[Federal Register Volume 75, Number 244 (Tuesday, December 21, 2010)]
[Proposed Rules]
[Pages 80220-80258]
[FR Doc No: 2010-31091]

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Part IV

Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Shipbuilding and Ship Repair (Surface
Coating); National Emission Standards for Wood Furniture Manufacturing
Operations; Proposed Rule

Federal Register / Vol. 75 , No. 244 / Tuesday, December 21, 2010 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2010-0786; FRL-9237-1]
RIN 2060-AQ42

National Emission Standards for Shipbuilding and Ship Repair
(Surface Coating); National Emission Standards for Wood Furniture
Manufacturing Operations

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: This action proposes how EPA will address the residual risk
and technology review conducted for two industrial source categories
regulated by separate national emission standards for hazardous air
pollutants. It also proposes to address provisions related to emissions
during periods of startup, shutdown, and malfunction.

DATES: Comments. Comments must be received on or before February 22,
2011. Under the Paperwork Reduction Act, comments on the information
collection provisions are best assured of having full effect if the
Office of Management and Budget receives a copy of your comments on or
before January 20, 2011.
    Public Hearing. If anyone contacts EPA requesting to speak at a
public hearing by January 5, 2011, a public hearing will be held on
January 20, 2011.

ADDRESSES: Submit your comments, identified by Docket ID Number EPA-HQ-
OAR-2010-0786, by one of the following methods:
     http://www.regulations.gov: Follow the on-line
instructions for submitting comments.
     E-mail<EMAIL_ADDRESS>Attention Docket ID Number
EPA-HQ-OAR-2010-0786.
     Facsimile:<PHONE_NUMBER>. Attention Docket ID Number EPA-
HQ-OAR-2010-0786.
     Mail: U.S. Postal Service, send comments to: EPA Docket
Center, EPA West (Air Docket), Attention Docket ID Number EPA-HQ-OAR-
2010-0786, U.S. Environmental Protection Agency, Mailcode: 2822T, 1200
Pennsylvania Ave., NW., Washington, DC 20460. Please include a total of
two copies. In addition, please mail a copy of your comments on the
information collection provisions to the Office of Information and
Regulatory Affairs, Office of Management and Budget, Attn: Desk Officer
for EPA, 725 17th Street, NW., Washington, DC 20503.
     Hand Delivery: U.S. Environmental Protection Agency, EPA
West (Air Docket), Room 3334, 1301 Constitution Ave., NW., Washington,
DC 20004. Attention Docket ID Number EPA-HQ-OAR-2010-0786. Such
deliveries are only accepted during the Docket's normal hours of
operation, and special arrangements should be made for deliveries of
boxed information.
    Instructions. Direct your comments to Docket ID Number EPA-HQ-OAR-
2010-0786. EPA's policy is that all comments received will be included
in the public docket without change and may be made available on-line
at http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
confidential business information or other information whose disclosure
is restricted by statute. Do not submit information that you consider
to be confidential business information or otherwise protected through
http://www.regulations.gov or e-mail. The http://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. The EPA has established a docket for this rulemaking under
Docket ID Number EPA-HQ-OAR-2010-0786. 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., confidential
business information or other information whose disclosure is
restricted by statute. Certain other material, such as copyrighted
material, is not placed on the Internet and 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, EPA West, Room 3334, 1301 Constitution Ave.,
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<PHONE_NUMBER>, and the
telephone number for the EPA Docket Center is<PHONE_NUMBER>.
    Public Hearing. If a public hearing is held, it will begin at 10
a.m. on January 20, 2011 and will be held at EPA's campus in Research
Triangle Park, North Carolina, or at an alternate facility nearby. For
information on the status of the public hearing, go to http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. Persons interested in presenting
oral testimony or inquiring as to whether a public hearing is to be
held should contact Ms. Joan Rogers, Office of Air Quality Planning and
Standards, Sector Policies and Programs Division, Natural Resources and
Commerce Group (E143-01), U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; telephone number: (919)
541-4487.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Ms. J. Kaye Whitfield, Sector Policies and Programs
Division (E143-01), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, telephone<PHONE_NUMBER>; facsimile number:<PHONE_NUMBER>; and
e-mail address<EMAIL_ADDRESS>For specific information
regarding the risk modeling methodology, contact Ms. Elaine Manning,
Health and Environmental Impacts Division (C539-02), Office of Air
Quality Planning and Standards, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; telephone number: (919)
541-5499; facsimile number:<PHONE_NUMBER>; and e-mail address:
<EMAIL_ADDRESS>For information about the applicability of
these two National Emissions Standards for Hazardous Air Pollutants to
a particular entity, contact the appropriate person listed in Table 1
to this preamble.

 Table 1--List of EPA Contacts for the National Emissions Standards for
   Hazardous Air Pollutants (NESHAP) Addressed in this Proposed Action
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         NESHAP for:            OECA Contact \1\      OAQPS Contact \2\
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Shipbuilding and Ship Repair  Mr. Leonard Lazarus,  Ms. J. Kaye
 (Surface Coating).<PHONE_NUMBER>,       Whitfield, (919)
                               lazarus.leonard@epa   541-2509,
                               .gov<EMAIL_ADDRESS>Wood Furniture Manufacturing  Mr. Leonard Lazarus,  Ms. J. Kaye
 Operations.<PHONE_NUMBER>,       Whitfield, (919)
                               lazarus.leonard@epa   541-2509,
                               .gov<EMAIL_ADDRESS>------------------------------------------------------------------------
\1\ OECA stands for EPA's Office of Enforcement and Compliance
  Assurance.
\2\ OAQPS stands for EPA's Office of Air Quality Planning and Standards.

SUPPLEMENTARY INFORMATION:

I. Preamble Acronyms and Abbreviations

    Several acronyms and terms used to describe industrial processes,
data inventories, and risk modeling are included in this preamble.
While this may not be an exhaustive list, to ease the reading of this
preamble and for reference purposes, the following terms and acronyms
are defined here:

ACA American Coatings Association
ACGIH American Conference of Governmental Industrial Hygienists
ADAF Age-dependent Adjustment Factors
AEGL Acute Exposure Guideline Levels
AERMOD The air dispersion model used by the HEM-3 model
AHFA American Home Furnishings Alliance
ANPRM Advance Notice of Proposed Rulemaking
APA Administrative Procedure Act
ATSDR Agency for Toxic Substances and Disease Registry
BACT Best Available Control Technology
BIFMA Business and Institutional Furniture Manufacturer's
Association
CalEPA California Environmental Protection Agency
CAA Clean Air Act
CBI Confidential Business Information
CEEL Community Emergency Exposure Levels
CEMS Continuous Emissions Monitoring System
CFR Code of Federal Regulations
CIIT Chemical Industry Institute of Toxicology
DGBE Diethylene Glycol Monobutyl Ether
EGME Ethylene Glycol Monomethyl Ether
EJ Environmental Justice
EPA Environmental Protection Agency
ERPG Emergency Response Planning Guidelines
HAP Hazardous Air Pollutants
HI Hazard Index
HEM-3 Human Exposure Model version 3
HON Hazardous Organic National Emissions Standards for Hazardous Air
Pollutants
HQ Hazard Quotient
ICR Information Collection Request
IRIS Integrated Risk Information System
KCMA Kitchen Cabinet Manufacturing Association
Kg Kilogram
Km Kilometer
LAER Lowest Achievable Emission Rate
MACT Maximum Achievable Control Technology
MACT Code Code within the NEI used to identify processes included in
a source category
MIR Maximum Individual Risk
MRL Minimum Risk Level
NAC/AEGL Committee National Advisory Committee for Acute Exposure
Guideline Levels for Hazardous Substances
NAICS North American Industry Classification System
NAS National Academy of Sciences
NATA National Air Toxics Assessment
NESHAP National Emissions Standards for Hazardous Air Pollutants
NEI National Emissions Inventory
NIOSH National Institutes for Occupational Safety and Health
NOAEL No Observed Adverse Effects Level
NOX Nitrous Oxide
NRC National Research Council
NTTAA National Technology Transfer and Advancement Act
OAQPS EPA's Office of Air Quality Planning and Standards
OECA EPA's Office of Enforcement and Compliance Assurance
OMB Office of Management and Budget
PB-HAP Hazardous air pollutants known to be persistent and bio-
accumulative in the environment
POM Polycyclic Organic Matter
PPRTV Provisional Peer Reviewed Toxicity Value
PRA Paperwork Reduction Act
RACT Reasonably Available Control Technology
RBLC RACT/BACT/LAER Clearinghouse
REL CalEPA Reference Exposure Level
RFA Regulatory Flexibility Act
RfC Reference Concentration
RfD Reference Dose
RTO Regenerative Thermal Oxidizer
RTR Residual Risk and Technology Review
SAB Science Advisory Board
SBA Small Business Administration
SCC Source Classification Codes
SF3 2000 Census of Population and Housing Summary File 3
SOP Standard Operating Procedures
SSM Startup, Shutdown, and Malfunction
TOSHI Target Organ-Specific Hazard Index
TPY Tons Per Year
TRIM Total Risk Integrated Modeling System
TRIM.FaTE A spatially explicit, compartmental mass balance model
that describes the movement and transformation of pollutants over
time, through a user-defined, bounded system that includes both
biotic and abiotic compartments
TTN Technology Transfer Network
UF Uncertainty Factor
UMRA Unfunded Mandates Reform Act
URE Unit Risk Estimate
VCS Voluntary Consensus Standards
VHAP Volatile Hazardous Air Pollutants
VOC Volatile Organic Compounds
VOHAP Volatile Organic Hazardous Air Pollutants
WWW Worldwide Web

    Organization of This Document. The following outline is provided to
aid in locating information in this preamble.

I. Preamble Acronyms and Abbreviations
II. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
    C. What should I consider as I prepare my comments for EPA?
III. Background
    A. What is the statutory authority for this action?
    B. How did we consider the risk results in making decisions for
this proposal?
    C. What other actions are we addressing in this proposal?
IV. Analyses Performed
    A. How did we estimate risks posed by the source categories?
    B. How did we perform the technology review?
V. Analyses Results and Proposed Decisions
    A. What are the results and proposed decisions for the
Shipbuilding and Ship Repair (Surface Coating) source category?
    B. What are the results and proposed decisions for the Wood
Furniture Manufacturing Operations source category?
VI. Proposed Action
    A. What actions are we proposing as a result of the technology
review?
    B. What actions are we proposing as a result of the residual
risk review?
    C. What other actions are we proposing?
VII. Request for Comments
VIII. Submitting Data Corrections
IX. 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

II. General Information

A. Does this action apply to me?

    The regulated industrial source categories that are the subject of
this proposal are listed in Table 2 of 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 action. The regulated
categories affected by this proposed action are shown in Table 2.

                TABLE 2--NESHAP AND INDUSTRIAL SOURCE CATEGORIES AFFECTED BY THIS PROPOSED ACTION
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         NESHAP and source category                            NAICS code \1\                     MACT code \2\
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Shipbuilding and Ship Repair (Surface         336611..........................................            0715-2
 Coating).
Wood Furniture Manufacturing Operations.....  3371, 3372, 3379................................              0716
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\1\ North American Industry Classification System.
\2\ Maximum Achievable Control Technology.

B. Where can I get a copy of this document and other related
information?

    In addition to being available in the docket, an electronic copy of
this proposal will also be available on the WWW through the EPA's TTN.
Following signature by the EPA Administrator, a copy of this 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/atw/rrisk/rtrpg.html. The TTN provides information and
technology exchange in various areas of air pollution control.
    Additional information is available on the RTR web page at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. This information includes the
most recent version of the rule, source category descriptions, detailed
emissions, and other data that were used as inputs to the risk
assessments.

C. What should I consider as I prepare my comments for EPA?

    Submitting CBI. Do not submit information containing CBI to EPA
through http://www.regulations.gov or e-mail. 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 EPA, 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 disk 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. Information marked as
CBI will not be disclosed except in accordance with procedures set
forth in 40 CFR part 2. Send or deliver information identified as CBI
only to the following address: Roberto Morales, OAQPS Document Control
Officer (C404-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, Attention Docket ID Number EPA-HQ-OAR-2010-0786.

III. Background

    A. What is the statutory authority for this action?
    Section 112 of the CAA establishes a two-stage regulatory process
to address emissions of HAP from stationary sources. In the first
stage, after EPA has identified categories of sources emitting one or
more of the HAP listed in section 112(b) of the CAA, section 112(d) of
the CAA calls for us to promulgate NESHAP for those sources. ``Major
sources'' are those that emit or have the potential to emit 10 TPY or
more of a single HAP or 25 TPY or more of any combination of HAP. For
major sources, these technology-based standards must reflect the
maximum degree of emission reductions of HAP achievable (after
considering cost, energy requirements, and nonair quality health and
environmental impacts) and are commonly referred to as MACT standards.
    MACT standards must reflect application of measures, processes,
methods, systems, or techniques, including, but not limited to,
measures which, (A) Reduce the volume of or eliminate pollutants
through process changes, substitution of materials or other
modifications; (B) enclose systems or processes to eliminate emissions;
(C) capture or treat pollutants when released from a process, stack,
storage, or fugitive emissions point; (D) are design, equipment, work
practice, or operational standards (including requirements for operator
training or certification); or (E) are a combination of the above. CAA
section 112(d)(2)(A)-(E). The MACT standards may take the form of
design, equipment, work practice, or operational standards where EPA
first determines either that, (A) a pollutant cannot be emitted through
a conveyance designed and constructed to emit or capture the
pollutants, or that any requirement for, or use of, such a conveyance
would be inconsistent with law; or (B) the application of measurement
methodology to a particular class of sources is not practicable due to
technological and economic limitations. CAA sections 112(h)(1)-(2).
    The MACT ``floor'' is the minimum control level allowed for MACT
standards promulgated under CAA section 112(d)(3) and may not be based
on cost considerations. For new sources, the MACT floor cannot be less
stringent than the emission control that is achieved in practice by the
best-controlled similar source. The MACT floors for existing sources
can be less stringent than floors for new sources, but they cannot be
less stringent than the average emissions limitation achieved by the
best-performing 12 percent of existing sources in the category or
subcategory (or the best-performing five sources for categories or
subcategories with fewer than 30 sources). In developing MACT
standards, we must also consider control options that are more
stringent than the floor. We may establish standards more stringent
than the floor

based on the consideration of the cost of achieving the emissions
reductions, any nonair quality health and environmental impacts, and
energy requirements.
    The EPA is required to review these technology-based standards and
to revise them ``as necessary (taking into account developments in
practices, processes, and control technologies)'' no less frequently
than every 8 years, under CAA section 112(d)(6). In conducting this
review, EPA is not obliged to completely recalculate the prior MACT
determination. NRDC v. EPA, 529 F.3d 1077, 1084 (DC Cir. 2008).
    The second stage in standard-setting focuses on reducing any
remaining ``residual'' risk according to CAA section 112(f). This
provision requires, first, that EPA prepare a Report to Congress
discussing (among other things) methods of calculating the risks posed
(or potentially posed) by sources after implementation of the MACT
standards, the public health significance of those risks, the means and
costs of controlling them, the actual health effects to persons in
proximity of emitting sources, and the recommendations regarding
legislation of such remaining risk. EPA prepared and submitted this
report (Residual Risk Report to Congress, EPA-453/R-99-001) in March
1999. Congress did not act in response to the report, thereby
triggering EPA's obligation under CAA section 112(f)(2) to analyze and
address residual risk.
    Section 112(f)(2) of the CAA requires us to determine, for source
categories subject to certain MACT standards, whether the emissions
standards provide an ample margin of safety to protect public health.
If the MACT standards for HAP ``classified as a known, probable, or
possible human carcinogen, do not reduce lifetime excess cancer risks
to the individual most exposed to emissions from a source in the
category or subcategory to less than 1-in-1 million,'' EPA must
promulgate residual risk standards for the source category (or
subcategory) as necessary to provide an ample margin of safety to
protect public health. In doing so, EPA may adopt standards equal to
existing MACT standards if EPA determines that the existing standards
are sufficiently protective. As stated in NRDC v. EPA, 529 F.3d 1077,
1083 (DC Cir. 2008), ``If EPA determines that the existing technology-
based standards provide an `ample margin of safety,' then the Agency is
free to readopt those standards during the residual risk rulemaking.''
CAA section 112(f)(2) further states that EPA must also adopt more
stringent standards if required, ``to prevent, taking into
consideration costs, energy, safety, and other relevant factors, an
adverse environmental effect.'' \1\
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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 be reasonably anticipated to wildlife, aquatic life, or natural
resources, including adverse impacts on populations of endangered or
threatened species or significant degradation of environmental
qualities over broad areas.
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    When Section 112(f)(2) of the CAA was enacted in 1990, it expressly
preserved our use of the two-step process for developing standards to
address any residual risk and our interpretation of ``ample margin of
safety'' developed in the National Emission Standards for Hazardous Air
Pollutants: Benzene Emissions from Maleic Anhydride Plants,
Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment
Leaks, and Coke By-Product Recovery Plants (Benzene NESHAP) (54 FR
38044, September 14, 1989). The first step in this process is the
determination of acceptable risk. The second step provides for an ample
margin of safety to protect public health, which is the level at which
the standards are set (unless a more stringent standard is required to
prevent, taking into consideration costs, energy, safety, and other
relevant factors, an adverse environmental effect).
    The terms ``individual most exposed,'' ``acceptable level,'' and
``ample margin of safety'' are not specifically defined in the CAA.
However, CAA section 112(f)(2)(B) preserves the interpretation set out
in the Benzene NESHAP, and the Court (in NRDC v. EPA) concluded that
EPA's interpretation of subsection 112(f)(2) is a reasonable one. See
NRDC v. EPA, 529 F.3d 1077, 1083 (DC Cir. 2008), which says
``[S]ubsection 112(f)(2)(B) expressly incorporates EPA's interpretation
of the Clean Air Act from the Benzene standard, complete with a
citation to the Federal Register.'' See also, A Legislative History of
the Clean Air Act Amendments of 1990, volume 1, p. 877 (Senate debate
on Conference Report). We notified Congress in the Residual Risk Report
to Congress that we intended to use the Benzene NESHAP approach in
making CAA section 112(f) residual risk determinations (EPA-453/R-99-
001, p. ES-11).
    In the Benzene NESHAP, we stated as an overall objective:

    * * * in protecting public health with an ample margin of
safety, we strive to provide maximum feasible protection against
risks to health from hazardous air pollutants by (1) protecting the
greatest number of persons possible to an individual lifetime risk
level no higher than approximately 1-in-1 million; and (2) limiting
to no higher than approximately 1-in-10 thousand [i.e., 100-in-1
million] the estimated risk that a person living near a facility
would have if he or she were exposed to the maximum pollutant
concentrations for 70 years.

    The EPA also stated that, ``The EPA also considers incidence (the
number of persons estimated to suffer cancer or other serious health
effects as a result of exposure to a pollutant) to be an important
measure of the health risk to the exposed population. Incidence
measures the extent of health risk to the exposed population as a
whole, by providing an estimate of the occurrence of cancer or other
serious health effects in the exposed population.'' The EPA went on to
conclude, ``estimated incidence would be weighed along with other
health risk information in judging acceptability.'' As explained more
fully in our Residual Risk Report to Congress, EPA does not define
``rigid line[s] of acceptability,'' but considers rather broad
objectives to be weighed with a series of other health measures and
factors (EPA-453/R-99-001, p. ES-11). The determination of what
represents an ``acceptable'' risk is based on a judgment of ``what
risks are acceptable in the world in which we live'' (Residual Risk
Report to Congress, p. 178, quoting the Vinyl Chloride decision at 824
F.2d 1165) recognizing that our world is not risk-free.
    In the Benzene NESHAP, we stated that ``EPA will generally presume
that if the risk to [the maximum exposed] individual is no higher than
approximately 1-in-10 thousand, that risk level is considered
acceptable.'' 54 FR 38045. We discussed the maximum individual lifetime
cancer risk as being ``the estimated risk that a person living near a
plant would have if he or she were exposed to the maximum pollutant
concentrations for 70 years.'' Id. We explained that this measure of
risk ``is an estimate of the upper bound of risk based on conservative
assumptions, such as continuous exposure for 24 hours per day for 70
years.'' Id. We acknowledge that maximum individual lifetime cancer
risk ``does not necessarily reflect the true risk, but displays a
conservative risk level which is an upper-bound that is unlikely to be
exceeded.'' Id.
    Understanding that there are both benefits and limitations to using
maximum individual lifetime cancer risk as a metric for determining
acceptability, we acknowledged in the 1989 Benzene NESHAP that
``consideration of maximum individual risk * * * must take into account
the strengths and weaknesses of this measure of risk.'' Id.
Consequently, the

presumptive risk level of 100-in-1 million (1-in-10 thousand) provides
a benchmark for judging the acceptability of maximum individual
lifetime cancer risk, but does not constitute a rigid line for making
that determination.
    The EPA also explained in the 1989 Benzene NESHAP the following:
``In establishing a presumption for MIR [maximum individual cancer
risk], rather than a rigid line for acceptability, the Agency intends
to weigh it with a series of other health measures and factors. These
include the overall incidence of cancer or other serious health effects
within the exposed population, the numbers of persons exposed within
each individual lifetime risk range and associated incidence within,
typically, a 50-km exposure radius around facilities, the science
policy assumptions and estimation uncertainties associated with the
risk measures, weight of the scientific evidence for human health
effects, other quantified or unquantified health effects, effects due
to co-location of facilities, and co-emission of pollutants.'' Id.
    In some cases, these health measures and factors taken together may
provide a more realistic description of the magnitude of risk in the
exposed population than that provided by maximum individual lifetime
cancer risk alone. As explained in the Benzene NESHAP, ``[e]ven though
the risks judged ``acceptable'' by EPA in the first step of the Vinyl
Chloride inquiry are already low, the second step of the inquiry,
determining an ``ample margin of safety,'' again includes consideration
of all of the health factors, and whether to reduce the risks even
further.'' In the ample margin of safety decision process, the EPA
again considers all of the health risks and other health information
considered in the first step. Beyond that information, additional
factors relating to the appropriate level of control will also be
considered, including costs and economic impacts of controls,
technological feasibility, uncertainties, and any other relevant
factors. Considering all of these factors, the EPA will establish the
standard at a level that provides an ample margin of safety to protect
the public health, as required by CAA section 112(f). 54 FR 38046.

B. How did we consider the risk results in making decisions for this
proposal?

    As discussed in section III.A of this preamble, we apply a two-step
process for developing standards to address residual risk. In the first
step, EPA determines if risks are acceptable. This determination
``considers all health information, including risk estimation
uncertainty, and includes a presumptive limit on MIR \2\ of
approximately 1-in-10 thousand [i.e., 100-in-1 million].'' 54 FR 38045.
In the second step of the process, EPA sets the standard at a level
that provides an ample margin of safety ``in consideration of all
health information, including the number of persons at risk levels
higher than approximately 1-in-1 million, as well as other relevant
factors, including costs and economic impacts, technological
feasibility, and other factors relevant to each particular decision.''
Id.
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    \2\ Although defined as ``maximum individual risk,'' MIR refers
only to cancer risk. MIR, one metric for assessing cancer risk, is
the estimated risk were an individual exposed to the maximum level
of a pollutant for a lifetime.
---------------------------------------------------------------------------

    In past residual risk determinations, EPA presented a number of
human health risk metrics associated with emissions from the category
under review, including: The MIR; the numbers of persons in various
risk ranges; cancer incidence; the maximum non-cancer HI; and the
maximum acute non-cancer hazard (72 FR 25138, May 3, 2007; 71 FR 42724,
July 27, 2006). EPA also discussed and considered risk estimation
uncertainties. In our most recent proposal (75 FR 65068), EPA also
presented and considered additional measures of health information to
support our decision-making, including: Estimates of ``total facility''
risks (risks from all HAP emissions from the facility at which the
source category is located); \3\ demographic analyses (analyses of the
distributions of HAP-related risks across different social,
demographic, and economic groups living near the facilities); and
estimates of the risks associated with emissions allowed by the MACT
standards (75 FR 65068, October 21, 2010). EPA is providing this same
type of information in support of the proposed actions described in
this Federal Register notice.
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    \3\ EPA previously provided estimates of total facility risk in
a residual risk proposal for coke oven batteries (69 FR 48338,
August 9, 2004).
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    The EPA is considering all available health information to inform
our determinations of risk acceptability and ample margin of safety
under CAA section 112(f). Specifically, as explained in the Benzene
NESHAP, ``the first step judgment on acceptability cannot be reduced to
any single factor'' and thus ``[t]he Administrator believes that the
acceptability of risk under section 112 is best judged on the basis of
a broad set of health risk measures and information.'' 54 FR 38044,
38046 (Sept. 14, 1989). Similarly, with regard to making the ample
margin of safety determination, as stated in the Benzene NESHAP ``[I]n
the ample margin decision, the EPA again considers all of the health
risk and other health information considered in the first step. Beyond
that information, additional factors relating to the appropriate level
of control will also be considered, including cost and economic impacts
of controls, technological feasibility, uncertainties, and any other
relevant factors.'' Id.
    The EPA acknowledges that flexibility is provided by the Benzene
NESHAP regarding what factors EPA might consider in making
determinations and how they might be weighed for each source category.
In responding to comment on our policy under the Benzene NESHAP, EPA
explained that: ``The policy chosen by the Administrator permits
consideration of multiple measures of health risk. Not only can the MIR
figure be considered, but also incidence, the presence of non-cancer
health effects, and the uncertainties of the risk estimates. In this
way, the effect on the most exposed individuals can be reviewed as well
as the impact on the general public. These factors can then be weighed
in each individual case. This approach complies with the Vinyl Chloride
mandate that the Administrator ascertain an acceptable level of risk to
the public by employing [her] expertise to assess available data. It
also complies with the Congressional intent behind the CAA, which did
not exclude the use of any particular measure of public health risk
from the EPA's consideration with respect to CAA section 112
regulations, and, thereby, implicitly permits consideration of any and
all measures of health risk which the Administrator, in [her] judgment,
believes are appropriate to determining what will `protect the public
health.' '' 54 FR 38057.
    For example, the level of the MIR is only one factor to be weighed
in determining acceptability of risks. It is explained in the Benzene
NESHAP ``an MIR of approximately 1-in-10 thousand should ordinarily be
the upper end of the range of acceptability. As risks increase above
this benchmark, they become presumptively less acceptable under CAA
section 112, and would be weighed with the other health risk measures
and information in making an overall judgment on acceptability. Or, the
EPA may find, in a particular case, that a risk that includes MIR less
than the presumptively acceptable level is unacceptable in the light of
other health risk factors.'' Id. at 38045. Similarly, with regard to
the ample margin of safety analysis, it is stated in the Benzene NESHAP
that: ``* * * EPA believes the relative weight of the many

factors that can be considered in selecting an ample margin of safety
can only be determined for each specific source category. This occurs
mainly because technological and economic factors (along with the
health-related factors) vary from source category to source category.''
Id. at 38061.
    EPA wishes to point out that certain health information has not
been considered in these decisions. In assessing risks to populations
in the vicinity of the facilities in each category, we present
estimates of risk associated with HAP emissions from the source
category alone (source category risk estimates) and HAP emissions from
the entire facilities at which the covered source categories are
located (facility-wide risk estimates). We do not attempt to
characterize the risks associated with all HAP emissions impacting the
populations living near the sources in these categories. That is, we
have not presented estimates of total HAP inhalation risks from all
sources in the vicinity of the covered sources (e.g., the sum of the
risks from ambient levels, emissions from the source category,
facility-wide emissions, and emissions from other facilities nearby),
nor have we attempted to include estimates of total HAP inhalation
risks from indoor sources such as from cooking or degassing from
consumer products.
    The EPA understands the potential importance of considering an
individual's total exposure to HAP in addition to considering exposure
to HAP emissions from the source category and facility. While such
considerations are relevant to both cancer and non-cancer risk
assessments, they can be particularly important when assessing
cumulative non-cancer risks, where pollutant-specific risk-based
exposure levels (e.g., RfC) are based on the assumption that thresholds
exist for adverse health effects. For example, the EPA recognizes that,
although exposures attributable to emissions from a source category or
facility alone may not indicate the potential for increased risk of
adverse non-cancer health effects in a population, the exposures
resulting from emissions from the facility in combination with
emissions from all of the other sources (e.g., other facilities) to
which an individual is exposed, may be sufficient to result in
increased risk of adverse non-cancer health effects. In May 2010, the
SAB advised us ``* * * that RTR assessments will be most useful to
decision makers and communities if results are presented in the broader
context of aggregate and cumulative risks, including background
concentrations and contributions from other sources in the area.'' \4\
---------------------------------------------------------------------------

    \4\ EPA's responses to this and all other key recommendations of
the SAB's advisory on RTR risk assessment methodologies (which is
available at: http://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf)
are outlined in a memo to this rulemaking docket from David Guinnup
entitled, EPA's Actions in Response to the Key Recommendations of
the SAB Review of RTR Risk Assessment Methodologies.
---------------------------------------------------------------------------

    While we are interested in placing source category and facility-
wide HAP risks in the context of total HAP risks from all sources
combined in the vicinity of each source, we are concerned about the
uncertainties of doing so. At this point, we believe that such
estimates of total HAP risks will have significantly greater associated
uncertainties than for the source category or facility-wide estimates,
hence compounding the uncertainty in any such comparison. This is
because we have not conducted a detailed technical review of HAP
emissions data for source categories and facilities that have not
previously undergone a RTR review or are not currently undergoing such
review. We are requesting comment on whether and how best to estimate
and evaluate total HAP exposure from outdoor sources in our
assessments, and, in particular, on whether and how it might be
appropriate to use information from EPA's NATA to support such
estimates. We also request comment whether and how to estimate total
HAP exposure from indoor sources in the context of these assessments.
We are also seeking comment on how best to consider various types and
scales of risk estimates when making our acceptability and ample margin
of safety determinations under CAA section 112(f). Additionally, we are
seeking comments and recommendations for any other comparative measures
that may be useful in the assessment of the distribution of HAP risks
across potentially affected demographic groups.

C. What other actions are we addressing in this proposal?

    We are also proposing to revise requirements in these MACT
standards related to emissions during periods of SSM. The United States
Court of Appeals for the District of Columbia Circuit vacated portions
of two provisions in EPA's CAA section 112 regulations governing the
emissions of HAP during periods of SSM. Sierra Club v. EPA, 551 F.3d
1019 (DC Cir. 2008), cert. denied, 130 S. Ct. 1735 (U.S. 2010).
Specifically, the Court vacated the SSM exemption contained in 40 CFR
63.6(f)(1) and 40 CFR 63.6(h)(1), that are part of a regulation,
commonly referred to as the General Provisions Rule, that EPA
promulgated under section 112 of the CAA. When incorporated into CAA
section 112(d) regulations for specific source categories, these two
provisions exempt sources from the requirement to comply with the
otherwise applicable CAA section 112(d) emission standard during
periods of SSM.
    We are proposing the elimination of the SSM exemption in both of
the MACT standards addressed in this proposal. Consistent with Sierra
Club v. EPA, EPA is proposing standards in these rules that apply at
all times. In proposing the standards in these rules, EPA has taken
into account startup and shutdown periods, and, because operations and
emissions do not differ from normal operations during these periods,
has not proposed different standards for these periods. We are also
proposing several revisions to the General Provisions Applicability
table in both of the MACT standards. For example, we are proposing to
eliminate the incorporation of the General Provisions' requirement that
the source develop a SSM plan. We are also proposing to eliminate or
revise certain recordkeeping and reporting requirements related to the
SSM exemption. EPA has attempted to ensure that we have not included in
the proposed regulatory language any provisions that are inappropriate,
unnecessary, or redundant in the absence of the SSM exemption. We are
specifically seeking comment on whether there are any such provisions
that we have inadvertently incorporated or overlooked.
    Periods of startup, normal operations, and shutdown are all
predictable and routine aspects of a source's operations. However, by
contrast, malfunction is defined as a ``sudden, infrequent, and not
reasonably preventable failure of air pollution control and monitoring
equipment, process equipment or a process to operate in a normal or
usual manner * * *'' (40 CFR 63.2). EPA has determined that
malfunctions should not be viewed as a distinct operating mode and,
therefore, any emissions that occur at such times do not need to be
factored into development of CAA section 112(d) standards, which, once
promulgated, apply at all times. In Mossville Environmental Action Now
v. EPA, 370 F.3d 1232, 1242 (DC Cir. 2004), the Court upheld as
reasonable standards that had factored in variability of emissions
under all operating conditions. However, nothing in CAA section 112(d)
or in case law requires that EPA anticipate and

account for the innumerable types of potential malfunction events in
setting emission standards. See Weyerhaeuser v. Costle, 590 F.2d 1011,
1058 (DC Cir. 1978), (``In the nature of things, no general limit,
individual permit, or even any upset provision can anticipate all upset
situations. After a certain point, the transgression of regulatory
limits caused by ``uncontrollable acts of third parties,'' such as
strikes, sabotage, operator intoxication or insanity, and a variety of
other eventualities, must be a matter for the administrative exercise
of case-by-case enforcement discretion, not for specification in
advance by regulation.''). Further, it is reasonable to interpret CAA
section 112(d) as not requiring EPA to account for malfunctions in
setting emissions standards. For example, we note that CAA section 112
uses the concept of ``best performing'' sources in defining MACT, the
level of stringency that major source standards must meet. Applying the
concept of ``best performing'' to a source that is malfunctioning
presents significant difficulties. The goal of best performing sources
is to operate in such a way as to avoid malfunctions of their units.
Moreover, even if malfunctions were considered a distinct operating
mode, we believe it would be impracticable to take malfunctions into
account in setting CAA section 112(d) standards for shipbuilding and
ship repair (surface coating) and wood furniture manufacturing
operations. As noted above, by definition, malfunctions are sudden and
unexpected events, and it would be difficult to set a standard that
takes into account the myriad different types of malfunctions that can
occur across all sources in each source category. Malfunctions can also
vary in frequency, degree, and duration, further complicating standard
setting.
    In the event that a source fails to comply with the applicable CAA
section 112(d) standards as a result of a malfunction event, EPA would
determine an appropriate response based on, among other things, the
good faith efforts of the source to minimize emissions during
malfunction periods, including preventative and corrective actions, as
well as root cause analyses to ascertain and rectify excess emissions.
EPA would also consider whether the source's failure to comply with the
CAA section 112(d) standard was, in fact, ``sudden, infrequent, not
reasonably preventable'' and was not instead ``caused in part by poor
maintenance or careless operation.'' 40 CFR 63.2 (definition of
malfunction).
    Finally, EPA recognizes that even equipment that is properly
designed and maintained can sometimes fail and that such failure can
sometimes cause or contribute to an exceedance of the relevant emission
standard. (See, e.g., State Implementation Plans: Policy Regarding
Excessive Emissions During Malfunctions, Startup, and Shutdown
(September 20, 1999); Policy on Excess Emissions During Startup,
Shutdown, Maintenance, and Malfunctions (February 15, 1983)). EPA is,
therefore, proposing to add to the final rule an affirmative defense to
civil penalties for exceedances of emission limits that are caused by
malfunctions in both of the MACT standards addressed in this proposal.
See 40 CFR 63.782 for sources subject to the Shipbuilding and Repair
(Surface Coating) MACT standards, or 40 CFR 63.801 for sources subject
to the Wood Furniture Manufacturing Operations MACT standards (defining
``affirmative defense'' to mean, in the context of an enforcement
proceeding, a response or defense put forward by a defendant, regarding
which the defendant has the burden of proof, and the merits of which
are independently and objectively evaluated in a judicial or
administrative proceeding). We also are proposing other regulatory
provisions to specify the elements that are necessary to establish this
affirmative defense; a source subject to the Shipbuilding and Ship
Repair (Surface Coating) MACT standards must prove by a preponderance
of the evidence that it has met all of the elements set forth in 40 CFR
63.781(d) and a source subject to the Wood Furniture Manufacturing
Operations MACT standards must prove by a preponderance of the evidence
that it has met all of the elements set forth in 40 CFR 63.800(h). (See
40 CFR 22.24.) The criteria ensure that the affirmative defense is
available only where the event that causes an exceedance of the
emission limit meets the narrow definition of malfunction in 40 CFR
63.2 (sudden, infrequent, not reasonably preventable and not caused by
poor maintenance and or careless operation). For example to
successfully assert the affirmative defense, the source must prove by a
preponderance of evidence that excess emissions ``[w]ere caused by a
sudden, short, infrequent, and unavoidable failure of air pollution
control and monitoring equipment, process equipment, or a process to
operate in a normal or usual manner. * * *'' The criteria also are
designed to ensure that steps are taken to correct the malfunction, to
minimize emissions in accordance with 40 CFR 63.783(b)(1) for sources
subject to the Shipbuilding and Ship Repair (Surface Coating) MACT
standards, or 40 CFR 63.802(c) for sources subject to the Wood
Furniture Manufacturing Operations MACT standards, and to prevent
future malfunctions. For example the source must prove by a
preponderance of evidence that ``[r]epairs were made as expeditiously
as possible when the applicable emission limitations were being
exceeded* * *'' and that ``[a]ll possible steps were taken to minimize
the impact of the excess emissions on ambient air quality, the
environment and human health* * *'' In any judicial or administrative
proceeding, the Administrator may challenge the assertion of the
affirmative defense and, if the respondent has not met its burden of
proving all of the requirements in the affirmative defense, appropriate
penalties may be assessed in accordance with section 113 of the CAA
(see also 40 CFR 22.77).

IV. Analyses Performed

    As discussed above, in this notice, we are taking the following
actions: (1) we are proposing action to address the RTR requirements of
CAA sections 112(d)(6) and (f)(2) for both the Shipbuilding and Ship
Repair (Surface Coating) and the Wood Furniture Manufacturing
Operations MACT standards; and, (2) we are proposing to revise the
provisions in both of these MACT standards to address SSM to ensure
that the SSM provisions are consistent with the Court decision in
Sierra Club v. EPA, 551 F. 3d 1019. In this section, we describe the
analyses performed to support the proposed decisions for the RTRs for
each of these source categories.

A. How did we estimate risks posed by the source categories?

    The EPA conducted risk assessments that provided estimates of the
MIR posed by the HAP emissions from each source in a category, and, by
each source category, the distribution of cancer risks within the
exposed populations, cancer incidence, HI for chronic exposures to HAP
with the potential to cause non-cancer health effects, HQ for acute
exposures to HAP with the potential to cause non-cancer health effects,
and an evaluation of the potential for adverse environmental effects.
The risk assessments consisted of seven primary steps, as discussed
below. The docket for this rulemaking contains the following documents
which provide more information on the risk assessment inputs and
models: Draft Residual Risk Assessment for the Wood Furniture
Manufacturing Operations Source Category, and Draft Residual Risk
Assessment for the

Shipbuilding and Ship Repair Source Category.
1. Establishing the Nature and Magnitude of Actual Emissions and
Identifying the Emissions Release Characteristics
    For the Shipbuilding and Ship Repair (Surface Coating) source
category, we compiled preliminary datasets using readily-available
information, reviewed the data, made changes where necessary, and
shared these data with the public via an ANPRM. 72 FR 29287, March 29,
2007. The preliminary dataset was based on data in the 2002 National
Emissions Inventory (NEI) Final Inventory, Version 1 (made publicly
available on February 26, 2006).\5\ The preliminary dataset was updated
with information received in response to the ANPRM; data from the 2005
NEI, when that data became available; and additional data gathered by
EPA. For more information see the Memoranda Documenting Changes to the
RTR Dataset for the Shipbuilding and Ship Repair (Surface Coating)
Source Category, dated November 22, 2010, which is available in the
docket for this action. The updated dataset contains 85 facilities and
was used to conduct the risk assessments and other analyses that form
the basis for the proposed actions for the Shipbuilding and Ship Repair
(Surface Coating) source category.
---------------------------------------------------------------------------

    \5\ The 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, non-point, and mobile sources in the 50
states, the District of Columbia, Puerto Rico, and the Virgin
Islands. The EPA collects this information and releases an updated
version of the NEI database every three years.
---------------------------------------------------------------------------

    For the Wood Furniture Manufacturing Operations source category, we
compiled preliminary datasets using the best data available, reviewed
the data, and made changes where necessary. For this source category,
we compiled the preliminary datasets using data in the 2005 NEI. After
incorporation of changes to the dataset based on additional information
gathered by EPA, an updated dataset was created. This updated dataset
contains 385 facilities and was used to conduct the risk assessments
and other analyses that form the basis for the proposed actions for the
Wood Furniture Manufacturing Operations source category.
2. Establishing the Relationship Between Actual Emissions and MACT-
Allowable Emissions Levels
    The available emissions data in the NEI and from other sources
typically represent the estimates of mass of emissions actually emitted
during the specified annual time period. These ``actual'' emission
levels are often lower than the emission levels that a facility might
be allowed to emit and still comply with the MACT standards. The
emissions level allowed to be emitted by the MACT standards is referred
to as the ``MACT-allowable'' emissions level. This represents the
highest emissions level that could be emitted by the facility without
violating the MACT standards.
    We discussed the use of both MACT-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 HON residual risk rules
(71 FR 34428, June 14, 2006, and 71 FR 76609, December 21, 2006,
respectively). In those previous actions, we noted that assessing the
risks at the MACT-allowable level is inherently reasonable since these
risks 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 risk analysis, in accordance with the Benzene
NESHAP. (54 FR 38044, September 14, 1989.) It is reasonable to consider
actual emissions because sources typically seek to perform better than
required by emission standards to provide an operational cushion to
accommodate the variability in manufacturing processes and control
device performance.
    As described above, the actual emissions data were compiled based
on the NEI, information gathered from companies, individual facilities,
industry trade associations, states, and information received in
response to the ANPRM. To estimate emissions at the MACT-allowable
level, we developed a ratio of MACT-allowable to actual emissions for
each emissions source type in each source category, based on the level
of control required by the MACT standards compared to the level of
reported actual emissions and available information on the level of
control achieved by the emissions controls in use. For example, if
there was information to suggest several facilities in the Shipbuilding
and Ship Repair (Surface Coating) source category were using coatings
that contain only 1 Kg of VOHAP compounds per Kg of coating solids (kg
VOHAP/kg solids) while the MACT standards required coatings to contain
no more than 2 kg VOHAP/kg solids, we would estimate that MACT-
allowable emissions from emission points using these coatings could be
as much as 2 times higher (VOHAP content of 2 kg/kg solids allowed
compared with VOHAP content of 1 kg/kg solids actually used), and the
ratio of MACT-allowable to actual would be 2:1 for the emission points
using these coatings at the facilities in this source category. After
developing these ratios for each emission point type in each source
category, we next applied these ratios on a facility-by-facility basis
to the maximum chronic risk estimates from the inhalation risk
assessment to obtain facility-specific maximum risk estimates based on
MACT-allowable emissions. The estimates of MACT-allowable emissions for
the Wood Furniture Manufacturing Operations and Shipbuilding and Ship
Repair (Surface Coating) source categories are described in section V
of this preamble.
3. Conducting Dispersion Modeling, Determining Inhalation Exposures,
and Estimating Individual and Population Inhalation Risks
    Both long-term and short-term inhalation exposure concentrations
and health risks from each of the source categories addressed in this
proposal were estimated using the HEM (Community and Sector HEM-3
version 1.1.0). The HEM-3 performs three of the primary risk assessment
activities listed above: (1) Conducting dispersion modeling to estimate
the concentrations of HAP in ambient air, (2) estimating long-term and
short-term inhalation exposures to individuals residing within 50 km of
the modeled sources, and (3) estimating individual and population-level
inhalation risks using the exposure estimates and quantitative dose-
response information.
    The dispersion model used by HEM-3 is AERMOD, which is one of EPA's
preferred models for assessing pollutant concentrations from industrial
facilities.\6\ 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 is used for dispersion
calculations. This library includes one year of hourly surface and
upper air observations for 130 meteorological stations, selected to
provide coverage of the United States and Puerto Rico. A second library
of United States Census Bureau census block \7\ internal point

locations and populations provides the basis of human exposure
calculations (Census, 2000). In addition, for each census block, the
census library includes the elevation and controlling hill height,
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. These values are available at http://www.epa.gov/ttn/atw/toxsource/summary.html and are discussed in more detail later in this
section.
---------------------------------------------------------------------------

    \6\ U.S. EPA. 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).
    \7\ A census block is generally the smallest geographic area for
which census statistics are tabulated.
---------------------------------------------------------------------------

    In developing the risk assessment for chronic exposures, we used
the estimated annual average ambient air concentration of each of the
HAP emitted by each source for which we have emissions data in the
source category. The air concentrations at each nearby census block
centroid were used as a surrogate for the chronic inhalation exposure
concentration for all the people who reside in that census block. We
calculated the MIR for each facility as the cancer risk associated with
a continuous lifetime (24 hours per day, 7 days per week, and 52 weeks
per year for a 70-year period) exposure to the maximum concentration at
the centroid of an inhabited census block. Individual cancer risks were
calculated by multiplying the estimated lifetime exposure to the
ambient concentration of each of the HAP (in micrograms per cubic
meter) by its URE, which is an upper bound estimate of an individual's
probability of contracting cancer over a lifetime of exposure to a
concentration of 1 microgram of the pollutant per cubic meter of air.
For residual risk assessments, we generally use URE values from EPA's
IRIS. For carcinogenic pollutants without EPA IRIS values, we look to
other reputable sources of cancer dose-response values, often using
CalEPA URE values, where available. In cases where new, scientifically
credible dose-response values have been developed in a manner
consistent with EPA guidelines and have undergone a peer review process
similar to that used by EPA, we may use such dose-response values in
place of, or in addition to, other values, if appropriate.
    Formaldehyde is a unique case. In 2004, EPA determined that the
CIIT dose-response value for formaldehyde (5.5 x 10-9 [mu]g/
m\3\) was based on better science than the IRIS dose-response value
(1.3 x 10-5 [mu]g/m\3\), and we switched from using the IRIS
value to the CIIT value in risk assessments supporting regulatory
actions. This determination was based on a substantial body of research
on the inhalation dosimetry for formaldehyde in rodents and primates by
the CIIT Centers for Health Research (formerly the CIIT), with a focus
on use of rodent data for refinement of the quantitative cancer dose-
response assessment.8 9 10 The CIIT's risk assessment of
formaldehyde incorporated mechanistic and dosimetric information on
formaldehyde. However, recent research published by EPA indicates that,
when the CIIT's two-stage modeling assumptions are varied, resulting
dose-response estimates can vary by several orders of
magnitude.11 12 13 14 These findings are not supportive of
interpreting the CIIT model results as providing a conservative
(health-protective) estimate of human risk.\15\ The recent EPA research
also examined the contribution of the two-stage modeling for
formaldehyde towards characterizing the relative weights of key events
in the mode-of-action of a carcinogen. For example, in the EPA
research, the model-based inference in the published CIIT study that
formaldehyde's direct mutagenic action is not relevant to the
compound's tumorigenicity was found not to hold under variations of
modeling assumptions.\16\ As a result of these findings, we no longer
considered the CIIT URE value health protective, and we are again using
the EPA's current value on IRIS, which was last revised in 1991, and
which is more than 2000 times greater than the CIIT value. We note that
a new IRIS re-assessment has been drafted and sent to the NAS for
review. The NAS review is expected to be completed by March of 2011. We
also note that POM, a carcinogenic HAP with a mutagenic mode of action,
is emitted by some of the facilities in these two categories.\17\ For
this compound group,\18\ the ADAF described in EPA's Supplemental
Guidance for Assessing Susceptibility from Early-Life Exposure to
Carcinogens \19\ were applied. This adjustment has the effect of
increasing the estimated lifetime risks for POM by a factor of 1.6. In
addition, although only a small fraction of the total POM emissions
were not reported as individual compounds, EPA expresses carcinogenic
potency for compounds in this group in terms of benzo[a]pyrene
equivalence, based on evidence that carcinogenic POM has the same
mutagenic mechanism of action as benzo[a]pyrene. For this reason, EPA's
Science Policy Council \20\ recommends applying the Supplemental
Guidance to all carcinogenic polycyclic aromatic hydrocarbons for which
risk estimates are based on relative potency. Accordingly, we have
applied the ADAF to the benzo[a]pyrene equivalent portion of all POM
mixtures.
---------------------------------------------------------------------------

    \8\ Conolly, RB, Kimbell, JS, Janszen, D, Schlosser, PM,
Kalisak, D, Preston, J, and Miller, FJ. 2003. Biologically Motivated
Computational Modeling of Formaldehyde Carcinogencity in the F344
Rat. Tox Sci 75: 432-447.
    \9\ Conolly, RB, Kimbell, JS, Janszen, D, Schlosser, PM,
Kalisak, D, Preston, J, and Miller, FJ. 2004. Human Respiratory
Tract Cancer Risks of Inhaled Formaldehyde: Dose-Response
Predictions Derived from Biologically-Motivated Computational
Modeling of a Combined Rodent and Human Dataset. Tox Sci 82: 279-
296.
    \10\ Chemical Industry Institute of Toxicology (CIIT). 1999.
Formaldehyde: Hazard Characterization and Dose-Response Assessment
for Carcinogenicity by the Route of Inhalation. CIIT, September 28,
1999. Research Triangle Park, NC.
    \11\ U.S. EPA. Analysis of the Sensitivity and Uncertainty in 2-
Stage Clonal Growth Models for Formaldehyde with Relevance to Other
Biologically-Based Dose Response (BBDR) Models. U.S. EPA,
Washington, D.C., EPA/600/R-08/103, 2008.
    \12\ Subramaniam, R; Chen, C; Crump, K; et al. (2008).
Uncertainties in Biologically-Based Modeling of Formaldehyde-Induced
Cancer Risk: Identification of Key Issues. Risk Anal 28 (4):907-923.
    \13\ Subramaniam RP; Crump KS; Van Landingham C; White P; Chen
C; Schlosser PM (2007). Uncertainties in the CIIT model for
formaldehyde-induced carcinogenicity in the rat: A limited
sensitivity analysis-I. Risk Anal, 27: 1237-1254.
    \14\ Crump, K; Chen, C; Fox, J; et al. (2008). Sensitivity
Analysis of Biologically Motivated Model for Formaldehyde-Induced
Respiratory Cancer in Humans. Ann Occup Hyg 52:481-495.
    \15\ Crump, K; Chen, C; Fox, J; et al. (2008). Sensitivity
Analysis of Biologically Motivated Model for Formaldehyde-Induced
Respiratory Cancer in Humans. Ann Occup Hyg 52:481-495.
    \16\ Subramaniam RP; Crump KS; Van Landingham C; White P; Chen
C; Schlosser PM (2007). Uncertainties in the CIIT model for
formaldehyde-induced carcinogenicity in the rat: A limited
sensitivity analysis-I. Risk Anal, 27: 1237-1254.
    \17\ U.S. EPA, 2005. Performing risk assessments that include
carcinogens described in the Supplemental Guidance as having a
mutagenic mode of action. Science Policy Council Cancer Guidelines
Implementation Work Group Communication II: Memo from W.H. Farland,
dated October 4, 2005.
    \18\ See the Risk Assessment for Source Categories document
available in the docket for a list of HAP with a mutagenic mode of
action.
    \19\ U.S. EPA, 2005. Supplemental Guidance for Assessing Early-
Life Exposure to Carcinogens. EPA/630/R-03/003F. http://www.epa.gov/ttn/atw/childrens_supplement_final.pdf.
    \20\ U.S. EPA, 2006. Science Policy Council Cancer Guidelines
Implementation Workgroup Communication II: Memo from W.H. Farland,
dated June 14, 2006.
---------------------------------------------------------------------------

    Incremental individual lifetime cancer risks associated with
emissions from the source category were estimated as the sum of the
risks for each of the carcinogenic HAP (including those classified as
carcinogenic to humans, likely to be carcinogenic to humans, and
suggestive evidence of carcinogenic

potential \21\) emitted by the modeled source. Cancer incidence and the
distribution of individual cancer risks for the population within 50 km
of any source were also estimated for the source category as part of
these assessments by summing individual risks. A distance of 50 km is
consistent with both the analysis supporting the 1989 Benzene NESHAP
(54 FR 38044) and the limitations of Gaussian dispersion models,
including AERMOD.
---------------------------------------------------------------------------

    \21\ These classifications also coincide with the terms ``known
carcinogen, probable carcinogen, and possible carcinogen,''
respectively, which are the terms advocated in the EPA's previous
Guidelines for Carcinogen Risk Assessment, published in 1986 (51 FR
33992, September 24, 1986). Summing the risks of these individual
compounds to obtain the cumulative cancer risks is an approach that
was recommended by the EPA's SAB in their 2002 peer review of EPA's
NATA entitled, NATA--Evaluating the National-scale Air Toxics
Assessment 1996 Data--an SAB Advisory, available at: http://
yosemite.epa.gov/sab/sabproduct.nsf/
214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf.
---------------------------------------------------------------------------

    To assess risk of non-cancer health effects from chronic exposures,
we summed the HQ for each of the HAP that affects a common target organ
system to obtain the HI for that target organ system (or target organ-
specific HI, TOSHI). The HQ for chronic exposures is the estimated
chronic exposure divided by the chronic reference level, which is
either the EPA RfC, defined as ``an estimate (with uncertainty spanning
perhaps an order of magnitude) of a continuous inhalation exposure to
the human population (including sensitive subgroups) that is likely to
be without an appreciable risk of deleterious effects during a
lifetime,'' or, in cases where an RfC from EPA's IRIS database is not
available, EPA will utilize the following prioritized sources for our
chronic dose-response values: (1) The ATSDR MRL, which is defined as
``an estimate of daily human exposure to a substance that is likely to
be without an appreciable risk of adverse effects (other than cancer)
over a specified duration of exposure''; (2) the CalEPA Chronic REL,
which is defined as ``the concentration level at or below which no
adverse health effects are anticipated for a specified exposure
duration;'' and (3) as noted above, in cases where scientifically
credible dose-response values have been developed in a manner
consistent with EPA guidelines and have undergone a peer review process
similar to that used by EPA, we may use those dose-response values in
place of, or in concert with other values.
    Screening estimates of acute exposures and risks were also
evaluated for each of the HAP at the point of highest off-site exposure
for each facility (i.e., not just the census block centroids) assuming
that a person is located at this spot at a time when both the peak
(hourly) emission rate and hourly dispersion conditions (1991 calendar
year data) occur. The acute HQ is the estimated acute exposure divided
by the acute dose-response value. In each case, acute HQ values were
calculated using best available, short-term dose-response values. These
acute dose-response values, which are described below, include the
acute REL, AEGL, and ERPG for 1-hour exposure durations. As discussed
below, we used conservative assumptions for emission rates,
meteorology, and exposure location for our acute analysis.
    As described in the CalEPA's Air Toxics Hot Spots Program Risk
Assessment Guidelines, Part I, The Determination of Acute Reference
Exposure Levels for Airborne Toxicants, an acute REL value (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.'' Acute REL values are
based on the most sensitive, relevant, adverse health effect reported
in the medical and toxicological literature. Acute REL values are
designed to protect the most sensitive individuals in the population by
the inclusion of margins of safety. Since margins of safety are
incorporated to address data gaps and uncertainties, exceeding the
acute REL does not automatically indicate an adverse health impact.
    Acute Exposure Guideline Levels values were derived in response to
recommendations from the NRC. As described in Standing Operating
Procedures (SOP) of the National Advisory Committee on Acute Exposure
Guideline Levels for Hazardous Substances (http://www.epa.gov/opptintr/aegl/pubs/sop.pdf),\22\ ``the NRC's previous name for acute exposure
levels--community emergency exposure levels (CEEL)-- was replaced by
the term AEGL to reflect the broad application of these values to
planning, response, and prevention in the community, the workplace,
transportation, the military, and the remediation of Superfund sites.''
This document also states that AEGL values ``represent threshold
exposure limits for the general public and are applicable to emergency
exposures ranging from 10 minutes to eight hours.'' The document lays
out the purpose and objectives of AEGL by stating (page 21) that ``the
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.''
In detailing the intended application of AEGL values, the document
states (page 31) that ``[i]t is anticipated that the AEGL values will
be used for regulatory and nonregulatory purposes by United States
Federal and State agencies, and possibly the international community in
conjunction with chemical emergency response, planning, and prevention
programs. More specifically, the AEGL values will be used for
conducting various risk assessments to aid in the development of
emergency preparedness and prevention plans, as well as real-time
emergency response actions, for accidental chemical releases at fixed
facilities and from transport carriers.''
---------------------------------------------------------------------------

    \22\ National Academies of Science, 2001. Standing Operating
Procedures for Developing Acute Exposure Levels for Hazardous
Chemicals, page 2.
---------------------------------------------------------------------------

    The AEGL-1 value is then specifically defined as ``the airborne
concentration 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.'' The document also notes (page
3) that, ``Airborne concentrations below AEGL-1 represent exposure
levels that can produce mild and progressively increasing but transient
and nondisabling odor, taste, and sensory irritation or certain
asymptomatic, nonsensory effects.'' Similarly, the document defines
AEGL-2 values as ``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
irreversible or other serious, long-lasting adverse health effects or
an impaired ability to escape.''
    Emergency Response Planning Guidelines values are derived for use
in emergency response, as described in the American Industrial Hygiene
Association's document entitled, Emergency Response Planning Guidelines
(ERPG) Procedures and Responsibilities (http://www.aiha.org/1documents/committees/ERPSOPs2006.pdf), which states that, ``Emergency Response
Planning Guidelines were developed for emergency planning and are
intended as health based guideline concentrations

for single exposures to chemicals.'' \23\ The ERPG-1 value is defined
as ``the maximum airborne concentration below which it is believed that
nearly all individuals could be exposed for up to one hour without
experiencing other than mild transient adverse health effects or
without perceiving a clearly defined, objectionable odor.'' Similarly,
the ERPG-2 value is defined as ``the maximum airborne concentration
below which it is believed that nearly all individuals could be exposed
for up to one hour without experiencing or developing irreversible or
other serious health effects or symptoms which could impair an
individual's ability to take protective action.''
---------------------------------------------------------------------------

    \23\ ERP Committee Procedures and Responsibilities. 1 November,
2006. American Industrial Hygiene Association.
---------------------------------------------------------------------------

    As can be seen from the definitions above, the AEGL and ERPG values
include the similarly-defined severity levels one and 2. For many
chemicals, a severity level one value AEGL or ERPG has not been
developed; in these instances, higher severity level AEGL-2 or ERPG-2
values are compared to our modeled exposure levels to screen for
potential acute concerns.
    Acute REL values for one hour exposure durations are typically
lower than their corresponding AEGL-1 and ERPG-1 values. Even though
their definitions are slightly different, AEGL-1 values are often the
same as the corresponding ERPG-1 values, and AEGL-2 values are often
equal to ERPG-2 values. Maximum HQ values from our acute screening risk
assessments typically result when basing them on the acute REL value
for a particular pollutant. In cases where our maximum acute HQ value
exceeds 1, we also report the HQ value based on the next highest acute
dose-response value (usually the AEGL-1 and/or the ERPG-1 value).
    To develop screening estimates of acute exposures, we developed
estimates of maximum hourly emission rates by multiplying the average
actual annual hourly emission rates by a factor to cover routinely
variable emissions. We chose the factor based on process knowledge and
engineering judgment and with awareness of a Texas study of short-term
emissions variability, which showed that most peak emission events, in
a heavily-industrialized 4-county area (Harris, Galveston, Chambers,
and Brazoria Counties, Texas) were less than twice the annual average
hourly emission rate. The highest peak emission event was 74 times the
annual average hourly emission rate, and the 99th percentile ratio of
peak hourly emission rate to the annual average hourly emission rate
was 9.\24\ This analysis is provided in Appendix 4 of the Draft
Residual Risk Assessment for Wood Furniture Manufacturing Operations,
and Draft Residual Risk Assessment for Shipbuilding and Ship Repair
(Surface Coating) which are available in the docket for this action.
Considering this analysis, unless specific process knowledge or data
are available to provide an alternate value, to account for more than
99 percent of the peak hourly emissions, we apply a conservative
screening multiplication factor of 10 to the average annual hourly
emission rate in these acute exposure screening assessments. For the
Shipbuilding and Ship Repair (Surface Coating) source category, this
factor of 10 was applied. For the Wood Furniture Manufacturing
Operations source category, a factor of 4 was applied, based on
emissions data provided by industry. More information supporting the
use of this factor for Wood Furniture Manufacturing Operations is
presented in the memorandum, Acute Effects Factor for Wood Furniture
Manufacturing Operations, dated November 23, 2010, which is available
in the docket for this action. We solicit comment on this factor and
the data used to calculate it.
---------------------------------------------------------------------------

    \24\ 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 all acute HQ values from the screening step were
less than or equal to 1, 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 1, additional site-specific data were
considered to develop a more refined estimate of the potential for
acute impacts of concern. The data refinements employed for these
source categories consisted of using the site-specific facility layout
to distinguish facility property from an area where the public could be
exposed. These refinements are discussed in the draft risk assessment
documents, which are available in the docket, for each of these source
categories. Ideally, we would prefer to have continuous measurements
over time to see how the emissions vary by each hour over an entire
year. Having a frequency distribution of hourly emission rates over a
year would allow us to perform a probabilistic analysis to estimate
potential threshold exceedances and their frequency of occurrence. Such
an evaluation could include a more complete statistical treatment of
the key parameters and elements adopted in this screening analysis.
However, we recognize that having this level of data is rare, hence our
use of the multiplier approach.
4. Conducting Multi-Pathway Exposure and Risk Modeling
    The potential for significant human health risks due to exposures
via routes other than inhalation (i.e., multi-pathway exposures) and
the potential for adverse environmental impacts were evaluated in a
three-step process. In the first step, we determined whether any
facilities emitted any HAP known to be PB-HAP. There are 14 PB-HAP
compounds or compound classes identified for this screening in EPA's
Air Toxics Risk Assessment Library (available at http://www.epa.gov/ttn/fera/risk_atra_vol1.html). They are cadmium compounds, chlordane,
chlorinated dibenzodioxins and furans,
dichlorodiphenyldichloroethylene, heptachlor, hexachlorobenzene,
hexachlorocyclohexane, lead compounds, mercury compounds, methoxychlor,
polychlorinated biphenyls, POM, toxaphene, and trifluralin.
    Since one or more of these PB-HAP are emitted by facilities in both
source categories, we proceeded to the second step of the evaluation.
In this step, we determined whether the facility-specific emission
rates of each of the emitted PB-HAP were large enough to create the
potential for significant non-inhalation risks. To facilitate this
step, we have developed emission rate thresholds for each PB-HAP using
a hypothetical screening exposure scenario developed for use in
conjunction with the EPA's TRIM.FaTE model. The hypothetical screening
scenario was subjected to a sensitivity analysis to ensure that its key
design parameters were established such that environmental media
concentrations were not underestimated (i.e., to minimize the
occurrence of false negatives, or results that suggest that risks might
be acceptable when, in fact, actual risks are high), and to also
minimize the occurrence of false positives for human health endpoints.
We call this application of the TRIM.FaTE model TRIM-Screen. The
facility-specific emission rates of each of the PB-HAP in each source
category were compared to the emission threshold values for each of the
PB-HAP identified in the source category datasets.
    For all of the facilities in the source categories addressed in
this proposal, all of the PB-HAP emission rates were less than the
emission threshold values. As a result of this, multi-pathway exposures
and environmental risks were

deemed negligible and no further analysis was performed. If the
emission rates of the PB-HAP had been above the emission threshold
values, the source categories would have been further evaluated for
potential non-inhalation risks and adverse environmental effects in a
third step through site-specific refined assessments using EPA's
TRIM.FaTE model.
    For further information on the multi-pathway analysis approach, see
the residual risk documentation as referenced in section IV.A of this
preamble.
5. Assessing Risks Considering Emissions Control Options
    In addition to assessing baseline inhalation risks and screening
for potential multi-pathway risks, where appropriate, we also estimated
risks considering the potential emission reductions that would be
achieved by the particular control options under consideration. In
these cases, the expected emissions reductions were applied to the
specific HAP and emissions sources in the source category dataset to
develop corresponding estimates of risk reductions.
6. Conducting Other Risk-Related Analyses, Including Facility-Wide
Assessments and Demographic Analyses
a. Facility-Wide Risk
    To put the source category risks in context, we also examined the
risks from the entire ``facility,'' where the facility includes all
HAP-emitting operations within a contiguous area and under common
control. In other words, for each facility that includes one or more
sources from one of the source categories under review, we examined the
HAP emissions, not only from the source category of interest, but also
emissions of HAP from all other emission sources at the facility. The
emissions data for generating these ``facility-wide'' risks were
obtained from the 2005 NATA emissions inventory (available at http://www.epa.gov/ttn/atw/nata2005). We estimated the risks due to the
inhalation of HAP that are emitted ``facility-wide'' for the
populations residing within 50 km of each facility, consistent with the
methods used for the source category analysis described above. For
these facility-wide risk analyses, the modeled source category risks
were compared to the facility-wide risks to determine the portion of
facility-wide risks that could be attributed to the source categories
addressed in this proposal. We specifically examined the facilities
associated with the highest estimates of risk and determined the
percentage of that risk attributable to the source category of
interest. The risk documentation available through the docket for this
action provides all the facility-wide risks and the percentage of
source category contribution for all source categories assessed.
    The methodology and the results of the facility-wide analyses for
each source category are included in the residual risk documentation as
referenced in section IV.A of this preamble, which is available in the
docket for this action.
b. Demographic Analysis
    To examine the potential for any EJ issues that might be associated
with each source category, we evaluated the distributions of HAP-
related cancer and non-cancer risks across different social,
demographic, and economic groups within the populations living near the
facilities where these source categories are located. The development
of demographic analyses to inform the consideration of EJ issues in EPA
rulemakings is an evolving science. The EPA offers the demographic
analyses in this rulemaking to inform the consideration of potential EJ
issues, and invites public comment on the approaches used and the
interpretations made from the results, with the hope that this will
support the refinement and improve the utility of such analyses for
future rulemakings.
    For the demographic analyses, we focus on the populations within 50
km of any facility estimated to have exposures to HAP which result in
cancer risks of 1-in-1 million or greater, or non-cancer HI of 1 or
greater (based on the emissions of the source category or the facility,
respectively). We examine the distributions of those risks across
various demographic groups, comparing the percentages of particular
demographic groups to the total number of people in those demographic
groups nationwide. The results, including other risk metrics, such as
average risks for the exposed populations, are documented in source
category-specific technical reports in the docket for both source
categories covered in this proposal.\25\
---------------------------------------------------------------------------

    \25\ For example, the report pertaining to the Shipbuilding and
Ship Repair (Surface Coating) source category is entitled Risk and
Technology Review--Analysis of Socio-Economic Factors for
Populations Living Near Shipbuilding and Ship Repair (Surface
Coating) Operations.
---------------------------------------------------------------------------

    The basis for the risk values used in these analyses were the
modeling results based on actual emissions levels obtained from the
HEM-3 model described above. The risk values for each census block were
linked to a database of information from the 2000 Decennial census that
includes data on race and ethnicity, age distributions, poverty status,
household incomes, and education level. The Census Department
Landview[reg] database was the source of the data on race and
ethnicity, and the data on age distributions, poverty status, household
incomes, and education level were obtained from the SF3 Long Form.
While race and ethnicity census data are available at the census block
level, the age and income census data are only available at the census
block group level (which includes an average of 26 blocks or an average
of 1,350 people). Where census data are available at the block group
level but not the block level, we assumed that all census blocks within
the block group have the same distribution of ages and incomes as the
block group.
    For each source category, we focused on those census blocks where
source category risk results show estimated lifetime inhalation cancer
risks above 1-in-1 million or chronic non-cancer indices above 1, and
determined the relative percentage of different racial and ethnic
groups, different age groups, adults with and without a high school
diploma, people living in households below the national median income,
and for people living below the poverty line within those census
blocks. The specific census population categories studied include:
     Total population
     White
     African American (or Black)
     Native Americans
     Other races and multiracial
     Hispanic or Latino
     Children 18 years of age and under
     Adults 19 to 64 years of age
     Adults 65 years of age and over
     Adults without a high school diploma
     Households earning under the national median income
     People living below the poverty line
    It should be noted that these categories overlap in some instances,
resulting in some populations being counted in more than one category
(e.g., other races and multiracial and Hispanic). In addition, while
not a specific census population category, we also examined risks to
``Minorities,'' a classification which is defined for these purposes as
all race population categories except white.
    For further information about risks to the populations located near
the facilities in these source categories, we also evaluated the
estimated distribution of inhalation cancer and chronic non-cancer
risks associated

with the HAP emissions from all the emissions sources at the facility
(i.e., facility-wide). This analysis used the facility-wide RTR
modeling results and the census data described above.
    The methodology and the results of the demographic analyses for
each source category are included in a source category-specific
technical report for each of the categories, which are available in the
docket for this action.
7. Considering Uncertainties in Risk Assessment
    Uncertainty and the potential for bias are inherent in all risk
assessments, including those performed for the source categories
addressed in this proposal. Although uncertainty exists, we believe
that our approach, which used conservative tools and assumptions,
ensures that our decisions are health-protective. A brief discussion of
the uncertainties in the emissions datasets, dispersion modeling,
inhalation exposure estimates, and dose-response relationships follows
below. A more thorough discussion of these uncertainties is included in
the risk assessment documentation (referenced earlier) available in the
docket for this action.
a. Uncertainties in the Emissions Datasets
    Although the development of the RTR datasets involved quality
assurance/quality control processes, the accuracy of emissions values
will vary depending on the source of the data, the degree to which data
are incomplete or missing, the degree to which assumptions made to
complete the datasets are inaccurate, errors in estimating emissions
values, and other factors. The emission estimates considered in this
analysis generally are annual totals for certain years that do not
reflect short-term fluctuations during the course of a year or
variations from year to year. Additionally, we are aware of a potential
impact on emissions from a chemical reaction during the curing and
gluing of parts in this source category,\26\ which may not be reflected
in our emissions inventory. For example, we believe formaldehyde may be
formed during the chemical process of curing of some coatings
formulations, such as conversion varnishes, which are commonly used at
some wood furniture manufacturing operations. Currently, there are no
EPA-approved methods for estimating formaldehyde emissions from wood
furniture coatings that could potentially be formed as a result of the
curing process. This is an uncertainty that could potentially bias the
risk estimates; however, the extent of this bias is unknown. We request
comment on the extent to which wood furniture coatings covered by this
source category, including but not limited to conversion varnishes,
undergo a chemical reaction during the curing process that yields
formaldehyde, and associated methods for quantifying the resultant
impact on emission levels.
---------------------------------------------------------------------------

    \26\ Howard et al. (1998). Indoor Emissions from Conversion
Varnishes. A[igrave]r & Waste Management Assoc. 48:924-930.
---------------------------------------------------------------------------

    The estimates of peak hourly emission rates for the acute effects
screening assessment were based on multiplication factors applied to
the average annual hourly emission rates (the default factor of 10 was
used for Shipbuilding and Ship Repair (Surface Coating) and a factor of
4 was used for Wood Furniture Manufacturing Operations), which are
intended to account for emission fluctuations due to normal facility
operations. Additionally, although we believe that we have data for
most facilities in these two source categories in our RTR dataset, our
dataset may not include data for all existing facilities. Moreover,
there are significant uncertainties with regard to the identification
of sources as major or area in the NEI for these source categories.
While we published an ANPRM for Shipbuilding and Ship Repair (Surface
Coating) and received additional data, we did not publish an ANPRM for
Wood Furniture Manufacturing due to time constraints.
b. Uncertainties in Dispersion Modeling
    While the analysis employed EPA's recommended regulatory dispersion
model, AERMOD, we recognize that there is uncertainty in ambient
concentration estimates associated with any model, including AERMOD. In
circumstances where we had to choose between various model options,
where possible, model options (e.g., rural/urban, plume depletion,
chemistry) were selected to provide an overestimate of ambient air
concentrations of the HAP rather than underestimates. 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 HAP 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
between census blocks in the modeling domain were not considered.\27\
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. Using the census block centroid to predict
chronic exposures tends to over-predict exposures for people in the
census block who live further from the facility, and under-predict
exposures for people in the census block who live closer to the
facility. Thus, using the census block centroid to predict chronic
exposures may lead to a potential understatement or overstatement of
the true maximum impact, but is an unbiased estimate of average risk
and incidence.
---------------------------------------------------------------------------

    \27\ 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 continuous pollutant exposures over a 70-year period, which is the
assumed lifetime of an individual. 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 United States facilities), will influence the risks posed by a given
source category. Depending on the characteristics of the industry,
these factors will, in most cases, result in an overestimate both in
individual risk levels and in the total estimated number of cancer
cases. However, in rare cases, where a facility maintains or increases
its emission levels beyond 70 years, residents live beyond 70 years at
the same location, and the residents spend most of their days at that
location, then the risks could potentially be underestimated. 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 as high, depending on the characteristics of the pollutants
modeled. For many of the 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.\28\
---------------------------------------------------------------------------

    \28\ U.S. EPA. 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 should
be highlighted. The accuracy of an acute inhalation exposure assessment
depends on the simultaneous 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
    There are uncertainties inherent in the development of the dose-
response values used in our risk assessments for cancer effects from
chronic exposures and non-cancer effects from both chronic and acute
exposures. Some uncertainties may be considered quantitatively, and
others generally are expressed in qualitative terms. We note as a
preface to this discussion a point on dose-response uncertainty that is
brought out in EPA's 2005 Cancer Guidelines; namely, that ``the primary
goal of EPA actions is protection of human health; accordingly, as an
Agency policy, risk assessment procedures, including default options
that are used in the absence of scientific data to the contrary, should
be health protective.'' (EPA 2005 Cancer Guidelines, pages 1-7.) This
is the approach followed here as summarized in the next several
paragraphs. A complete detailed discussion of uncertainties and
variability in dose-response relationships is given in the residual
risk documentation as referenced in section IV.A of this preamble,
which is available in the docket for this action.
    Cancer URE values used in our risk assessments are those that have
been developed to generally provide an upper bound estimate of risk.
That is, they represent a ``plausible upper limit to the true value of
a quantity'' (although this is usually not a true statistical
confidence limit).\29\ In some circumstances, the true risk could be as
low as zero; however, in other circumstances the risk could also be
greater.\30\ When developing an upper bound estimate of risk and to
provide risk values that do not underestimate risk, health-protective
default approaches are generally used. To err on the side of ensuring
adequate health-protection, EPA typically uses the upper bound
estimates rather than lower bound or central tendency estimates in our
risk assessments, an approach that may have limitations for other uses
(e.g., priority-setting or expected benefits analysis).
---------------------------------------------------------------------------

    \29\ IRIS glossary (http://www.epa.gov/NCEA/iris/help_gloss.htm).
    \30\ An exception to this is the URE for benzene, which is
considered to cover a range of values, each end of which is
considered to be equally plausible, and which is based on maximum
likelihood estimates.
---------------------------------------------------------------------------

    Chronic non-cancer reference (RfC and RfD) values represent chronic
exposure levels that are intended to be health-protective levels.
Specifically, these values provide an estimate (with uncertainty
spanning perhaps an order of magnitude) of daily oral exposure (RfD) or
of a continuous inhalation exposure (RfC) to the human population
(including sensitive subgroups) that is likely to be without an
appreciable risk of deleterious effects during a lifetime. To derive
values that are intended to be ``without appreciable risk,'' the
methodology relies upon an UF approach (U.S. EPA, 1993, 1994) which
includes consideration of both uncertainty and variability. When there
are gaps in the available information, UF are applied to derive
reference values that are intended to protect against appreciable risk
of deleterious effects. The UF are commonly default values,\31\ e.g.,
factors of 10 or 3, used in the absence of compound-specific data;
where data are available, UF may also be developed using compound-
specific information. When data are limited, more assumptions are
needed and more UF are used. Thus, there may be a greater tendency to
overestimate risk in the sense that further study might support
development of reference values that are higher (i.e., less potent)
because fewer default assumptions are needed. However, for some
pollutants, it is possible that risks may be underestimated. While
collectively termed ``UF,'' these factors account for a number of
different quantitative considerations when using observed animal
(usually rodent) or human toxicity data in the development of the RfC.
The UF are intended to account for: (1) Variation in susceptibility
among the members of the human population (i.e., inter-individual
variability); (2) uncertainty in extrapolating from experimental animal
data to humans (i.e., interspecies differences); (3) uncertainty in
extrapolating from data obtained in a study with less-than-lifetime
exposure (i.e., extrapolating from sub-chronic to chronic exposure);
(4) uncertainty in extrapolating the observed data to obtain an
estimate of the exposure associated with no adverse effects; and (5)
uncertainty when the database is incomplete or there are problems with
the applicability of available studies. Many of the UF used to account
for variability and uncertainty in the development of acute reference
values are quite similar to those developed for chronic durations, but
they more often use individual UF values that may be less than 10.
Uncertainty factors are applied based on chemical-specific or health
effect-specific information (e.g., simple irritation effects do not
vary appreciably between human individuals, hence a value of 3 is
typically used), or based on the purpose for the reference value (see
the following paragraph). The UF applied in acute reference value
derivation include: (1) Heterogeneity among humans; (2) uncertainty in
extrapolating from animals to humans; (3) uncertainty in lowest
observed adverse effect (exposure) level to no observed adverse effect
(exposure) level adjustments; and (4) uncertainty in accounting for an
incomplete database on toxic effects of potential concern. Additional
adjustments are often

applied to account for uncertainty in extrapolation from observations
at one exposure duration (e.g., four hours) to derive an acute
reference value at another exposure duration (e.g., one hour).
---------------------------------------------------------------------------

    \31\ According to the NRC report, Science and Judgment in Risk
Assessment (NRC, 1994) ``[Default] options are generic approaches,
based on general scientific knowledge and policy judgment, that are
applied to various elements of the risk assessment process when the
correct scientific model is unknown or uncertain.'' The 1983 NRC
report, Risk Assessment in the Federal Government: Managing the
Process, defined default option as ``the option chosen on the basis
of risk assessment policy that appears to be the best choice in the
absence of data to the contrary'' (NRC, 1983a, p. 63). Therefore,
default options are not rules that bind the Agency; rather, the
Agency may depart from them in evaluating the risks posed by a
specific substance when it believes this to be appropriate. In
keeping with EPA's goal of protecting public health and the
environment, default assumptions are used to ensure that risk to
chemicals is not underestimated (although defaults are not intended
to overtly overestimate risk). See EPA, 2004, An Examination of EPA
Risk Assessment Principles and Practices, EPA/100/B-04/001 available
at:
    http://www.epa.gov/osa/pdfs/ratf-final.pdf.
---------------------------------------------------------------------------

    Not all acute reference values are developed for the same purpose,
and care must be taken when interpreting the results of an acute
assessment of human health effects relative to the reference value or
values being exceeded. Where relevant to the estimated exposures, the
lack of short-term dose-response values at different levels of severity
should be factored into the risk characterization as potential
uncertainties.
    Although every effort is made to identify peer-reviewed reference
values for cancer and non-cancer effects for all pollutants emitted by
the sources included in this assessment, some HAP continue to have no
reference values for cancer or chronic non-cancer or acute effects.
Since exposures to these pollutants cannot be included in a
quantitative risk estimate, an understatement of risk for these
pollutants at environmental exposure levels is possible. For a group of
compounds that are either unspeciated or do not have reference values
for every individual compound (e.g., glycol ethers), we conservatively
use the most protective reference value to estimate risk from
individual compounds in the group of compounds.
    Additionally, chronic reference values for several of the compounds
included in this assessment are currently under EPA IRIS review, and
revised assessments may determine that these pollutants are more or
less potent than the current value. We may re-evaluate residual risks
for the final rulemaking if, as a result of these reviews, a dose-
response metric changes enough to indicate that the risk assessment
supporting this notice may significantly understate human health risk.
e. Uncertainties in the Multi-Pathway and Environmental Effects
Assessment
    We generally assume that when exposure levels are not anticipated
to adversely affect human health, they also are not anticipated to
adversely affect the environment. For each source category, we
generally rely on the site-specific levels of PB-HAP emissions to
determine whether a full assessment of the multi-pathway and
environmental effects is necessary. Because site-specific PB-HAP
emission levels were so far below levels which would trigger a refined
assessment of multi-pathway impacts, we are confident that these types
of impacts are insignificant for these source categories.
f. Uncertainties in the Facility-Wide Risk Assessment
    Given that the same general analytical approach and the same models
were used to generate facility-wide risk results as were used to
generate the source category risk results, the same types of
uncertainties discussed above for our source category risk assessments
apply to the facility-wide risk assessments. Additionally, the degree
of uncertainty associated with facility-wide emissions and risks is
likely greater because we generally have not conducted a thorough
engineering review of emissions data for source categories not
currently undergoing an RTR review.
g. Uncertainties in the Demographic Analysis
    Our analysis of the distribution of risks across various
demographic groups is subject to the typical uncertainties associated
with census data (e.g., errors in filling out and transcribing census
forms), as well as the additional uncertainties associated with the
extrapolation of census-block group data (e.g., income level and
education level) down to the census block level.

B. How did we perform the technology review?

    Our technology review is focused on the identification and
evaluation of ``developments in practices, processes, and control
technologies'' since the promulgation of the existing MACT standard. If
a review of available information identifies such developments, then we
conduct an analysis of the technical feasibility of requiring the
implementation of these developments, along with the impacts (costs,
emission reductions, risk reductions, etc.). We then make a decision on
whether it is necessary to amend the regulation to require these
developments.
    Based on specific knowledge of each source category, we began by
identifying known developments in practices, processes, and control
technologies. For the purpose of this exercise, we considered any of
the following to be a ``development'':
     Any add-on control technology or other equipment that was
not identified and considered during MACT development;
     Any improvements in add-on control technology or other
equipment (that was identified and considered during MACT development)
that could result in significant additional emission reduction;
     Any work practice or operational procedure that was not
identified and considered during MACT development; and
     Any process change or pollution prevention alternative
that could be broadly applied that was not identified and considered
during MACT development.
    In addition to looking back at practices, processes, or control
technologies reviewed at the time we developed the MACT standards, we
reviewed a variety of sources of data to aid in our evaluation of
whether there were additional practices, processes, or controls to
consider. One of these sources of data was subsequent air toxics rules.
Since the promulgation of the MACT standards for the source categories
addressed in this proposal, EPA has developed air toxics regulations
for a number of additional source categories. We reviewed the
regulatory requirements and/or technical analyses associated with these
subsequent regulatory actions to identify any practices, processes, and
control technologies considered in these efforts that could possibly be
applied to emission sources in the source categories under this current
RTR review.
    We also consulted EPA's RBLC. The terms ``RACT,'' ``BACT,'' and
``LAER'' are acronyms for different program requirements under the CAA
provisions addressing the national ambient air quality standards.
Control technologies classified as RACT, BACT, or LAER apply to
stationary sources depending on whether the source is existing or new,
and on the size, age, and location of the facility. Best Available
Control Technology and LAER (and sometimes RACT) are determined on a
case-by-case basis, usually by state or local permitting agencies. EPA
established the RBLC to provide a central database of air pollution
technology information (including technologies required in source-
specific permits) to promote the sharing of information among
permitting agencies and to aid in identifying future possible control
technology options that might apply broadly to numerous sources within
a category or apply only on a source-by-source basis. The RBLC contains
over 5,000 air pollution control permit determinations that can help
identify appropriate technologies to mitigate many air pollutant
emission streams. We searched this database to determine whether any
practices, processes, or control technologies are included for the
types of processes used for emission

sources (e.g., spray booths) in the source categories under
consideration in this proposal.
    We also requested information from industry regarding developments
in practices, processes, or control technology. Finally, we reviewed
other information sources, such as state or local permitting agency
databases and industry-supported databases.

V. Analyses Results and Proposed Decisions

    This section of the preamble provides background information on the
MACT standards and source categories, the results of our RTR for each
source category, and our proposed decisions concerning the SSM
provisions in each MACT standard.

A. What are the results and proposed decisions for the Shipbuilding and
Ship Repair (Surface Coating) source category?

1. Overview of the Source Category and MACT Standards
    The National Emission Standards for Shipbuilding and Ship Repair
(Surface Coating) were promulgated on December 15, 1995 (60 FR 64330)
and codified at 40 CFR part 63, subpart II. The Shipbuilding and Ship
Repair (Surface Coating) MACT standards (i.e., Shipbuilding MACT
standards) apply to shipbuilding and ship repair operations at any
facility that is a major source of HAP. We estimate that there are
approximately 85 shipbuilding and ship repair facilities currently
subject to the Shipbuilding MACT standards.
    The shipbuilding and ship repair industry consists of
establishments that build, repair, repaint, convert, and alter ships,
which are marine or fresh-water vessels used for military or commercial
operations. In general, activities and processes involved in ship
repair and new ship construction are relatively similar. Operations
include fabrication of basic components from raw materials, welding
components and parts together, painting and repainting, overhauls, ship
conversions, and other alterations. Nearly all shipyards that construct
new ships also perform ship repairs. The source category covered by
this MACT standard only includes the surface coating operations that
occur at these facilities during shipbuilding and ship repair.
    Emissions of VOHAP from surface coating operations at shipbuilding
and ship repair facilities result from the application of coatings and
the use of cleaning solvents containing VOHAP during ship repair and
shipbuilding operations. To reduce VOHAP emissions, the Shipbuilding
MACT standards limit the coatings that can be used to those with as-
applied VOHAP content less than or equal to the applicable level
specified in Table 2 to Subpart II of Part 63--Volatile Organic HAP
Limits for Marine Coatings. This table contains as-applied VOHAP
content limits of a variety of marine surface coatings categories,
including a general use category and 22 specialty coatings categories.
The Shipbuilding MACT standards also specify work practice standards
that minimize evaporative emissions and spills from the handling,
transfer, and storage of VOHAP-containing materials such as organic
thinning solvents and paint wastes.
2. What data were used in our risk analyses?
    We initially created a preliminary dataset for the source category
using data in the 2002 NEI Final Inventory, Version 1 (made publicly
available on February 26, 2006). We reviewed the NEI dataset and made
changes where necessary to ensure that the proper facilities were
included and that the proper processes were allocated to the
Shipbuilding and Ship Repair (Surface Coating) source category. We also
reviewed the emissions and other data to identify data anomalies that
could affect risk estimates. On March 29, 2007, we published an ANPRM
(72 FR 29287) for the express purpose of requesting comments and
updates to this dataset, as well as to the datasets for the other
source categories addressed in that ANPRM. Approximately 20 comments,
received in response to the ANPRM, were reviewed and considered, and we
made adjustments to the dataset where we concluded the comments
supported such adjustment. Adjustments were also made to the dataset to
reflect updates made to the data in the 2005 NEI and to remove
emissions from the dataset that were from sources that are not part of
the Shipbuilding and Ship Repair (Surface Coating) source category, as
determined through further engineering review. Based on the data
collection and review process, we developed model input files to be
used in the risk analysis for 71 facilities. As mentioned previously,
there are a total of approximately 85 facilities subject to the
Shipbuilding MACT standards. Therefore, we developed model input files
for about 84 percent of the total facilities.
    Nevertheless, after the adjustments described above were made to
the dataset, approximately 40 facilities included in our list of 85
facilities still had some missing or incomplete HAP emissions data,
based on NEI and EPA's Toxics Release Inventory searches. Thus, a HAP
profile was developed to populate the Shipbuilding and Ship Repair
(Surface Coating) dataset with representative data for these 40
facilities, using several assumptions and decisions. For more
information see Memoranda Documenting Changes to the RTR Dataset for
the Shipbuilding and Ship Repair (Surface Coating) Source Category,
dated November 22, 2010, which includes the memorandum Default
Emissions Assumptions for Shipbuilding RTR Dataset. For three
facilities that provided VOC emissions data, but did not provide HAP
emissions data, we speciated the VOC emissions into specific HAP
emissions, making the worst-case assumption that all the VOC were HAP.
The HAP profile we developed and applied to the VOC emissions for these
three facilities was based on the top three solvents reported by the
other facilities in the source category, which accounted for more than
90 percent of the total HAP emissions at those facilities. This HAP
speciation profile was: Xylene (all isomers)--78 percent; ethyl
benzene--15 percent; and toluene--7 percent.
    There were also 44 facilities subject to the Shipbuilding MACT
standards with no available emissions data, and we decided to assign
them to one of two possible categories based on available information
from company Web sites, operating permits, previous MACT project
information, or similar facilities. The first category included 11
facilities that emitted greater than or equal to 25 TPY of total HAP.
The second category included 33 facilities that emitted less than 25
TPY. Based on a small number of available operating permits and
industry information collected for the original MACT rule, we
determined which facilities belonged in each category. We then used the
available emissions data reported for those facilities to calculate
average total HAP emissions for each source type. The average HAP
emissions level for facilities in the first category was estimated to
be about 25 TPY, and the average HAP emissions level for facilities in
the second category was estimated to be 7 TPY. Thus, the 11 facilities
in the first category with no emissions data were assigned emissions of
25 tons total HAP per year, and 33 facilities in the second category
with no emissions data were assigned emissions of 7 tons total HAP per
year. The same default HAP solvent profile discussed above was used to
speciate the HAP emissions for these facilities. For a more complete
description of the default

assumptions used to populate the dataset, see Default Emissions
Assumptions for Shipbuilding RTR Dataset memorandum, dated August 30,
2010, which is available in the docket for this action. These updated
data were used to conduct the risk assessments and other analyses that
form the basis for this proposed action.
    Mixed xylenes and ethyl benzene account for the majority of the HAP
emissions from the Shipbuilding and Ship Repair (Surface Coating)
source category (approximately 855 TPY, or 90 percent of the total HAP
emissions by mass). These estimates are based on actual reported
emissions data. These facilities also reported relatively small
emissions of 33 other HAP. For more detail, see the memorandum in the
docket for this action describing the risk assessment inputs and models
for the Shipbuilding and Ship Repair (Surface Coating) source category.
    We estimate that MACT-allowable emissions from this source category
could be up to 2 times greater than the actual emissions for some types
of coatings, based on information obtained for the highest usage
coating categories at several major source facilities. However, we do
not have facility-specific information for all facilities or all
coatings, and we request comment on this estimate. For more detail
about how this estimate of the ratio of actual to MACT-allowable
emissions was derived, see the Maximum Achievable Control Technology
(MACT) Allowable Emission Estimates memorandum, dated August 5, 2010,
in the docket for this action describing the estimation of MACT-
allowable emission levels and associated risks and impacts. For the
``facility-wide'' risk analysis, facility-specific emissions data from
the 2005 NEI were used.
3. What are the results of the risk assessments and analyses?
    We conducted an inhalation risk assessment for the Shipbuilding and
Ship Repair (Surface Coating) source category. We also conducted an
assessment of facility-wide risk and performed a demographic analysis
of population risks. Details of the risk assessments and analyses can
be found in the residual risk documentation referenced in section IV.A
of this preamble, which is available in the docket for this action.
a. Inhalation Risk Assessment Results
    Table 3 provides an overall summary of the results of the
inhalation risk assessment.

                               Table 3--Shipbuilding and Ship Repair (Surface Coating) Inhalation Risk Assessment Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                           Maximum individual cancer                  Estimated   Maximum chronic non-cancer
                                            risk (in 1 million) \2\     Estimated      annual              TOSHI \3\
                                         ----------------------------  population      cancer    ---------------------------- Maximum off-site acute non-
        Number of  facilities \1\            Actual       Allowable   at risk >= 1-   incidence      Actual       Allowable          cancer HQ \4\
                                            emissions     emissions   in-1 million   (cases per     emissions     emissions
                                              level         level                       year)         level         Level
--------------------------------------------------------------------------------------------------------------------------------------------------------
85......................................           10            20         4,000         0.003           0.5             1   HQREL = 0.1 glycol ethers.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number of facilities evaluated in the risk analysis.
\2\ Estimated maximum individual excess lifetime cancer risk.
\3\ Maximum TOSHI. The target organ with the highest TOSHI for the Shipbuilding and Ship Repair (Surface Coating) source category is the reproductive
  system.
\4\ The maximum estimated acute exposure concentration was divided by available short-term dose-response values to develop an array of HQ values. HQ
  values shown use the lowest available acute dose-response value, which, in most cases, is the REL. See section IV.A of this preamble for explanation
  of acute dose-response values.