,
actual levels of exposure and actual number residents exposed.  The
commenter also recommends that EPA exempt the small number of small
businesses that are currently emitting in excess of 10 tons per year.
The commenter also recommends that EPA apply the final rule to new
facilities so businesses can adequately plan for manufacturing and
cleaning processes.

Response:  EPA agrees that PCE has been reduced by a significant amount
since the 1994 NESHAP.  The EPA is nonetheless required, pursuant to
§112 (f) and §112(d)(6), to review these technology-based standards
and to revise them ‘‘as necessary, taking into account developments
in practices, processes and control technologies,’’ no less
frequently than every 8 years.  The second stage in standard-setting is
described in section 112(f) of the CAA.  Section 112(f)(2) of the CAA
requires us to determine for each section 112(d) source category whether
the MACT standards protect public health with an ample margin of safety.
 If the MACT standards for HAP ‘‘classified as a known, probable, or
possible human carcinogen do not reduce lifetime excess cancer risks to
the individual most exposed to emissions from a source in the category
or subcategory to less than 1-in-1-million,’’ EPA must promulgate
residual risk standards for the source category (or subcategory) as
necessary to protect public health with an ample margin of safety.

Concerning the commenter’s request to exempt small businesses that
emit in excess of 10 tons per year,   SEQ CHAPTER \h \r 1 EPA does not
believe that it is appropriate to establish exemptions for any small
business or any facility that emits over the threshold for defining a
major source, namely, a facility emitting in excess of 10 tons per year
of a single HAP.

Further, prior to our proposal, EPA was aware of the requirements of the
Occupational Health and Safety Administration concerning worker safety
when MC is used.  29 CFR part 1910, which are the applicable OSHA
regulations, require employers to make an initial determination of each
employee's exposure to MC.  If the employer determines that employees
are exposed below the action level, employers are required to make a
record of the determination.  Conversely, if the employees are exposed
to MC above the action levels, employers are required to perform
exposure monitoring.

In addition, EPA did not consider any costs associated with MC
monitoring at proposal.  EPA believes, however, that a facility would
not incur costs if MC emissions do not exceed the OSHA levels.  If a
facility experiences worker exposure of MC emissions over the OSHA
level, the facility incur costs to develop a control plan for fugitive
emissions and possibly implement an employee medical monitoring plan.
To account for the possibility of increased costs, we reduced the number
of units assumed to use solvent switching.

Comment:  Commenter (OAR-2002-0009-0095) indicates disagreement that
methylene chloride, TCE and PCE are likely to cause cancer in humans,
based on available mechanistic and pharmacokinetic information that
shows the tumor increases seen in certain test animals are not relevant
to humans because of species differences.

Response:  In section 112(f) of the Clean Air Act (the Residual Risk
section), we are to set standards if “….sources emitting a pollutant
(or pollutants) classified as known, probable, or possible human
carcinogen do not reduce the lifetime excess cancer risks to the
individual most exposed to emissions from a source in the category …
to less than one in one million, the Administrator shall promulgate
standards under this subsection for such source category”.   While
certainly true that EPA does not currently have a carcinogenic
classification for TCE and PCE, both were classified as “possible”
or “probable” human carcinogens under previous assessments and have
been listed as such by the International Agency for Research on Cancer
(IARC).  It remains to be seen whether these “weight of evidence”
classifications get carried forward into the new EPA assessments.   It
certainly is possible that new data and a more thorough understanding of
the metabolism and /or mechanism of action of these HAP may emerge from
their reassessments.  In the event that new data warrant it, we will
revisit this decision and amend the rule, if necessary.

	Comment:  Commenter (OAR-2002-0009-0099) opposes EPA’s use of
emergency guideline values (i.e. “Immediately Dangerous to Life or
Health”/10, “Acute Exposure Guideline Levels” and “Emergency
Response Planning Guideline” levels) to assess the acute public
health impacts.  Unlike the residual risk assessment for ethylene oxide
commercial sterilizers, this assessment represents a positive step
forward by using CalEPA’s Acute Reference Exposure Levels (RELs) to
assess potential acute effects.  The commenter is also concerned about
the use of 50 meters as the generic distance to the nearest receptor
because, in urban settings, the proximity to receptors can be much
closer.

Response:  We appreciate the commenter’s support for our use of the
CalEPA REL value in this assessment, but in addition to that, we have
utilized a variety of health benchmarks to gauge the broader potential
for acute effects.  If a value were to be exceeded, then a close
examination of that value would be taken to determine the
appropriateness of that value to the exposures, (i.e., are they
temporally related).  In addition, our approach has been to assess
possible acute responses across a spectrum of effects ranging from mild
to severe.

While we agree that individual exposures may occur closer in than 50
meters, we based the assumption of a 50 meter fence line on the fact
that we did not have site-specific data on the minimum distance to the
fence line and on what we knew about the average size of a facility that
has solvent cleaning machines.  In addition, the HEM-SCREEN model uses
assumptions that make this assessment very conservative, (e.g.,
worst-case meteorology versus site-specific meteorology).  For these
reasons, we believe our assessment is reasonable for this category.

II.  General Comments on the Proposed Rule

II.A.	Co-proposal of Option 1 versus Option 2

Comment:  Commenters (OAR-2002-0009-0095 and OAR-2002-0009-0100) state
that EPA’s proposed “one-size-fits-all” solution to determining
the technology and costs required to achieve the necessary reductions is
flawed.  Commenter (0100) states the emission limits are inappropriate
and unsuited for the continuous web subcategory facilities.  The
commenter says that compliance approaches were selected by EPA, not on
the basis of the facilities’ ability to implement them, but based on
how much reduction is necessary to achieve proposed limits.  The
commenters contend that the cap-only approach has no logical or rational
basis.  The result is a significantly overstated potential for emission
reductions in the source category and a considerable understatement of
the costs associated with achieving these potential reductions.

Response:  As stated in earlier responses, this final rule requirements
are not applicable to continuous web cleaning machines, halogenated
solvent cleaning machines that are associated with the narrow tubing
manufacturing industry, and aerospace manufacturing and maintenance
industry and facilities.  The requirements of the 1994 NESHAP and its
subsequent amendments (where relevant) remain applicable to all the
continuous web and halogenated solvent cleaning machines associated with
the above-noted facilities.

Comment:  One commenter (OAR-2002-0009-0095) stated that EPA’s
approach to identifying regulatory options was inconsistent with
determinations for other NESHAP.  The commenter stated that the Coke
Oven, Dry Cleaning, and SOCMI NESHAP developed regulatory options by
identifying the available control technologies through discussions with
the potentially affected sources and then evaluating the potential risk
and cost impacts.  The commenter stated that for this rulemaking there
is no indication that EPA made any attempt to contact the affected
facilities, or at least those with the largest emissions or highest
estimated risk.  In addition, the commenter asserted that the  options
are based on a mechanical application of UREs to projected emissions and
the assessment of available control options to achieve the proposed
limit represent an arbitrary assessment of the viability of six possible
compliance approaches – based primarily on the amount of reduction
necessary for a facility to achieve the limit.

Commenter 0093 believes that EPA proposed application of facility-wide
emission limits on solvent emissions in an arbitrary and inequitable way
of reducing risk from vapor degreasing operations.  The commenter states
that under EPA’s proposal, facilities must comply with the limits
regardless of facility size or the number or size of degreasers
operated.  The commenter states that the burden of compliance is
disproportionately high for facilities that operate multiple degreasers
and conduct a higher level of degreasing operations.  The commenter
suggests that EPA should establish limits on each degreaser in terms of
either kilograms per degreaser or kilograms per square meter of
solvent/air interface area.  The commenter also suggest that if EPA were
to take this approach, the commenter recommends that EPA include
provisions to allow facilities with multiple degreasers to average their
emissions across multiple degreasers.

Response:  Historically, environmental policies and rules have often set
relative emission limits, i.e., emission limits proportional to the
source category’s size or output.  The original HSC MACT set emission
limits in units of emissions per square meter of the machines.  Another
factor in the development of the MACT is that the volume of emissions is
closely linked to output.  As a consequence, a higher emission level
occurs if the production level is relatively high or more than expected.
 It is an emission level that is only proportional to machine size and
proportional to output.  This emission level does not account for
emissions that may rise above the threshold for protecting human health
and the environment.   It would seem that the commenter is putting forth
the argument that since a larger machine and a higher production output
entails more emissions, more allowances should be distributed to
high-output facilities, to prevent too high a compliance cost.

Considering the results of the CAA §112(f) residual risk assessment
that after implementation of the MACT standard directs EPA to  evaluate
the human health or environmental risks that may remain as a result of
routine emissions of HAP from the source category.  EPA’s findings
indicated risks above 1-in-a-million associated with large HSC machines
that were presumed to be implementing the requirements of the HSC MACT.
After considering economics of establishing further controls on such
machines, EPA set an absolute annual emission limit or an annual
emissions cap that ensures an ample margin of safety and moves more
people to a level of risk at or below 1 in a million.

Comment:  The commenter (OAR-2002-0009-0104) believes that facility wide
emission caps leave source owners only two compliance options: 1)
establish internal production restrictions or 2) install add-on capture
and control equipment to insure operating flexibility.  The commenter
states that for halogenated batch cold cleaning units, Subpart T does
not include capture and control as a compliance option to meet the
standard.  Therefore, the commenter believes that installation/operation
of a capture and control device that is subject to explicit
federally-enforceable monitoring conditions in a Title V permit
represents a reduction in residual risk beyond MACT for halogenated
batch cold cleaning units.  The commenter also believes that the
reduction in residual risk is at least equivalent to any reduction that
would be achieved by the facility wide cap.  The commenter requests that
halogenated batch cold cleaning units, operating with a capture and
control device that is subject to federally-enforceable monitoring
conditions in a Title V permit be specifically exempted from the
facility-wide cap.  Additional recordkeeping beyond what is required to
satisfy the Title V requirements should not be required.

	Response:  EPA disagrees with the commenter’s assertion that the
emissions cap leaves source owners only two options: 1) production
restrictions and 2) add-on capture and control equipment.  The commenter
is correct in stating that halogenated batch cold cleaning units,
Subpart T does not include capture and control as a compliance option to
meet the standard.  In implementing the proposed emissions cap, EPA
attempted to imply that owners and operators to whom the emissions cap
reductions may apply, that any option to reduce emissions can be
available to them to comply, and that may include measures not
specifically indicated in the rule.  EPA wanted to allow for flexibility
in applying innovation, technological and procedural, in reducing
emissions.  The final rule will clarify this point.

Concerning the commenter’s request to exempt batch cold cleaners with
add-on capture and control devices from the proposed facility-wide
emission cap, EPA set the emission cap as the low-risk threshold.  EPA
contends that if a facility is below the emissions cap after reviewing
12-months emission data, then the established MACT technology
requirements are still in effect and it will be business-as-usual.  EPA
is not considering exempting from the MACT requirements, any facility
that is below the risk-based emission cap threshold.

Comment:  The commenter (OAR-2002-0009-0099) an association of state air
program administrators believes that Option 2 still presents
unacceptably high risks; but notes that it is preferable over Option 1.
The commenter recommends that EPA reassess the risks (taking into the
consideration the issues identified below) and consider other options
that will result in lower emissions and greater protection for public
health.  The commenter expressed concern about the residual risk
analysis conducted.  In particular, the commenter does not agree with
the conclusions in the residual risk analysis that state that the
procedures used in the analysis are likely to over-predict the risk.
The commenter believes the analysis under-predicts the risk because the
residual risks were determined using point-source emissions and did not
include fugitive emissions, that using average stack parameters would
yield questionable results. The commenter states that EPA acknowledges
that "carry out" emissions are substantial, but there is no attempt in
the residual risk assessment to characterize or model them.  These
emissions will have a significant near-source impact on the maximum
individual risk (MIR) determination, which is lost when the sources are
modeled using average facility stack parameters.

	Response: We state in the risk report that overall, the assessment done
is more likely to over-predict risks than under-predict them.  This
conclusion is based on a variety of factors.  The commenter is concerned
that we are underestimating risks because we modeled releases as stack
releases and “ignored” the possibility that some emissions may be
fugitive.  When we looked at the NEI data to determine the best way to
model these emissions, it was unclear what the exact number of fugitive
versus stack releases were.  When no specific designation of release
type was present in the NEI, we made some assumptions of stack versus
fugitive based on the height of the reported release.  Releases over 10
feet were considered stack releases. Releases under 10 feet were
considered fugitive.  Given this type of information and its
uncertainty, we concluded that modeling all releases as stack releases
was reasonable.  We acknowledge that fugitive emissions could have
significant near-source impacts, but the stack height chosen for the
“average” was not so tall that the maximum impacts were far away
from the facility emission location.  In fact most of the maximum
concentrations around these facilities were within a few hundred meters
from the source.  Although stack versus fugitive releases may have more
significant impacts on other sources, we do not believe their affect on
this source would be that significant.  This is supported somewhat by
the uncertainty analysis which showed that there was only a slight
change in the risk results when the “average” stack release was
compared with a “low stack” release.

	This commenter is also concerned that our stack data only came from an
analysis of 611 facilities and that perhaps 50% of these may be
defaults.  They also questioned the use of “average” stack height
versus a “median” value.   We acknowledge the uncertainty in these
data but based on our understanding of this source’s characteristics
and our best engineering judgment, the choice of an average stack height
was a reasonable one.  The range of stack heights in the NEI are not as
skewed as would be assumed from looking at the maximum versus minimum
stack heights.  An analysis of the distribution of heights shows that
the “average” and the “median” values are not that different for
any of the release parameters chosen, (e.g., the average stack height is
30.9 feet versus the median stack height of 29 feet).

	Comment:  One commenter (OAR-2002-0009-0095) stated that, when
determining what compliance options a facility would use to meet the
proposed limits, EPA should have contacted the facilities or
associations representing the facilities for additional data.  The
commenter stated that, while it may be time-consuming and prohibitively
expensive to contact all of the companies affected by the rule, they
believe that such contact has been, and should continue to be, an
essential part of the Agency’s determination of an ample margin of
safety.  The commenter pointed out that the dockets for the coke oven
battery and (major source) dry cleaning determinations include
information from all of the affected sources.  In addition, the
commenter suggested that the EPA should have at least contacted a subset
of facilities identified based on such factors as: emissions, risk,
size, equipment type, or other factors.  The commenter offered examples
such as the nine web cleaning facilities that were identified or the 19
facilities identified as having the highest risk.  The commenter
contended that, had EPA conducted such as survey as part of its
analysis, it would have found that many of its assumptions about the
applicability and cost of the risk reduction measures it has identified
are incorrect.

Response:  Concerning the initial comment,   SEQ CHAPTER \h \r 1 EPA
does not have provisions for industry to serve on internal EPA
workgroups.  However, the Agency will contact the commenters to inform
them of any industry symposium that may be planned on solvent cleaning
where their input could be used.  EPA disagrees with the commenter that
for this source category, as compared to other source categories, that
specific facility information must be included.  EPA conducted a
screening that was designed to overestimate, rather than underestimate,
risks.  The results indicate risks for potential chronic cancer, but do
not demonstrate risks for potential chronic noncancer, and acute
noncancer health endpoints.  Also, no significant human health
multipathway or ecological risks were identified.  Since the resulting
risks been determined to be negligible, a more refined analysis with
site-specific data was conducted.  Such an assessment was more
data-intensive; however, it also presented a more accurate estimate of
risks which could then be used as the basis for regulatory decision
making.  The findings of the screening risk assessment for the HSC
source category were positive (i.e., the statutory cancer risk trigger
level was exceeded).  It became necessary to conduct a more refined risk
assessment using more specific population data, site data, chemical data
and exposure data.  We gleaned that data from the EPA’s best available
source, the NEI database.  The database provided enough information to
complete our refined assessment and the need to contact individual
facilities was never indicated as necessary.

	Comment: Commenter (OAR-2002-0009-0097) an aerospace industry
association supports Option 1 and the use of EPA’s risk factors.  The
commenter requests that EPA consider alternative regulatory approaches
to the existing “one-size-fits-all” facility-wide emissions cap
across a variety of affected industries.  The commenter contends that
the aerospace industry has unique challenges and requirements and they
support a facility-specific approach to risk evaluation and emissions
limit for HSC operations rather than the emissions cap.  The commenter
further states that EPA should allow facilities to opt out of the
emission controls if they can show that emissions from their facilities
do not exceed the risks EPA believes will result from implementation of
the rule.

Commenter (OAR-2002-0009-0110) compels EPA to consider regulatory
approaches other than the single facility-wide emissions cap that do not
result in a disproportionate and unfair regulatory burden on large
facilities with unique, complex and stringent production requirements
related to materials cleaning and for whom few compliance options are
available.

	Response:  As stated in earlier responses, this final rule requirements
are not applicable to continuous web cleaning machines, halogenated
solvent cleaning machines that are associated with the narrow tubing
manufacturing industry, and aerospace manufacturing and maintenance
industry and facilities.  The requirements of the 1994 NESHAP and its
subsequent amendments (where relevant) remain applicable to all the
continuous web and halogenated solvent cleaning machines associated with
the above-noted facilities.  See also Section III.B2 and II.B.4. of the
Preamble for the final rule on our rational for the final rule
requirements.

Comment:  Commenter (OAR-2002-0009-0091) recommends that EPA not
promulgate either Option 1 or Options 2 of the proposed rule.  They
recommend that EPA defer promulgating a risk-based standard for
degreasers using TCE until it has completed in re-evaluation of the
carcinogenicity of TCE.  Commenters 0107 recommend that EPA defer
promulgating a risk-based standard for degreasers using TCE until it has
completed its re-evaluation of the carcinogenicity of TCE.

Response:  As stated in earlier responses, for those situations where a
particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for accessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as the California
Environmental Protection Agency (CalEPA).  Further, as stated earlier,
we have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  Thus, it may become necessary at some time in the future to
revise the facility emission limits if the pending Agency's Integrated
Risk Information System’s(IRIS) assessments result in significant
changes to the UREs for PCE, TCE, or MC.

II. B.	Suitability of using CalEPA URE versus OPPTS URE for PCE

Comment:   Two commenters (OAR-2002-0009-0090 & 0088) a municipality and
a state agency, respectively supported the emission limits outlined in
Option 2 of the proposal.  They further indicated support for  Option 2
because of the significant emissions reductions and that greater
protection of public health, safety and welfare would be achieved.  The
state agency supported Option 2 because the additional reductions of TCE
would augment efforts to achieve attainment of the 8-hour ozone
standard.

Commenter (OAR 2002-0009-0088) noted that EPA included two different
facility-wide annual emission limits for perchloroethylene for the two
options in the proposed Subpart T residual risk rule.  One facility-wide
annual emission limit for perchloroethylene was based on the cancer unit
risk estimate [URE] developed by EPA’s Office of Prevention,
Pesticides, and Toxic Substances (OPPTS).  The other facility-wide
emission limit was based on the cancer URE developed by the California
EPA (CalEPA).  The commenter noted that this request was made because
the IRIS URE will not be available before 2008.  The commenter supported
using CalEPA URE because it clearly more appropriate than the OPPTS URE
and was somewhat surprised that EPA would have even considered the
latter choice.

Response:  EPA has explained that when a particular chemical does not
have a cancer potency value in IRIS, we have established a
prioritization process for assessing other health assessment information
(as described in our “Residual Risk Report to Congress” on pages 56
through 58).  This hierarchy includes peer reviewed cancer potency
values from EPA as well as from other agencies that conduct chemical
carcinogenicity assessments such as CalEPA.  See also our response to
comments on this issue in the final Coke Oven Batteries NESHAP (70 FR
19998-20000, (April 15, 2005)).

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

Comment:  Commenter (OAR-2002-0009-0092) ), the world’s largest
integrated producer of aluminum and aluminum semi-fabricated products
operating 2 continuous web cleaning lines, stated that the two UREs
differ by a factor of 10 and selection of the URE will obviously have a
significant impact on control options available to their facility.  They
indicated concern that EPA plans to finalize this standard with
insufficient data to select an appropriate URE and without having
completed its own Integrated Risk Information System (IRIS) reassessment
for PCE.  The fact that the final IRIS URE "may be different from both
the CalEPA and OPPTS values" means that inappropriate or unnecessary
emission reduction strategies could be required as a result of EPA's
promulgating the wrong PCE facility-wide limit in a final rule.

The commenter further stated that if the proposed facility-wide limit of
27,000 kg/yr of PCE were promulgated (based on OPPTS), their facility
would need to achieve 25% further reduction in PCE emissions.  This
level of reduction might be achieved by improving capture efficiency,
reducing contamination levels of the incoming sheet and eliminating
solvent washing for some products.  None of the retrofit controls (and
associated costs) examined by EPA for (e.g., use of freeboard, working
mode cover, longer drying time and refrigeration devices) have
applicability to continuous web cleaning lines like those at the
facility, so other control means would have to be developed.  If
on-the-other-hand the proposed facility wide limit of 3200 kg/yr of PCE
were promulgated, the facility would need to achieve 91% further
reduction in PCE emissions.  This would require the development of a
replacement cleaner for PCE and/or replacement of the entire web
cleaning line with an alternate design. The commenter stated that they
have been working to identify or develop replacement cleaners for PCE.
Use of VOC containing solvents have been ruled out because of permitting
issues, potential PSD implications and fire protection issues with using
a flammable solvent.  The commenter has also examined the use of HFE
type solvents that are not ozone depleting substances nor are they VOCs.
 The purchase cost of these materials make them cost prohibitive on
these continuous web cleaning lines.  Another potential alternative for
consideration is the use of a water-base cleaner.  However, this type of
cleaner introduces new issues regarding increased contact time between
the cleaner and the sheet, staining or etching the product sheet and
drying the web after cleaning.  Addressing these operating issues would
likely require the installation of a completely new and larger line for
water-base cleaning because the foot print of the existing line is not
large enough for the additional contact time and drying requirements
imposed by a water-base cleaner.  Given the significant range of
economic impacts, we strongly recommend that EPA wait for better
scientific data before promulgating a final rule. Otherwise, the final
rule may impose

control requirements (and potentially shutdown of on-going operations)
unnecessarily by applying a URE that is overly conservative.  If EPA
cannot delay promulgating the rule due to statutory requirements, EPA
should base the final rule on the OPPTS URE and then issue a timely
revision of the residual risk rule, if necessary, once the IRIS
reassessment is completed.

Response: As stated in earlier responses, EPA has explained that when a
particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for assessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as CalEPA.  See
also our response to comments on this issue in the final Coke Oven
Batteries NESHAP (70 FR 19998-20000, (April 15, 2005)).

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

Comment:  Commenter (OAR-2002-0009-0095) stated that the URE derived by
CalEPA is not an appropriate value for assessing the potential cancer
risk presented by PCE emissions.  The commenter stated that the CalEPA
value is an order of magnitude higher than other published estimates
because it is based on a much higher value for the fraction of PCE
metabolized.  The commenter cited several studies to support their
assertion that a lower value for the faction of PCE metabolized is more
appropriate.  The commenter added that the use of the higher URE for PCE
significantly inflates the risk estimates.   The commenter stated that
EPA should use the OPPTS URE value for PCE.  The commenter argued that
the OPPTS estimate has been subject to public comment and scientific
peer review, and is based on a more comprehensive assessment and more
accurate estimates of human metabolism rates than the CalEPA estimate.
The commenter concluded by stating that using the existing OPPTS URE
would be more consistent with existing regulatory initiatives.

Response:  See earlier response.  In addition, EPA’s Office of Air
Quality, Planning and Standards [OAQPS] has recommended the use of the
CalEPA URE for perchloroethylene in Volume 1 of the Air Toxics Risk
Assessment Reference Library.  OAQPS has recommended the use of the
CalEPA URE as its next preference when there is no IRIS cancer data
available on the Prioritization of Data Sources for Chronic Exposure web
page.  EPA has not recognized OPPTS in their priority scheme to the
sources of chronic dose response information.  OAQPS has use the CalEPA
URE for PCE cancer effects in the risk assessment phase of the 1999 NATA
project.

We believe we have used the best available science in the risk
assessment supporting this rule proposal.  The CalEPA has a development
and peer review process that resembles the process for IRIS development.
 We presented the OPPTS URE for PCE as a way of “bounding” the risk
estimates in order to provide the risk managers with a sense of the
possible uncertainty.  As stated, PCE is currently undergoing a potency
reassessment for IRIS, and information such as that mentioned by the
commenter, should be evaluated along with other, relevant toxicity
information in this reassessment.  Given that we do not have any
indication that the URE may be higher, lower, or stay the same, we will
evaluate the new URE when finalized and assess whether there are any
significant changes that warrant amending the rule.

Comment:  Commenter (OAR)-2002-0009-0105) states that since the URE for
methylene chloride is the crucial determining factor in calculating the
emission limits of the other solvents, one might wonder why the most
recent data used by the California Air Resources Board was not used. The
commenter further states that EPA readily used the California EPA
derivations for the UREs for PCE and TCE, but apparently not for MC.
The commenter poses, why EPA was not consistent in utilizing data from
the California sources.  The commenter recognized that EPA did indicate
that it is reassessing potential toxicity and carcinogenicity of the
chlorinated solvents involved in this proposed rulemaking.  The
commenter states that using the CalEPA numbers should at least provided
the most current thinking on the relative carcinogenicity of these
solvents.  However, “given the uncertainties associated with these
risk estimates”, the commenter states that EPA should have completed
these critical reassessments before publishing this proposed rule.

Response: As stated in earlier responses, EPA has explained that when a
particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for assessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as CalEPA.  See
also our response to comments on this issue in the final Coke Oven
Batteries NESHAP (70 FR 19998-20000, (April 15, 2005)).

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

Comment:  Commenter (OAR-2002-0009-0092), the world’s largest
integrated producer of aluminum and aluminum semi-fabricated products,
fully shares and supports EPA’s objective to minimize public health
risks.  However the commenter states that in setting risk-based NESHAP
standards, they believe that EPA has an obligation to base the standards
on sound science.  It is clear from the proposed preamble and rule that
EPA has not yet determined which URE is correct and that selection of
the best URE requires further analysis.  Given the significant range of
economic impacts, we strongly recommend that EPA wait for better science
data before promulgating a final rule.  Otherwise, the final rule may
impose control requirements (and potentially shutdown of ongoing
operations unnecessarily by applying a URE that is overly conservative.
The commenter also states that if EPA cannot delay promulgating the rule
due to statutory requirements, EPA should base the final rule on the
OPPTS URE and then issue a timely revision of the residual risk, if
necessary, once the IRIS reassessment is completed.

	Response: See earlier responses, In addition, EPA notes that
development of URE's is a time-intensive process and is independent of
the rulemaking schedule which is established by statutory and
court-ordered deadlines.  Although the Agency has not yet completed its
own cancer assessment for PCE, we disagree with commenter that the risk
estimates are not based on good science since we have evaluated PCE
cancer risk based on consideration of both CalEPA and OPPTS cancer
dose-response assessments, as well as more recently available data.  We
are under a court-ordered to finalize this rule by December 15, 2006.
While we recognize that there is uncertainty in the potency factors due
to the fact that all three of the relevant HAP are under review, we have
tried to account for that uncertainty, at least for PCE which accounts
for some of the highest risk estimates for this source, by using an
alternative URE which provides some bounding context for the decision
makers.  Once final UREs emerge from the IRIS reviews, we will consider
the necessity of revisiting this rule and making adjustments through a
rule amendment if necessary.

	Comment:  Commenter (OAR-2002-0009-0099) recommends that EPA use the
CalEPA URE for several reasons:  1) EPA’s Air Toxics Risk Assessment
Reference Library recommended the use of the CalEPA URE for PCE, 2) the
EPA Office of Air Quality Planning and Standards (OAQPS) recommended the
use of the CalEPA URE in situations in which there are no Integrated
Risk Information System (IRIS) data available (see EPA’s
“Prioritization of Data Sources for Chronic Exposure” web site), and
3) OAQPS used the CalEPA URE for PCE when conducting the 1999 risk
assessment for the National-Scale Air Toxics Assessment.  We believe
there is an established precedent for EPA’s use of the CalEPA URE and
recommend it be selected for this residual risk standard as well.

	Response:  As stated in earlier responses, EPA has explained that when
a particular chemical does not have a cancer potency value in IRIS, we
have established a prioritization process for assessing other health
assessment information (as described in our “Residual Risk Report to
Congress” on pages 56 through 58).  This hierarchy includes peer
reviewed cancer potency values from EPA as well as from other agencies
that conduct chemical carcinogenicity assessments such as CalEPA.  See
also our response to comments on this issue in the final Coke Oven
Batteries NESHAP (70 FR 19998-20000, (April 15, 2005)).

Because we have not yet issued a final IRIS health assessment for PCE,
we are using the CalEPA unit risk estimate (URE) of 5.9 X 10-6 (ug/m3)-1
to implement the emission limit for PCE in this final rule.  See section
III.D. of this Preamble for further discussion of our decision to use
the CalEPA cancer URE.

	We also have the authority to revisit (and revise, if necessary) any
rulemaking if sufficient evidence becomes available that changes within
the affected industry or significant improvements to the underlying
science suggest that the public is exposed to significantly more or less
risk than estimated in the risk assessment prepared for this rulemaking
(See CAA section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

	Comment:  Commenter (OAR-2002-0009-0108) states that the cancer URE
estimates and risk assessments upon which the proposed rules are based
are not “consensus” standards and will be reassessed in the near
future under the recently revised guidelines for cancer risk.  The
commenter also states that while EPA referenced both the EPA Office of
Prevention, Pesticides and Toxic Substances (OPPTS) URE and the
California EPA (CalEPA) URE, there was little or no mention made of
other URE studies conducted for PCE which would potentially indicate a
different URE.  The commenter says the same is believed to be true
regarding the URE for TCE.  The commenter believes EPA should seek to
identify and evaluate the potential cancer risks associated with the
identified chemicals based on the most recent and scientifically agree
upon evidence/assessment available.  Also regarding MC, the commenter
also states that EPA will reassess its potential toxicity and
carcinogenicity, expected to be completed in 2007.  The commenter avers
that the chemical dose-response value is an important source of
uncertainty in any risk assessment and that EPA’ re-assessment of MC,
PCE, and TCE may result in new dose-response values.  The commenter
requests that EPA complete such reassessments before subjecting industry
to promulgated emission limitations which may and possibly will be
revised based on the outcome of the reassessments.

	Response:  See earlier responses on this comment. 	We also have the
authority to revisit (and revise, if necessary) any rulemaking if
sufficient evidence becomes available that changes within the affected
industry or significant improvements to the underlying science suggest
that the public is exposed to significantly more or less risk than
estimated in the risk assessment prepared for this rulemaking (See CAA
section 301).  See also Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk Rules (71 FR 17712, 17715, (April
7, 2006)).  In particular, it may become necessary at some time in the
future to revise the facility emission limits if the pending IRIS
assessments result in significant changes to the UREs for PCE, TCE, or
MC.

	Comment:  Commenter (OAR-2002-0009-0095) stated that pending EPA
reassessments of the potential health effects of MC, PCE, and TCE will
include the development of Agency-wide UREs for PCE and TCE, and the MC
review likely will result in the revision of the Agency’s current URE.
 The commenter stated that, given these expected changes, the Agency’s
proposal to establish facility-wide emission limits and compliance
options tied directly to the current UREs is problematic.  Based on the
alternative UREs for PCE discussed in the preamble, the commenter stated
that the allowable facility-wide emissions limit applicable to PCE could
be three-fold lower or 2.5 times greater than the limit for TCE.  In
addition, the commenter indicated that the anticipated reductions in
risks could be eliminated with changes to the UREs for the solvents.

	In addition, the commenter stated that basing the limits on the UREs,
rather than the available control technology, also means that facilities
using TCE and PCE are required to achieve significantly greater
reductions.  The commenter stated that in the case of PCE, using
CalEPA’s URE, the only compliance options available to most affected
facilities would be vacuum technology or solvent switching.

	Response:   See earlier responses on this issue.  Additionally, EPA
notes that in proposing an emissions cap rather than specific control
strategies, we provided the industry with the flexibility to reduce
their emissions in ways that may suit their specific processes and allow
them to control their costs as well.  This approach also focuses on
those facilities whose emissions represent the highest risk and,
therefore, warrant the most attention.

	EPA agrees with the commenter stating that limits based on UREs, rather
than on available technology, requires facilities using TCE and PCE to
achieve significantly greater reductions than those facilities using MC.
 EPA acknowledges in previous responses that establishing such an
absolute emission limit based on UREs was preferred since ample margins
of safety could be achieved beyond the MACT with what EPA determined to
be no serious economic impacts.

III. Rationale for the Proposed Rule

III.A.	What is our approach for developing residual risk standards?

Comment:  The commenter (OAR-2002-0009-0095) states that under the
framework outlined in the 1989 Benzene NESHAP and the 1999 /Residual
Risk Report to Congress, and codified in §112(f)(2), EPA is to conduct
a two-step process in providing “an ample margin of safety to protect
public health” following a determination that MACT standards
promulgated pursuant to subsection §112(d) “do not reduce lifetime
excess cancer risks to the individual most exposed to emissions from a
source in the category or subcategory to less than one in one million.
42 U.S.C . §7412(f)(2).

The commenter further states that as outlined in the Benzene NESHAP and
the Residual Risk Report, the one-in-one-million individual additional
cancer risk level is not a “bright line” mandated level of
protection for establishing residual risk standards, but rather a
trigger point to evaluate whether additional reductions are necessary to
provide an ample margin of safety to protect public health.

The commenter states their belief that the proposed acceptable risk
determination is consistent with the Benzene NESHAP Decision Framework.
The commenter indicates that EPA’s estimates that the maximum
individual risk (MIR) associated with the 1999 NESHAP is between 90 and
200 in a million.  The commenter states that an MIR of 1-in-ten thousand
clearly falls within the range of acceptable risks established in
EPA’s first residual risk rule for emission from coke oven batteries.
The commenter indicates that EPA found an MIR of 300 in a million
acceptable under the Benzene NESHAP framework after considering the
number of exposed people with cancer risk estimates greater that 1 in a
million (12% of the exposed population), the number of people for whom
cancer risk levels were greater than 10-4 (approximately 70), the
estimate of annual incidence of cancer, and the projected absence of
adverse noncancer effects.  The commenter states, by comparison, less
than 5% of the exposed population has estimated risk above 1 in a
million and only about 90 people in the exposed population (near only 7
of the 1,900 HSC facilities) are estimated to be exposed at risk levels
above 1 in ten thousand in EPA’s baseline assessment.

The commenter also states that the Benzene NESHAP decision framework
requires EPA to take into account the weight of scientific evidence on
which the risk estimates are based.  The commenter state that EPA’s
assessment of the HSC source category has not considered the weight of
evidence of the HSC solvents.  The commenter supports EPA’s
determination that the MIR associated with the 1994 NESHAP is
acceptable.  The commenter believes that consideration of the weight of
evidence for the HSC solvents lends further strength to the Agency’s
proposed acceptability determination.  The commenter states that in the
coke oven rulemaking, coke oven emissions are arsenic and benzene, known
human carcinogens under EPA’s cancer classification scheme.  However,
by contrast MC is characterized by EPA as a probable human carcinogen
and PCE and TCE remain unclassified as to carcinogenicity.  Thus the
application of the Benzene NESHAP framework to emissions from the HSC
source category clearly supports the acceptability of the baseline
risks.

Response:  The majority of the commenter’s submission as described
above seems to be a reiteration and affirmation of what the requirements
of section (112)(f) and agreement with what EPA has done under this
section in this proposal, particularly in the area of making a
determination of the acceptability of the MIR.  We thank the commenter
for taking the time to respond.

Comment:  Commenter (OAR-2002-0009-0095) stated that the proposed rule
to establish an ample margin of safety for HSC completely disregards the
Benzene NESHAP decision framework.  The commenter states that EPA’s
proposed facility-wide emission limit to provide an ample margin of
safety for protecting public health is based on the mechanical
application of UREs to projected emission from HSC operations, with
little consideration of the technical feasibility and economic impacts.
The commenter states that EPA has made no effort to validate its
assumptions or to provide affected facilities the opportunity to conduct
site-specific assessments.

Response: We disagree with this comment that our proposal does not
consider technical feasibility or costs.  Our ample margin of safety
decisions is based on a number of factors, the level of risk, technical
feasibility and the costs.  We have determined a level of risk that
would ensure that the level of risk is acceptable to as many people as
possible have risks below 1 in a million while taking into account the
potential costs.  Our risk analysis showed that more stringent emission
caps were possible, (i.e., further risk reductions were possible), but
we decided on the proposed options once consideration of possible
technologies and costs were included.  The proposed emission caps do not
require specific control technologies, but our proposal would allow each
facility the flexibility to control their emissions (and therefore their
costs), if needed, using technologies that would be appropriate for
their machines.  Based on our analysis of a few possible control
options, we determined that facilities would see cost savings.

We have not proposed an option that would allow facilities to conduct
site-specific risk assessments.  Our emissions cap approach provides a
way for facilities to determine their applicability based on their
emission levels, (i.e., if you are below the emissions cap (versus below
a specific risk level)), you do not have any control requirements under
this rulemaking.  This approach focuses on the higher emitting
facilities which are the ones that most likely would not be exempt based
on a site-specific risk level approach.  Additionally, this approach
provides facilities the flexibility to reduce their emissions, if
necessary, by means that are appropriate for their specific process, and
thus provides them the ability and flexibility to control not only their
emissions but their costs as well.

Comment:  Commenter (OAR-2002-0009-0091) believes EPA’s approach
toward estimating residual risk for TCE and extrapolating that risk to a
generally applicable facility emission cap is flawed.  The commenter
asserts that EPA is currently in the process of re-evaluating the
carcinogenicity of TCE.  The commenter states that any determinations of
residual risk at this time may be invalidated by EPA’s pending
carcinogenicity findings, and is inappropriate.  Secondly, the commenter
references data from only 61% of facilities in the source category was
available in EPA’s residual risk assessment, extrapolated from the
1999 NEI data.  The commenter states that EPA’s scaling up of the data
may not be representative of actual conditions.  The commenter asserts
that EPA should have used data from the 2002 NEI database.

Response:  We disagree that our determination of residual risk is
inappropriate at this time.  When we published our 1999 Residual Risk
Report to Congress, we stated that in the absence of IRIS values for the
HAP on the CAA list, we would use a potency values from other sources
based on a hierarchy of sources.  Our use of CalEPA potency values for
TCE and PCE follows that process.  An alternative approach would be to
not consider the potency of these HAP because no IRIS value exists.  To
balance this out, we acknowledge the possible uncertainty our hierarchy
approach entails and used the OPPTS URE versus the CalEPA value as a way
to indicate that uncertainty to our risk managers.  We disagree that our
analysis is “flawed and inappropriate”.  We acknowledge that these
HAP are undergoing a reassessment, but in the meantime, we have used the
best science currently available to support this decision.  This is
consistent with how we have used the existing data in other decisions,
and we will continue to rely on this approach.  Also, as part of this
approach, we acknowledge the uncertainty to the risk managers and state
that we will evaluate the new UREs for possible effects on this
decisions and consider amending the rule if these effects are
significant..

The commenter’s second point is that our scaling up of the data may
not be representative of actual conditions and that we should have used
the more recent 2002 NEI data.  We acknowledge that there is uncertainty
in our use of the 1999 NEI data since we know these data represent
approximately 60% of the estimated number of sources in the category.
We also assume that there would be some uncertainty in the 2002 NEI data
since it isn’t known if the approximately 40% of the sources estimated
to be missing from the 1999 NEI would be found in the 2002 NEI.

Further, in this final rule, as stated in earlier responses, we have
used the 2002 NEI inventory to re-analyze the risk from this source
category.  The resulting re-analysis of risk at the baseline emission
level (i.e., the level of emissions allowed by the 1994 MACT) indicated
that the maximum individual cancer risk (MIR) associated with this
source category is 100-in-a-million with an annual cancer incidence of
0.55.  This is as compared to the 200-in-a-million MIR and 0.40 annual
cancer incidence level that we presented at proposal, which was based on
the 1999 NEI database.  We consider both MIR values to be acceptable
levels of maximum individual risk considering the number of people
exposed at these levels and the absence of other adverse human and
environmental health effects.  We note that the MIR of 100-in-a-million
(calculated using the 2002 NEI data) is the same regardless of the URE
for PCE chosen for the risk analysis (i.e., the CalEPA value or the
OPPTS value, which results were contrasted at proposal).  This is
because PCE is not the only driver of the MIR risk level for the highest
risk facilities.

Given the uncertainties associated with the development of emission
inventories, neither the 1999 nor the 2002 NEI inventory should be
considered as correct in an absolute sense or as suggesting temporal
trends in degreasing machine populations or emissions.  Rather, we
consider them to be “snapshots” of the true long-term inventory of
emissions for this source category, each carrying its own degree of
uncertainty.  As such, the derived risk assessment results compared
above should be regarded as ranges within which the true risk metrics
are likely to fall.

The revised population risk distribution at baseline emission levels
shows that about 25 people are exposed to the MIR risk level, about
22,000 people are at estimated risks of ≥ 10-in-a-million risk level,
and about 4,000,000 people are at estimated risks of ≥ 1-in-a-million.
 This is compared to approximately 90 people exposed to risks at the MIR
level (200-in-a-million), about 42,000 people at estimated risks of ≥
10-in-a-million risk level, and about 6,000,000 people at estimated
risks of ≥ 1-in-a-million that we presented at proposal.  Similar to
the MIR and annual cancer incidence metrics, these values may be an
indication of the uncertainty presented by the databases because, as
earlier explained, both inventories are “snapshots” of the industry
rather than an absolute reflection of the “current” state of the
industry.

We did not reassess the environmental risks using the 2002 NEI inventory
but believe that no "adverse environmental effects," as defined in CAA
section 112(a)(7), would occur given the similarities of the human
health risk results between the 1999 NEI data and 2002 NEI data and the
fact that we showed in the proposal that no adverse environmental
effects would likely occur using the 1999 NEI inventory.

Comment:  One commenter (OAR-2002-0009-0095) stated that the 1999 NEI
data does not reflect current emission levels and is not a sufficient
basis for assessing technical or economic feasibility.  The commenter
expressed concern that the data has not been confirmed with the
individual facilities and may be too old to provide an accurate
assessment of the category.  The commenter stated that the industry has
changed since 1999 due to local, regional, and state regulatory
pressures.  The commenter indicated that the most significant change
since 1999 has been the phase out of TCA manufacture for emissive use,
which has effectively eliminated its use for solvent cleaning.  The
commenter pointed out that EPA’s analysis comparing the 1999 NEI data
to the 2002 NEI data shows that, for those facilities included in both
inventories, emissions of PCE, TCA, and MC decreased by 18 to 37
percent.  The commenter questioned the completeness of the 1999 NEI data
based on the fact that EPA found only 23 percent of the facilities
identified from the MACT compliance reports in the 1999 NEI database.

Commenters (OAR-2002-0009-0107), consisting of five narrow tube
manufacturers, state that EPA relied on an obsolete and incomplete
emission database when it used the 1999 NEI as the primary source of
data for halogenated solvent emissions.  The commenters state that EPA
had access to 1999 and 2002 NEI data and reviewed both sets of data, yet
EPA failed to use the more recent data.  The commenters believe the
failure to use the most representative data is unreasonable.   The
commenter adds that two signatory parties of these comments, are missing
from the 1999 database.  They state the two facilities are major TCE
emitting facilities with greater than 40 tons per year emitted.  The
commenters EPA use of the 1999 NEI database that did not include these
facilities skews EPA’s calculation of average degreaser size to a
value lower than the correct value.

Response:  See earlier responses on this issue.

Comment:  Commenters (OAR-2002-0009-0091 and 0097) state that applying
the HEM Screen model to emission from the affected facilities, EPA
normalized factors that are critical to a risk assessment, including
stack height, stack diameter, exit gas velocity and exit gas
temperature.   The commenter also states that EPA acknowledges that many
of the available values were default parameters.  The commenter believes
EPA modeling sensitivity analysis indicates that there are major effects
on ground-level concentrations and risk when stack, building downwash
assumptions and environmental parameters are varied.

Response:  This commenter is concerned that we “normalized” release
parameters critical to the risk assessment and may be affecting major
ground level concentrations.  Our sensitivity analysis did show that
stack height was the release parameter that had the most impact on the
risk seen around these particular facilities.  While we acknowledge that
perhaps 50% of these stack values may be default values, we believe that
our understanding of this category based on our best engineering
judgment, is reasonable, (e.g., the range of stack heights in the NEI
are reasonable for this industry, the emissions from these machines tend
to be from lower stacks, and the impacts would be expected closer to the
emitting sources).   This assumption is supported by the sensitivity
data which showed that the use of an average stack height versus a low
stack height (where the near-source impacts would be anticipated to be
higher) yielded risk results that were not that different.   We also
believe our use of “average” values is a good representative of the
range of values in the NEI because the NEI data are not so skewed,
(i.e., the average and median values are not that different), to make
that assumption unreasonable, (e.g., the average stack height is 30.9
feet versus the median stack height of 29 feet).

Comment:   Commenter (OAR-2002-0009-0097) believed EPA’s methodology
and data modeling created uncertainties and overestimated risks. The
commenter EPA’s use of the 1999 NEI emissions data does not take into
account emissions reductions that followed Subpart T MACT for HSC or the
current state of solvent usage among various industries.  The commenter
also states that with the limited set of available emission data,
combined with the  fact that the input data and parameters for modeling
were outdated and do not reflect current situations, it is likely that
more than half of the facility-specific release values utilized by EPA
were default parameters rather than actual values extrapolated from the
1999 NEI.

Response:  In this final rule, we have used the 2002 NEI inventory to
re-analyze the risk from this source category.  The resulting
re-analysis of risk at the baseline emission level (i.e., the level of
emissions allowed by the 1994 MACT) indicated that the maximum
individual cancer risk (MIR) associated with this source category is
100-in-a-million with an annual cancer incidence of 0.55.  This is as
compared to the 200-in-a-million MIR and 0.40 annual cancer incidence
level that we presented at proposal, which was based on the 1999 NEI
database.  We consider both MIR values to be acceptable levels of
maximum individual risk considering the number of people exposed at
these levels and the absence of other adverse human and environmental
health effects.  We note that the MIR of 100-in-a-million  (calculated
using the 2002 NEI data) is the same regardless of the URE for PCE
chosen for the risk analysis (i.e., the CalEPA value or the OPPTS value,