[Federal Register Volume 83, Number 95 (Wednesday, May 16, 2018)]
[Proposed Rules]
[Pages 22754-22794]
[FR Doc No: 2018-09080]

Vol. 83

Wednesday,

No. 95

May 16, 2018

Part II

Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Hazardous Air Pollutants: Surface
Coating of Wood Building Products Residual Risk and Technology Review;
Proposed Rule

Federal Register / Vol. 83 , No. 95 / Wednesday, May 16, 2018 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2016-0678; FRL-9977-32-OAR]
RIN 2060-AT71

National Emission Standards for Hazardous Air Pollutants: Surface
Coating of Wood Building Products Residual Risk and Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is proposing
amendments to the National Emission Standards for Hazardous Air
Pollutants (NESHAP) for Surface Coating of Wood Building Products to
address the results of the residual risk and technology review (RTR)
that the EPA is required to conduct under the Clean Air Act (CAA). We
found risks due to emissions of air toxics to be acceptable from this
source category and determined that the current NESHAP provides an
ample margin of safety to protect public health. We identified no new
cost-effective controls under the technology review to achieve further
emissions reductions. The EPA is proposing: To add an alternative
compliance demonstration equation; to amend provisions addressing
periods of startup, shutdown and malfunction (SSM); to amend provisions
regarding electronic reporting; and to make technical and editorial
changes. The EPA is proposing these amendments to improve the
effectiveness of the NESHAP. This action also proposes a new EPA test
method to measure isocyanate compounds in certain surface coatings.

DATES: Comments. Comments must be received on or before June 15, 2018
unless a public hearing is requested by May 21, 2018. If a public
hearing is requested, comments must be received on or before July 2,
2018. Under the Paperwork Reduction Act (PRA), comments on the
information collection provisions are best assured of consideration if
the Office of Management and Budget (OMB) receives a copy of your
comments on or before June 15, 2018.
    Public Hearing. If a public hearing is requested by May 21, 2018,
then we will hold a public hearing on May 31, 2018 at the location
described in the ADDRESSES section. The last day to pre-register in
advance to speak at the public hearing will be May 29, 2018.

ADDRESSES: Comments. Submit your comments, identified by Docket ID No.
EPA-HQ-OAR-2016-0678, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. Regulations.gov is our
preferred method of receiving comments. However, other submission
formats are accepted. To ship or send mail via the United States Postal
Service, use the following address: U.S. Environmental Protection
Agency, EPA Docket Center, Docket ID No. EPA-HQ-OAR-2016-0678, Mail
Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460. Use the
following Docket Center address if you are using express mail,
commercial delivery, hand delivery or courier: EPA Docket Center, EPA
WJC West Building, Room 3334, 1301 Constitution Avenue NW, Washington,
DC 20004. Delivery verification signatures will be available only
during regular business hours.
    Do not submit electronically any information you consider to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Send or deliver information
identified as CBI only to the following address: OAQPS Document Control
Officer (C404-02), Office of Air Quality Planning and Standards,
Environmental Protection Agency, Research Triangle Park, NC 27711,
Attention EPA-HQ-OAR-2016-0678. Clearly mark the part or all of the
information that you claim to be CBI. For CBI information in a disk or
CD-ROM that you mail to the 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.
Information so marked will not be disclosed except in accordance with
procedures set forth in 40 CFR part 2.
    For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    The EPA may publish any comment received to its public docket.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the Web, cloud, or other
file sharing system).
    Public Hearing. If a public hearing is requested, it will be held
at the EPA's Washington DC Campus located at 1201 Constitution Avenue,
NW, Washington, DC. If a public hearing is requested, then we will
provide details about the public hearing on our website at: https://www.epa.gov/stationary-sources-air-pollution/surface-coating-wood-building-products-national-emission-standard-1. The EPA does not intend
to publish another document in the Federal Register announcing any
updates on the request for a public hearing. Please contact Ms. Aimee
St. Clair at<PHONE_NUMBER> or by email at [email protected] to
request a public hearing, to register to speak at the public hearing,
or to inquire as to whether a public hearing will be held.
    The EPA will make every effort to accommodate all speakers who
arrive and register. If a hearing is held at a U.S. government
facility, individuals planning to attend should be prepared to show a
current, valid state- or federal-approved picture identification to the
security staff in order to gain access to the meeting room. An expired
form of identification will not be permitted. Please note that the Real
ID Act, passed by Congress in 2005, established new requirements for
entering federal facilities. If your driver's license is issued by a
noncompliant state, you must present an additional form of
identification to enter a federal facility. Acceptable alternative
forms of identification include: Federal employee badge, passports,
enhanced driver's licenses, and military identification cards.
Additional information on the Real ID Act is available at https://www.dhs.gov/real-id-frequently-asked-questions. In addition, you will
need to obtain a property pass for any personal belongings you bring
with you. Upon leaving the building, you will be required to return
this property pass to the security desk. No large signs will be allowed
in the building, cameras may only be used outside of the building, and
demonstrations will not be allowed on federal property for security
reasons.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Mr. John Bradfield, Sector Policies and Programs
Division (E143-03), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone

number:<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and email address:
[email protected]. For specific information regarding the risk
modeling methodology, contact Mr. James Hirtz, 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:<PHONE_NUMBER>; fax
number:<PHONE_NUMBER>; and email address: [email protected]. For
information about the applicability of the NESHAP to a particular
entity, contact Mr. John Cox, Office of Enforcement and Compliance
Assurance, U.S. Environmental Protection Agency, EPA WJC South Building
(Mail Code 2221A), 1200 Pennsylvania Avenue NW, Washington DC 20460;
telephone number:<PHONE_NUMBER>; and email address: [email protected].

SUPPLEMENTARY INFORMATION:
    Docket. The EPA has established a docket for this rulemaking under
Docket ID No. EPA-HQ-OAR-2016-0678. All documents in the docket are
listed in the Regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the Internet and will be
publicly available only in hard copy. Publicly available docket
materials are available either electronically in Regulations.gov or in
hard copy at the EPA Docket Center, Room 3334, EPA WJC West Building,
1301 Constitution Avenue NW, Washington, DC. The Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the EPA Docket Center is
(202) 566-1742.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2016-0678. The EPA's policy is that all comments received will be
included in the public docket without change and may be made available
online at http://www.regulations.gov, including any personal
information provided, unless the comment includes information claimed
to be CBI or other information whose disclosure is restricted by
statute. Do not submit information that you consider to be CBI or
otherwise protected through http://www.regulations.gov or email. The
http://www.regulations.gov Web site is an ``anonymous access'' system,
which means the EPA will not know your identity or contact information
unless you provide it in the body of your comment. If you send an email
comment directly to the EPA without going through http://www.regulations.gov, your email 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, the 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 the EPA cannot read your comment due to technical
difficulties and cannot contact you for clarification, the EPA may not
be able to consider your comment. Electronic files should not include
special characters or any form of encryption and be free of any defects
or viruses. For additional information about the EPA's public docket,
visit the EPA Docket Center homepage at http://www.epa.gov/dockets.
    Preamble Acronyms and Abbreviations. We use multiple acronyms and
terms in this preamble. While this list may not be exhaustive, to ease
the reading of this preamble and for reference purposes, the EPA
defines the following terms and acronyms here:

AEGL acute exposure guideline level
AERMOD air dispersion model used by the HEM-3 model
ANSI American National Standards Institute
ASTM American Society for Testing and Materials
ATSDR Agency for Toxic Substances and Disease Registry
BACT best available control technology
CAA Clean Air Act
CalEPA California EPA
CAP criteria air pollutant
CBI Confidential Business Information
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CFR Code of Federal Regulations
CHIEF Clearinghouse for Inventories and Emissions Factors
CO catalytic oxidizers
ECHO Enforcement and Compliance History Online
EJ environmental justice
EPA Environmental Protection Agency
ERPG Emergency Response Planning Guideline
ERT Electronic Reporting Tool
GACT generally available control technology
HAP hazardous air pollutant(s)
HCl hydrochloric acid
HDI hex methylene 1,6 diisocyanate
HEM-3 Human Exposure Model, Version 1.1.0
HF hydrogen fluoride
HI hazard index
HQ hazard quotient
IBR incorporation by reference
ICR information collection request
IRIS Integrated Risk Information System
km kilometer
LAER lowest achievable emission rate
m\3\ cubic meter
MACT maximum achievable control technology
MDI methylene diphenyl diisocyanate
MI methyl isocyanate
MIR maximum individual risk
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NAS National Academy of Sciences
NEI National Emissions Inventory
NESHAP national emission standards for hazardous air pollutants
No. Number
NRDC Natural Resources Defense Council
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PB-HAP hazardous air pollutants known to be persistent and bio-
accumulative in the environment
PDF portable document format
PRA Paperwork Reduction Act
QA quality assurance
QC quality control
RACT reasonably available control technology
RBLC RACT/BACT/LAER Clearinghouse
REL reference exposure level
RFA Regulatory Flexibility Act
RfC reference concentration
RfD reference dose
RTR residual risk and technology review
SAB Science Advisory Board
SSM startup, shutdown, and malfunction
TDI 2,4 toluene diisocyanate
TO thermal oxidizers
TOSHI target organ-specific hazard index
tpy tons per year
TRI Toxics Release Inventory
UF uncertainty factor
UMRA Unfunded Mandates Reform Act
URE unit risk estimate
U.S. United States
U.S.C. United States Code
VCS voluntary consensus standards
VOC volatile organic compounds
VOHAP volatile organic hazardous air pollutants
WebFIRE Web Factor Information Retrieval System
XML extensible markup language

    Organization of this Document. The information in this preamble is
organized as follows:

I. 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 the EPA?
II. Background
    A. What is the statutory authority for this action?
    B. What is this source category and how does the current NESHAP
regulate its HAP emissions?
    C. What data collection activities were conducted to support
this action?

    D. What other relevant background information and data are
available?
III. Analytical Procedures
    A. How do we consider risk in our decision-making?
    B. How do we perform the technology review?
    C. How did we estimate post-MACT risks posed by the source
category?
IV. Analytical Results and Proposed Decisions
    A. What are the results of the risk assessment and analyses?
    B. What are our proposed decisions regarding risk acceptability,
ample margin of safety, and adverse environmental effects?
    C. What are the results and proposed decisions based on our
technology review?
    D. What other actions are we proposing?
    E. What compliance dates are we proposing?
V. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
VI. Request for Comments
VII. Submitting Data Corrections
VIII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulation and Controlling
Regulatory Costs
    C. Paperwork Reduction Act (PRA)
    D. Regulatory Flexibility Act (RFA)
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination with
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR part 51
    K. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. General Information

A. Does this action apply to me?

    Table 1 of this preamble lists the NESHAP and associated regulated
industrial source category that is the subject of this proposal. Table
1 is not intended to be exhaustive, but rather provides a guide for
readers regarding the entities that this proposed action is likely to
affect. The proposed standards, once promulgated, will be directly
applicable to the affected sources. Federal, state, local and tribal
government entities would not be affected by this proposed action. As
defined in the Initial List of Categories of Sources Under Section
112(c)(1) of the Clean Air Act Amendments of 1990 (see 57 FR 31576,
July 16, 1992), the ``Surface Coating of Wood Building Products''
source category is any facility engaged in the surface coating of wood
building products. Wood building products are defined as any product
that contains more than 50 percent by weight wood or wood fiber,
excluding the weight of glass components, and is used in the
construction, either interior or exterior, of a residential,
commercial, or institutional building. This NESHAP, 40 Code of Federal
regulations (CFR) part 63, subpart QQQQ, regulates all operations
associated with the surface coating of wood building products, which
includes preparation of the coating for application (e.g., mixing with
thinners); surface preparation of the wood building products; coating
application, curing, and drying equipment; equipment cleaning; and
storage, transfer, and handling of coatings, thinners, cleaning
materials, and waste materials.

    Table 1--NESHAP and Industrial Source Categories Affected by This
                             Proposed Action
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         Source category                NESHAP          NAICS code \1\
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Wood Building Products..........  Surface Coating of  321211, 321212,
                                   Wood Building       321218, 321219,
                                   Products.           321911, 321999.
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\1\ North American Industry Classification System.

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 action is available on the Internet. Following signature by the
EPA Administrator, the EPA will post a copy of this proposed action at:
https://www.epa.gov/stationary-sources-air-pollution/surface-coating-wood-building-products-national-emission-standard-1. Following
publication in the Federal Register, the EPA will post the Federal
Register version of the proposal and key technical documents at this
same website. Information on the overall RTR program is available at
http://www3.epa.gov/ttn/atw/rrisk/rtrpg.html.
    A redline version of the regulatory language that incorporates the
proposed changes in this action is available in the docket for this
action (Docket ID No. EPA-HQ-OAR-2016-0678).

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

    Submitting CBI. Do not submit information containing CBI to the EPA
through http://www.regulations.gov or email. 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 the 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 comments that includes information claimed
as CBI, you must submit a copy of the comments that does not contain
the information claimed as CBI 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 the 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: OAQPS Document Control Officer (C404-
02), OAQPS, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2016-
0678.

II. Background

 A. What is the statutory authority for this action?

    The statutory authority for this action is provided by sections 112
and 301 of the CAA, as amended (42 U.S.C. 7401 et seq.). Section 112 of
the CAA establishes a two-stage regulatory process to develop standards
for emissions of hazardous air pollutants (HAP) from stationary
sources. Generally, the first stage involves establishing technology-
based standards

and the second stage involves evaluating those standards that are based
on maximum achievable control technology (MACT) to determine whether
additional standards are needed to further address any remaining risk
associated with HAP emissions. This second stage is commonly referred
to as the ``residual risk review.'' In addition to the residual risk
review, the CAA also requires the EPA to review standards set under CAA
section 112 every 8 years to determine if there are ``developments in
practices, processes, or control technologies'' that may be appropriate
to incorporate into the standards. This review is commonly referred to
as the ``technology review.'' When the two reviews are combined into a
single rulemaking, it is commonly referred to as the ``risk and
technology review.'' The discussion that follows identifies the most
relevant statutory sections and briefly explains the contours of the
methodology used to implement these statutory requirements. A more
comprehensive discussion appears in the document titled CAA Section 112
Risk and Technology Reviews: Statutory Authority and Methodology in the
docket for this rulemaking.
    In the first stage of the CAA section 112 standard setting process,
the EPA promulgates technology-based standards under CAA section 112(d)
for categories of sources identified as emitting one or more of the HAP
listed in CAA section 112(b). Sources of HAP emissions are either major
sources or area sources, and CAA section 112 establishes different
requirements for major source standards and area source standards.
``Major sources'' are those that emit or have the potential to emit 10
tons per year (tpy) or more of a single HAP or 25 tpy or more of any
combination of HAP. All other sources are ``area sources.'' For major
sources, CAA section 112(d) provides that the technology-based NESHAP
must reflect the maximum degree of emission reductions of HAP
achievable (after considering cost, energy requirements, and non-air
quality health and environmental impacts). These standards are commonly
referred to as MACT standards. CAA section 112(d)(3) also establishes a
minimum control level for MACT standards, known as the MACT ``floor.''
The EPA must also consider control options that are more stringent than
the floor. Standards more stringent than the floor are commonly
referred to as beyond-the-floor standards. In certain instances, as
provided in CAA section 112(h), the EPA may set work practice standards
where it is not feasible to prescribe or enforce a numerical emission
standard. For area sources, CAA section 112(d)(5) gives the EPA
discretion to set standards based on generally available control
technologies or management practices (GACT standards) in lieu of MACT
standards.
    The second stage in standard-setting focuses on identifying and
addressing any remaining (i.e., ``residual'') risk according to CAA
section 112(f). Section 112(f)(2) of the CAA requires the EPA to
determine for source categories subject to MACT standards whether
promulgation of additional standards is needed to provide an ample
margin of safety to protect public health or to prevent an adverse
environmental effect. CAA section 112(d)(5) provides that this residual
risk review is not required for categories of area sources subject to
GACT standards. Section 112(f)(2)(B) of the CAA further expressly
preserves the EPA's use of the two-step approach for developing
standards to address any residual risk and the Agency's interpretation
of ``ample margin of safety'' developed in the National Emissions
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 EPA notified Congress in
the Risk Report that the Agency intended to use the Benzene NESHAP
approach in making CAA section 112(f) residual risk determinations
(EPA-453/R-99-001, p. ES-11). The EPA subsequently adopted this
approach in its residual risk determinations, and the United States
Court of Appeals for the District of Columbia Circuit (the Court)
upheld the EPA's interpretation that CAA section 112(f)(2) incorporates
the approach established in the Benzene NESHAP. See Natural Resources
Defense Council (NRDC) v. EPA, 529 F.3d 1077, 1083 (D.C. Cir. 2008).
    The approach incorporated into the CAA and used by the EPA to
evaluate residual risk and to develop standards under CAA section
112(f)(2) is a two-step approach. In the first step, the EPA determines
whether risks are acceptable. This determination ``considers all health
information, including risk estimation uncertainty, and includes a
presumptive limit on maximum individual lifetime [cancer] risk (MIR)
\1\ of approximately [1-in-10 thousand] [i.e., 100-in-1 million].'' 54
FR 38045, September 14, 1989. If risks are unacceptable, the EPA must
determine the emissions standards necessary to bring risks to an
acceptable level without considering costs. In the second step of the
process, the EPA considers whether the emissions standards provide 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. The EPA must
promulgate emission standards necessary to provide an ample margin of
safety to protect public health. After conducting the ample margin of
safety analysis, we consider whether a more stringent standard is
necessary to prevent, taking into consideration costs, energy, safety,
and other relevant factors, an adverse environmental effect.
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    \1\ \\ Although defined as ``maximum individual risk,'' MIR
refers only to cancer risk. MIR, one metric for assessing cancer
risk, is the estimated risk if an individual were exposed to the
maximum level of a pollutant for a lifetime.
---------------------------------------------------------------------------

    CAA section 112(d)(6) separately requires the EPA to review
standards promulgated under CAA section 112 and revise them ``as
necessary (taking into account developments in practices, processes,
and control technologies)'' no less frequently than every 8 years. In
conducting this review, which we call the ``technology review,'' the
EPA is not required to recalculate the MACT floor. NRDC v. EPA, 529
F.3d 1077, 1084 (D.C. Cir. 2008); Association of Battery Recyclers,
Inc. v. EPA, 716 F.3d 667 (D.C. Cir. 2013). The EPA may consider cost
in deciding whether to revise the standards pursuant to CAA section
112(d)(6).

B. What is this source category and how does the current NESHAP
regulate its HAP emissions?

    The ``Surface Coating of Wood Building Products'' source category
includes any facility engaged in the surface coating of wood building
products, which means the application of coatings using, for example,
roll coaters or curtain coaters in the finishing or laminating of any
wood building product that contains more than 50 percent by weight wood
or wood fiber, excluding the weight of any glass components, and is
used in the construction, either interior or exterior, of a
residential, commercial, or institutional building. Regulated
operations include all processes and process units incorporating wood
building products surface coating operations. The processes include,
but are not limited to, coating application production lines, emissions
capture and exhaust ducting systems, cleanup stations, coating
preparation stations

(e.g., mixing with thinners), surface preparation of the wood building
products, curing and drying equipment; and storage, transfer, and
handling of coatings, thinners, cleaning materials, and waste
materials. This NESHAP, 40 CFR part 63, subpart QQQQ, regulates surface
coating of wood building products (referred to in this document as the
Surface Coating of Wood Building Products NESHAP).
    This proposal includes both a residual risk assessment and a
technology review of the emission sources subject to the Surface
Coating of Wood Building Products NESHAP, which includes numerical
emission limits for five subcategories of wood building products:
     Exterior siding and primed doorskins;
     Flooring;
     Interior wall paneling or tileboard;
     Other interior panels; and
     Doors, windows, and miscellaneous.

C. What data collection activities were conducted to support this
action?

    The EPA collected data from several environmental databases that
included information pertaining to wood building products manufacturing
facilities with surface coating operations in the United States. The
primary databases were the Enforcement and Compliance History Online
(ECHO) database, the Toxics Release Inventory (TRI), and the National
Emissions Inventory (NEI) for 2011 and 2014. Title V operating permits
were obtained from states that have facilities subject to 40 CFR part
63, subpart QQQQ. For more details of the title V operating permit
review, see the memorandum titled Preparation of the Residual Risk
Modeling Input File for Subpart QQQQ in the docket for this rulemaking
(Docket ID No. EPA-HQ-OAR-2016-0678). No formal information collection
request was performed.

D. What other relevant background information and data are available?

    In addition to the ECHO, TRI, and NEI databases, the EPA reviewed
the additional information sources listed below and consulted with
stakeholders regulated under the Surface Coating of Wood Building
Products NESHAP to determine if there have been developments in
practices, processes, or control technologies by wood building products
surface coating sources. These include:
     Permit limits and selected compliance options from permits
collected from state agencies;
     Information on air pollution control options in the wood
building products surface coating industry from the reasonably
available control technology (RACT)/best achievable control technology
(BACT)/lowest achievable emission limits (LAER) Clearinghouse (RBLC);
     Information on the most effective ways to control
emissions of volatile organic compounds (VOC) and volatile organic HAP
(VOHAP) from sources in various industries, including the wood building
products manufacturing industry;
     Product Data Sheets and Material Safety Data Sheets
submitted with compliance demonstrations; and
     Communication with trade groups and associations
representing industries in the affected NAICS categories and their
members.

III. Analytical Procedures

    In this section, we describe the analyses performed to support the
proposed decisions for the RTR and other issues addressed in this
proposal.

A. How do we consider risk in our decision-making?

    As discussed in section II.A of this preamble and in the Benzene
NESHAP, in evaluating and developing standards under CAA section
112(f)(2), we apply a two-step approach to determine whether or not
risks are acceptable and to determine if the standards provide an ample
margin of safety to protect public health. 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 38046,
September 14, 1989. Similarly, with regard to the ample margin of
safety determination, ``the Agency 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 Benzene NESHAP approach provides flexibility regarding factors
the EPA may consider in making determinations and how the EPA may weigh
those factors for each source category. The EPA conducts a risk
assessment that provides estimates of the MIR posed by the HAP
emissions from each source in the source category, the hazard index
(HI) for chronic exposures to HAP with the potential to cause noncancer
health effects, and the hazard quotient (HQ) for acute exposures to HAP
with the potential to cause noncancer health effects.\2\ The assessment
also provides estimates of the distribution of cancer risks within the
exposed populations, cancer incidence, and an evaluation of the
potential for adverse environmental effects. The scope of the EPA's
risk analysis is consistent with the EPA's response to comment on our
policy under the Benzene NESHAP where the EPA explained that:
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    \2\ The MIR is defined as the cancer risk associated with a
lifetime of exposure at the highest concentration of HAP where
people are likely to live. The HQ is the ratio of the potential
exposure to the HAP to the level at or below which no adverse
chronic noncancer effects are expected; the HI is the sum of HQs for
HAP that affect the same target organ or organ system.

    ``[t]he 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 noncancer 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 his 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 his judgment, believes are
---------------------------------------------------------------------------
appropriate to determining what will `protect the public health'.''

See 54 FR 38057, September 14, 1989. Thus, the level of the MIR is only
one factor to be weighed in determining acceptability of risks. The
Benzene NESHAP explained that ``an MIR of approximately one 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 Agency 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, the EPA 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. We also consider the uncertainties associated with the
various risk analyses, as discussed earlier in this preamble, in our
determinations of acceptability and ample margin of safety.
    The EPA notes that it has not considered certain health information
to date in making residual risk determinations. At this time, we do not
attempt to quantify those HAP risks that may be associated with
emissions from other facilities that do not include the source category
under review, mobile source emissions, natural source emissions,
persistent environmental pollution, or atmospheric transformation in
the vicinity of the sources in the category.
    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. We recognize
that such consideration may be particularly important when assessing
noncancer risks, where pollutant-specific exposure health reference
levels (e.g., reference concentrations (RfCs)) 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 noncancer 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 noncancer health effects. In May
2010, the Science Advisory Board (SAB) advised the EPA ``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.'' \3\
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    \3\ The 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 memorandum to this rulemaking
docket from David Guinnup titled, EPA's Actions in Response to the
Key Recommendations of the SAB Review of RTR Risk Assessment
Methodologies.
---------------------------------------------------------------------------

    In response to the SAB recommendations, the EPA is incorporating
cumulative risk analyses into its RTR risk assessments, including those
reflected in this proposal. The Agency is (1) conducting facility-wide
assessments, which include source category emission points, as well as
other emission points within the facilities; (2) combining exposures
from multiple sources in the same category that could affect the same
individuals; and (3) for some persistent and bioaccumulative
pollutants, analyzing the ingestion route of exposure. In addition, the
RTR risk assessments have always considered aggregate cancer risk from
all carcinogens and aggregate noncancer HI from all noncarcinogens
affecting the same target organ system.
    Although 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. Because of the contribution to total HAP
risk from emission sources other than those that we have studied in
depth during this RTR review, such estimates of total HAP risks would
have significantly greater associated uncertainties than the source
category or facility-wide estimates. Such aggregate or cumulative
assessments would compound those uncertainties, making the assessments
too unreliable.

B. How do we perform the technology review?

    Our technology review focuses on the identification and evaluation
of developments in practices, processes, and control technologies that
have occurred since the MACT standards were promulgated. Where we
identify such developments, in order to inform our decision of whether
it is ``necessary'' to revise the emissions standards, we analyze the
technical feasibility of applying these developments and the estimated
costs, energy implications, and non-air environmental impacts, and we
also consider the emission reductions. In addition, we consider the
appropriateness of applying controls to new sources versus retrofitting
existing sources.
    For this exercise, we consider any of the following to be a
``development'':
     Any add-on control technology or other equipment that was
not identified and considered during development of the original MACT
standards;
     Any improvements in add-on control technology or other
equipment (that were identified and considered during development of
the original MACT standards) that could result in additional emissions
reduction;
     Any work practice or operational procedure that was not
identified or considered during development of the original MACT
standards;
     Any process change or pollution prevention alternative
that could be broadly applied to the industry and that was not
identified or considered during development of the original MACT
standards; and
     Any significant changes in the cost (including cost
effectiveness) of applying controls (including controls the EPA
considered during the development of the original MACT standards).
    In addition to reviewing the practices, processes, and control
technologies that were considered at the time we originally developed
(or last updated) the NESHAP, we review a variety of data sources in
our investigation of potential practices, processes, or controls to
consider. Among the sources we reviewed were the NESHAP for various
industries that were promulgated since the MACT standards being
reviewed in this action. We reviewed the regulatory requirements and/or
technical analyses associated with these regulatory actions to identify
any practices, processes, and control technologies considered in these
efforts that could be applied to emission sources in the Surface
Coating of Wood Building Products source category, as well as the
costs, non-air impacts, and energy implications associated with the use
of these technologies. Finally, we reviewed information from other
sources, such as state and/or local permitting agency databases and
industry-supported databases.

C. How did we estimate post-MACT risks posed by the source category?

    The EPA conducted a risk assessment that provides estimates of the
MIR for cancer posed by the HAP emissions from each source in the
source category, the HI for chronic exposures to HAP with the potential
to cause noncancer health effects, and the HQ for acute exposures to
HAP with the potential to cause noncancer health effects. The
assessment also provides estimates of the distribution of cancer risks
within the exposed populations, cancer incidence, and an evaluation of
the potential for adverse environmental effects. The seven sections
that follow this paragraph describe how we estimated emissions and
conducted the risk assessment. The docket for this rulemaking contains
the following document which provides more information on the risk
assessment

inputs and models: Residual Risk Assessment for the Surface Coating of
Wood Building Products Source Category in Support of the March 2018
Risk and Technology Review Proposed Rule. The methods used to assess
risks (as described in the seven primary steps below) are consistent
with those peer-reviewed by a panel of the SAB in 2009 and described in
their peer review report issued in 2010; \4\ they are also consistent
with the key recommendations contained in that report.
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    \4\ U.S. EPA SAB. Risk and Technology Review (RTR) Risk
Assessment Methodologies: For Review by the EPA's Science Advisory
Board with Case Studies--MACT I Petroleum Refining Sources and
Portland Cement Manufacturing, May 2010.
---------------------------------------------------------------------------

1. How did we estimate actual emissions and identify the emissions
release characteristics?
    Data were extracted from the ECHO database to determine which
facilities were potentially subject to the Surface Coating of Wood
Building Products NESHAP to develop a facility list. The ECHO database
provides integrated compliance and enforcement information for about
800,000 regulated facilities nationwide and it allows for the search of
information on permit data, inspection dates and findings, violations,
and enforcement actions. For more details on ECHO, see https://echo.epa.gov/resources/general-info/learn-more-about-echo. The ECHO
database identified 135 facilities as potentially subject to the
Surface Coating of Wood Building Products NESHAP. Further review of the
permits for these facilities found that 64 facilities have surface
coating of wood building products operations, and 55 of those
facilities are subject to the requirements of 40 CFR part 63, subpart
QQQQ. We are interested in your comments on the development of the
facility list used in our analysis. For more details on the facility
list development, see the memorandum titled Preparation of the Residual
Risk Modeling Input File for Subpart QQQQ in the docket for this
rulemaking (Docket ID No. EPA-HQ-OAR-2016-0678).
    As discussed in section II.C of this preamble, we used data from
facility permits, the 2014 NEI (version 1), and the TRI as the basis
for the emissions used in the risk assessment for the Surface Coating
of Wood Building Products source category. The NEI is a database that
contains information about sources that emit criteria air pollutants
(CAP), CAP precursors, and HAP. The NEI is released every 3 years based
primarily on data provided by state, local, and tribal air agencies for
sources in their jurisdictions and supplemented with data developed by
the EPA. The NEI database includes estimates of actual annual air
pollutant emissions from point and fugitive sources and emission
release characteristic data, such as emission release height,
temperature, diameter, velocity, and flow rates. The NEI database also
includes locational latitude/longitude coordinates. For more details on
the NEI, see https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei. The TRI tracks the management of certain toxic
chemicals that may pose a threat to human health and the environment
through annual facility reporting of how much of each chemical is
released into the environment. For more details on the TRI, see https://www.epa.gov/toxics-release-inventory-tri-program/learn-about-toxics-release-inventory.
    We began compiling an initial draft residual risk modeling input
file for use in the Surface Coating of Wood Building Products NESHAP
residual risk review in 2016.\5\ We made further updates to the source
category facility list to account for facilities that recently closed
or reopened, added new products covered by the Surface Coating of Wood
Building Products NESHAP, and/or changed their surface coating
equipment or application techniques.
---------------------------------------------------------------------------

    \5\ For more information, see the memorandum in the docket
titled Preparation of Residual Risk Modeling Input File for Subpart
QQQQ. The memorandum describes the source of the inventory data,
discusses quality assurance of the 40 CFR part 63, subpart QQQQ
data, provides actual versus allowable and acute risk multipliers
for subpart QQQQ sources, and identifies potential outliers and
suspect data for further review.
---------------------------------------------------------------------------

    We estimated actual emissions based on the 2014 NEI,
preferentially, and subsequent site-specific inventory revisions
provided by states or individual facilities. Where 2014 NEI data were
not available for a facility, we used data from the 2011 NEI and then
the 2014 TRI. Using this combination of EPA databases, we collected
emissions information on the 55 sources in the category. We identified
nine facilities that reported zero HAP emissions for the Surface
Coating of Wood Building Products source category, and they were
excluded from the risk modeling file. As a result, the risk modeling
file characterized the impact of emissions from 46 sources.\6\
---------------------------------------------------------------------------

    \6\ Id.
---------------------------------------------------------------------------

    The total HAP emissions for the source category, which were
included in the modeling file, are approximately 260 tpy. Based on the
available data, the HAP emitted in the largest quantities are methanol,
toluene, xylenes, ethyl benzene, methyl isobutyl ketone, glycol ethers,
vinyl acetate, ethylene glycol, methyl methacrylate, formaldehyde, and
dimethyl phthalate. Other than lead, persistent and bioaccumulative HAP
(PB-HAP) were not reported as being emitted from this source category.
Therefore, the only assessment of multipathway risk was for lead, and
that assessment compared the ambient air lead concentrations to the
lead National Ambient Air Quality Standard (NAAQS). Further information
about the multipathway analysis performed for this category follows in
section III.C.3.d.
2. How did we estimate MACT-allowable emissions?
    The available emissions data in the RTR emissions dataset include
estimates of the mass of HAP emitted during a specified annual time
period. These ``actual'' emission levels are often lower than the
emission levels allowed under the requirements of the current MACT
standards. The emissions level allowed to be emitted under the MACT
standards is referred to as the ``MACT-allowable'' emissions level. We
discussed the use of both MACT-allowable and actual emissions in the
final Coke Oven Batteries RTR (70 FR 19998-19999, April 15, 2005) and
in the proposed and final Hazardous Organic NESHAP RTRs (71 FR 34428,
June 14, 2006, and 71 FR 76609, December 21, 2006, respectively). In
those actions, we noted that assessing the risks at the MACT-allowable
level is inherently reasonable since these risks reflect the maximum
level facilities could emit and still comply with national emission
standards. 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 approach. (54 FR 38044,
September 14, 1989.)
    Actual emissions are often lower than MACT-allowable emissions due
to compliance margins, more stringent state or local rules, or over-
control due to use of control technologies, equipment, or work
practices that are significantly better than required to meet the
NESHAP limits. However, over 90 percent of wood building products
manufacturers use compliant coatings with low- or no-HAP emissions and
production rate limits. We assume that coatings in the category are
engineered to meet the standard with a reasonable compliance margin.
For those operations, we would expect actual emissions to equal MACT-
allowable emissions, because of the use of the compliant coatings and/
or low-HAP coatings. Additionally, for new sources,

three of five new source limits in the NESHAP are zero-HAP limits, and,
as a result, we assumed that the reported actual emissions were equal
to the MACT-allowable emissions for these sources since the MACT-
allowable emissions are zero. For facilities using an add-on control,
the operating permits indicate that the coating lines may not operate
without controls. Therefore, we assumed that MACT-allowable emissions
were equal to actual emissions. We are requesting comment on the
assumption that actual and MACT-allowable emissions are the same for
this source category.
    3. How did we conduct dispersion modeling, determine inhalation
exposures, and estimate individual and population inhalation risks?
    Both long-term and short-term inhalation exposure concentrations
and health risks from the source category addressed in this proposal
were estimated using the Human Exposure Model (HEM-3). The HEM-3
performs three primary risk assessment activities: (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 kilometers (km) of the modeled sources,
and (3) estimating individual and population-level inhalation risks
using the exposure estimates and quantitative dose-response
information.
a. Dispersion Modeling
    The air dispersion model AERMOD, used by the HEM-3 model, is one of
the EPA's preferred models for assessing air pollutant concentrations
from industrial facilities.\7\ 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 1 year (2016) of
hourly surface and upper air observations from 824 meteorological
stations selected to provide coverage of the United States and Puerto
Rico. A second library of United States Census Bureau census block \8\
internal point locations and populations provides the basis of human
exposure calculations (U.S. Census, 2010). 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-specific dose-response values is used to estimate health
risks. These dose-response values are the latest values recommended by
the EPA for HAP. They are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants and are discussed in more detail later in this
section.
---------------------------------------------------------------------------

    \7\ 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).
    \8\ A census block is the smallest geographic area for which
census statistics are tabulated.
---------------------------------------------------------------------------

b. Risk From Chronic Exposure to HAP That May Cause Cancer
    In developing the risk assessment for chronic exposures, we used
the estimated annual average ambient air concentrations of each 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, 52 weeks per
year, for a 70-year period) exposure to the maximum concentration at
the centroid of inhabited census blocks. Individual cancer risks were
calculated by multiplying the estimated lifetime exposure to the
ambient concentration of each HAP (in micrograms per cubic meter
([mu]g/m\3\)) by its unit risk estimate (URE). The URE 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 UREs from the EPA's Integrated Risk Information System
(IRIS). For carcinogenic pollutants without IRIS values, we look to
other reputable sources of cancer dose-response values, often using
California EPA (CalEPA) UREs, where available. In cases where new,
scientifically credible dose-response values have been developed in a
manner consistent with the EPA guidelines and have undergone a peer
review process similar to that used by the EPA, we may use such dose-
response values in place of, or in addition to, other values, if
appropriate.
    To estimate incremental individual lifetime cancer risks associated
with emissions from the facilities in the source category, the EPA
summed the risks for each of the carcinogenic HAP \9\ emitted by the
modeled sources. Cancer incidence and the distribution of individual
cancer risks for the population within 50 km of the sources were also
estimated for the source category by summing individual risks. A
distance of 50 km is consistent with both the analysis supporting the
1989 Benzene NESHAP (54 FR 38044, September 14, 1989) and the
limitations of Gaussian dispersion models, including AERMOD.
---------------------------------------------------------------------------

    \9\ The EPA classifies carcinogens as: carcinogenic to humans,
likely to be carcinogenic to humans, and suggestive evidence of
carcinogenic potential. These classifications also coincide with the
terms ``known carcinogen, probable carcinogen, and possible
carcinogen,'' respectively, which are the terms advocated in the
EPA's Guidelines for Carcinogen Risk Assessment, published in 1986
(51 FR 33992, September 24, 1986). In August 2000, the document,
Supplemental Guidance for Conducting Health Risk Assessment of
Chemical Mixtures (EPA/630/R-00/002), was published as a supplement
to the 1986 document. Copies of both documents can be obtained from
https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=20533&CFID=70315376&CFTOKEN=71597944. 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 the EPA's National Air Toxics Assessment
(NATA) titled 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.
---------------------------------------------------------------------------

c. Risk From Chronic Exposure to HAP That May Cause Health Effects
Other Than Cancer
    To assess the risk of noncancer health effects from chronic
exposure to HAP, we calculate either an HQ or a target organ-specific
hazard index (TOSHI). We calculate an HQ when a single noncancer HAP is
emitted. Where more than one noncancer HAP is emitted, we sum the HQ
for each of the HAP that affects a common target organ system to obtain
a TOSHI. The HQ is the estimated exposure divided by the chronic
noncancer dose-response value, which is a value selected from one of
several sources. The preferred chronic noncancer dose-response value is
the EPA RfC (https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glossary), 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.'' In cases where an RfC from
the EPA's IRIS database is not available or where the EPA determines
that using a value other than the RfC is appropriate, the chronic
noncancer dose-response value can be a value from the following
prioritized sources, which

define their dose-response values similarly to the EPA: (1) The Agency
for Toxic Substances and Disease Registry (ATSDR) Minimum Risk Level
(http://www.atsdr.cdc.gov/mrls/index.asp); (2) the CalEPA Chronic
Reference Exposure Level (REL) (http://oehha.ca.gov/air/crnr/notice-adoption-air-toxics-hot-spots-program-guidance-manual-preparation-health-risk-0); or (3), as noted above, a scientifically credible dose-
response value that has been developed in a manner consistent with the
EPA guidelines and has undergone a peer review process similar to that
used by the EPA.
d. Risk From Acute Exposure to HAP That May Cause Health Effects Other
Than Cancer
    For each HAP for which appropriate acute inhalation dose-response
values are available, the EPA also assesses the potential health risks
due to acute exposure. For these assessments, in order to avoid under-
estimating effects, the EPA makes conservative assumptions about
emission rates, meteorology, and exposure location. We use the peak
hourly emission rate,\10\ worst-case dispersion conditions, and, in
accordance with our mandate under section 112 of the CAA, the point of
highest off-site exposure to assess the potential risk to the maximally
exposed individual.
---------------------------------------------------------------------------

    \10\ In the absence of hourly emission data, we develop
estimates of maximum hourly emission rates by multiplying the
average actual annual emissions rates by a default factor (usually
10) to account for variability. This is documented in Residual Risk
Assessment for Residual Risk Assessment for the Surface Coating of
Wood Building Products Source Category in Support of the March 2018
Risk and Technology Review Proposed Rule, September, 2017 Risk and
Technology Review Proposed Rule and in Appendix 5 of the report:
Analysis of Data on Short-term Emission Rates Relative to Long-term
Emission Rates. Both are available in the docket for this
rulemaking.
---------------------------------------------------------------------------

    To characterize the potential health risks associated with
estimated acute inhalation exposures to a HAP, we generally use
multiple acute dose-response values, including acute RELs, acute
exposure guideline levels (AEGLs), and emergency response planning
guidelines (ERPG) for 1-hour exposure durations), if available, to
calculate acute HQs. The acute HQ is calculated by dividing the
estimated acute exposure by the acute dose-response value. For each HAP
for which acute dose-response values are available, the EPA calculates
acute HQs.
    An acute REL is defined as ``the concentration level at or below
which no adverse health effects are anticipated for a specified
exposure duration.'' \11\ Acute RELs are based on the most sensitive,
relevant, adverse health effect reported in the peer-reviewed medical
and toxicological literature. They are designed to protect the most
sensitive individuals in the population through the inclusion of
margins of safety. Because margins of safety are incorporated to
address data gaps and uncertainties, exceeding the REL does not
automatically indicate an adverse health impact. AEGLs represent
threshold exposure limits for the general public and are applicable to
emergency exposures ranging from 10 minutes to 8 hours.\12\ They are
guideline levels for ``once-in-a-lifetime, short-term exposures to
airborne concentrations of acutely toxic, high-priority chemicals.''
Id. at 21. The AEGL-1 is specifically defined as ``the airborne
concentration (expressed as ppm (parts per million) or mg/m\3\
(milligrams per cubic meter)) 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.'' 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.'' Id. AEGL-2 are defined as ``the
airborne concentration (expressed as parts per million or milligrams
per cubic meter) 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.'' Id.
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    \11\ CalEPA issues acute RELs as part of its Air Toxics Hot
Spots Program, and the 1-hour and 8-hour values are documented in
Air Toxics Hot Spots Program Risk Assessment Guidelines, Part I, The
Determination of Acute Reference Exposure Levels for Airborne
Toxicants, which is available at http://oehha.ca.gov/air/general-info/oehha-acute-8-hour-and-chronic-reference-exposure-level-rel-summary.
    \12\ National Academy of Sciences, 2001. Standing Operating
Procedures for Developing Acute Exposure Levels for Hazardous
Chemicals, page 2. Available at https://www.epa.gov/sites/production/files/2015-09/documents/sop_final_standing_operating_procedures_2001.pdf. Note that the
National Advisory Committee/AEGL Committee ended in October 2011,
but the AEGL program continues to operate at the EPA and works with
the National Academies to publish final AEGLs (https://www.epa.gov/aegl).
---------------------------------------------------------------------------

    ERPGs are developed for emergency planning and are intended as
health-based guideline concentrations for single exposures to
chemicals.'' \13\ Id. at 1. The ERPG-1 is defined as ``the maximum
airborne concentration below which it is believed that nearly all
individuals could be exposed for up to 1 hour without experiencing
other than mild transient adverse health effects or without perceiving
a clearly defined, objectionable odor.'' Id. at 2. Similarly, the ERPG-
2 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.'' Id. at 1.
---------------------------------------------------------------------------

    \13\ ERPGS Procedures and Responsibilities. March 2014. American
Industrial Hygiene Association. Available at: https://www.aiha.org/get-involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERPG%20Committee%20Standard%20Operating%20Procedures%20%20-%20March%202014%20Revision%20%28Updated%2010-2-2014%29.pdf.
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    An acute REL for 1-hour exposure durations is typically lower than
its corresponding AEGL-1 and ERPG-1. Even though their definitions are
slightly different, AEGL-1s are often the same as the corresponding
ERPG-1s, and AEGL-2s are often equal to ERPG-2s. The maximum HQs from
our acute inhalation screening risk assessment typically result when we
use the acute REL for a HAP. In cases where the maximum acute HQ
exceeds 1, we also report the HQ based on the next highest acute dose-
response value (usually the AEGL-1 and/or the ERPG-1).
    For this source category, we did not have short-term emissions
data; therefore, we estimated the peak, short-term emissions using
available annual emissions data from the NEI. We assumed that the peak,
1-hour emission rate could exceed a facility's annual average hourly
emission rate by as much as a factor of 10, under worst-case
meteorological conditions. For facilities that used compliant coatings,
the default acute multiplier of 10 is overly conservative because
compliant coatings result in an emissions profile that is not expected
to have significant fluctuations in HAP emissions. Further review of
permits found that two facilities utilizing the compliant coating
approach only operate coating operations for one 8-hour shift per day,
therefore, an acute multiplier of 3 was used. The default multiplier of
10 was applied to all other facilities. A further discussion of why
these factors were chosen can be found in the memorandum, Preparation
of the Residual Risk Modeling Input File for

Subpart QQQQ, available in the docket for this rulemaking.
    In our acute inhalation screening risk assessment, acute impacts
are deemed negligible for HAP where acute HQs are less than or equal to
1 (even under the conservative assumptions of the screening
assessment), and no further analysis is performed for these HAP. In
cases where an acute HQ from the screening step is greater than 1, we
consider additional site-specific data to develop a more refined
estimate of the potential for acute impacts of concern. For this source
category, we refined our analysis by reviewing the receptor locations
where the maximum HQ occurred. These refinements are discussed more
fully in the Residual Risk Assessment for the Surface Coating of Wood
Building Products Source Category in Support of the March 2018 Risk and
Technology Review Proposed Rule, which is available in the docket for
this source category.
4. How did we conduct the multipathway exposure and risk screening
assessment?
    The EPA conducted a tiered screening assessment examining the
potential for significant human health risks due to exposures via
routes other than inhalation (i.e., ingestion). We first determined
whether any sources in the source category emitted any PB-HAP, as
identified in the EPA's Air Toxics Risk Assessment Library (see Volume
1, Appendix D, at http://www2.epa.gov/fera/risk-assessment-and-modeling-air-toxics-risk-assessment-reference-library).
    For the Surface Coating of Wood Building Products source category,
we did not identify emissions of any PB-HAP except for lead compounds,
for which the lead NAAQS was applied to assess multipathway impacts.
Because we did not identify PB-HAP emissions requiring further
evaluation, no further evaluation of multipathway risk was conducted
for this source category.
    In evaluating the potential multipathway risk from emissions of
lead compounds, rather than developing a screening threshold emission
rate, we compare maximum estimated chronic inhalation exposure
concentrations with the level of the current NAAQS for lead.\14\ Values
below the level of the primary (health-based) lead NAAQS are considered
to have a low potential for multipathway risk.
---------------------------------------------------------------------------

    \14\ In doing so, the EPA notes that the legal standard for a
primary NAAQS--that a standard is requisite to protect public health
and provide an adequate margin of safety (CAA section 109(b))--
differs from the CAA section 112(f) standard (requiring, among other
things, that the standard provide an ``ample margin of safety'').
However, the primary lead NAAQS is a reasonable measure of
determining risk acceptability (i.e., the first step of the Benzene
NESHAP analysis) since it is designed to protect the most
susceptible group in the human population--children, including
children living near major lead emitting sources. 73 FR 67002/3; 73
FR 67000/3; 73 FR 67005/1. In addition, applying the level of the
primary lead NAAQS at the risk acceptability step is conservative,
since that primary lead NAAQS reflects an adequate margin of safety.
---------------------------------------------------------------------------

    For further information on the multipathway assessment approach,
see the Residual Risk Assessment for the Surface Coating of Wood
Building Products Source Category in Support of the March 2018 Risk and
Technology Review Proposed Rule, which is available in the docket for
this action.
5. How did we conduct the environmental risk screening assessment?
a. Adverse Environmental Effects, Environmental HAP, and Ecological
Benchmarks
    The EPA conducts a screening assessment to examine the potential
for adverse environmental effects as required under section
112(f)(2)(A) of the CAA. Section 112(a)(7) of the CAA defines ``adverse
environmental effect'' as ``any significant and widespread adverse
effect, which may reasonably be anticipated, to wildlife, aquatic life,
or other natural resources, including adverse impacts on populations of
endangered or threatened species or significant degradation of
environmental quality over broad areas.''
    The EPA focuses on eight HAP, which are referred to as
``environmental HAP,'' in its screening assessment: six PB-HAP and two
acid gases. The PB-HAP included in the screening assessment are arsenic
compounds, cadmium compounds, dioxins/furans, polycyclic organic
matter, mercury (both inorganic mercury and methyl mercury), and lead
compounds. The acid gases included in the screening assessment are
hydrochloric acid (HCl) and hydrogen fluoride (HF).
    The HAP that persist and bioaccumulate are of particular
environmental concern because they accumulate in the soil, sediment,
and water. The acid gases, HCl and HF, were included due to their well-
documented potential to cause direct damage to terrestrial plants. In
the environmental risk screening assessment, we evaluate the following
four exposure media: Terrestrial soils, surface water bodies (includes
water-column and benthic sediments), fish consumed by wildlife, and
air. Within these four exposure media, we evaluate nine ecological
assessment endpoints, which are defined by the ecological entity and
its attributes. For PB-HAP (other than lead), both community-level and
population-level endpoints are included. For acid gases, the ecological
assessment evaluated is terrestrial plant communities.
    An ecological benchmark represents a concentration of HAP that has
been linked to a particular environmental effect level. For each
environmental HAP, we identified the available ecological benchmarks
for each assessment endpoint. We identified, where possible, ecological
benchmarks at the following effect levels: Probable effect levels,
lowest-observed-adverse-effect level, and no-observed-adverse-effect
level. In cases where multiple effect levels were available for a
particular PB-HAP and assessment endpoint, we use all of the available
effect levels to help us to determine whether ecological risks exist
and, if so, whether the risks could be considered significant and
widespread.
    For further information on how the environmental risk screening
assessment was conducted, including a discussion of the risk metrics
used, how the environmental HAP were identified, and how the ecological
benchmarks were selected, see Appendix 9 of the Residual Risk
Assessment for the Surface Coating of Wood Building Products Source
Category in Support of the March 2018 Risk and Technology Review
Proposed Rule, which is available in the docket for this action.
b. Environmental Risk Screening Methodology
    For the environmental risk screening assessment, the EPA first
determined whether any facilities in the Surface Coating of Wood
Building Products source category emitted any of the environmental HAP.
For the Surface Coating of Wood Building Products source category, we
identified emissions of lead compounds.
    Because one or more of the environmental HAP evaluated are emitted
by at least one facility in the source category, we proceeded to the
second step of the evaluation.
    To evaluate the potential for adverse environmental effects from
lead, we compared the average modeled air concentrations (from HEM-3)
of lead around each facility in the source category to the level of the
secondary NAAQS for lead. The secondary lead NAAQS is a reasonable
means of evaluating environmental risk because it is set to provide
substantial protection against adverse welfare effects which

can include ``effects on soils, water, crops, vegetation, man-made
materials, animals, wildlife, weather, visibility and climate, damage
to and deterioration of property, and hazards to transportation, as
well as effects on economic values and on personal comfort and well-
being.''
6. How did we conduct facility-wide assessments?
    To put the source category risks in context, we typically examine
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, we examine the HAP emissions not only from the
source category emission points of interest, but also emissions of HAP
from all other emission sources at the facility for which we have data.
    For this source category, we conducted the facility-wide assessment
using a dataset that the EPA compiled from the 2014 NEI. We used the
NEI data for the facility and did not adjust any category or ``non-
category'' data. Therefore, there could be differences in the dataset
from that used for the source category assessments described in this
preamble. We analyzed 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, we
made a reasonable attempt to identify the source category risks, and
these risks were compared to the facility-wide risks to determine the
portion of facility-wide risks that could be attributed to the source
category addressed in this proposal. We also specifically examined the
facility that was associated with the highest estimate of risk and
determined the percentage of that risk attributable to the source
category of interest. The Residual Risk Assessment for the Surface
Coating of Wood Building Products Source Category in Support of the
March 2018 Risk and Technology Review Proposed Rule, available through
the docket for this action, provides the methodology and results of the
facility-wide analyses, including all facility-wide risks and the
percentage of source category contribution to facility-wide risks.
7. How did we consider uncertainties in risk assessment?
    Uncertainty and the potential for bias are inherent in all risk
assessments, including those performed for this proposal. Although
uncertainty exists, we believe that our approach, which used
conservative tools and assumptions in order to avoid under-estimating
effects, ensures that our decisions are health and environmentally
protective. A brief discussion of the uncertainties in the RTR
emissions dataset, dispersion modeling, inhalation exposure estimates,
and dose-response relationships follows below. Also included are those
uncertainties specific to our acute screening assessments, multipathway
screening assessments, and our environmental risk screening
assessments. A more thorough discussion of these uncertainties is
included in the Residual Risk Assessment for the Surface Coating of
Wood Building Products Source Category in Support of the March 2018
Risk and Technology Review Proposed Rule, which is available in the
docket for this action. If a multipathway site-specific assessment was
performed for this source category, a full discussion of the
uncertainties associated with that assessment can be found in Appendix
11 of that document, Site-Specific Human Health Multipathway Residual
Risk Assessment Report.
a. Uncertainties in the RTR Emissions Dataset
    Although the development of the RTR emissions dataset involved
quality assurance/quality control (QC) 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 accurate, errors in
emission estimates, and other factors. The emission estimates
considered in this analysis generally are annual totals for certain
years, and they do not reflect short-term fluctuations during the
course of a year or variations from year to year. The estimates of peak
hourly emission rates for the acute effects screening assessment were
based on an emission adjustment factor applied to the average annual
hourly emission rates, which are intended to account for emission
fluctuations due to normal facility operations.
b. Uncertainties in Dispersion Modeling
    We recognize there is uncertainty in ambient concentration
estimates associated with any model, including the EPA's recommended
regulatory dispersion model, AERMOD. In using a model to estimate
ambient pollutant concentrations, the user chooses certain options to
apply. For RTR assessments, we select some model options that have the
potential to overestimate ambient air concentrations (e.g., not
including plume depletion or pollutant transformation). We select other
model options that have the potential to underestimate ambient impacts
(e.g., not including building downwash). Other options that we select
have the potential to either under- or overestimate ambient levels
(e.g., meteorology and receptor locations). On balance, considering the
directional nature of the uncertainties commonly present in ambient
concentrations estimated by dispersion models, the approach we apply in
the RTR assessments should yield unbiased estimates of ambient HAP
concentrations. We also note that the selection of meteorology dataset
location could have an impact on the risk estimates. As we continue to
update and expand our library of meteorological station data used in
our risk assessments, we expect to reduce this variability.
c. Uncertainties in Inhalation Exposure Assessment
    Although every effort is made to identify all of the relevant
facilities and emission points, as well as to develop accurate
estimates of the annual emission rates for all relevant HAP, the
uncertainties in our emission inventory likely dominate the
uncertainties in the exposure assessment. Some uncertainties in our
exposure assessment include human mobility, using the centroid of each
census block, assuming lifetime exposure, and assuming only outdoor
exposures. For most of these factors, there is neither an under nor
overestimate when looking at the maximum individual risks or the
incidence, but the shape of the distribution of risks may be affected.
With respect to outdoor exposures, actual exposures may not be as high
if people spend time indoors, especially for very reactive pollutants
or larger particles. For all factors, we reduce uncertainty when
possible. For example, with respect to census-block centroids, we
analyze large blocks using aerial imagery and adjust locations of the
block centroids to better represent the population in the blocks. We
also add additional receptor locations where the population of a block
is not well represented by a single location.
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 noncancer effects from both chronic and acute
exposures. Some uncertainties are generally expressed quantitatively,
and others are generally expressed in qualitative terms. We note,

as a preface to this discussion, a point on dose-response uncertainty
that is stated in the 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's 2005 Cancer Guidelines,
pages 1-7). This is the approach followed here as summarized in the
next paragraphs.
    Cancer UREs 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).\15\ In some circumstances, the true risk could be as low as
zero; however, in other circumstances the risk could be greater.\16\
Chronic noncancer RfC and reference dose (RfD) values represent chronic
exposure levels that are intended to be health-protective levels. To
derive dose-response values that are intended to be ``without
appreciable risk,'' the methodology relies upon an uncertainty factor
(UF) approach (U.S. EPA, 1993 and 1994) which considers uncertainty,
variability, and gaps in the available data. The UFs are applied to
derive dose-response values that are intended to protect against
appreciable risk of deleterious effects.
---------------------------------------------------------------------------

    \15\ IRIS glossary (https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&glossaryName=IRIS%20Glossary).
    \16\ 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.
---------------------------------------------------------------------------

    Many of the UFs used to account for variability and uncertainty in
the development of acute dose-response values are quite similar to
those developed for chronic durations. Additional adjustments are often
applied to account for uncertainty in extrapolation from observations
at one exposure duration (e.g., 4 hours) to derive an acute dose-
response value at another exposure duration (e.g., 1 hour). Not all
acute dose-response 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 dose-response value or values
being exceeded. Where relevant to the estimated exposures, the lack of
acute dose-response values at different levels of severity should be
factored into the risk characterization as potential uncertainties.
    Uncertainty also exists in the selection of ecological benchmarks
for the environmental risk screening assessment. We established a
hierarchy of preferred benchmark sources to allow selection of
benchmarks for each environmental HAP at each ecological assessment
endpoint. We searched for benchmarks for three effect levels (i.e., no-
effects level, threshold-effect level, and probable effect level), but
not all combinations of ecological assessment/environmental HAP had
benchmarks for all three effect levels. Where multiple effect levels
were available for a particular HAP and assessment endpoint, we used
all of the available effect levels to help us determine whether risk
exists and whether the risk could be considered significant and
widespread.
    Although every effort is made to identify appropriate human health
effect dose-response values for all pollutants emitted by the sources
in this risk assessment, some HAP emitted by this source category are
lacking dose-response assessments. Accordingly, these pollutants cannot
be included in the quantitative risk assessment, which could result in
quantitative estimates understating HAP risk. To help to alleviate this
potential underestimate, where we conclude similarity with a HAP for
which a dose-response value is available, we use that value as a
surrogate for the assessment of the HAP for which no value is
available. To the extent use of surrogates indicates appreciable risk,
we may identify a need to increase priority for an IRIS assessment for
that substance. We additionally note that, generally speaking, HAP of
greatest concern due to environmental exposures and hazard are those
for which dose-response assessments have been performed, reducing the
likelihood of understating risk. Further, HAP not included in the
quantitative assessment are assessed qualitatively and considered in
the risk characterization that informs the risk management decisions,
including consideration of HAP reductions achieved by various control
options.
    For a group of compounds that are unspeciated (e.g., glycol
ethers), we conservatively use the most protective dose-response value
of an individual compound in that group to estimate risk. Similarly,
for an individual compound in a group (e.g., ethylene glycol diethyl
ether) that does not have a specified dose-response value, we also
apply the most protective dose-response value from the other compounds
in the group to estimate risk.
e. Uncertainties in Acute Inhalation Screening Assessments
    In addition to the uncertainties highlighted above, there are
several factors specific to the acute exposure assessment that the EPA
conducts as part of the risk review under section 112 of the CAA. 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 the presence of humans
at the location of the maximum concentration. In the acute screening
assessment that we conduct under the RTR program, we assume that peak
emissions from the source category and worst-case meteorological
conditions co-occur, thus, resulting in maximum ambient concentrations.
These two events are unlikely to occur at the same time, making these
assumptions conservative in the sense that they may over-estimate
effects. We then include the additional assumption that a person is
located at this point during this same time period. For this source
category, these assumptions would tend to be worst-case actual
exposures as it is unlikely that a person would be located at the point
of maximum exposure during the time when peak emissions and worst-case
meteorological conditions occur simultaneously.

IV. Analytical Results and Proposed Decisions

A. What are the results of the risk assessment and analyses?

    As described above, for the Surface Coating of Wood Building
Products source category, we conducted an inhalation risk assessment
for all HAP emitted, and multipathway and environmental risk screening
assessments on the only PB-HAP emitted, lead. We present results of the
risk assessment briefly below and in more detail in the residual risk
document titled Residual Risk Assessment for the Surface Coating of
Wood Building Products Source Category in Support of the March 2018
Risk and Technology Review Proposed Rule, which is available in the
docket for this action.
1. Inhalation Risk Assessment Results
    Table 2 of this preamble provides an overall summary of the results
of the inhalation risk assessment. As discussed in section III.C.2 of
this preamble, we set MACT-allowable HAP emission levels equal to
actual emissions. For more detail about the MACT-allowable emission
levels, see the memorandum,

Preparation of Residual Risk Modeling Input File for Subpart QQQQ,\5\
which is available in the docket for this action.

                                Table 2--Surface Coating of Wood Building Products Inhalation Risk Assessment Results \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Estimated
                                                                Maximum         population at     Estimated annual   Maximum chronic   Maximum screening
            Risk assessment                 Number of      individual cancer  increased risk of   cancer incidence   noncancer TOSHI    acute noncancer
                                          facilities \2\       risk (in 1      cancer >=1-in-1    (cases per year)         \4\               HQ \5\
                                                              million) \3\         Million
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category.......................                 46                  6                800             0.0006               0.05                  1
Facility-Wide.........................                 46                 30             26,000              0.004                  7  .................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Based on actual and allowable emissions. For this source category, actual and allowable emissions are identical, so a separate risk assessment was
  not conducted for allowable emissions.
\2\ Number of facilities evaluated in the risk assessment. As described elsewhere, there are additional facilities included in the data set for the
  technology review.
\3\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\4\ Maximum TOSHI. The target organ with the highest TOSHI for the wood building products source category is the respiratory system.
\5\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. HQ values
  shown use the lowest available acute threshold value, which in most cases is the REL. When an HQ exceeds 1, we also show the HQ using the next lowest
  available acute dose-response value.

    The inhalation risk modeling performed to estimate risks based on
actual and allowable emissions relied primarily on emissions data from
the NEI. The results of the inhalation cancer risk assessment, as shown
in Table 2 of this preamble, indicate that the MIR could be up to 6-in-
1 million, with formaldehyde from the melamine laminating process as
the sole contributor (100 percent) to the MIR. The total estimated
cancer incidence from wood building product coating sources based on
actual emission levels is 0.0006 excess cancer cases per year or one
case every 1,667 years, with emissions of formaldehyde (35 percent),
naphthalene (27 percent), ethyl benzene (21 percent), and chromium (VI)
compounds (17 percent) contributing to the cancer incidence. In
addition, we estimate that approximately 800 people have cancer risks
greater than or equal to 1-in-1 million.
    The maximum modeled chronic noncancer HI (TOSHI) value for the
source category based on actual emissions is estimated to be 0.05, with
emissions of formaldehyde from the melamine laminating process as the
sole contributor (100 percent) to the TOSHI. The target organ affected
is the respiratory system. There are not any people estimated to have
exposure to HI levels greater than 1 as a result of emissions from this
source category.
2. Acute Risk Results
    Table 2 of this preamble shows the acute risk results for this
category. The screening analysis for acute impacts was based on actual
emissions, and to estimate the peak emission rates from the average
rates, an industry-specific multiplier of 3 was used for two
facilities, and a default factor of 10 was used for the remaining
facilities. The results of the acute screening analysis indicate that
the maximum off-facility-site acute HQ is 1, based on the REL value for
formaldehyde, and occurs at two facilities. One of these two facilities
used the acute factor of 3 to characterize short-term emissions, while
the other used the factor of 10. For all other HAP and facilities,
acute HQ values are less than 1. Refer to the document titled
Preparation of the Residual Risk Modeling Input File for Subpart QQQQ
(available in the docket for this action) for a detailed description of
how the acute factors were developed for this source category. For more
detailed acute risk results, refer to the residual risk document titled
Residual Risk Assessment for the Surface Coating of Wood Building
Products Source Category in Support of the March 2018 Risk and
Technology Review Proposed Rule, which is available in the docket for
this action.
3. Multipathway Risk Screening Results
    The only PB-HAP emitted by facilities in this source category is
lead. Results of the analysis for lead indicate that based on actual
emissions, the maximum annual off-site ambient lead concentration was
only 0.1 percent of the primary NAAQS for lead, and if the total annual
emissions occurred during a 3-month period, the maximum 3-month rolling
average concentration would still be only 0.5 percent of the NAAQS.
Therefore, we do not expect any human health multipathway risks as a
result of emissions from this source category.
4. Environmental Risk Screening Results
    The only environmental HAP emitted by facilities in this source
category is lead. Results of the analysis for lead indicate that based
on actual emissions, the maximum annual off-site ambient lead
concentration was only 0.1 percent of the secondary NAAQS for lead, and
if the total annual emissions occurred during a 3-month period, the
maximum 3-month rolling average concentration would still be only 0.5
percent of the NAAQS. Therefore, we do not expect an adverse
environmental effect as a result of HAP emissions from this source
category.
5. Facility-Wide Risk Results
    An assessment of the facility-wide risks was performed to provide
context for the source category risks, using NEI data as described
above. The maximum facility-wide cancer MIR is 30-in-1 million, mainly
driven by formaldehyde, chromium (VI) compounds, and nickel compounds
emissions from wood drying and enamel coating operations. Wood drying
is regulated under 40 CFR part 63, subpart DDDD, the Plywood and
Composite Wood Products NESHAP, and enamel coating is regulated under
40 CFR part 63, subpart RRRR, the Surface Coating of Metal Furniture
NESHAP. Risk and technology reviews are currently underway for both
NESHAP categories. The total estimated cancer incidence from the
facility-wide assessment is 0.004 excess cancer cases per year, or one
excess case in every 250 years. Approximately 26,000 people are
estimated to have cancer risks greater than 1-in-1 million from
exposure to HAP emitted from both MACT and non-MACT sources. The
maximum facility-wide TOSHI is estimated to be 7, mainly driven by
emissions of acrolein from industrial processes related to wood
products that are characterized as ``other, not classified'' in NEI.
Wood drying, regulated under 40 CFR part 63, subpart DDDD, noted above,
is presumably the source of the acrolein since the facilities
identified as sources also dry wood. We estimate that

approximately 900 people are exposed to noncancer HI levels above 1,
based on facility-wide emissions.
6. What demographic groups might benefit from this regulation?
    To examine the potential for any environmental justice (EJ) issues
that might be associated with the source category, we performed a
demographic analysis, which is an assessment of risks to individual
demographic groups of the populations living within 5 km and within 50
km of the facilities. In the analysis, we evaluated the distribution of
HAP-related cancer and noncancer risks from the Surface Coating of Wood
Building Products source category across different demographic groups
within the populations living near facilities.\17\
---------------------------------------------------------------------------

    \17\ Demographic groups included in the analysis are: White,
African American, Native American, other races and multiracial,
Hispanic or Latino, children 17 years of age and under, adults 18 to
64 years of age, adults 65 years of age and over, adults without a
high school diploma, people living below the poverty level, people
living two times the poverty level, and linguistically isolated
people.
---------------------------------------------------------------------------

    The results of the demographic analysis are summarized in Table 3
below. These results, for various demographic groups, are based on the
estimated risks from actual emissions levels for the population living
within 50 km of the facilities.

      Table 3--Surface Coating of Wood Building Products Source Category Demographic Risk Analysis Results
----------------------------------------------------------------------------------------------------------------
                                                                             Population with
                                                                            cancer risk at or   Population with
                                                                               above 1-in-1      chronic hazard
                                                             Nationwide       million due to   index above 1 due
                                                                              wood building     to wood building
                                                                             products surface   products surface
                                                                                coating            coating
----------------------------------------------------------------------------------------------------------------
Total Population.......................................        317,746,049                800                  0
----------------------------------------------------------------------------------------------------------------
                                                 Race by Percent
----------------------------------------------------------------------------------------------------------------
White..................................................                 62                 16                  0
All Other Races........................................                 38                 84                  0
----------------------------------------------------------------------------------------------------------------
                                                 Race by Percent
----------------------------------------------------------------------------------------------------------------
White..................................................                 62                 16                  0
African American.......................................                 12                 75                  0
Native American........................................                0.8                0.0                  0
Other and Multiracial..................................                  7                  3                  0
----------------------------------------------------------------------------------------------------------------
                                              Ethnicity by Percent
----------------------------------------------------------------------------------------------------------------
Hispanic...............................................                 18                  6                  0
Non-Hispanic...........................................                 82                 94                  0
----------------------------------------------------------------------------------------------------------------
                                                Income by Percent
----------------------------------------------------------------------------------------------------------------
Below Poverty Level....................................                 14                 19                  0
Above Poverty Level....................................                 86                 81                  0
----------------------------------------------------------------------------------------------------------------
                                              Education by Percent
----------------------------------------------------------------------------------------------------------------
Over 25 and without High School Diploma................                 14                 25                  0
Over 25 and with a High School Diploma.................                 86                 75                  0
----------------------------------------------------------------------------------------------------------------

    The results of the Surface Coating of Wood Building Products source
category demographic analysis indicate that emissions from the source
category expose approximately 800 people to a cancer risk at or above
1-in-1 million and no people to a chronic noncancer TOSHI greater than
1. The percentages of the at-risk population are greater than their
respective nationwide percentages for the following demographic groups
(excluding non-Hispanic): African American, people over 25 without a
high school diploma, and people living below the poverty level. The
other demographic groups within the exposed population were similar to
or lower than the corresponding nationwide percentages.
    The methodology and the results of the demographic analysis are
presented in a technical report, Risk and Technology Review--Analysis
of Demographic Factors for Populations Living Near Wood Building
Products Surface Coating Facilities, available in the docket for this
action.

B. What are our proposed decisions regarding risk acceptability, ample
margin of safety, and adverse environmental effects?

1. Risk Acceptability
    As noted in section II.A of this preamble, the EPA sets standards
under CAA section 112(f)(2) using ``a two-step standard-setting
approach, with an analytical first step to determine an `acceptable
risk' that considers all health information, including risk estimation
uncertainty, and includes a presumptive limit on MIR of ``approximately
1-in-10 thousand'' (54 FR 38045, September 14, 1989). We weigh all
health risk factors in our risk

acceptability determination, including the cancer MIR, cancer
incidence, the maximum cancer TOSHI, the maximum acute noncancer HQ,
the extent of noncancer risks, the distribution of cancer and noncancer
risks in the exposed population, and the risk estimation uncertainties.
    For this risk assessment, the EPA estimated risks based on actual
and allowable emissions from wood building products surface coating
sources. Allowable emissions were estimated to be equal to actual
emissions. The estimated inhalation cancer risk to the individual most
exposed to emissions from the source category is 6-in-1-million.
Approximately 800 people face an increased cancer risk greater than 1-
in-1 million due to inhalation exposure to HAP emissions from this
source category. The risk analysis indicates very low cancer incidence
(0.0006 excess cancer cases per year, or one excess case every 1,667
years), as well as low potential for adverse chronic noncancer health
effects. The acute screening assessment indicates no pollutants or
facilities exceeding an HQ value of 1. Therefore, we find there is
little potential concern of acute noncancer health impacts. In
evaluating the potential for multipathway effects from emissions of
lead from the source category, the risk assessment indicates no
significant potential for multipathway effects.
    Considering all of the health risk information and factors
discussed above, including the uncertainties discussed in section III
of this preamble, the EPA proposes that the risks from the Surface
Coating of Wood Building Products source category are acceptable.
2. Ample Margin of Safety Analysis and Proposed Controls
    As directed by CAA section 112(f)(2), we conducted an analysis to
determine if the current emissions standards provide an ample margin of
safety to protect public health. Under the ample margin of safety
analysis, the EPA considers all health factors evaluated in the risk
assessment and evaluates the cost and feasibility of available control
technologies and other measures (including the controls, measures, and
costs reviewed under the technology review) that could be applied to
this source category to further reduce the risks (or potential risks)
due to emissions of HAP identified in our risk assessment. In this
analysis, we considered the results of the technology review, risk
assessment, and other aspects of our MACT rule review to determine
whether there are any cost-effective controls or other measures that
would reduce emissions further to provide an ample margin of safety
with respect to the risks associated with these emissions.
    Although we are proposing that the risks from this source category
are acceptable, risk estimates for approximately 800 people in the
exposed population are above 1-in-1 million, caused by formaldehyde
emissions from one facility. The maximum acute risk is an HQ of 1 also
caused by formaldehyde. As a result, we further considered whether the
MACT standards for this source category provide an ample margin of
safety to protect public health.
    Our technology review did not identify any new practices, controls,
or process options that are being used in this industry, or in other
industries, that would be cost effective and result in further
reduction of formaldehyde emissions.\18\ Our review of the operating
permits for major sources subject to the Surface Coating of Wood
Building Products MACT did not reveal any facilities with limits set
below the current new or existing source limits (Tables 1 and 2, 40 CFR
part 63, subpart QQQQ). Limits set below the current standards would
have been an indication that improved controls or lower emission
compliant coatings were available. As discussed in the technology
review memorandum, our review of the RACT/BACT/LAER Clearinghouse
(RBLC) identified three sources that are potentially covered under 40
CFR part 63, subpart QQQQ, but none contained new control methods.
---------------------------------------------------------------------------

    \18\ Technology Review for the Surface Coating of Wood Building
Products Source Category--Proposed Rule; see Docket ID No. EPA-HQ-
OAR-2016-0678.
---------------------------------------------------------------------------

    Because no new controls, technologies, processes, or work practices
were identified to reduce formaldehyde emissions and the risk
assessment determined that the health risks associated with HAP
emissions remaining after implementation of the Surface Coating of Wood
Building Products MACT were acceptable, we are proposing that the
current standards protect public health with an ample margin of safety.
3. Adverse Environmental Effects
    The emissions data for this source category indicate the presence
of one environmental HAP, lead, emitted by sources within this source
category. Based on the results of our environmental risk screening
assessment, we conclude that there is not an adverse environmental
effect as a result of HAP emissions from the Surface Coatings of Wood
Building Products source category.\19\ Thus, we are proposing that it
is not necessary to set a more stringent standard.
---------------------------------------------------------------------------

    \19\ The environmental screening analysis is documented in
Residual Risk Assessment for Wood Building Products Surface Coating
Sources in Support of the February 2018 Risk and Technology Review
Proposed Rule, in the docket for this action.
---------------------------------------------------------------------------

C. What are the results and proposed decisions based on our technology
review?

1. How did we evaluate technological developments?
    Section 112(d)(6) of the CAA requires a review of ``developments in
practices, processes and control technologies'' in each source category
as part of the technology review process. For this technology review,
the ``developments'' we consider include:
     Add-on control technology that was not identified during
the NESHAP development;
     improvement to an existing add-on control technology
resulting in significant additional HAP emissions reductions;
     work practice or operational procedure that was not
previously identified;
     process change or pollution prevention alternative that
was not identified; or
     a coating formulation or application technique that was
not previously identified.
2. What was our analysis and conclusions regarding technological
developments?
    Our review of the developments in technology for the Surface
Coating of Wood Building Products source category did not reveal any
changes that require revisions to the emission standards. In the
original NESHAP, it was noted that ``the most prevalent form of
emission control for surface coating of wood building products is the
use of low-VOC and low-HAP coatings, such as waterborne or ultraviolet-
cured coatings.'' \20\
---------------------------------------------------------------------------

    \20\ Preliminary Industry Characterization: Wood Building
Products Surface Coating. Publication No. EPA-453/R-00-004.
September 1998. Available at https://www3.epa.gov/airtoxics/coat/flatw/wbppic.pdf.
---------------------------------------------------------------------------

    Our review did not identify any new or improved add-on control
technology, any new work practices, operational procedures, process
changes, or new pollution prevention approaches that reduce emissions
in the category that have been implemented at wood building products
surface coating

operations since promulgation of the current NESHAP. Consequently, we
propose that no revisions to the NESHAP are necessary pursuant to CAA
section 112(d)(6).

D. What other actions are we proposing?

    In addition to the proposed determinations described above, we are
proposing additional revisions. We are proposing revisions to the SSM
provisions of the MACT rule in order to ensure that they are consistent
with the Court decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir.
2008), which vacated two provisions that exempted sources from the
requirement to comply with otherwise applicable CAA section 112(d)
emission standards during periods of SSM. We also are proposing various
other changes, including an alternative compliance calculation,
electronic submittal of notifications, compliance reports, and
performance test reports, a new EPA test method, incorporation by
reference (IBR) of several test methods (listed in section IV.D.5
below), and various technical and editorial changes. Additionally, we
are requesting comment on repeat emissions testing requirements for
facilities that demonstrate compliance with the standards using add-on
control devices. Our analyses and proposed changes related to these
issues are discussed in sections IV.D.1 through 6 of this preamble.
1. Startup, Shutdown, and Malfunction
    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C.
Cir. 2008), the Court vacated portions of two provisions in the EPA's
CAA section 112 regulations governing the emissions of HAP during
periods of SSM. Specifically, the Court vacated the SSM exemption
contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), holding that
under section 302(k) of the CAA, emissions standards or limitations
must be continuous in nature and that the SSM exemption violates the
CAA's requirement that some CAA section 112 standards apply
continuously.
    We are proposing the elimination of the SSM exemption in this rule,
which appears at 40 CFR 63.4700, 40 CFR 63.4720, and in Table 4 to
Subpart QQQQ of Part 63. Consistent with Sierra Club v. EPA, we are
proposing standards in this rule that apply at all times. We are also
proposing several revisions to Table 4 (the General Provisions
Applicability Table) as is explained in more detail below. For example,
we are proposing to eliminate the incorporation of the General
Provisions' requirement that the source develop an SSM plan. We also
are proposing to eliminate and revise certain recordkeeping and
reporting requirements related to the SSM exemption as further
described below.
    The EPA has attempted to ensure that the provisions we are
proposing to eliminate are inappropriate, unnecessary, or redundant in
the absence of the SSM exemption. We are specifically seeking comment
on whether we have successfully done so. The EPA believes the removal
of the SSM exemption creates no additional burden to facilities
regulated under the Surface Coating of Wood Building Products NESHAP.
Deviations currently addressed by a facility's SSM Plan are required to
be reported in the Semiannual Compliance Report, a requirement that
remains under the proposal (40 CFR 63.4720). Facilities will no longer
need to develop an SSM Plan or keep it current (Table 4, 40 CFR part
63, subpart QQQQ). Facilities will also no longer have to file special
SSM reports for deviations not described in the their SSM Plan [40 CFR
63.4720(c)(2)]. We are specifically seeking comment on whether we have
successfully removed SSM exemptions without adding unforeseen burden.
    Periods of startup and shutdown. In proposing the standards in this
rule, the EPA has taken into account startup and shutdown periods and,
for the reasons explained below, is not proposing alternate standards
for those periods.
    For add-on control systems, the Surface Coating of Wood Building
Products NESHAP requires the measurement of thermal oxidizer (TO)
operating temperature or catalytic oxidizer (CO) average temperature
across the catalyst bed as well as other types of parameter monitoring.
Parameter limits apply at all times, including during periods of
startup and shutdown. The Surface Coating of Wood Building Products
NESHAP requires TO or CO operating temperature and other add-on control
device operating parameters to be recorded at least once every 15
minutes. The Surface Coating of Wood Building Products NESHAP specifies
in 40 CFR 63.4763(c) that if an operating parameter is out of the
allowed range, this is a deviation from the operating limit and must be
reported as specified in 40 CFR 63.4710(c)(6) and 63.4720(a)(7).
    Our permit review of the facilities using add-on control as a
compliance approach indicated that all were required, by permit, to
have their control system in operation during all time periods when
coating processes were operational. The rule requires compliance based
on a 12-month rolling average emissions calculation. Periods of startup
and shutdown are included, but, because of operational requirements in
the category, are a very small component of the emissions calculation.
Therefore, we are not proposing separate standards for startup and/or
shutdown periods.
    Periods of malfunction. Periods of startup, normal operations, and
shutdown are all predictable and routine aspects of a source's
operations. Malfunctions, in contrast, are neither predictable nor
routine. Instead they are, by definition, sudden, infrequent, and not
reasonably preventable failures of emissions control, process or
monitoring equipment. (40 CFR 63.2, definition of malfunction). The EPA
interprets CAA section 112 as not requiring emissions that occur during
periods of malfunction to be factored into development of CAA section
112 standards and this reading has been upheld as reasonable by the
Court in U.S. Sugar Corp. v. EPA, 830 F.3d 579, 606-610 (2016). Under
CAA section 112, emissions standards for new sources must be no less
stringent than the level ``achieved'' by the best controlled similar
source and for existing sources generally must be no less stringent
than the average emission limitation ``achieved'' by the best
performing 12 percent of sources in the category. There is nothing in
CAA section 112 that directs the Agency to consider malfunctions in
determining the level ``achieved'' by the best performing sources when
setting emission standards. As the Court has recognized, the phrase
``average emissions limitation achieved by the best performing 12
percent of'' sources ``says nothing about how the performance of the
best units is to be calculated.'' National Association of Clean Water
Agencies v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 2013). While the EPA
accounts for variability in setting emissions standards, nothing in CAA
section 112 requires the Agency to consider malfunctions as part of
that analysis. The EPA is not required to treat a malfunction in the
same manner as the type of variation in performance that occurs during
routine operations of a source. A malfunction is a failure of the
source to perform in ``normal or usual manner,'' and no statutory
language compels the EPA to consider such events in setting CAA section
112 standards.
    As the Court recognized in U.S. Sugar Corporation, accounting for
malfunctions in setting standards would be difficult, if not
impossible, given the myriad different types of malfunctions that can
occur across all sources in the category and given the difficulties

associated with predicting or accounting for the frequency, degree, and
duration of various malfunctions that might occur. Id. at 608 (``the
EPA would have to conceive of a standard that could apply equally to
the wide range of possible boiler malfunctions, ranging from an
explosion to minor mechanical defects. Any possible standard is likely
to be hopelessly generic to govern such a wide array of
circumstances.'') As such, the performance of units that are
malfunctioning is not ``reasonably'' foreseeable. See, e.g., Sierra
Club v. EPA, 167 F.3d 658, 662 (D.C. Cir. 1999) (``The EPA typically
has wide latitude in determining the extent of data-gathering necessary
to solve a problem. We generally defer to an agency's decision to
proceed on the basis of imperfect scientific information, rather than
to `invest the resources to conduct the perfect study.''') See also,
Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. 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.''). In
addition, emissions during a malfunction event can be significantly
higher than emissions at any other time of source operation. For
example, if an air pollution control device with 99-percent removal
goes off-line as a result of a malfunction (as might happen if, for
example, the bags in a baghouse catch fire) and the emission unit is a
steady state type unit that would take days to shut down, the source
would go from 99-percent control to zero control until the control
device was repaired. The source's emissions during the malfunction
would be 100 times higher than during normal operations. As such, the
emissions over a 4-day malfunction period would exceed the annual
emissions of the source during normal operations. As this example
illustrates, accounting for malfunctions could lead to standards that
are not reflective of (and significantly less stringent than) levels
that are achieved by a well-performing non-malfunctioning source. It is
reasonable to interpret CAA section 112 to avoid such a result. The
EPA's approach to malfunctions is consistent with CAA section 112 and
is a reasonable interpretation of the statute.
    Although no statutory language compels the EPA to set standards for
malfunctions, the EPA has the discretion to do so where feasible. For
example, in the Petroleum Refinery Sector RTR, the EPA established a
work practice standard for unique types of malfunction that result in
releases from pressure relief devices or emergency flaring events
because information was available to determine that such work practices
reflected the level of control that applies to the best performing
sources. 80 FR 75178, 75211-14 (December 1, 2015). The EPA will
consider whether circumstances warrant setting work practice standards
for a particular type of malfunction and, if so, whether the EPA has
sufficient information to identify the relevant best performing sources
and establish a standard for such malfunctions. We also encourage
commenters to provide any such information.
    In the event that a source fails to comply with the applicable CAA
section 112(d) standards as a result of a malfunction event, the 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.
The 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).
    If the EPA determines in a particular case that an enforcement
action against a source for violation of an emission standard is
warranted, the source can raise any and all defenses in that
enforcement action and the federal district court will determine what,
if any, relief is appropriate. The same is true for citizen enforcement
actions. Similarly, the presiding officer in an administrative
proceeding can consider any defense raised and determine whether
administrative penalties are appropriate.
    In summary, the EPA interpretation of the CAA and, in particular,
CAA section 112 is reasonable and encourages practices that will avoid
malfunctions. Administrative and judicial procedures for addressing
exceedances of the standards fully recognize that violations may occur
despite good faith efforts to comply and can accommodate those
situations. U.S. Sugar Corporation v. EPA, 830 F.3d 579, 606-610
(2016).
a. General Duty
    We are proposing to revise the General Provisions table (Table 4)
entry for 40 CFR 63.6(e)(1)-(2) by redesignating it as 40 CFR
63.6(e)(1)(i) and changing the ``yes'' in column 3 to a ``no.'' Section