[Federal Register Volume 83, Number 67 (Friday, April 6, 2018)]
[Proposed Rules]
[Pages 14984-15014]
[FR Doc No: 2018-06541]

Vol. 83

Friday,

No. 67

April 6, 2018

Part III

Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Hazardous Air Pollutants: Wet-Formed
Fiberglass Mat Production Residual Risk and Technology Review; Proposed
Rule

Federal Register / Vol. 83 , No. 67 / Friday, April 6, 2018 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2004-0309; FRL-9975-99-OAR]
RIN 2060-AT47

National Emission Standards for Hazardous Air Pollutants: Wet-
Formed Fiberglass Mat Production Residual Risk and Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing
amendments to the National Emission Standards for Hazardous Air
Pollutants for Wet-Formed Fiberglass Mat Production to address the
results of the residual risk and technology review (RTR) that the EPA
is required to conduct in accordance with section 112 of the Clean Air
Act (CAA). We found risks due to emissions of air toxics to be
acceptable from this source category, determined that the current
standards provide an ample margin of safety to protect public health,
and identified no new cost-effective controls under the technology
review to achieve further emissions reductions. Therefore, we are
proposing no revisions to the numerical emission limits based on these
analyses. However, the EPA is proposing to revise provisions pertaining
to emissions during periods of startup, shutdown, and malfunction
(SSM); add requirements for electronic submittal of performance test
results; revise certain monitoring, recordkeeping, and reporting
requirements; and make other miscellaneous technical and editorial
changes. While the proposed amendments would not result in reductions
in emissions of hazardous air pollutants (HAP), if finalized, they
would result in improved compliance and implementation of the rule.

DATES:
    Comments. Comments must be received on or before May 21, 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 May 7, 2018.
    Public Hearing. If a public hearing is requested by April 11, 2018,
then we will hold a public hearing on April 23, 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 April 19, 2018.

ADDRESSES:  Comments. Submit your comments, identified by Docket ID No.
EPA-HQ-OAR-2004-0309, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. (See SUPPLEMENTARY
INFORMATION for detail about how EPA treats submitted comments.)
Regulations.gov is our preferred method of receiving comments. However,
other submission methods 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-2004-0309, 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 William Jefferson Clinton (WJC) West Building,
Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. Delivery
verification signatures will be available only during regular business
hours.
    Public Hearing. If a public hearing is requested, it will be held
at EPA Headquarters, EPA WJC East Building, 1201 Constitution Avenue
NW, Washington, DC 20004. 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/wet-formed-fiberglass-mat-production-national-emission-standards. 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
Virginia Hunt 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. See
SUPPLEMENTARY INFORMATION for instructions on registering and attending
a public hearing.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Mary Johnson, Sector Policies and Programs Division
(Mail Code D243-01), 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] or Christian Fellner, Sector
Policies and Programs Division (Mail Code D243-01), Office of Air
Quality Planning and Standards, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; telephone number: (919)
541-4003; fax number:<PHONE_NUMBER>; and email address:
[email protected].
    For specific information regarding the risk modeling methodology,
contact Ted Palma, Health and Environmental Impacts Division (Mail Code
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 national emissions
standards for hazardous air pollutants (NESHAP) to a particular entity,
contact Sara Ayres, Office of Enforcement and Compliance Assurance,
U.S. Environmental Protection Agency, USEPA Region 5 (Mail Code E-19J),
77 West Jackson Boulevard, Chicago, Illinois 60604; telephone number:
(312) 353-6266; and email address: [email protected].

SUPPLEMENTARY INFORMATION:
    Public hearing. 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.
    Docket. The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2004-0309. 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<PHONE_NUMBER>, and the telephone number for the EPA
Docket Center is<PHONE_NUMBER>.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2004-0309. 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. This
type of information should be submitted by mail as discussed in section
I.C of this preamble.
    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). 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://www2.epa.gov/dockets/commenting-epa-dockets.
    The http://www.regulations.gov website 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
    ARMA Asphalt Roofing Manufacturers Association
    ATSDR Agency for Toxic Substances and Disease Registry
    BACT best available control technology
    BBDR biologically based dose response
    CAA Clean Air Act
    CalEPA California EPA
    CBI Confidential Business Information
    CDX Central Data Exchange
    CEDRI Compliance and Emissions Data Reporting Interface
    CFR Code of Federal Regulations
    CIIT Chemical Industry Institute of Toxicology
    ECHO Enforcement and Compliance History Online
    EPA Environmental Protection Agency
    ERPG Emergency Response Planning Guideline
    ERT Electronic Reporting Tool
    HAP hazardous air pollutant(s)
    HCl hydrochloric acid
    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
    kg/Mg kilograms per megagram
    km kilometer
    LAER lowest achievable emission rate
    lb/ton pounds per ton
    MACT maximum achievable control technology
    mg/m\3\ milligrams per cubic meter
    MIR maximum individual risk
    NAICS North American Industry Classification System
    NAS National Academy of Sciences
    NATA National Air Toxics Assessment
    NEI National Emissions Inventory
    NESHAP national emission standards for hazardous air pollutants
    NRDC Natural Resources Defense Council
    NSR New Source Review
    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
    PRA Paperwork Reduction Act
    QA quality assurance
    RACT reasonably available control technology
    RBLC RACT/BACT/LAER Clearinghouse
    REL reference exposure level
    RFA Regulatory Flexibility Act
    RfC reference concentration
    RTR residual risk and technology review
    SAB Science Advisory Board
    SSM startup, shutdown, and malfunction
    TOSHI target organ-specific hazard index
    tpy tons per year
    UF uncertainty factor
    [micro]g/m\3\ microgram per cubic meter
    UMRA Unfunded Mandates Reform Act
    URE unit risk estimate
    VCS voluntary consensus standards

    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 the 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. The Wet-Formed Fiberglass Mat Production source category was
added to the list of categories of major sources of HAP published under
section 112(c) of the CAA in an action that concurrently promulgated
NESHAP for the Wet-Formed Fiberglass Mat Production source category (67
FR 17824, April 11, 2002). As defined in that action, in wet-formed
fiberglass mat production, glass fibers are bonded with an organic
resin. The mat is formed as the resin is dried and cured in heated
ovens.

    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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Wet-Formed Fiberglass Mat        Wet-Formed Fiberglass            327212
 Production.                      Mat Production.
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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/wet-formed-fiberglass-mat-production-national-emission-standards. 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
https://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-2004-0309).

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 Code of Federal Regulations (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-2004-0309.

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 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, CAA Section 112 Risk
and Technology Reviews: Statutory Authority and Methodology, which is
available 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), 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. Section 112(d)(5) of the CAA 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 NRDC
v. EPA, 529 F.3d 1077, 1083 (DC 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
approach, 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.
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    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. Natural Resources
Defense Council (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 NESHAP for the Wet-Formed Fiberglass Mat Production source
category were promulgated on April 11, 2002 (67 FR 17824), in an action
that also added the source category to the list of categories of major
sources of HAP published under section 112(c) of the CAA and to the
source category schedule for NESHAP. The NESHAP are codified at 40 CFR
part 63, subpart HHHH. Wet-formed fiberglass mat is used as a substrate
for multiple roofing products, as reinforcement for various plastic,
cement, and gypsum products, and in miscellaneous specialty products.
The fiberglass mat is made of glass fibers that have been bonded with a
formaldehyde-based resin. Methanol is also present in some, but not
all, resins used to produce wet-formed fiberglass mat. In a typical
wet-formed fiberglass mat production line, glass fibers are mixed with
water and emulsifiers in large mixing vats to form a slurry of fibers
and water. The glass fiber slurry is then pumped to a mat forming
machine, where it is dispensed in a uniform curtain over a moving
screen belt. The mat is then carried beneath a binder saturator, where
binder solution is uniformly applied onto the surface of the mat. This
resin-binder application process includes the screen passing over a
vacuum which draws away the excess binder solution for recycling. The
mat of fibers and binder then passes into drying and curing ovens that
use heated air to carry away excess moisture and harden (i.e., cure)
the binder. Upon exiting the ovens, the mat is cooled, trimmed, wound,
and packaged to product specifications. The primary HAP emitted during
production of wet-formed fiberglass mat are formaldehyde, which is
classified as a known, probable, or possible carcinogen, and methanol.
We are aware of seven wet-formed fiberglass mat production facilities
that are subject to the NESHAP. Five of the affected facilities have
single mat lines and two of the affected facilities have two mat lines.
    The affected source is each wet-formed fiberglass mat drying and
curing oven. The NESHAP regulates emissions of HAP through emission
standards for formaldehyde, which is also used as a surrogate for total
HAP emissions. Facilities subject to the NESHAP must meet either a mass
emission limit or percentage reduction requirement for each drying and
curing oven. The emission standards are the same for new and existing
drying and curing ovens. The emission limits for the exhaust from

new and existing drying and curing ovens are (1) a maximum formaldehyde
emission rate of 0.03 kilograms per megagram (kg/Mg) of wet-formed
fiberglass mat produced (0.05 pounds per ton (lb/ton) of wet-formed
fiberglass mat produced) or (2) a minimum of 96-percent destruction
efficiency of formaldehyde. Thermal oxidizers or similar controls
(e.g., regenerative thermal oxidizer, regenerative catalytic oxidizer)
are used by facilities subject to the NESHAP to control their drying
and curing oven exhausts.

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

    The EPA used several means to collect the information necessary to
conduct the residual risk assessment and technology review for the Wet-
Formed Fiberglass Mat Production source category. To confirm whether
facilities identified as potentially subject to the NESHAP were in fact
subject to the standards, we requested air permits and/or performance
test data from various state and local agencies. After developing our
final list of affected facilities, the status of each facility was
confirmed in consultation with the Asphalt Roofing Manufacturers
Association (ARMA) and ARMA-member companies. The EPA had discussions
with the four companies that own one or more of the affected facilities
regarding each facility's production process and emission sources,
available emissions test data and emissions estimates, measures used to
control emissions, and other aspects of facility operations. The
facility-specific information from state and local agencies and
companies with affected facilities provided support for this action's
risk and technology reviews.

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

    The EPA used multiple sources of information to support this
proposed action. Before developing the final list of affected
facilities described in section II.C of this preamble, the EPA's
Enforcement and Compliance History Online (ECHO) database was used as a
tool to identify potentially affected facilities with wet-formed
fiberglass mat production operations that are subject to the NESHAP.
The ECHO database provides integrated compliance and enforcement
information for approximately 800,000 regulated facilities nationwide.
    The 2014 National Emissions Inventory (NEI) database provided
facility-specific data and MACT category data that were used to
supplement the performance test data in developing the modeling file
for the risk review. The NEI is a database that contains information
about sources that emit criteria air pollutants, their precursors, and
HAP. The database includes estimates of annual air pollutant emissions
from point, nonpoint, and mobile sources in the 50 states, the District
of Columbia, Puerto Rico, and the Virgin Islands. The EPA collects this
information and releases an updated version of the NEI database every 3
years. The NEI includes information necessary for conducting risk
modeling, including annual HAP emissions estimates from individual
emission points at facilities and the related emissions release
parameters.
    In conducting the technology review, we examined information in the
Reasonably Available Control Technology (RACT)/Best Available Control
Technology (BACT)/Lowest Achievable Emission Rate (LAER) Clearinghouse
(RBLC) to identify technologies in use and determine if there have been
developments in practices, processes, or control technologies. The RBLC
is a database that contains case-specific information of air pollution
technologies that have been required to reduce the emissions of air
pollutants from stationary sources. Under the EPA's New Source Review
(NSR) program, if a facility is planning new construction or a
modification that will increase the air emissions by a large amount, an
NSR permit must be obtained. This central database promotes the sharing
of information among permitting agencies and aids in case-by-case
determinations for NSR permits. The EPA also reviewed other information
sources to determine if there have been developments in practices,
processes, or control technologies in the Wet-Formed Fiberglass Mat
Production source category. We reviewed regulatory actions for emission
sources similar to mat drying and curing ovens and conducted a review
of literature published by industry organizations, technical journals,
and government organizations.

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 EPA's risk
analysis is consistent with EPA's response to comment on our policy
under the Benzene NESHAP where the EPA explained that:
---------------------------------------------------------------------------

    \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 non-cancer health
effects, and the uncertainties of the risk estimates. In this way,
the effect on the most exposed individuals can be reviewed as well
as the impact on the general public. These factors can then be
weighed in each individual case. This approach complies with the
Vinyl Chloride mandate that the Administrator ascertain an
acceptable level of risk to the public by employing 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 Wet-Formed Fiberglass
Mat Production source category, specifically drying and curing ovens,
as well as the costs, non-air impacts, and energy implications
associated with the use of these technologies. Additionally, during
discussions with affected facilities, we asked about developments in
practices, processes, or control technology. 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 action contains the
following document which provides more information on the risk
assessment inputs and models: Residual Risk Assessment for the Wet-
Formed Fiberglass Mat Production Source Category in Support of the
February 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 EPA's Science
Advisory Board (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.
---------------------------------------------------------------------------

    \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 for nine wet-formed fiberglass mat production lines at seven
facilities were used to create the RTR emissions dataset as described
in sections II.C and II.D of this preamble. The emission sources
included in the RTR emissions dataset include drying and curing ovens,
which are the primary HAP emission sources at wet-formed fiberglass mat
production facilities and currently regulated by the NESHAP. The RTR
emissions dataset also includes emissions from the binder application
vacuum exhaust which is the emission release point for the resin-binder
application process. As stated in section II.B of this preamble, the
primary HAP emitted are formaldehyde and methanol.
    Actual emissions estimates for drying and curing oven exhaust and
binder application vacuum exhaust at the seven affected facilities were
based on stack test data, NEI data, and engineering estimates. For
drying and curing oven exhaust, actual formaldehyde emissions were
based on emissions data from the most recent stack test. For the
facilities using binders containing methanol in addition to
formaldehyde, actual methanol emissions from the drying and curing oven
exhaust were estimated by adjusting each drying and curing oven's
actual formaldehyde emissions estimate based on the ratio of methanol
to formaldehyde emissions reported to the 2014 NEI for each oven. For
binder application vacuum exhaust, actual formaldehyde emissions and
actual methanol emissions at facilities using binders containing
methanol were based on stack test emissions data in the limited
instances where available. Where formaldehyde data were unavailable,
actual formaldehyde emissions were estimated using a factor based on
data from one affected facility that tested both the uncontrolled
emissions from the drying and curing oven and the emissions from the
binder application vacuum exhaust. Where methanol data were
unavailable, actual methanol emissions from the binder application
vacuum exhaust were estimated by adjusting the actual formaldehyde
emissions estimate for the binder application vacuum exhaust based on
the ratio of methanol to formaldehyde emissions reported to the 2014
NEI for the oven associated with each binder application process.
    For each emission release point (i.e., drying and curing oven
exhaust and binder application vacuum exhaust), emissions release
characteristic data such as emission release height, diameter,
temperature, velocity, flow rate, and locational latitude/longitude
coordinates were identified. For drying and curing ovens, the emission
release point is an exhaust stack. For the resin-binder application
process, the emission release point is the location of the binder
application vacuum exhaust, which is most commonly routed to one or
more roof vents. With one exception, the binder application vacuum
exhaust release points were modeled as stacks. The one process that
exhausts to a louvered sidewall was modeled as a fugitive release.
Parameters for the emission release points were primarily obtained from
performance tests, the 2014 NEI database, air permits, and information
collected in consultation with each facility. Default parameter values
based on MACT source category 2014 NEI information were used for the
binder application vacuum exhaust when site-specific information was
not available.
    The EPA conducted a quality assurance (QA) check of source
locations, emission release characteristics, and annual emissions
estimates. In addition, each company had the opportunity to review the
information regarding their sources and provide updated source data.
The revisions we received and incorporated into the modeling file
regarded emission release point details (e.g., number of emission
release points, release height and diameter, latitude/longitude
coordinates).
    Additional details on the data and methods used to develop actual
emissions estimates for the risk modeling, including EPA's QA review,
are provided in the memorandum, Wet-Formed Fiberglass: Residual Risk
Modeling File Documentation (Modeling File Documentation Memo), which
is available in the docket for this action.
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.)
    MACT-allowable emissions estimates were based on the level of
control required by the Wet-formed Fiberglass Mat Production NESHAP.
For drying and curing ovens, 40 CFR part 63, subpart HHHH requires a
96-percent destruction efficiency for formaldehyde. The MACT-allowable
formaldehyde emissions for drying and curing oven exhaust were
calculated based on the actual formaldehyde emissions levels adjusted
to reflect 96 percent control, which is the minimum percent destruction
efficiency for formaldehyde allowed under the NESHAP. MACT-allowable
methanol emissions from drying and curing oven exhaust were estimated
by adjusting each drying and curing oven's MACT-allowable formaldehyde
emissions estimate based on the ratio of methanol to formaldehyde
emissions reported to the 2014 NEI for each oven. For binder
application vacuum exhaust, which has no control requirements under the
NESHAP, the MACT-allowable formaldehyde and methanol emissions were
assumed equal to the actual emissions estimates with the exception of
one facility where the binder application vacuum exhaust is combined
with the drying and curing oven exhaust. The Modeling File
Documentation Memo, available in the docket for this action, contains
additional information on the development of estimated MACT-allowable
emissions for the risk modeling.
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.\5\ 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 \6\ 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.
---------------------------------------------------------------------------

    \5\ 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).
    \6\ 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.
    In 2004, the EPA determined that the Chemical Industry Institute of
Toxicology (CIIT) cancer dose-response value for formaldehyde (5.5 x
10-9 per milligrams per cubic meter (mg/m\3\)) was based on better
science than the 1991 IRIS dose-response value (1.3 x 10-5 per mg/
m\3\), and we switched from using the IRIS value to the CIIT value in
risk assessments supporting regulatory actions. Based on subsequent
published research, however, the EPA changed its determination
regarding the CIIT model, and, in 2010, the EPA returned to using the
1991 IRIS value. The National Academy of Sciences (NAS) completed its
review of the EPA's draft assessment in April of 2011 (http://www.nap.edu/catalog.php?recordid=13142), and the EPA has been working
on revising the formaldehyde assessment. The EPA will follow the NAS
Report recommendations and will present results obtained by
implementing the biologically based dose response (BBDR) model for
formaldehyde. The EPA will compare these estimates with those currently
presented in the External Review draft of the assessment and will
discuss their strengths and weaknesses. As recommended by the NAS
committee, appropriate sensitivity and uncertainty analyses will be an
integral component of implementing the BBDR model. The draft IRIS
assessment will be revised in response to the NAS peer review and
public comments and the final assessment will be posted on the IRIS
database. In the interim, we will present findings using the 1991 IRIS
value as a primary estimate and may also consider other information as
the science evolves. To estimate incremental individual lifetime cancer
risks associated with emissions from the facilities in the source
category, EPA summed the risks for each of the

carcinogenic HAP \7\ 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.
---------------------------------------------------------------------------

    \7\ 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 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 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, the EPA makes
conservative assumptions about emission rates, meteorology, and
exposure location. We use the peak hourly emission rate,\8\ 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.
---------------------------------------------------------------------------

    \8\ 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
the Wet-Formed Fiberglass Mat Production Source Category in Support
of the February 2018 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.'' \9\ 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.\10\ 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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    \9\ 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.
    \10\ NAS, 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.'' \11\ 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.
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    \11\ 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, hourly emissions data were used to
estimate maximum hourly emissions. In general, emissions used to assess
the potential health risks due to acute exposure were estimated using
the same approach used to develop actual emissions estimates described
in section III.C.1 of this preamble, except that emissions used to
estimate acute exposure were based on maximum hourly emission rates
reported during stack tests. For drying and curing oven exhaust,
formaldehyde emissions were based on maximum hourly emissions data,
considering all test runs from available stack tests. For the
facilities using binders containing methanol, methanol emissions from
the drying and curing oven exhaust were estimated by adjusting each
drying and curing oven's formaldehyde emissions estimate based on the
ratio of methanol to formaldehyde emissions reported to the 2014 NEI
for each oven. For binder application vacuum exhaust, formaldehyde
emissions and methanol emissions at facilities using binders containing
methanol were based on maximum hourly emissions data from stack tests
in the limited instances where available. Where formaldehyde data were
unavailable, formaldehyde emissions were estimated using a factor based
on one facility's uncontrolled emissions from its drying and curing
oven and emissions from its binder application vacuum exhaust. Where
methanol data were unavailable, methanol emissions were estimated by
adjusting the formaldehyde emissions estimate for the binder
application vacuum exhaust based on the ratio of methanol to
formaldehyde emissions reported to the 2014 NEI for the oven associated
with each binder application vacuum exhaust.
    A further discussion of the development of emissions used to
estimate acute exposure for the risk modeling can be found in the risk
document, Residual Risk Assessment for the Wet-Formed Fiberglass Mat
Production Source Category in Support of the February 2018 Risk and
Technology Review Proposed Rule, which is available in the docket for
this action.
    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.
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 HAP known to be
persistent and bioaccumulative in the environment (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 Wet-Formed Fiberglass Mat Production source category, we
did not identify emissions of any PB-HAP. Because we did not identify
PB-HAP emissions, no further evaluation of multipathway risk was
conducted for this source category.
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).
    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 Wet-Formed Fiberglass Mat Production Source Category
in Support of the Risk and Technology Review February 2018 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 Wet-Formed Fiberglass Mat
Production source category emitted any of the environmental HAP. For
the Wet-Formed Fiberglass Mat Production source category, we did not
identify emissions of any of the seven environmental HAP included in
the screen. Because we did not identify environmental HAP emissions, no
further evaluation of environmental risk was conducted.
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 Wet-Formed
Fiberglass Mat Production Source Category in Support of the Risk and
Technology Review February 2018 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, 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
Wet-Formed Fiberglass Mat Production Source Category in Support of the
Risk and Technology Review February 2018 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 QA/
quality control processes, the accuracy of emissions values will vary
depending on the source of the data, the degree to which data are
incomplete or missing, the degree to which assumptions made to complete
the datasets are 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 maximum hourly emission rates and
emission adjustment factors, 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).\12\ In some circumstances, the true risk could be as low as
zero; however, in other circumstances the risk could be greater.\13\
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.
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    \12\ IRIS glossary (https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&glossaryName=IRIS%20Glossary).
    \13\ 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.
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    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.
    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. 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?

1. Inhalation Risk Assessment Results
    The results of the chronic inhalation cancer risk assessment, based
on actual emissions, show the cancer MIR posed by the seven facilities
is less than 1-in-1 million, with formaldehyde as the major contributor
to the risk. The total estimated cancer incidence from this source
category is 0.0003 excess cancer cases per year, or one excess case in
every 3,000 years. No people were estimated to have cancer risks above
1-in-1 million from HAP emitted from the seven facilities in this
source category. The maximum chronic noncancer HI value for the source
category could be up to 0.006 (respiratory) driven by emissions of
formaldehyde. No one is exposed to TOSHI levels above 1.
    Risk results from the inhalation risk assessment using the MACT-
allowable emissions indicate that the cancer MIR could be as high as 1-
in-1 million with formaldehyde emissions driving the risks, and that
the maximum chronic noncancer TOSHI value could be as high as 0.009 at
the MACT-allowable

emissions level with formaldehyde emissions driving the TOSHI. The
total estimated cancer incidence from this source category considering
allowable emissions is expected to be about 0.0009 excess cancer cases
per year or 1 excess case in every 1,000 years. Based on allowable
emission rates, no people were estimated to have cancer risks above 1-
in-1 million.
2. Acute Risk Results
    Worst-case acute HQs were calculated for every HAP that has an
acute dose-response value (formaldehyde and methanol). Based on actual
emissions, the highest screening acute HQ value was 0.6 (based on the
acute REL for formaldehyde). Since none of the screening HQ were
greater than 1, further refinement of the estimates was not warranted.
3. Multipathway Risk Screening Results
    No PB-HAP were emitted from this source category; therefore, a
multipathway assessment was not warranted.
4. Environmental Risk Screening Results
    We did not identify any PB-HAP or acid gas emissions from this
source category. We are unaware of any adverse environmental effect
caused by emissions of HAP that are emitted by the source category.
Therefore, we do not expect an adverse environmental effect as a result
of HAP emissions from this source category.
5. Facility-Wide Risk Results
    The results of the facility-wide (both MACT and non-MACT sources)
assessment indicate that four of the seven facilities included in the
analysis have a facility-wide cancer MIR greater than 1-in-1 million.
The maximum facility-wide cancer MIR is 6-in-1 million, mainly driven
by formaldehyde emissions from non-MACT sources. The total estimated
cancer incidence from the seven facilities is 0.001 excess cancer cases
per year, or one excess case in every 1,000 years. Approximately 13,000
people were estimated to have cancer risks above 1-in-1 million from
exposure to HAP emitted from both MACT and non-MACT sources of the
seven facilities in this source category. The maximum facility-wide
TOSHI for the source category is estimated to be less than 1 (at a
respiratory HI of 0.5), mainly driven by emissions of acrylic acid and
formaldehyde from non-MACT sources.
6. What demographic groups might benefit from this regulation?
    To examine the potential for any environmental justice 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 Wet-Formed Fiberglass
Mat Production source category across different demographic groups
within the populations living near facilities.\14\
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    \14\ 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, and
linguistically isolated people.
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    Results of the demographic analysis indicate that, for two of the
11 demographic groups, African American and people living below the
poverty level, the percentage of the population living within 5 km of
facilities in the source category is greater than the corresponding
national percentage for the same demographic groups. When examining the
risk levels of those exposed to source category emissions from the wet-
formed fiberglass mat production facilities, we find that no one is
exposed to a cancer risk at or above 1-in-1 million or to a chronic
noncancer TOSHI greater than 1.
    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 Wet-Formed Fiberglass
Mat Production, which is 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).
    In this proposal, the EPA estimated risks based on actual and
allowable emissions from the Wet-Formed Fiberglass Mat Production
source category. As discussed above, we consider our analysis of risk
from allowable emissions to be conservative and, as such, to represent
an upper bound estimate of risk from emissions allowed under the NESHAP
for the source category.
    The inhalation cancer risk to the individual most exposed to
emissions from sources in the Wet-Formed Fiberglass Mat Production
source category is less than 1-in-1 million, based on actual emissions.
The estimated incidence of cancer due to inhalation exposure is 0.0003
excess cancer cases per year, or 1 case in 3,000 years, based on actual
emissions. For allowable emissions, we estimate that the inhalation
cancer risk to the individual most exposed to emissions from sources in
this source category is 1-in-1 million. The estimated incidence of
cancer due to inhalation exposure is 0.0009 excess cancer cases per
year, or one case in every 1,000 years, based on allowable emissions.
    The Agency estimates that the maximum chronic noncancer TOSHI from
inhalation exposure is 0.006 due to actual emissions and 0.009 due to
allowable emissions. The screening assessment of worst-case acute
inhalation impacts from worst-case 1-hour emissions indicates that no
HAP exceed an acute HQ of 1.
    Since no PB-HAP are emitted by this source category, a multipathway
risk assessment was not warranted.
    In determining whether risk is acceptable, the EPA considered all
available health information and risk estimation uncertainty, as
described above. The results indicate that both the actual and
allowable inhalation cancer risks to the individual most exposed are
less than or equal to 1-in-1 million, well below the presumptive limit
of acceptability of 100-in-1 million. The maximum chronic noncancer
TOSHI due to inhalation exposures is less than 1 for actual and
allowable emissions. Finally, the evaluation of acute noncancer risks
was conservative and showed that acute risks are below a level of
concern. Further, since no PB-HAP are emitted, no multipathway risks
are expected as a result of HAP emissions from this source category.
    Taking into account this information, the EPA proposes that the
risk remaining after implementation of the of the existing MACT
standards for the Wet-Formed Fiberglass Mat Production source category
is acceptable.
2. Ample Margin of Safety
    Under the ample margin of safety analysis, we evaluated 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 in
this source category to further reduce the risks (or potential risks)
due to emissions of HAP, considering all of the health risks and other
health information considered in the risk acceptability determination
described above. 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 and would be
necessary to provide an ample margin of safety to protect public
health.
    Our risk analysis indicated the risks from the source category are
low for both cancer and noncancer health effects, and, therefore, any
risk reductions, from further available control options would result in
minimal health benefits. Moreover, as noted in our discussion of the
technology review in section IV.C of this preamble, no additional
measures were identified for reducing HAP emissions from affected
sources in the Wet-Formed Fiberglass Mat Production source category.
Thus, we are proposing that the 2002 Wet-Formed Fiberglass Mat
Production NESHAP requirements provide an ample margin of safety to
protect public health.
3. Adverse Environmental Effects
    We did not identify emissions of any of the seven environmental HAP
included in our environmental risk screening, and we are unaware of any
adverse environmental effects caused by HAP emitted by the Wet-Formed
Fiberglass Mat Production source category. Therefore, we do not expect
adverse environmental effects as a result of HAP emissions from this
source category and we are proposing that it is not necessary to set a
more stringent standard to prevent, taking into consideration costs,
energy, safety, and other relevant factors, an adverse environmental
effect.

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

    As described in section III.B of this preamble, our technology
review focused on identifying developments in practices, processes, and
control technologies for control of formaldehyde emissions from drying
and curing ovens at wet-formed fiberglass mat production facilities. In
conducting the technology review, we reviewed various informational
sources regarding the emissions from drying and curing ovens. The
review included a search of the RBLC database and reviews of air
permits for wet-formed fiberglass mat production facilities, regulatory
actions for emission sources similar to mat drying and curing ovens,
and a review of relevant literature. We reviewed these data sources for
information on practices, processes, and control technologies that were
not considered during the development of the Wet-Formed Fiberglass Mat
Production NESHAP. We also looked for information on improvements in
practices, processes, and control technologies that have occurred since
development of the Wet-Formed Fiberglass Mat Production NEHSAP.
    After reviewing information from the aforementioned sources, we did
not identify any developments in practices, processes, or control
technologies to reduce formaldehyde emissions from the drying and
curing ovens used at wet-formed fiberglass mat production facilities.
We considered the following four control technologies and processes in
our review: carbon absorbers, biofilters, thermal oxidizers, and low-
HAP or no-HAP binder formulations. Due to the characteristics of the
drying and curing oven exhaust, we concluded that neither carbon
adsorbers or biofilters are technically feasible control options.
Further, while advancements have been made with low and no-HAP binder
formulations, they are not broadly available for the various types of
wet-formed fiberglass produced. For example, some wet-formed fiberglass
products are used in roofing applications, and mats that are produced
with low or no-HAP binders tend to sag, shrink, or become distorted
when they come into contact with hot asphalt used in roofing
applications. Therefore, we concluded the use of low or no-HAP binder
formulations is not a technically feasible process change. We
considered improvements in thermal oxidizers given they were identified
as technically feasible for reducing HAP emission from drying and
curing ovens in the 2002 rulemaking and because all facilities
currently subject to 40 CFR part 63, subpart HHHH use thermal oxidizers
to reduce formaldehyde emissions. We did not identify any improvements
in performance of thermal oxidizers at existing facilities that
consistently demonstrated greater reduction in formaldehyde emissions
than is currently required by the NESHAP. Furthermore, a more stringent
standard could have the perverse environmental impact of increasing HAP
emissions. As owner/operators move towards use of lower HAP binders,
HAP emissions are reduced. However, due to the relatively dilute HAP
emissions in the exhaust gases, it becomes more difficult to maintain
high percent reductions in emissions. A more stringent standard would
likely require the refurbishment or replacement of existing thermal
oxidizers and could slow the development and adoption of the lower HAP
binders. Finally, there are cost considerations that militate against
setting more stringent standards for formaldehyde under CAA section
112(d(6). For example, any new facility that becomes subject to 40 CFR
part 63, subpart HHHH would likely be a rebuilt line at an existing
location and would likely use the existing thermal oxidizer rather than
installing a new thermal oxidizer. A more stringent standard could
instead require the replacement of the existing thermal oxidizer,
resulting in a large capital expenditure for minor HAP reductions.
    Based on the technology review, we determined that there are no
cost-effective developments in practices, processes, and control
technologies that warrant revisions to the MACT standards for this
source category. Therefore, we are not proposing revisions to 40 CFR
part 63, subpart HHHH under CAA section 112(d)(6). Additional details
of our technology review can be found in the memorandum, Section
112(d)(6) Technology Review for Wet-Formed Fiberglass Mat Production,
which is available in the docket for this action. We solicit comment on
our proposed decision.

D. What other actions are we proposing?

    In addition to the proposed actions described above, the EPA is
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 to monitoring, recordkeeping, and reporting requirements
and miscellaneous technical and editorial changes to the regulatory
text. Our analyses and proposed changes related to these issues are
discussed below.
1. Startup, Shutdown, and Malfunction Requirements
    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 63.2986(g)(1). 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 2 to 40 CFR part 63,
subpart HHHH (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.
    In proposing the standards in this rule, the EPA has taken into
account startup and shutdown periods and, for the reasons explained
below, has not proposed alternate standards for those periods.
    Periods of startup, normal operations, and shutdown are all
predictable and routine aspects of a source's operations. Owners and
operators of all seven wet-formed fiberglass mat production facilities
employ thermal oxidizer controls to limit emissions from drying and
curing ovens. Ovens along with their thermal oxidizer controls begin
operating and reach designated operational temperatures prior to
fiberglass mat first entering the oven and remain operating at those
temperatures at least until mat is no longer being dried and cured in
the oven. Because thermal oxidizer controls are employed during all
periods that the drying and curing oven is processing fiberglass mat,
there is no need to establish separate formaldehyde standards for
periods of startup and shutdown. We do, however, find it necessary to
propose establishing definitions of startup and shutdown for purposes
of 40 CFR part 63, subpart HHHH. The proposed definitions are needed to
clarify that it is not the setting in operation of, and cessation of
operation of, the drying and curing oven (i.e., affected source) that
accurately define startup and shutdown, but, rather, the setting in
operation of, and cessation of operation of, the drying and curing of
wet-formed fiberglass mat. The formaldehyde standards can only be met
during periods that fiberglass mat is being dried and cured in the
oven. Therefore, it is appropriate to define startup and shutdown on
such periods.
    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.'' Nat'l Ass'n 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 a ``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 Corp, 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 EPA to set standards for
malfunctions, the EPA has the discretion to do so where feasible. For
example, in the Petroleum Refinery Sector Risk and Technology Review,
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 the EPA had information to determine
that such work practices reflected the level of control that applies to
the best performers. 80 FR 75178, 75211-14 (December 1, 2015). The EPA
will consider whether circumstances warrant setting 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 Corp. v. EPA, 830 F.3d 579, 606-610 (2016).
a. 40 CFR 63.2986 General Duty
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.6(e)(1)(i) by
changing the ``yes'' in column 3 to a ``no.'' Section 63.6(e)(1)(i)
describes the general duty to minimize emissions. Some of the language
in that section is no longer necessary or appropriate in light of the
elimination of the SSM exemption. We are proposing instead to add
general duty regulatory text at 40 CFR 63.2986(g) that reflects the
general duty to minimize emissions while eliminating the reference to
periods covered by an SSM exemption. The current language in 40 CFR
63.6(e)(1)(i) characterizes what the general duty entails during
periods of SSM. With the elimination of the SSM exemption, there is no
need to differentiate between normal operations, startup and shutdown,
and malfunction events in describing the general duty. Therefore, the
language the EPA is proposing for 40 CFR 63.2986(g) does not include
that language from 40 CFR 63.6(e)(1).
    We are also proposing to revise the General Provisions table (Table
2 to 40 CFR part 63, subpart HHHH) entry for 40 CFR 63.6(e)(1)(ii) by
changing the ``yes'' in column 3 to a ``no.'' Section 63.6(e)(1)(ii)
imposes requirements that are not necessary with the elimination of the
SSM exemption or are redundant with the general duty requirement being
added at 40 CFR 63.2986.
b. SSM Plan
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.6(e)(3) by changing
the ``yes'' in column 3 to a ``no.'' Generally, these paragraphs
require development of an SSM plan and specify SSM recordkeeping and
reporting requirements related to the SSM plan. As noted, the EPA is
proposing to remove the SSM exemptions. Therefore, affected units will
be subject to an emission standard during such events. The
applicability of a standard during such events will ensure that sources
have ample incentive to plan for and achieve compliance and, thus, the
SSM plan requirements are no longer necessary.
c. Compliance With Standards
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.6(f)(1) by changing
the ``yes'' in column 3 to a ``no.'' The current language of 40 CFR
63.6(f)(1) exempts sources from non-opacity standards during periods of
SSM. As discussed above, the Court in Sierra Club vacated the
exemptions contained in this provision and held that the CAA requires
that some CAA section 112 standards apply continuously. Consistent with
Sierra Club, the EPA is proposing to revise standards in this rule to
apply at all times.
d. 40 CFR 63.2992 Performance Testing
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.7(e)(1) by changing
the ``yes'' in column 3 to a ``no.'' Section 63.7(e)(1) describes
performance testing requirements. The EPA is instead proposing to add a
performance testing requirement at 40 CFR 63.2992(e). The performance
testing requirements we are proposing to add differ from the General
Provisions performance testing provisions in several respects. The
regulatory text does not include the language in 40 CFR 63.7(e)(1) that
restated the SSM exemption and language that precluded startup and
shutdown periods from being considered ``representative'' for purposes
of performance testing. The proposed performance testing provisions
exclude periods of startup and shutdown. As in 40 CFR 63.7(e)(1),
performance tests conducted under this subpart should not be conducted
during malfunctions because conditions during malfunctions are often
not representative of normal operating conditions. The EPA is proposing
to add language that requires the owner or operator to record the
process information that is necessary to document operating conditions
during the test and include in such record an explanation to support
that such conditions represent normal operation. Section 63.7(e)
requires that the owner or operator make available to the Administrator
such records ``as may be necessary to determine the condition of the
performance test'' available to the Administrator upon request, but
does not specifically require the information to be recorded. The
regulatory text the EPA is proposing to add to this provision builds on
that requirement and makes explicit the requirement to record the
information.
e. Monitoring
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.8(c)(1)(i) and (iii)
by changing the ``yes'' in column 3 to a

``no.'' The cross-references to the general duty and SSM plan
requirements in those subparagraphs are not necessary in light of other
requirements of 40 CFR 63.8 that require good air pollution control
practices (40 CFR 63.8(c)(1)) and that set out the requirements of a
quality control program for monitoring equipment (40 CFR 63.8(d)).
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.8(d)(3) by changing
the ``yes'' in column 3 to a ``no.'' The final sentence in 40 CFR
63.8(d)(3) refers to the General Provisions' SSM plan requirement which
is no longer applicable. The EPA is proposing to add to the rule at 40
CFR 63.2994(a)(2) text that is identical to 40 CFR 63.8(d)(3) except
that the final sentence is replaced with the following sentence: ``The
program of corrective action should be included in the plan required
under Sec.  63.8(d)(2).''
f. 40 CFR 63.2998 Recordkeeping
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.10(b)(2)(i) by
changing the ``yes'' in column 3 to a ``no.'' Section 63.10(b)(2)(i)
describes the recordkeeping requirements during startup and shutdown.
These recording provisions are no longer necessary because the EPA is
proposing that recordkeeping and reporting applicable to normal
operations will apply to startup and shutdown. In the absence of
special provisions applicable to startup and shutdown, such as a
startup and shutdown plan, there is no reason to retain additional
recordkeeping for startup and shutdown periods.
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.10(b)(2)(ii) by
changing the ``yes'' in column 3 to a ``no.'' Section 63.10(b)(2)(ii)
describes the recordkeeping requirements during a malfunction. The EPA
is proposing to add such requirements to 40 CFR 63.2998(e). The
regulatory text we are proposing to add differs from the General
Provisions it is replacing in that the General Provisions requires the
creation and retention of a record of the occurrence and duration of
each malfunction of process, air pollution control, and monitoring
equipment. The EPA is proposing that this requirement apply to any
failure to meet an applicable standard and is requiring that the source
record the date, time, and duration of the failure rather than the
``occurrence.'' The EPA is also proposing to add to 40 CFR 63.2998(e) a
requirement that sources keep records that include a list of the
affected source or equipment and actions taken to minimize emissions,
an estimate of the quantity of each regulated pollutant emitted over
any emission limit, and a description of the method used to estimate
the emissions. Examples of such methods would include product-loss
calculations, mass balance calculations, measurements when available,
or engineering judgment based on known process parameters. The EPA is
proposing to require that sources keep records of this information to
ensure that there is adequate information to allow the EPA to determine
the severity of any failure to meet a standard, and to provide data
that may document how the source met the general duty to minimize
emissions when the source has failed to meet an applicable standard.
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.10(b)(2)(iv) by
changing the ``yes'' in column 3 to a ``no.'' When applicable, the
provision requires sources to record actions taken during SSM events
when actions were inconsistent with their SSM plan. The requirement is
no longer appropriate because SSM plans will no longer be required. The
requirement previously applicable under 40 CFR 63.10(b)(2)(iv)(B) to
record actions to minimize emissions and record corrective actions is
now applicable by reference to 40 CFR 63.2988(e).
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.10(b)(2)(v) by
changing the ``yes'' in column 3 to a ``no.'' When applicable, the
provision requires sources to record actions taken during SSM events to
show that actions taken were consistent with their SSM plan. The
requirement is no longer appropriate because SSM plans will no longer
be required.
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.10(c)(15) by changing
the ``yes'' in column 3 to a ``no.'' The EPA is proposing that 40 CFR
63.10(c)(15) no longer apply. When applicable, the provision allows an
owner or operator to use the affected source's SSM plan or records kept
to satisfy the recordkeeping requirements of the SSM plan, specified in
40 CFR 63.6(e), to also satisfy the requirements of 40 CFR 63.10(c)(10)
through (12). The EPA is proposing to eliminate this requirement
because SSM plans would no longer be required, and, therefore, 40 CFR
63.10(c)(15) no longer serves any useful purpose for affected units.
g. 40 CFR 63.3000 Reporting
    We are proposing to revise the General Provisions table (Table 2 to
40 CFR part 63, subpart HHHH) entry for 40 CFR 63.10(d)(5) by changing
the ``yes'' in column 3 to a ``no.'' Section 63.10(d)(5) describes the
reporting requirements for startups, shutdowns, and malfunctions. To
replace the General Provisions reporting requirement, the EPA is
proposing to add reporting requirements to 40 CFR 63.3000(c). The
replacement language differs from the General Provisions requirement in
that it eliminates periodic SSM reports as a stand-alone report. We are
proposing language that requires sources that fail to meet an
applicable standard at any time to report the information concerning
such events in a compliance report already required under this rule on
a semiannual basis. We are proposing that the report must contain the
number, date, time, duration, and the cause of such events (including
unknown cause, if applicable), a list of the affected sources or
equipment, an estimate of the quantity of each regulated pollutant
emitted over any emission limit, and a description of the method used
to estimate the emissions.
    Examples of such methods would include product-loss calculations,
mass balance calculations, measurements when available, or engineering
judgment based on known process parameters. The EPA is proposing this
requirement to ensure that there is adequate information to determine
compliance, to allow the EPA to determine the severity of the failure