[Federal Register: December 12, 2007 (Volume 72, Number 238)]
[Proposed Rules]
[Page 70543-70558]
[DOCID:fr12de07-13]

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2007-0211; FRL-8505-1]
RIN 2060-AO16

National Emission Standards for Hazardous Air Pollutant
Emissions: Group I Polymers and Resins (Polysulfide Rubber Production,
Ethylene Propylene Rubber Production, Butyl Rubber Production, Neoprene
Production); National Emission Standards for Hazardous Air Pollutants
for Epoxy Resins Production and Non-Nylon Polyamides Production;
National Emission Standards for Hazardous Air Pollutants for Source
Categories: Generic Maximum Achievable Control Technology Standards
(Acetal Resins Production and Hydrogen Fluoride Production)

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: This proposed rule requests public comment on the residual
risk and technology reviews for eight industrial source categories
regulated by four national emission standards for hazardous air
pollutants (HAP). The eight industrial source categories and the four
national emission standards are listed in Table 3 of this preamble. The
underlying national emission standards that are under review in this
action limit and control HAP.
    We are proposing that no revisions to the national emission
standards regulating the eight source categories listed in Table 3 of
this preamble are required at this time under section 112(f)(2) or
112(d)(6) of the Clean Air Act.

DATES: Comments. Comments must be received on or before February 11,
2008.
    Public Hearing. If anyone contacts EPA requesting to speak at a
public hearing by December 27, 2007, a public hearing will be held on
January 11, 2008.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2007-0211, by one of the following methods:
     http://www.regulations.gov. Follow the on-line instructions for

submitting comments.
     E-mail<EMAIL_ADDRESS>     Fax:<PHONE_NUMBER>.
     Mail: U.S. Postal Service, send comments to: EPA Docket
Center (2822T), Docket ID No. EPA-HQ-OAR-2007-0211, 1200 Pennsylvania
Avenue, NW., Washington, DC 20460. Please include a total of two
copies.
     Hand Delivery: In person or by courier, deliver comments
to: EPA Docket Center (2822T), EPA West Building, Room 3334, 1301
Constitution Ave., NW., Washington, DC 20004. Such deliveries are only
accepted during the Docket's normal hours of operation, and special
arrangements should be made for deliveries of boxed information. Please
include a total of two copies.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2007-0211. If commenting on the data in the Risk and Technology Review
(RTR) database, please format your comments as described in section III
and IV of this preamble. EPA's policy is that all comments received
will be included in the public docket without change and may be made
available online at http://www.regulations.gov, including any personal

information provided, unless the comment includes information claimed
to be confidential business information (CBI) or other information
whose disclosure is restricted by statute. Do not submit information
that you consider to be CBI or otherwise protected through
http://www.regulations.gov or e-mail. The www.regulations.gov Web site is an

``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA without
going through http://www.regulations.gov, your e-mail address will be

automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. For additional information about EPA's public
docket visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm
.

    Docket: All documents in the docket are listed in the
http://www.regulations.gov index. Although listed in the index, some

information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the EPA Docket Center, Docket

ID No. EPA-HQ-OAR-2007-0211, EPA West Building, Room 3334, 1301
Constitution Avenue, NW., Washington, DC. The Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the EPA Docket Center is
(202) 566-1742.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Ms. Mary Tom Kissell, Office of Air Quality Planning
and Standards, Sector Policies and Programs Division, Coatings and
Chemicals Group (E143-01), U.S. Environmental Protection Agency,
Research Triangle Park, NC 27711; telephone number:<PHONE_NUMBER>; fax
number:<PHONE_NUMBER>; and e-mail address<EMAIL_ADDRESS>For
specific information regarding the modeling methodology, contact Ms.
Elaine Manning, Office and Air Quality Planning and Standards, Health
and Environmental Impacts Division, Sector Based Assessment Group
(C539-02), U.S. Environmental Protection Agency, Research Triangle
Park, NC 27711; telephone number:<PHONE_NUMBER>; fax number: (919)
541-0840; and e-mail address<EMAIL_ADDRESS>For information
about the applicability of these four national emission standards for
hazardous air pollutants (NESHAP) to a particular entity, contact the
appropriate person listed in Table 1 to this preamble.

Table 1.--List of EPA Contacts for Group I Polymers and Resins, Group II
  Polymers and Resins, Acetal Resins Production, and Hydrogen Fluoride
                               Production
------------------------------------------------------------------------
         NESHAP for:            OECA Contact \1\      OAQPS Contact \2\
------------------------------------------------------------------------
Polymers and Resins, Group I  Scott Throwe (202)    David Markwordt
                               564-7013,<PHONE_NUMBER>,
<EMAIL_ADDRESS> markwordt.david@epa

                               v.                    .gov.

Polymers and Resins, Group    Scott Throwe (202)    Randy McDonald (919)
 II.                           564-7013,             541-5402,
<EMAIL_ADDRESS>mcdonald.randy@epa.

                               v.                    ov.
Acetal Resins Production....  Marcia Mia (202) 564- David Markwordt
                               7042,<PHONE_NUMBER>,
<EMAIL_ADDRESS><EMAIL_ADDRESS>
                                                     gov.
Hydrogen Fluoride Production  Marcia Mia (202) 564- Bill Neuffer (919)
                               7042,                 541-5435,
<EMAIL_ADDRESS><EMAIL_ADDRESS>
                                                     v.
------------------------------------------------------------------------
\1\ OECA stands for the EPA's Office of Enforcement and Compliance
  Assurance.
\2\ OAQPS stands for EPA's Office of Air Quality Planning and Standards.

SUPPLEMENTARY INFORMATION: Regulated Entities. The eight regulated
industrial source categories that are the subject of today's proposal
are listed in Table 2 to this preamble. Table 2 is not intended to be
exhaustive, but rather provides a guide for readers regarding entities
likely to be affected by the proposed action for the source categories
listed. These standards, and any changes considered in this rulemaking,
would be directly applicable to sources as a Federal program. Thus,
Federal, State, local, and tribal government entities are not affected
by this proposed rule. The regulated categories affected by this action
include:

         Table 2.--NESHAP for Eight Industrial Source Categories
------------------------------------------------------------------------
                Category                  NAICS \1\ Code   MACT \2\ Code
------------------------------------------------------------------------
Butyl Rubber Production.................          325212            1307
Ethylene-Propylene Rubber Production....          325212            1313
Polysulfide Rubber Production...........          325212            1332
Neoprene Production.....................          325212            1320
Epoxy Resins Production.................          325211            1312
Non-nylon Polyamides Production.........          325211            1322
Acetal Resins Production................          325211            1301
Hydrogen Fluoride Production............          325120            1409
------------------------------------------------------------------------
\1\ North American Industry Classification System.
\2\ Maximum Achievable Control Technology.

    To determine whether your facility would be affected, you should
examine the applicability criteria in the appropriate NESHAP. If you
have any questions regarding the applicability of any of these NESHAP,
please contact the appropriate person listed in Table 1 of this
preamble in the preceding FOR FURTHER INFORMATION CONTACT section.
    Submitting Comments/CBI. Direct your comments to Docket ID No. EPA-
HQ-OAR-2007-0211. If commenting on changes to the RTR database, please
submit your comments in the format described in sections III and IV of
this preamble. Do not submit CBI to EPA through http://www.regulations.gov or

e-mail. Instead, send or deliver information identified as CBI only to
the following address: Mr. Roberto Morales, OAQPS Document Control
Officer (C404-02), U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park, NC 27711,
Attention Docket ID No. EPA-HQ-OAR-2007-0211. Clearly mark the part or
all of the information that you claim to be CBI. For CBI information on
a disk or CD-ROM that you mail to Mr. Morales, mark the outside of the
disk or CD-ROM as CBI and then identify electronically within the disk
or CD-ROM the specific information that is claimed as CBI.
    In addition to one complete version of the comment that includes
information claimed as CBI, a copy of the comment that does not contain
the information claimed as CBI must be submitted for inclusion in the
public docket. If you submit a CD-ROM or disc that does not contain
CBI, mark the outside of the disk or CD-ROM clearly that it does not
contain CBI. Information not marked as CBI will be included in the
public docket and EPA's electronic public docket without prior notice.
    If you have any questions about CBI or the procedures for claiming
CBI, please consult the person identified in the FOR FURTHER
INFORMATION CONTACT section. Information marked as CBI will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.
    Worldwide Web (WWW). In addition to being available in the docket,
an electronic copy of today's proposed action will also be available on
the WWW through the Technology Transfer Network (TTN). Following
signature, a copy of the proposed action will be posted on the TTN(s
policy and guidance page for newly proposed or promulgated rules at the
following address: http://www.epa.gov/ttn/oarpg/. The TTN provides

information and technology exchange in various areas of air pollution
control.
    As discussed in more detail in sections III and IV of this
preamble, additional information is available on the Risk and
Technology Review Phase II webpage at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html.
 This information includes source category descriptions and

detailed emissions and other data that were used as inputs to the risk
assessments.
    Public Hearing. If a public hearing is held, it will begin at 10
a.m. and will be held at EPA's campus in Research Triangle Park, North
Carolina, or at an alternate facility nearby. Persons interested in
presenting oral testimony or inquiring as to whether a public hearing
is to be held should contact Ms. Mary Tom Kissell, Office of Air
Quality Planning and Standards, Sector Policies and Programs Division,
Coatings and Chemicals Group (E143-01), U.S. Environmental Protection
Agency, Research Triangle Park, NC 27711; telephone number: (919) 541-
4516.
    Outline. The information presented in this preamble is organized as
follows:

I. Background

    A. What is the statutory authority for this action?
    B. Overview of the Four NESHAP
    C. How did we estimate risk posed by the eight source
categories?
    D. What are the conclusions of the risk review?
    E. What are the conclusions of the technology review?
II. Proposed Action
III. How do I access and review the facility-specific data?
IV. How do I submit suggested data corrections?
V. Statutory and Executive Order Reviews
    A. Executive Order 12866, Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132, Federalism
    F. Executive Order 13175, Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045, Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211, Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898, Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. Background

A. What is the statutory authority for this action?

    Section 112 of the Clean Air Act (CAA) establishes a comprehensive
regulatory process to address emissions of hazardous air pollutants
(HAP) from stationary sources. In accordance with CAA section 112(c),
EPA identifies categories and subcategories of major sources that emit
one or more of the HAP listed in CAA section 112(b). CAA section 112(d)
then calls for EPA to promulgate national technology-based emission
standards for each listed category or subcategory of sources. For
``major sources'' that emit or have the potential to emit any single
HAP at a rate of 10 tons or more per year or any combination of HAP at
a rate of 25 tons or more per year, these technology-based standards
must reflect the maximum reductions of HAP achievable (after
considering cost, energy requirements, and non-air health and
environmental impacts) and are commonly referred to as maximum
achievable control technology (MACT) standards. The source categories
listed in Table 3 to this preamble are eight source categories for
which we have promulgated MACT standards.
    In what we refer to as the technology review, CAA section 112(d)(6)
then requires EPA to review the CAA section 112(d) 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. If we conclude a revision is
necessary, we must revise the standards.
    The residual risk review is described in section 112(f) of the CAA.
CAA section 112(f)(2) requires us to promulgate standards for each
category or subcategory of CAA section 112(d) sources ``if promulgation
of such standards is required in order to provide an ample margin of
safety to protect public health * * * or to prevent, taking into
consideration costs, energy, safety, and other relevant factors, an
adverse environmental effect.\1\ If standards promulgated pursuant to
CAA section 112(d) and applicable to a category or subcategory of
source emitting a pollutant (or pollutants) 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, the
Administrator shall promulgate standards under this subsection'' for
the source category (or subcategory). EPA's framework for making ample
margin of safety determinations under CAA section 112(f)(2) is provided
in the Benzene NESHAP (54 FR 38044, September 14, 1989) and was
codified by Congress in CAA section 112(f)(2)(B).
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    \1\ Adverse environmental effect is defined in CAA section
112(a)(7) as any significant and widespread adverse effect, which
may reasonably be anticipated, to wildlife, aquatic life, or other
natural resources, including adverse impacts on populations of
endangered or threatened species or significant degradation of
environmental quality over broad areas.
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B. Overview of the Four NESHAP

    The eight industrial source categories and four NESHAP that are the
subject of today's proposal are listed in Table 3 to this preamble.
NESHAP limit and control HAP that are known or suspected to cause
cancer or have other serious human health or environmental effects. The
NESHAP for these eight source categories generally required
implementation of technologies such as steam strippers and
incineration.

    Table 3.--List of National Emission Standards for Hazardous Air Pollutants (NESHAP) and Industrial Source
                                     Categories Affected by Today's Proposal
----------------------------------------------------------------------------------------------------------------
                                    Source categories
         Title of NESHAP           affected by today's    Promulgated rule     Compliance     NESHAP as referred
                                         proposal            reference            date       to in this preamble
----------------------------------------------------------------------------------------------------------------
NESHAP for Group I Polymers and    Polysulfide Rubber   61 FR 46905 (09/05/      07/31/1997  Polymers and Resins
 Resins\1\.                         Production.          1996).                               I.
                                   Ethylene Propylene
                                    Rubber Production.
                                   Butyl Rubber
                                    Production.
                                   Neoprene Production
NESHAP for Epoxy Resins            Epoxy Resins         60 FR 12670 (03/08/      03/03/1998  Polymers and Resins
 Production and Non-nylon           Production.          1995).                               II.
 Polyamides Production.            Non-nylon
                                    Polyamides
                                    Production..
NESHAP for GMACT\2\..............  Acetal Resins        64 FR 34853 (06/29/      06/29/2002  GMACT.
                                    Production.          1999).
                                   Hydrogen Fluoride
                                    Production..
----------------------------------------------------------------------------------------------------------------
\1\ The Polymers and Resins I NESHAP regulates nine source categories. We are performing the residual risk and
  technology review for four of them in this proposal. We will address the remaining five source categories in a
  separate risk and technology review rulemaking.
\2\ The source categories subject to the standards in the GMACT NESHAP are Acetal Resins Production and Hydrogen
  Fluoride Production.

1. Polymers and Resins I
    The Polymers and Resins I NESHAP applies to major sources and
regulates HAP emissions from nine source categories. In today's
proposal, we address four of the Polymer and Resins I sources
categories--Polysulfide Rubber Production, Ethylene Propylene Rubber
Production, Butyl Rubber Production, and Neoprene Production. HAP
emissions from these processes can be released from storage tanks,
process vents, equipment leaks, and wastewater operations.
    These four source categories involve the production of elastomers
(i.e., synthetic rubber). An elastomer is a synthetic polymeric
material that can stretch at least twice its original length and then
return rapidly to approximately its original length when released.
Elastomers have long, flexible, chainlike molecules that are able to
undergo rapid rotation (i.e., flex) as a result of thermal agitation.
Elastomers are produced via a polymerization process, in which monomers
undergo intermolecular chemical bonds to form an insoluble, three-
dimensional network (i.e., a polymer). Generally, the production of
elastomers entails four processes: (1) Raw material (i.e., solvent)
storage and refining; (2) polymer formation in a reactor (either via
the solution process, where monomers are dissolved in an organic
solvent, or the emulsion process, where monomers are dispersed in water
using a soap solution); (3) stripping and material recovery; and (4)
finishing (i.e., blending, aging, coagulation, washing, and drying
processes).
    a. Polysulfide Rubber Production. Polysulfide rubber is a synthetic
rubber produced by the reaction of sodium sulfide and p-dichlorobenzene
(1,4-dichlorobenzene) at an elevated temperature in a polar solvent.
Polysulfide rubber is resilient, resistant to solvents, and has low
temperature flexibility, facilitating its use in seals, caulks,
automotive parts, rubber molds for casting sculpture, and other
products.
    During the development of the NESHAP, we identified one polysulfide
rubber production facility as a major source and subject to the
Polymers and Resins I NESHAP. This facility consisted of raw material
storage vessels and was designated as a major source because it was co-
located with another source. This polysulfide facility has been
dismantled and we are not aware of any other facilities currently
subject to the NESHAP. (Even though no polysulfide rubber facilities
are currently in operation, we completed a risk analysis based on the
available information on this facility as of 2002.) The only HAP
reported for this category in the 2002 National Emissions Inventory
(NEI) was methylene diphenyl diisocyanate.
    b. Ethylene Propylene Rubber Production. Ethylene propylene
elastomer is an elastomer prepared from ethylene and propylene
monomers. Common uses for these elastomers include radiator and heater
hoses, weather stripping, door and window seals for cars, construction
plastics blending, wire and cable insulation and jackets, and single-
ply roofing membranes.
    We believe five ethylene propylene rubber production facilities are
currently subject to the Polymers and Resins I NESHAP. Hexane, which is
the HAP used as the solvent at three of the plants, accounts for the
majority of the HAP emissions from these facilities (over 95 percent of
the total HAP emissions by mass). These facilities also reported
relatively small emissions of ethyl chloride, ethylene glycol, and
hydrogen chloride. Two facilities do not use hexane in their processes.
One facility uses toluene instead of hexane as a solvent and the other
facility uses a gas-phase process where methanol is the only HAP
emitted.
    c. Butyl Rubber Production. The Butyl Rubber Production source
category includes any facility that manufactures copolymers of
isobutylene and isoprene. Butyl rubber is very impermeable to common
gases and resists oxidation. A specialty group of butyl rubbers are
halogenated butyl rubbers, which are produced commercially by
dissolving butyl rubber in hydrocarbon solvent and contacting the
solution with gaseous or liquid elemental halogens such as chlorine or
bromine. Halogenated butyl rubber resists aging to a higher degree than
the nonhalogenated type and is more compatible with other types of
rubber. Uses for butyl rubber include tires, tubes, and tire products;
automotive mechanical goods; adhesives, caulks, and sealants; and
pharmaceutical uses.
    We believe two butyl rubber production facilities are currently
subject to the Polymers and Resins I NESHAP. The primary HAP emitted
from butyl rubber production facilities are methyl chloride (53 percent
of the total HAP emissions by mass) and hydrochloric acid (34 percent).
Hexane is also emitted from the production of halobutyl rubber, and it
makes up around 13 percent of the total HAP emissions from the
category.
    d. Neoprene Production. Neoprene is a polymer of chloroprene.
Neoprene was originally developed as an oil-resistant substitute for
natural rubber, and its properties allow its use in a wide variety of
applications including wetsuits, gaskets and seals, hoses and tubing,
plumbing fixtures, adhesives, and other products.
    We believe that one neoprene production facility is currently
subject to the Polymers and Resins I NESHAP. The primary HAP emitted by
production are chloroprene and toluene, with chloroprene accounting for
over 80 percent of the total emissions.
2. Polymers and Resins II
    The Polymers and Resins II NESHAP applies to major sources and
regulates HAP emissions from two source categories--epoxy resins
production and non-nylon polyamides production. HAP emissions from
these source categories can be released from storage tanks, process
vents, equipment leaks, and wastewater operations.
    a. Epoxy Resins Production. The Epoxy Resins Production source
category generates HAP emissions from the manufacture of basic liquid
epoxy resins used in the production of glues, adhesives, plastic parts,
and surface coatings. This source category does not include specialty
or modified epoxy resins.
    We believe three epoxy resins production facilities are currently
subject to the Polymers and Resins II NESHAP. The HAP emitted in the
greatest quantity by mass from these facilities are epichlorohydrin
(referred to by its synonym 1-chloro-2,3-epoxypropane in the NEI and in
the accompanying emissions summary table) and chlorobenzene. The total
emissions for these two HAP account for approximately 87 percent of the
total HAP mass emitted by the facilities regulated by the NESHAP.
Epichlorohydrin is emitted in the greatest quantity and is reported as
an emission of all three facilities. Other HAP such as phenol, xylenes,
ethyl benzene, propylene dichloride, allyl chloride, 1,3-
dichloropropene, glycol ethers, methyl chloride, toluene, acrolein,
benzyl chloride, and ethyl acrylate are emitted in smaller quantities.
All the other HAP are reported as emissions by only one or two of the
facilities.
    b. Non-nylon Polyamides Production. The Non-nylon Polyamides
Production source category generates HAP emissions from the manufacture
of epichlorohydrin cross-linked non-nylon polyamides used primarily by
the paper industry as an additive to paper products. Natural polymers,
such as those contained in paper products, have

little cross-linking, which allows their fibers to change position or
separate completely when in contact with water. The addition of
epichlorohydrin cross-linked non-nylon polyamides to these polymers
causes the formation of a stable polymeric web among the natural
fibers. Because the polymeric web holds the fibers in place even in the
presence of water, epichlorohydrin cross-linked non-nylon polyamides
are also referred to as wet-strength resins.
    We believe four non-nylon polyamides production facilities are
currently subject to the Polymers and Resins II NESHAP. Epichlorohydrin
(64 percent) and hydrochloric acid (36 percent) are the only HAP
emitted from this category.
3. GMACT--Acetal Resins Production
    The GMACT set national emission standards for certain source
categories consisting of five or fewer facilities. The basic purpose of
the GMACT approach was to use public and private sector resources
efficiently, and to promote regulatory consistency and predictability
in the MACT standards development.
    Emission sources from acetal resin production include storage
vessels that hold process feed materials, process vents, process
wastewater treatment systems, and equipment leaks from compressors,
agitators, pressure relief devices, sampling connection systems,
valves, connectors, and instrumentation systems. The storage vessels
associated with acetal resin production are primarily used for storage
of solvents. Back end process vent emissions occur from reactor units,
mixing vessels, solvent recovery operations, and other operations.
    Acetal resins are characterized by the use of formaldehyde in the
polymerization process to manufacture homopolymers or copolymers of
alternating oxymethylene units. Acetal resins, also known as
polyoxymethylenes, polyacetals, or aldehyde resins, are a type of
plastic possessing relatively high strength and rigidity without being
brittle. They have good frictional properties and are resistant to
moisture, heat, fatigue, and solvents. Acetal resins are used as parts
in a variety of industrial applications, e.g., gears, bearings,
bushings, and various other moving parts in appliances and machines,
and in a range of consumer products, e.g., automotive door handles,
seat belt components, plumbing fixtures, shaver cartridges, zippers,
and gas tank caps.
    We believe three facilities are currently subject to the acetal
resins production provisions in the GMACT. The primary HAP emitted by
acetal resin production are formaldehyde and methanol, which make up 92
percent of the total HAP emissions by mass.
4. GMACT--Hydrogen Fluoride Production
    The Hydrogen Fluoride Production source category includes any
facility engaged in the production and recovery of hydrogen fluoride by
reacting calcium fluoride with sulfuric acid. Potential sources of HAP
emissions at hydrogen fluoride production facilities include: Process
vents on hydrogen fluoride recovery and refining equipment, storage
vessels used to store hydrogen fluoride, bulk loading of tank trucks
and tank rail cars, leaks from hydrogen fluoride handling equipment,
and reaction kiln seal leaks. The only HAP emitted from the processes
in this source category is hydrogen fluoride. We believe two facilities
are currently subject to the hydrogen fluoride production provisions in
the GMACT.

C. How did we estimate risk posed by the eight source categories?

    To support the proposed decisions presented in today's notice, EPA
conducted an inhalation risk assessment \2\ that provided estimates of
maximum individual cancer risk, cancer risk distribution within the
exposed populations, cancer incidence, hazard indices for chronic
exposures to HAP with non-cancer health effects, and hazard quotients
(HQ) for acute exposures to HAP with non-cancer health effects. The
risk assessment consisted of six primary activities: (1) Establishing
the nature and magnitude of emissions from the sources of interest, (2)
identifying the emissions release characteristics (e.g., stack
parameters), (3) conducting dispersion modeling to estimate the
concentrations of HAP in ambient air, (4) estimating long-term and
short-term inhalation exposures to individuals residing within 50 km of
the modeled sources, (5) estimating individual and population-level
risks using the exposure estimates and quantitative dose-response
information, and (6) characterizing risk. In general the risk
assessment followed a tiered, iterative approach, beginning with a
conservative screening-level analysis and, where the screening analysis
indicated the potential for non-negligible risks, following that with
more refined analyses. The following sections summarize the results of
these efforts.
---------------------------------------------------------------------------

    \2\ For more information on the risk assessment inputs and
models, see ``Residual Risk Assessment for Eight Source
Categories,'' available in the docket.
---------------------------------------------------------------------------

1. Emissions Data
    For the Ethylene Propylene Rubber Production, Butyl Rubber
Production, Neoprene Production, Epoxy Resins Production, and Non-nylon
Polyamides Production source categories, we relied primarily on
emissions data and emissions release characteristic data we collected
directly from industry. We reviewed these data and consider them to be
the best emissions and emissions release characteristic data available
for these five source categories.
    For the remaining three source categories, Polysulfide Rubber
Production, Acetal Resins Production, and Hydrogen Fluoride Production,
we relied primarily on data in the 2002 NEI Final Inventory,\3\ Version
1 (made publicly available on February 26, 2006). For the Polysulfide
Rubber source category, the data in the 2002 NEI were used without
further investigation because the only facility in the source category
closed in 2002. For the Acetal Resins and Hydrogen Fluoride source
categories, the 2002 NEI data were supplemented with information from
industry and, for one hydrogen fluoride facility, with information from
the State permitting agency.
---------------------------------------------------------------------------

    \3\ The National Emission Inventory (NEI) is a database that
contains information about sources that emit criteria air pollutants
and their precursors, and HAP. The database includes estimates of
annual air pollutant emissions from point, nonpoint, and mobile
sources in the 50 States, the District of Columbia, Puerto Rico, and
the Virgin Islands. EPA collects this information and releases an
updated version of the NEI database every 3 years.
---------------------------------------------------------------------------

    In response to an advanced notice of proposed rulemaking \4\ we
published on March 29, 2007, we received comments on emissions data and
emissions release characteristics data for an acetal resins production
facility, two ethylene propylene production facilities, and a neoprene
production facility. We will include these comments in the docket for
this proposal (docket ID EPA-HQ-OAR-2007-0211) and will evaluate them
with other comments we receive in response to today's proposal. The
data files for the eight source categories, which are posted on the RTR
webpage and are described in Section III of this preamble, will include
the new data provided by the commenters.
---------------------------------------------------------------------------

    \4\ Risk and Technology Review, Phase II, Group 2 at 72 FR
29287.
---------------------------------------------------------------------------

    Emissions data and emissions release characteristics data for these
eight source categories are documented in the docket in ``Documentation
of Emissions Data and Emissions Release

Characteristics Data Used for the RTR Group 1.'' We specifically
request comment on whether the facilities listed in our emissions data
set accurately reflect the universe of sources within the source
categories. For example, are there records remaining in the data set
that are not part of the relevant source category or any missing
emissions data that should be included for the relevant source
category?
2. Risk Assessment
    Both long-term and short-term inhalation exposure concentrations
and health risk from each of the eight source categories addressed in
today's proposal were estimated using the Human Exposure Model
(Community and Sector HEM-3 version 1.1.0). The HEM-3 model performs
three main operations: Dispersion modeling, estimation of population
exposure, and estimation of human health risks. The dispersion model
used by HEM-3 is AERMOD, which is one of EPA's preferred models for
assessing pollutant concentrations from industrial facilities.\5\
---------------------------------------------------------------------------

    \5\ Environmental Protection Agency. Revision to the Guideline
on Air Quality Models: Adoption of a Preferred General Purpose (Flat
and Complex Terrain) Dispersion Model and Other Revisions (70 FR
68218). November 9, 2005.
---------------------------------------------------------------------------

    To perform the dispersion modeling and to develop the preliminary
risk estimates, HEM-3 draws on three data libraries. The first is a
library of meteorological data, which are used for dispersion
calculations. This library includes 1 year of hourly surface and upper
air observations for 130 meteorological stations, selected to provide
thorough coverage of the U.S. and Puerto Rico. A second library of U.S.
Census Bureau census block internal point locations and populations
provides the basis of human exposure calculations (Census, 2000). In
addition, the census library includes the elevation and controlling
hill height for each census block, which are also used in dispersion
calculations. A third library of pollutant unit risk factors and other
health benchmarks is used to estimate health risks. These risk factors
and health benchmarks are the latest values recommended by EPA for HAP
and other toxic air pollutants, and are discussed in more detail below.
These values are available at http://www.epa.gov/ttn/atw/toxsource/summary.html
.

    The risk assessment for chronic exposures used the estimated annual
average ambient air concentration of each HAP emitted by each source
for which we have emissions data in the source category at each nearby
census block \6\ centroid as a surrogate for the chronic inhalation
exposure concentration for all the people who reside in that census
block. We calculated the maximum individual risk for each facility as
the risk associated with a lifetime (70-year) exposure to the maximum
concentration at the centroid of an inhabited census block. Individual
cancer risks were calculated as the lifetime exposure to the ambient
concentration of each HAP multiplied by its Unit Risk Estimate (URE);
total cancer risks were the sum of the risks of each carcinogenic HAP
(including known, probable, and possible carcinogens) emitted by the
modeled source. Air concentrations of HAP from sources other than the
modeled source were not estimated. Total cancer incidence and the
distribution of individual cancer risks across the population within 50
kilometers of any source were also estimated as part of these
assessments by summing individual risks. We are using 50 kilometers to
be consistent with both the analysis supporting the 1989 Benzene NESHAP
(54 FR 38044) and the limitations of Gaussian dispersion modeling.
---------------------------------------------------------------------------

    \6\ A typical census block is comprised of approximately 40
people or about 10 households.
---------------------------------------------------------------------------

    To assess risk of noncancer health effects from chronic exposures,
we summed the HQ for each HAP that affects a common target organ system
to obtain the hazard index (HI) for that target organ system (or target
organ-specific hazard index, TOSHI), where the HQ is the estimated
exposure divided by the chronic reference level (e.g., the U.S. EPA
Reference Concentration (RfC) which is provided through the Integrated
Risk Information System (IRIS)).
    Health protective screening estimates of acute exposures and risks
were also evaluated for each HAP at any location off-site of each
facility (i.e., not just the census block centroids) assuming the
combination of a peak (hourly) emission rate and hourly dispersion
conditions for the 1991 calendar year that would tend to maximize
exposure. In each case, acute HQ were calculated using best available
short-term health indices. We assumed that 10 times the average annual
hourly emission rate represented a health protective emissions estimate
to evaluate acute exposures and risks for these initial screens. The
factor of 10 is intended to cover routinely variable emissions and
startup, shutdown, and malfunction emissions. We chose to use a factor
of 10 based on: (1) Engineering judgment, and (2) a review of short-
term emissions data that compared hourly and annual emissions data for
volatile organic compounds for all facilities in a heavily-
industrialized 4-county area (Harris, Galveston, Chambers, and Brazoria
Counties, TX) over an 11-month time period in 2001.\7\ Most peak
emission events were less than twice the annual average hourly emission
rate and the highest peak emission event was 8.5 times the annual
average hourly emission rate. We request comment on the interpretation
of these data and the appropriateness of using a factor of 10 times the
average annual hourly emission rate in these acute exposure screening
assessments.
---------------------------------------------------------------------------

    \7\ See http://www.tceq.state.tx.us/compliance/field_ops/eer/index.html
 or docket to access the source of these data.

---------------------------------------------------------------------------

    In cases where acute HQ values from the screening step were less
than or equal to one, acute impacts were deemed negligible and no
further analysis was performed. In the cases where an acute HQ from the
screening step was greater than one, site-specific data were sought to
develop a more refined estimate of the potential for acute impacts of
concern. These data refinements included using a better representation
of the peak-to-mean hourly emissions ratio (instead of using the
default factor of 10) and using the site-specific facility layout to
distinguish facility property from an area where the public could be
exposed. The screening analysis resulted in an HQ less than or equal to
one for all of the source categories except Acetal Resins Production
and Hydrogen Fluoride Production. The specific refinements used for
acetal resins production and hydrogen fluoride production are described
in the results section for the two source categories.
    We engaged in a consultation with a panel from the Science Advisory
Board (SAB) on the ``Risk and Technology Review (RTR) Assessment Plan''
in December of 2006. The results of this consultation were transmitted
to us in June 2007 in a letter from the SAB which also contained a
summary listing of the key messages from the panel. The letter is
available from the docket and from http://www.epa.gov/sab/pdf/sab-07-003_response_04-20-07.pdf.
 In developing the risk assessments for the

eight source categories covered by this proposal, we followed the RTR
Assessment Plan, addressing the key recommendations from the panel,
where appropriate and relevant to these assessments, but not the
individual recommendations from each panel member. Our responses to
each of the SAB's key recommendations are summarized in an appendix to
the

``Residual Risk Assessment for Eight Source Categories,'' available in
the docket.
3. Noncancer Inhalation Reference Values
    The most appropriate noncancer inhalation reference values for
chronic durations in the Residual Risk Program are in order of
preference: (1) The RfC which is provided through the IRIS; (2) the
Agency for Toxic Substances and Disease Registry Chronic Minimal Risk
Levels; or (3) California Office of Environment and Human Health
Assessment's chronic Reference Exposure Level (REL).
    No such hierarchy was developed for acute noncancer reference
values. Instead, we use acute inhalation values from multiple sources
because the various assessments are based on methods that are different
enough to render them not directly comparable, nor does any one set of
reference values provide coverage across the majority of chemicals. We
looked to reference values developed for other purposes, such as
Reference Exposure Levels (REL), Acute Exposure Guideline Levels
(AEGLs), and Emergency Response Planning Guideline (ERPGs).
    The acute REL (http://www.oehha.ca.gov/air/pdf/acuterel.pdf) is

defined as the concentration level at or below which no adverse health
effects are anticipated for a specified exposure duration. The REL
incorporates factors to address data gaps, uncertainty, and to protect
the most sensitive individuals in the population, and exceeding the REL
does not automatically indicate an adverse health impact.
    The AEGL-1 is ``the airborne concentration (expressed as ppm or mg/
m\3\) of a substance above which it is predicted that the general
population, including susceptible individuals, could experience notable
discomfort, irritation, or certain asymptomatic nonsensory effects.''
The AEGL values are designed to be applicable to the general
population, including sensitive subgroups; however, as stated in the
AEGL guidelines and the definitions, ``it is recognized that certain
individuals, subject to unique and idiosyncratic responses, could
experience effects at concentrations below the corresponding AEGL.''
The National Research Council states that ``[t]he primary purpose of
the AEGL program and the NAC/AEGL Committee is to develop guideline
levels for once-in-a-lifetime, short-term exposures to airborne
concentrations of acutely toxic, high-priority chemicals.'' \8\
---------------------------------------------------------------------------

    \8\ See Standing Operating Procedures for Developing Acute
Exposure Guideline Levels for Hazardous Chemicals (2001, National
Academies Press, Washington, DC, page 21, PURPOSE AND OBJECTIVES OF
THE AEGL PROGRAM AND THE NAC/AEGL COMMITTEE; http://books.nap.edu/openbook.php?record_id=10122&page=21
).

---------------------------------------------------------------------------

    The ERPG-1, developed specifically for emergency response
situations, is the maximum airborne concentration below which it is
believed that nearly all individuals could be exposed for up to 1 hour
without experiencing other than mild transient adverse health effects
or perceiving a clearly defined, objectionable odor. The ERPG
documentation also states that ``in all populations there are
hypersensitive individuals who will show adverse responses at exposure
concentrations far below levels where most individuals normally would
respond.''
    The AEGL and ERPG values include three levels of severity generally
referred to as mild, severe, and lethal. In contrast, the REL
represents an exposure at which no adverse effects are expected. For
many chemicals (e.g., ethylene oxide and phosgene) the available
information does not allow development of a mild effect AEGL or ERPG.
AEGL and ERPG values are usually established at higher exposure levels
than Acute California REL reference values. Exceedances of REL, AEGL,
or ERPG values in the context of a residual risk assessment should be
interpreted on a case-by-case basis.
4. Consideration of Actual and Allowable Emissions
    Generally, the emissions values in our data set represent actual
emission levels. We discussed the use of both allowable and actual
emissions in the final Coke Oven Batteries residual risk rule (70 FR
19998-19999, April 15, 2005) and in the proposed and final Hazardous
Organic NESHAP (HON) residual risk rules (71 FR 34428, June 14, 2006,
and 71 FR 76603, December 21, 2006, respectively). In those previous
actions, we noted that modeling the allowable levels of emissions
(i.e., the highest emission levels that could be emitted while still
complying with the MACT requirements) is inherently reasonable since
they reflect the maximum level sources could emit and still comply with
national emission standards. But we also explained that it is
reasonable to consider actual emissions, where such data are available,
in both steps of the Benzene NESHAP analysis. Doing so avoids
overestimating emissions and their associated health risks and accounts
for how sources typically strive to perform better than required by
standards to allow for process variability and to prevent exceeding
standards due to emissions increases on individual days. Failure to
consider these data in risk assessments, we said, would unrealistically
inflate actual risk levels. 71 FR at 76609.
    For the eight source categories addressed in this package, we do
not have information regarding allowable emissions. This is similar to
the circumstance we faced in the HON. In the preamble to the HON
proposed rule, we acknowledged that there is some uncertainty regarding
the difference between actual and allowable emissions. We also
explained in the HON preamble that it was not possible to estimate
allowable emissions for all emission points from the available
information, but that for equipment leaks, which represent the most
significant impact on cancer risk at HON facilities, the actual and
allowable emissions are likely the same. We further concluded that
there was no evidence of substantial overcontrol, such that actual
emissions would not be a reasonable approximation of allowable
emissions, and that there was no evidence that the sources subject to
the HON could make changes that would result in a substantial increase
of emissions, and thus risk, while still complying with the MACT.
Therefore, we concluded for the HON final rule that basing the analysis
on actual emissions provided an acceptable method for determining the
remaining risks to public health and the environment after application
of the MACT standards.
    The production processes for polymers and resins use the same
process equipment and air pollution control equipment as HON processes.
Thus, we believe we can draw the same conclusions for polysulfide
rubber production, ethylene propylene rubber production, butyl rubber
production, neoprene rubber production, epoxy resins production, non-
nylon polyamides production, and acetal resins as we did for the HON--
that estimating risk using actual emissions will reasonably reflect the
risk after application of the relevant MACT standards.
    For the Hydrogen Fluoride Production source category, we expect
actual and allowable emissions to be similar, if not the same. Hydrogen
fluoride facilities employed stringent controls prior to the
development of the MACT standards (we based the MACT standards on these
pre-MACT controls) and we have no

reason to believe control performance will decline.
    We believe the differences between actual and allowable emissions
are likely insignificant for these eight source categories and that
using the actual emission levels results in a reasonable approximation
of the allowable emissions. Therefore, we conclude that the risk
assessment results using actual emissions closely approximate those for
an assessment using allowable emissions and that the difference would
not be likely to substantially affect the estimated risk associated
with exposure to HAP emitted by any of the eight source categories.
Nevertheless, if commenters have data that demonstrate that allowable
emissions could be higher or lower than actual emissions for these
eight source categories we request the submission of this data.
5. Adverse Environmental Effects Assessment
    None of the eight source categories emit persistent or
bioaccumulative HAP; therefore, EPA's assessment of environmental
effects evaluated only non-persistent and non-bioaccumulative HAP.\9\
For animal populations, the potential for significant direct adverse
environmental effects due to non-persistent and non-bioaccumulative HAP
was evaluated implicitly by checking for exceedances of any human
health inhalation dose-response limit values near the assessed
facilities. \10\ Because these values generally reflect the inclusion
of uncertainty factors \11\ (often 100 or 1,000), the human threshold
values are generally believed to be significantly lower than any levels
which have been shown to cause an adverse effect in an exposed animal.
Therefore, if the maximum inhalation hazard in an ecosystem is below
the level of concern for humans, we have concluded that, in general,
environmental receptors should be at little risk of adverse effects due
to airborne exposures.
---------------------------------------------------------------------------

    \9\ Persistent and bioaccumulative HAP are those which persist
in the environment and which also may bioaccumulate or biomagnify in
food chains.
    \10\ While environmental effects thresholds are often available
for HAP in water and soil, very few are available for direct
airborne exposures.
    \11\ The uncertainty factors account for various data
methodological uncertainties, for example, most inhalation dose-
response limit values are derived from studies of laboratory
animals.
---------------------------------------------------------------------------

    One possible exception is pollutants that may directly impact
various species of vegetation. For the seven polymers and resins
production source categories affected by today's proposal, we have no
scientific data, informal observations or other information that would
indicate any concern for adverse environmental effects of HAP on
vegetation at the expected air concentrations.
    For the two facilities in the Hydrogen Fluoride Production source
category (both of which emit hydrogen fluoride), we have some general
information on the possible effects of hydrogen fluoride on vegetation
at ambient concentrations well below the California chronic REL value
of 14 microgram per cubic meter ([mu]g/m\3\). In separate and unrelated
studies, air concentrations of hydrogen fluoride greater than about 1
[mu]g/m\3\ have been shown to adversely affect specific sensitive plant
species. \12\ We note that responses to hydrogen fluoride are highly
variable among plant species and responses may be influenced by co-
exposures to other air pollutants. In this particular case, the maximum
chronic ambient concentration estimated in the vicinity of the hydrogen
fluoride production facilities was about 1.5 [mu]g/m\3\, meaning that
concentrations of hydrogen fluoride in all areas other than the maximum
point are lower than 1.5 [mu]g/m\3\, and perhaps substantially lower as
the distance from the point of release increases. Because the
spatially-averaged hydrogen fluoride concentration within several
kilometers of each facility is likely well below 1 [mu]g/m\3\, we are
led to the conclusion that any significant and widespread adverse
environmental effects on plants due to hydrogen fluoride emissions are
unlikely. Further, we have no information suggesting that there are
currently observed adverse impacts of hydrogen fluoride emissions on
plants surrounding the two facilities.
---------------------------------------------------------------------------

    \12\ 1 [mu]g/m\3\ was the lowest concentration for which adverse
effects were observed in the most sensitive flora for which data
exists. We note that the studies were limited to certain species and
1 [mu]g/m\3\ cannot be interpreted as an appropriate or definitive
concentration level for all plant species. (See ``List of References
for Effects of Hydrogen Fluoride on Vegetation'' in docket.)
---------------------------------------------------------------------------

6. Uncertainties in Risk Assessments
    Uncertainty and the potential for bias are inherent in all risk
assessments, including those performed for the eight source categories
affected by today's proposal. We reduced some of these uncertainties by
developing a new emissions data set, the RTR database, that is based on
the NEI, but that includes more accurate replacement or supplemental
data for the specific facilities in these eight source categories.
    Although uncertainty exists, we believe the risk assessments
performed for the eight source categories most likely overestimate the
potential for risks due to the conservative (i.e., health-protective)
assessment approach. Because these health protective risk assessments
indicate little, if any, potential for significant risk, we believe
they support our proposed decision not to issue residual risk standards
for these eight source categories. A brief discussion of the
uncertainties in the emissions data set, dispersion modeling,
inhalation exposure estimates, and dose-response relationships is
presented in this section of the preamble. A fuller discussion of these
uncertainties is discussed in both the ``Residual Risk Assessment for
Eight Source Categories'' (July 2007) and the ``Risk and Technology
Review (RTR) Assessment Plan'' (November 2006), both of which are
available in the docket.
    a. Uncertainties in the RTR Emissions Database. Although the
development of the RTR database involved quality assurance/quality
control processes, the accuracy of emissions values will vary depending
on the source of the data present, incomplete or missing data, errors
in estimating emissions values, and other factors. The emission values
considered in this analysis are annual totals that do not reflect
actual fluctuations during the course of a year (2002) or variations
from year to year. These annual emissions estimates do not consider
operations such as startup/shutdown and malfunctions. The estimates of
health protective short-term emission rates for the screening
assessment were based on a health-protective default assumption
applicable to these source categories (10 times the annual rate). More
refined estimates were used for source categories where the screening
estimates did not ``screen out'' all sources and more specific
information was available.
    Facilities in some of the seven polymers and resins source
categories emit chlorinated compounds and use incineration devices,
creating the possibility for the formation of polychlorinated dioxins.
However, we have no test reports or measurements, conducted by
manufacturers or anyone else, indicating the presence of dioxins in the
emissions from any of these source categories and EPA's dioxins
inventory \13\ does not specifically link

dioxins emissions to any of these source categories. Furthermore, in
our judgment, it is improbable that dioxins are emitted in measurable
amounts from the seven polymers and resins source categories,
especially given the low quantity of particulate matter present.
Therefore, we did not consider dioxins in our assessment of the seven
polymers and resins production source categories. Because no
chlorinated compounds are emitted from the hydrogen fluoride production
source category, we believe there is no possibility for dioxins to be
emitted and we did not consider dioxins in our assessment of the source
category.
---------------------------------------------------------------------------

    \13\ An Inventory of Sources and Environmental Releases of
Dioxin-Like Compounds in the United States for the Years 1987, 1995,
and 2000. (EPA/600/P-03/002f, Final Report, November 2006). The
dioxins inventory (http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=159286
) classifies ``rubber manufacturing'' as

an unquantifiable dioxins emission source. A source was defined as
unquantifiable if dioxins releases were possible, but the data were
inadequate to support even rudimentary calculations of emissions.
Furthermore, the process could be very different from the polymers
and resins processes of concern in this proposal.
---------------------------------------------------------------------------

    Overall we believe that the emissions data considered in this
assessment are the most accurate available representation of the eight
source categories for the stated purpose. Nevertheless, we request
comment on our emissions data set in general, and specifically on our
approach to short-term emissions estimates and on the potential for
dioxins emissions from the facilities in the seven polymers and resins
production source categories affected by today's proposal.
    b. Uncertainties in Dispersion Modeling. While the analysis
employed EPA's suggested regulatory dispersion model, AERMOD, there is
uncertainty in ambient concentration estimates associated with EPA's
choice and application of the model. Where possible, model options
(e.g., rural/urban, plume depletion, chemistry) were selected as to
provide an overestimate of ambient air concentrations. However, because
of practicality and data limitation reasons, some factors (e.g.,
meteorology, building downwash) have the potential in some situations
to overestimate or underestimate ambient impacts. For example,
meteorological data were taken from a single year (1991), and facility
locations can be a significant distance from the site where these data
were taken. Despite these uncertainties, we believe that at off-site
locations and census block centroids, the approach considered in the
dispersion modeling analysis should generally yield overestimates of
ambient concentrations.
    c. Uncertainties in Inhalation Exposure. The effects of human
mobility on exposures were not included in the assessment.
Specifically, short-term mobility and long-term mobility\14\ between
census blocks in the modeling domain was not considered. As a result,
this simplification will likely bias the assessment toward
overestimating the highest exposures. In addition, the assessment
predicted the chronic exposures at the centroid of each populated
census block as surrogates for the exposure concentrations for all
people living in that block. (On average census blocks are populated by
approximately 40 people.) Using the census block centroid to predict
chronic exposures tends to overpredict exposures for people in the
census block who live further from the facility and underpredict
exposures for people in the census block who live closer to the
facility. Thus, in general, using the census block centroid to predict
chronic exposures leads to a potential understatement or overstatement
of maximum impact and an unbiased estimate of average risk and
incidence.
---------------------------------------------------------------------------

    \14\ Short-term mobility is movement from one microenvironment
to another over the course of hours or days. Long-term mobility is
movement from one residence to another over the course of a
lifetime.
---------------------------------------------------------------------------

    The assessments evaluate the cancer inhalation risks associated
with pollutant exposures over a 70-year period, the assumed lifetime of
individuals. In reality, both the length of time that modeled emissions
sources at facilities actually operate (i.e., more or less than 70
years), and the domestic growth or decline of the modeled industry
(i.e., the increase or decrease in the number or size of U.S.
facilities), will influence the risks posed by a given source category.
Depending on the characteristics of the industry, these factors may
result in an overestimate (or possibly an underestimate in the extreme
case where a facility maintains or increases its emission levels beyond
70 years and residents live beyond 70 years at the same location) both
in individual risk levels and in the total estimated number of cancer
cases. Annual cancer incidence estimates from exposures to emissions
from these sources would not be affected by uncertainty in the length
of time emissions sources operate.
    The exposure estimates used in these analyses assume chronic
exposures to ambient levels of pollutants. Because most people spend
the majority of their time indoors, actual exposures may not be the
same, depending on characteristics of the pollutants modeled. For many
HAP, indoor levels are roughly equivalent to ambient levels, but for
very reactive pollutants or larger particles, these levels are
typically lower. This factor has the potential to result in an
overstatement of 25 to 30 percent of exposures.\15\
---------------------------------------------------------------------------

    \15\ National-Scale Air Toxics Assessment for 1996. (EPA 453/R-
01-003; January 2001; page 85.)
---------------------------------------------------------------------------

    In addition to the uncertainties highlighted above, there are
several factors specific to the acute exposure assessment that need to
be highlighted. The accuracy of an acute inhalation exposure assessment
depends on the joint occurrence of independent factors that may vary
greatly, such as hourly emissions rates, meteorology, and human
activity patterns. In this assessment, we assume that individuals
remain for one hour at the point of maximum ambient concentration as
determined by the co-occurrence of peak emissions and worst-case
meteorological conditions. These assumptions would tend to overestimate
actual exposures since it is unlikely that a person would be located at
the point of maximum exposure during the time of worst-case impact.
    d. Uncertainties in Dose-Response Relationships. These assessments
use toxicological dose-response values typically extrapolated from
high-dose animal exposure or occupational exposures, to estimate risk.
Consistent with EPA guidance, RfCs are developed by using order-of-
magnitude factors to account for uncertainties in developing values
protective of sensitive subpopulations. Most of the URE in this
assessment were developed using linear low-dose extrapolation. Risks
could be overestimated if the true dose-response relationship (which is
usually unknown) is sublinear and underestimated when the dose-response
curve is actually superlinear. Impacts have been extrapolated from
short-duration, high-dose animal or occupational exposures to longer
durations and lower doses, using uncertain interspecies scaling
methods. In general, EPA considers these URE's to be upper bound
estimates based on the method of extrapolation, meaning they represent
a plausible upper limit to the true value. (Note that this is usually
not a true statistical confidence limit.) The true risk is therefore
likely to be less, could be as low as zero, but also could be greater.
As previously noted, benzene cancer risks were estimated from the
reported URE range, which is considered to be based on maximum
likelihood exposure and risk estimates.
    Some HAP have no dose-response values for cancer, chronic non-
cancer, and/or acute effects. Therefore, an understatement of risk for
certain HAP at environmental exposure levels is possible if there are
no health effects reference values available on which to

base an assessment of health risk. Additionally, some chronic dose-
response values used in the assessments for these 8 source categories
are currently under EPA IRIS review (e.g., formaldehyde and methanol)
and revised assessments may determine that these HAP are more or less
potent than currently thought. We will consider the outcome of new
assessments and reevaluate residual risk if application of new dose-
response values indicates the potential for unacceptable risks to human
health and/or the environment.
    e. Uncertainties in the Adverse Environmental Effects Assessment.
As previously discussed, we generally believe that when exposure levels
are not anticipated to adversely affect human health, they also are not
anticipated to adversely affect the environment. However, we recognize
that this may not be the case for all HAP. Hydrogen fluoride in the air
has the potential to adversely affect plant tissues, having been
associated with necrosis (lesions) in plants and reduced plant growth
and productivity. Determining the effects of hydrogen fluoride on
vegetation is complicated by the high degree of variability among plant
species in the extent of uptake and response to atmospheric hydrogen
fluoride, and by co-exposure to other atmospheric pollutants, such as
sulfur dioxide, that influences the impacts of hydrogen fluoride. (For
references concerning the effects of hydrogen fluoride on plants, see
docket item ``List of References for Effects of Hydrogen Fluoride on
Vegetation''.)
    EPA requests comment on this issue, including: Submissions of any
data that should be considered; observations, if any, of impacts on
vegetation near the two facilities in the hydrogen fluoride production
source category; and suggestions of how EPA should assess the potential
for adverse environmental effects as defined in CAA section
112(a)(7).\16\
---------------------------------------------------------------------------

    \16\ CAA section 112(a)(7) defines ``adverse environmental
effect'' as meaning ``any significant and widespread adverse effect,
which may reasonably be anticipated, to wildlife, aquatic life, or
other natural resources, including adverse impacts on populations of
endangered or threatened species or significant degradation of
environmental quality over broad areas.
---------------------------------------------------------------------------

D. What are the conclusions of the risk review?

    The human health risks estimated for the eight source categories
are summarized in this section of the preamble. Details of the
assessment are located in the docket, especially see ``How to Reproduce
Modeling of Group 1 Source Categories'' (May 2007). We believe that our
assessment covers all potential health risks associated with HAP
emissions from the eight source categories affected by today's
proposal. We further believe that the reported emissions are consistent
with the expected constituents and amounts for these source categories.
The sections below provide more detailed discussions about the human
health risk assessment results for each of the eight source categories.

                 Table 4.--Summary of Estimated Inhalation Risks for the Eight Source Categories
----------------------------------------------------------------------------------------------------------------
                                                  Maximum
                                                 individual       Estimated                        Maximum off-
                                 Number of    cancer risk (in   annual cancer   Max. HI \3\ and   site acute HQ
       Source category         facilities\1\   a million) \2\   incidence and     HAP of most    and HAP of most
                                              and HAP of most    HAP of most        concern        \4\ concern
                                                  concern          concern
----------------------------------------------------------------------------------------------------------------
Polysulfide Rubber                         1  0 \6\..........  0 \6\..........  < 0.01 (MDI \5\)  0.0004\AEGL\
 Production.                                                                                \1\ (MDI\4\).
Ethylene Propylene Rubber                  5  0 \6\..........  0 \6\..........  0.5 (hexane)...  0.3\REL\
 Production.                                                                                (toluene).
Butyl Rubber Production.....               2  0 \6\..........  0 \6\..........  0.2 (methyl      0.1AEGL	2(methy
                                                                                chloride).       l chloride
                                                                                \7\).
Neoprene Production.........               1  0 \6\..........  0 \6\..........  0.8              0.4\REL\
                                                                                (chloroprene).   (toluene).
Epoxy Resins Production.....               3  0.1              0.00002          0.1              0.6\REL\
                                               (epichlorohydr   (epichlorohydr   (epichlorohydr   (epichlorohydr
                                               in).             in).             in).             in).
Non-nylon Polyamides                       4  0.4              0.00003          0.3              0.2\REL\
 Production.                                   (epichlorohydr   (epichlorohydr   (epichlorohydr   (epichlorohydr
                                               in).             in).             in).             in).
Acetal Resins Production....               3  0.3 (allyl       0.00004 (allyl   0.2 (chlorine).  1.7\REL\
                                               chloride).       chloride).                        (formaldehyde)
                                                                                .
Hydrogen Fluoride Production               2  0 \6\..........  0 \6\..........  < 0.01            0.3\REL\
                                                                                (hydrofluoric    (hydrofluoric
                                                                                acid).           acid).
----------------------------------------------------------------------------------------------------------------
\1\ Number of facilities believed to be in the source category and used in the risk analysis.
\2\ Maximum individual excess lifetime cancer risk.
\3\ Maximum hazard index (HI) is maximum respiratory HI for all except two source categories. Maximum HI for
  butyl rubber production is based on neurological effects. Maximum HI for hydrogen fluoride production is based
  on skeletal effects.
\4\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to
  develop an array of hazard quotient (HQ) values. These include RELs and AEGL-1 and AEGL-2 values. The acute
  REL is an exposure that is not likely to cause adverse effects in a human population, including sensitive
  subgroups, exposed to that concentration for one hour on an intermittent basis. AEGL-1 is the airborne
  concentration (expressed as ppm or mg/m\3\) of a substance above which it is predicted that the general
  population, including susceptible individuals, could experience notable discomfort, irritation, or certain
  asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon
  cessation of exposure. AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above
  which it is predicted that the general population, including susceptible individuals, could experience
  irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.
\5\ MDI is methylene diphenyl diisocyanate.
\6\ No HAP which are known, probable, or possible human carcinogens.
\7\ For methyl chloride, REL and AEGL-1 were not available.

    As shown in Table 4, we estimate that the residual risk remaining
from HAP emissions from these eight source categories affected by
today's proposal do not pose cancer risks equal to or greater than 1-
in-1 million to the individual most exposed, do not result in
meaningful rates of cancer incidence, and do not result in a concern
regarding either chronic or acute noncancer health effects for the
individual most exposed.
    No chronic inhalation human health thresholds were exceeded at
ecological receptors for any of the eight source

categories; therefore, we believe there is low potential for adverse
environmental effects due to direct airborne exposures. We also believe
that there is no potential for an adverse effect on threatened or
endangered species or on their critical habitat within the meaning of
50 CFR 402.13(a) because our screening analyses indicate no potential
for any adverse ecological impacts. Thus, we conclude that a
consultation with the Fish and Wildlife Service is not necessary for
any of the eight source categories.
    Human health multipathway risks were determined not to be a concern
for the eight source categories addressed in today's proposal due to
the absence of persistent and bioaccumulative (PB) \17\ HAP emissions
at all of these sources. The lack of PB HAP emissions also provides
assurance that there will be no potential for adverse ecological
effects due to indirect ecological exposures (i.e., exposures resulting
from the deposition of PB HAP from the atmosphere).
---------------------------------------------------------------------------

    \17\ Persistent and bioaccumulative (PB) HAP are the list of 14
HAP that have the ability to persist in the environment for long
periods of time and may also have the ability to build up in the
food chain to levels that are harmful to human health and the
environment.
---------------------------------------------------------------------------

1. Polymers and Resins I--Polysulfide Rubber Production
    The only HAP emitted by the Polysulfide Rubber Production source
category in 2002 was 4,4'-methylene diphenyl diisocyanate (MDI), whose
carcinogenic potential was evaluated in EPA's IRIS in 1998, and
characterized as ``cannot be determined, but for which there is
suggestive evidence that raises concern for carcinogenic effects.''
    The maximum chronic noncancer TOSHI associated with emissions from
polysulfide rubber production is less than 0.01, indicating that
chronic noncancer risks are negligible. Further, our analysis, based on
available information, indicates this source category poses no
potential for adverse environmental impacts. Combining these results
with the lack of information on potential cancer risks and the
additional fact that no sources in this category are currently in
operation, we conclude that there is no reason to modify the existing
standard.
2. Polymers and Resins I--Ethylene Propylene Rubber Production
    Because none of the HAP emitted are known, probable, or possible
human carcinogens, we currently believe there are no cancer risks
associated with exposures to the HAP emissions from this source
category. The maximum chronic noncancer TOSHI value associated with
emissions from ethylene propylene rubber production is 0.5. No adverse
noncancer health effects associated with the modeled acute or chronic
inhalation exposures are expected from the Ethylene Propylene Rubber
Production source category. Our analysis, based on available
information, indicates this source category poses no potential for
adverse environmental impacts.
3. Polymers and Resins I--Butyl Rubber Production
    Because none of the HAP emitted are known, probable, or possible
human carcinogens, we currently believe there are no cancer risks
associated with exposures to the HAP emissions from this source
category. The maximum chronic noncancer TOSHI value associated with
emissions from butyl rubber production is 0.2. We saw no exceedances of
any available acute thresholds. Our analysis, based on available
information, indicates this source category poses no potential for
adverse environmental impacts.
    A source of uncertainty unique to this source category is the lack
of certain acute dose-response values (REL and AEGL) for methyl
chloride. Since the only acute dose-response value available is for
methyl chloride is the ERPG2 \18\ value which doesn't account for
possible mild transient effects, there is some uncertainty regarding
the conclusion that there are no possible acute impacts of concern.
---------------------------------------------------------------------------

    \18\ ERPG-2 is the maximum airborne concentration below which it
is believed that nearly all individuals could be exposed for up to 1
hour without experiencing or developing irreversible or other
serious health effects or symptoms which could impair an
individual's ability to take protective action.
---------------------------------------------------------------------------

4. Polymers and Resins I--Neoprene Production
    Because none of the HAP emitted are known, probable, or possible
human carcinogens, we currently believe there are no cancer risks
associated with exposures to the HAP emissions from this source
category. The maximum chronic noncancer TOSHI value associated with
emissions from neoprene production is 0.8. There are no expected
adverse noncancer health effects associated with the modeled acute or
chronic inhalation exposures from the Neoprene Production source
category. Our analysis, based on available information, indicates this
source category poses no potential for adverse environmental impacts.
5. Polymers and Resins II--Epoxy Resins Production
    All lifetime cancer risks associated with emissions from the three
epoxy resins production facilities are estimated to be less than 1-in-1
million. The highest maximum lifetime individual cancer risk was
estimated at 0.1-in-1 million. The total estimated cancer incidence
from these facilities is 0.00002 excess cancer cases per year. The
maximum chronic noncancer TOSHI value associated with emissions from
epoxy resins production is 0.1. We saw no exceedances of any available
acute thresholds. Our analysis, based on available information,
indicates this source category poses no potential for adverse
environmental impacts.
6. Polymers and Resins II--Non-Nylon Polyamides Production
    All lifetime cancer risks associated with emissions from the four
non-nylon polyamides production facilities are estimated to be less
than 1-in-1 million. The highest maximum lifetime individual cancer
risk was estimated at 0.4-in-1 million. The total estimated cancer
incidence from these facilities is 0.00003 excess cancer cases per
year. The maximum chronic noncancer TOSHI value associated with
emissions from non-nylon polyamides production is 0.3. There are no
expected adverse noncancer health effects associated with the modeled
acute or chronic exposures from the neoprene production source
category. Our analysis, based on available information, indicates this
source category poses no potential for adverse environmental impacts.
7. GMACT--Acetal Resins Production
    All lifetime cancer risks associated with emissions from the three
acetal resins production facilities are estimated to be less than 1-in-
1 million. The highest maximum lifetime individual cancer risk was
estimated at 0.3-in-1 million. The total estimated cancer incidence
from these facilities is 0.00004 excess cancer cases per year. The
maximum chronic noncancer TOSHI value associated with emissions from
acetal resins production is 0.2. Our analysis, based on available
information, indicates this source category poses no potential for
adverse environmental impacts.
    The initial screening assessment for acute impacts suggested that
short-term formaldehyde concentrations at the three modeled facilities
could exceed acute thresholds if worst-case meteorological conditions
are present and if maximum hourly emissions of formaldehyde exceed the
average hourly

emission rate by a factor of 10. One of the facilities showed potential
exceedances of the REL only, and two facilities showed potential
exceedances of both the REL and the AEGL-1. Therefore, we performed
further site-specific analysis and mapped the screening results as a
series of concentration isopleths overlaid against the aerial
photograph of the facility in question. The results of this exercise
for the first facility were that the isopleths that exceeded the REL
did not extend off the facility site. Therefore, acute exposures to HAP
emitted by this facility are not expected to pose any public health
concerns. We further refined the assessments using better site-specific
data for the other two facilities. Discussions with a plant engineer
for one facility revealed that the acetal resins processes operate
continuously and that a reasonable worst-case emissions multiplier
would be 1.5 instead of our default multiplier of 10. We performed more
refined modeling (AERMOD) for these two facilities using the emissions
multiplier of 1.5. The results for the second facility indicated no
potential for exceeding the AEGL-1 and showed that the potential for
exceedances of the REL did not extend off-site, except for a small
extension over a river to the north of the facility. The maximum off-
site REL HQ corresponding to these locations is 1.7 (HQ = 0.14 using
the AEGL-1). The analysis showed that meteorological conditions
resulting in exceedances of the REL may occur up to 2 hours per year
along the river. We believe the potential for adverse acute health
effects surrounding this facility is low. The results for the third
facility showed potential for exceeding the REL in an area immediately
adjacent to the facility along a roadway. The maximum off-site HQ for
this facility is 1.6 for the REL (HQ = 0.13 using the AEGL-1). The
analysis showed that meteorological conditions resulting in exceedances
of the REL may occur up to 46 hours per year along the roadway.
Additionally, the third facility reports that current actual emissions
for this facility are significantly less than those used for this
assessment because one of the higher emission sources listed for this
facility in the 2002 NEI data has been shut down. Based on this new
information, we believe that the actual projected maximum off-site HQ
for this facility is less than 1.0. We request interpretation and
comment on this as well as any additional data regarding the potential
acute impacts of these facilities.
    A source of uncertainty that is unique to this source category is
associated with annual emissions of HAP and the relationship between
annual emissions and maximum hourly emissions. One facility reports
emissions of benzene and allyl chloride, which are two relatively toxic
HAP not expected to be emitted from this source category. Since the
risk assessment shows allyl chloride to be the cancer risk driver for
the source category, this indicates a potential overestimate of the
cancer risks
8. GMACT--Hydrogen Fluoride Production
    Because hydrogen fluoride, the only HAP emitted from the source
category, is not a known, probable, or possible human carcinogen, we
currently believe there are no cancer risks associated with exposures
to the HAP emissions from this source category. The maximum chronic
noncancer TOSHI value associated with emissions from hydrogen fluoride
production is less than 0.01.
    The initial screening assessment for acute impacts suggests that
short-term hydrofluoric acid concentrations at the two modeled
facilities could exceed acute thresholds if worst-case meteorological
conditions are present and if maximum hourly emissions of hydrofluoric
acid exceed the average hourly emission rate by a factor of 10. Since
one of the facilities showed potential exceedances of the REL only, and
one facility showed potential exceedances of both the REL and the AEGL-
1, we performed additional site specific assessments. We contacted the
permitting agency and a process engineer at one of the facilities to
gather additional source specific information. Based on discussions
with the permitting agency and the process engineer, we determined that
these facilities operate continuously and that the peak hourly
emissions are not expected to exceed twice the hourly average. By
adjusting the short-term emission rate to more accurately represent the
true facility operating conditions (from 10 to 2), no offsite impacts
above the REL were predicted from the first facility. For the second
facility that exceeded both the REL and AEGL-1, we remodeled using the
AERMOD model to more accurately predict the worst case acute impacts.
By adjusting the short-term emission rate to more accurately represent
facility operating conditions (from 10 to 2), exceedances of the REL
and AEGL-1 were predicted to occur within the facility property
boundary, but not offsite.
    A source of uncertainty unique to this source category involves the
adequacy of our screening for potential adverse environmental effects
for the pollutant hydrogen fluoride, as discussed in section I.C.6.e of
this preamble. Indeed, there is a significant lack of scientific
understanding and assessment methodologies for such potential adverse
environmental effects. However, we believe acute and chronic noncancer
assessment results (maximum chronic TOSHI less than 0.01 and maximum
acute HQ of 0.3 for REL and 0.09 for AGEL-1) support our conclusion
that no adverse environmental impacts are expected for this source
category.

E. What are the conclusions of the technology review?

    For seven of the source categories affected by today's proposal
(all except the Hydrogen Fluoride Production source category), we
relied on the technology review conducted for the HON, which did not
identify any significant developments in practices, processes, or
control technologies since promulgation of the original HON standards
in 1994.\19\ These seven source categories are similar to those under
the HON because they use the same kinds of process and pollution
control equipment and are subject to similar control requirements.\20\
For the seven HON-like source categories affected by today's proposal,
we conclude that imposing additional controls under any control option
would achieve, at best, minimal emission and risk reductions.
Furthermore, elimination of all HAP, if it were possible, from all
seven of these source categories combined would reduce estimated cancer
incidence by less than 0.0002 cases per year. For HAP with available
dose-response values, the maximum HI for these facilities are all below
one and the cancer risks are all below 1-in-1 million.
---------------------------------------------------------------------------

    \19\ Discussed in the proposed and final HON residual risk
preambles (71 FR 34428, June 14, 2006, and 71 FR 76603, December 21,
2006, respectively).
    \20\ Process equipment, pollution control equipment, and control
requirements are summarized in the proposal BID.
---------------------------------------------------------------------------

    Elimination of all HAP \21\ emissions from the Hydrogen Fluoride
source category, if it were possible, would reduce HAP emissions by 8
tons per year and would not affect cancer incidence, which is 0
(hydrogen fluoride is not a known, probable, or possible human
carcinogens). The noncancer risk is low (the maximum HI is less than
0.01 with the current level of emissions achieved by the GMACT)

and further emissions reductions would provide insignificant, if any,
health benefits. In addition, all hydrogen fluoride emissions are from
control device vents equipped with control devices that achieve 99
percent reductions. Improvements in hydrogen fluoride controls are not
feasible.
---------------------------------------------------------------------------

    \21\ Hydrogen fluoride is the only HAP emitted from the Hydrogen
Fluoride source category.
---------------------------------------------------------------------------

    We conclude that the existing MACT standards effectively address
HAP emissions for all eight source categories: Cancer risks and
incidence to humans, chronic and acute exposure noncancer risks to
humans, and adverse environmental effects from these facilities are
insignificant based on available health benchmarks, and no advancements
in practices, processes, or control technology that make additional
controls cost-effective are known.

II. Proposed Action

    Section 112(f) of the CAA requires that EPA promulgate standards
for a category if promulgation of such standards is required to provide
an ample margin of safety to protect public health or to prevent,
taking into consideration costs, energy, safety, and other relevant
factors, an adverse environmental effect. The approach we use is that
set forth in the preamble to the Benzene NESHAP. First we exclusively
evaluate health risk measures and information in determining whether
risks are acceptable. Second, we may consider costs and other factors
in deciding whether further emission reductions are necessary to
protect public health with an ample margin of safety. The Benzene
NESHAP preamble explained that in protecting public health with an
ample margin of safety under CAA section 112, EPA strives to provide
maximum feasible protection against risks to health from HAP by
protecting the greatest number of persons possible to an individual
lifetime risk level no higher than approximately 1-in-1 million.
    EPA is not required to promulgate standards for a source category
under section 112(f) if public health is protected with an ample margin
of safety and adverse environmental effects are prevented. For the
eight source categories that are the subject of today's notice, we have
concluded (based on the results of risk assessments) that the existing
MACT standards protect public health with an ample margin of safety and
prevent an adverse environmental effect. In making this conclusion, we
determined that the source categories addressed in today's proposal
that emit one or more HAP which are known or potential carcinogens pose
cancer risks less than or equal to 1-in-1 million to the individual
most exposed. In addition, we also determined that emissions from these
source categories result in chronic noncancer target organ-specific HI
less than or equal to 1 for the individual most exposed, are unlikely
to result in health effects under acute scenarios and are not
anticipated to pose any significant and widespread adverse
environmental effects. In reaching this conclusion, we did not consider
costs.
    Furthermore, as explained in section I.E. of this preamble, there
have been no significant developments in practices, processes, or
control technologies since promulgation of the MACT standards. Because
there have been no such significant developments and because public
health is protected with an ample margin of safety, we conclude that no
further revisions to the standards affected by today's proposal are
needed under section 112(d)(6) of the CAA.
    Therefore, we propose no revisions to the standards for the eight
source categories: Butyl Rubber Production, Ethylene-Propylene Rubber
Production, Polysulfide Rubber Production, Neoprene Production, Epoxy
Resins Production, Ethylene-Propylene Rubber Production, Acetal Resins
Production, and Hydrogen Fluoride Production.

III. How do I access and review the facility-specific data?

    The facility-specific data for each source category are available
for download on the RTR webpage at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html.
 The eight source categories affected by today's proposal

are referred to as Group 1 of RTR Phase 2. These data files include
detailed information for each emissions release point at each facility
in the source category. For large integrated facilities with multiple
processes representing multiple source categories, it is often
difficult to clearly distinguish the source category to which each
emission point belongs. For this reason, the data available for
download for each source category include all emission points for each
facility in the source category, though only the emission points marked
as belonging to the specific source category in question were included
in the analysis for that source category.
    The data files for each source category must be downloaded from the
RTR Web page to be viewed (http://www.epa.gov/ttn/atw/rrisk/rtrpg.html
). These are Microsoft[supreg] Access files, which require

Microsoft[supreg] Access to be viewed (if you do not have
Microsoft[supreg] Access, contact us by e-mail at RTR@epa.gov). Each
file contains the following information from the NEI for each facility
in the source category:

----------------------------------------------------------------------------------------------------------------
              Facility data                                            Emissions data
----------------------------------------------------------------------------------------------------------------
EPA Region...............................  Pollutant Code.
Tribal Code..............................  Pollutant Code Description.
Tribe Name...............................  HAP Category Name.
State Abbreviation.......................  Emissions (TPY).
County Name..............................  MACT Code.
State County FIPS........................  MACT Source Category Name.
NEI Site ID..............................  MACT Flag.
Facility Name............................  MACT Compliance Status Code.
Location Address.........................  SCC Code.
City Name................................  SCC Code Description.
 State Name..............................  Emission Unit ID.
Zip Code.................................  Process ID.
Facility Registry........................  Emission Release Point ID.
State Facility Identifier................  Emission Release Point Type Code.
SIC Code.................................  Emission Release Point Type.
SIC Code Description.....................  Stack Default Flag.
NAICS Code...............................  Stack Default Flag Description.
Facility Category Code...................  Stack height.

Facility Category........................  Exit Gas Temperature.
                                           Stack Diameter.
                                           Exit Gas Velocity.
                                           Exit Gas Flow Rate.
                                           Fugitive Length.
                                           Fugitive Width.
                                           Fugitive Angle.
                                           Longitude.
                                           Latitude.
                                           Location Default Flag.
                                           Data Source Code.
                                           Data Source Description.
                                           HAP Emissions Performance Level Code.
                                           HAP Emissions Performance Level Description.
                                           Start Date.
                                           End Date.
----------------------------------------------------------------------------------------------------------------

More information on these NEI data fields can be found in the NEI
documentation at http://www.epa.gov/ttn/chief/net/2002inventory.html#documentation
.

IV. How do I submit suggested data corrections?

    If you believe that the data are not representative or are
inaccurate, please identify the data in question, provide your reason
for concern, and provide improved data if available. When submitting
data, we ask that you provide documentation of the basis for the
revised values to support any suggested changes.
    To submit comments on the data downloaded from the RTR Web page,
complete the following steps:
    1. Within this downloaded file, enter suggested revisions in the
data fields appropriate for that information. The data fields that may
be revised include the following:

----------------------------------------------------------------------------------------------------------------
              Facility data                                            Emissions data
----------------------------------------------------------------------------------------------------------------
REVISED Tribal Code......................  REVISED Emissions (TPY).
REVISED County Name......................  Emissions Calculation Method Code.
REVISED Facility Name....................  REVISED MACT Code.
REVISED Location Address.................  REVISED SCC Code.
REVISED City Name........................  REVISED Emission Release Point Type.
REVISED State Name.......................  REVISED Start Date.
REVISED Zip Code.........................  REVISED End Date.
REVISED Facility Registry Identifier.....  Revised Pollutant Code.
REVISED Facility Category Code...........  REVISED Stack height.
                                           REVISED Exit Gas Temperature.
                                           REVISED Stack Diameter.
                                           REVISED Exit Gas Velocity.
                                           REVISED Exit Gas Flow Rate.
                                           REVISED Longitude.
                                           REVISED Latitude.
                                           REVISED HAP Emissions Performance Level.
----------------------------------------------------------------------------------------------------------------

    2. Fill in the following commenter information fields for each
suggested revision:
     Commenter Name.
     Commenter Organization.
     Commenter E-Mail Address.
     Commenter Phone Number.
     Revision Comments.
    3. Gather documentation for any suggested emissions revisions
(e.g., performance test reports, material balance calculations, etc.).
    4. Send the entire downloaded file with suggested revisions in
Microsoft([reg]) Access format and all accompanying documentation to
Docket ID No. EPA-HQ-OAR-2007-0211 (through one of the methods
described in the ADDRESSES section of this preamble). To answer
questions on navigating through the data and to help expedite review of
the revisions, it would also be helpful to submit revisions to EPA
directly at<EMAIL_ADDRESS>in addition to submitting them to the docket.
    5. If you are providing comments on a facility with multiple source
categories, you need only submit one file for that facility, which
should contain all suggested changes for all source categories at that
facility.
    We strongly urge that all data revision comments be submitted in
the form of updated Microsoft([reg]) Access files, which are provided
on the http://www.epa.gov/ttn/atw/rrisk/rtrpg.html webpage. Data in the

form of written descriptions or other electronic file formats will be
difficult for EPA to translate into the necessary format in a timely
manner.

V. Statutory and Executive Order Reviews

A. Executive Order 12866, Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), this
action is a ``significant regulatory action.'' This action is a
significant regulatory action because it raises novel legal and policy
issues. Accordingly, EPA submitted this action to the Office of
Management and Budget (OMB) for review under Executive Order 12866 and
any changes made in response to OMB recommendations have been

documented in the docket for this action.

B. Paperwork Reduction Act

    This action does not impose any new information collection burden.
This action is proposing no changes to the existing regulations
affecting the eight source categories affected by today's proposal and
will impose no additional information collection burden.
    Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required
to respond to a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impact of today's proposed action on
small entities, small entity is defined as: (1) A small business whose
parent company has fewer than 750 to 1,000 employees, depending on the
size definition for the affected NAICS code (as defined by Small
Business Administration size standards); (2) a small governmental
jurisdiction that is a government of a city, county, town, school
district, or special district with a population of less than 50,000;
and (3) a small organization that is any not-for-profit enterprise
which is independently owned and operated and is not dominant in its
field.
    After considering the economic impact of today's proposed action on
small entities, we certify that this action will not have a significant
economic impact on a substantial number of small entities. The proposed
action will not impose any requirements on small entities. We are
proposing no further action at this time to revise the NESHAP. Today's
proposed action requests public comments on the residual risk and
technology review.
    We continue to be interested in the potential impacts of the
proposed action on small entities and welcome comments on issues
related to such impacts.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effect of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective, or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective, or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
    EPA has determined that the proposed action does not contain a
Federal mandate that may result in expenditures of $100 million or more
for State, local, and tribal governments in the aggregate, or to the
private sector in any one year. The rule imposes no enforceable duty on
State, local, or tribal governments, or the private sector. Thus,
today's proposed action is not subject to the requirements of sections
202 and 205 of the UMRA.
    In addition, EPA has determined that the proposed action contains
no regulatory requirements that might significantly or uniquely affect
small governments, because it contains no requirements that apply to
such governments or impose obligations upon them.

E. Executive Order 13132, Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
    This proposed action does not have federalism implications. It will
not have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. Thus, Executive Order 13132 does
not apply to this proposed action.
    In the spirit of Executive Order 13132, and consistent with EPA
policy to promote communications between EPA and State and local
governments, EPA specifically solicits comment on this proposed action
from State and local officials.

F. Executive Order 13175, Consultation and Coordination with Indian
Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by tribal officials in the development of

regulatory policies that have tribal implications.'' This proposed
action does not have tribal implications as specified in Executive
Order 13175. It will not have substantial direct effect on tribal
governments, on the relationship between the Federal government and
Indian tribes, or on the distribution of power and responsibilities
between the Federal government and Indian tribes, as specified in
Executive Order 13175. Thus, Executive Order 13175 does not apply to
this proposed action.
    EPA specifically solicits additional comment on this proposed rule
from tribal officials.

G. Executive Order 13045, Protection of Children From Environmental
Health Risks and Safety Risks

    Executive Order 13045, ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) Is determined to be ``economically significant''
as defined under Executive Order 12866, and (2) concerns an
environmental health or safety risk that EPA has reason to believe may
have a disproportionate effect on children. If the regulatory action
meets both criteria, the Agency must evaluate the environmental health
or safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.
    This proposed rule is not subject to the Executive Order because it
is not economically significant as defined in Executive Order 12866,
and because the Agency does not have reason to believe the
environmental health or safety risks addressed by this action present a
disproportionate risk to children because EPA's risk assessment
demonstrates that the existing regulations are health protective.

H. Executive Order 13211, Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use

    This proposed rule is not a ``significant energy action'' as
defined in Executive Order 13211 (66 FR 28355, May 22, 2001) because it
is not likely to have a significant adverse effect on the supply,
distribution, or use of energy. Further, we have concluded that this
proposed rule is not likely to have any adverse energy effects.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law No. 104-113, 12(d) (15 U.S.C. 272 note)
directs EPA to use voluntary consensus standards (VCS) in its
regulatory activities, unless to do so would be inconsistent with
applicable law or otherwise impractical. VCS are technical standards
(e.g., materials specifications, test methods, sampling procedures, and
business practices) that are developed or adopted by VCS bodies. The
NTTAA directs EPA to provide Congress, through OMB, explanations when
the Agency decides not to use available and applicable VCS.
    The proposed action does not involve technical standards.
Therefore, EPA is not considering the use of any VCS. EPA welcomes
comments on this aspect of the proposed rulemaking and, specifically,
invites the public to identify potentially applicable VCS and to
explain why such standards should be used in this proposed action.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898 (59 FR 7629, February 16, 1994) establishes
Federal executive policy on environmental justice. Its main provision
directs Federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the United States.
    EPA has determined that this proposed rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it does not
affect the level of protection provided to human health or the
environment. This proposed rule would not relax the control measures on
sources regulated by the rule and, therefore, would not cause emissions
increases from these sources.

List of Subjects for 40 CFR Part 63

    Environmental protection, Administrative practice and procedures,
Air pollution control, Hazardous substances, Intergovernmental
relations, Reporting and recordkeeping requirements.

    Dated: December 6, 2007.
Stephen L. Johnson,
Administrator.
[FR Doc. E7-24076 Filed 12-11-07; 8:45 am]

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