[Federal Register Volume 84, Number 182 (Thursday, September 19, 2019)]
[Proposed Rules]
[Pages 49382-49433]
[FR Doc No: 2019-19101]

Vol. 84

Thursday,

No. 182

September 19, 2019

Part II

Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Hazardous Air Pollutants: Paper and
Other Web Coating Residual Risk and Technology Review; Proposed Rule

Federal Register / Vol. 84 , No. 182 / Thursday, September 19, 2019 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2018-0416; FRL-9999-14-OAR]
RIN 2060-AU22

National Emission Standards for Hazardous Air Pollutants: Paper
and Other Web Coating Residual Risk and Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is conducting
the residual risk and technology review (RTR) of the National Emission
Standards for Hazardous Air Pollutants (NESHAP) for the Paper and Other
Web Coating (POWC) source category that is required under the Clean Air
Act (CAA). We are proposing to find the risks due to emissions of air
toxics to be acceptable from this source category and that the current
NESHAP provides an ample margin of safety to protect public health.
Further, we identified no new cost-effective controls under the
technology review that would achieve significant further emissions
reductions, and, thus, are proposing to find that no revisions are
necessary based on developments in practices, processes, or control
technologies. In addition to performing the RTR, we are proposing
certain amendments to the POWC NESHAP. Specifically, the EPA is
proposing to add a compliance demonstration equation that accounts for
retained volatiles in the web coating; to amend provisions addressing
periods of startup, shutdown, and malfunction (SSM); to add repeat
testing and electronic reporting requirements; and to make technical
and editorial changes. The EPA is proposing these amendments to improve
the effectiveness of the NESHAP.

DATES: Comments. Comments must be received on or before November 4,
2019. 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 October 21, 2019.
    Public hearing. If anyone contacts us requesting a public hearing
on or before September 24, 2019, we will hold a hearing. Additional
information about the hearing, if requested, will be published in a
subsequent Federal Register document and posted at https://www.epa.gov/stationary-sources-air-pollution/paper-and-other-web-coating-national-emission-standards-hazardous-0. See SUPPLEMENTARY INFORMATION for
information on requesting and registering for a public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2018-0416, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/
(our preferred method). Follow the online instructions for submitting
comments.
     Email<EMAIL_ADDRESS>Include Docket ID No. EPA-
HQ-OAR-2018-0416 in the subject line of the message.
     Fax:<PHONE_NUMBER>. Attention Docket ID No. EPA-HQ-OAR-
2018-0416.
     Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Docket ID No. EPA-HQ-OAR-2018-0416, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
     Hand/Courier Delivery: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except federal holidays).
    Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov/, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the SUPPLEMENTARY
INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Dr. Kelley Spence, Sector Policies and Programs
Division (Mail Code E143-03), Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; telephone number:<PHONE_NUMBER>; fax
number:<PHONE_NUMBER>; and email address<EMAIL_ADDRESS>For
specific information regarding the risk modeling methodology, contact
Mr. James Hirtz, Health and Environmental Impacts Division (C539-02),
Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina 27711;
telephone number:<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and email
address<EMAIL_ADDRESS>For questions about monitoring and
testing requirements, contact Mr. Barrett Parker, Sector Policies and
Programs Division (Mail Code D243-05), 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_ADDRESS>For
information about the applicability of the NESHAP to a particular
entity, contact Mr. John Cox, Office of Enforcement and Compliance
Assurance, U.S. Environmental Protection Agency, WJC South Building
(Mail Code 2221A), 1200 Pennsylvania Avenue NW, Washington, DC 20460;
telephone number:<PHONE_NUMBER>; and email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Public hearing. Please contact Ms. Virginia Hunt at<PHONE_NUMBER>
or by email at<EMAIL_ADDRESS>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.
    Docket. The EPA has established a docket for this rulemaking under
Docket ID No. EPA-HQ-OAR-2018-0416. All documents in the docket are
listed in Regulations.gov. Although listed, some information is not
publicly available, e.g., Confidential Business Information (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,
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-
2018-0416. 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 https://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 https://www.regulations.gov/ or email. This

type of information should be submitted by mail as discussed below.
    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://www.epa.gov/dockets/commenting-epa-dockets.
    The https://www.regulations.gov/ website allows you to submit your
comment anonymously, 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
https://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
digital storage media 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 https://www.epa.gov/dockets.
    Submitting CBI. Do not submit information containing CBI to the EPA
through https://www.regulations.gov/ or email. Clearly mark the part or
all of the information that you claim to be CBI. For CBI information on
any digital storage media that you mail to the EPA, mark the outside of
the digital storage media as CBI and then identify electronically
within the digital storage media 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 directly
to the public docket through the procedures outlined in Instructions
above. If you submit any digital storage media that does not contain
CBI, mark the outside of the digital storage media 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-2018-0416.
    Preamble acronyms and abbreviations. We use multiple acronyms and
terms in this preamble. While this list may not be exhaustive, to ease
the reading of this preamble and for reference purposes, the EPA
defines the following terms and acronyms here:

AEGL acute exposure guideline level
AERMOD air dispersion model used by the HEM-3 model
ANSI American National Standards Institute
ASME American Society of Mechanical Engineers
ASTM American Society for Testing and Materials
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
DGME diethylene glycol monoethyl ether
ECHO Enforcement and Compliance History Online
EPA Environmental Protection Agency
ERPG emergency response planning guideline
ERT Electronic Reporting Tool
GACT generally available control technology
HAP hazardous air pollutant(s)
HCl hydrochloric acid
HEM-3 Human Exposure Model, Version 1.5.5
HF hydrogen fluoride
HI hazard index
HQ hazard quotient
IBR incorporation by reference
ICR Information Collection Request
IRIS Integrated Risk Information System
km kilometer
MACT maximum achievable control technology
MIR maximum individual risk
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NEI National Emissions Inventory
NESHAP national emission standards for hazardous air pollutants
NRDC Natural Resources Defense Council
NSPS new source performance standards
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
bioaccumulative in the environment
PDF portable document format
POM polycyclic organic matter
POWC paper and other web coating
ppm parts per million
ppmv parts per million by volume
PRA Paperwork Reduction Act
QA quality assurance
RBLC Reasonably Available Control Technology/Best Available Control
Technology/Lowest Achievable Emission Rate 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
TCE trichloroethylene
TOSHI target organ-specific hazard index
tpy tons per year
TRI Toxics Release Inventory
TRIM.FaTE Total Risk Integrated Methodology.Fate, Transport, and
Ecological Exposure model
UF uncertainty factor
UMRA Unfunded Mandates Reform Act
URE unit risk estimate
U.S.C. United States Code
USGS U.S. Geological Survey
VCS voluntary consensus standards
VOC volatile organic compound(s)

    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?
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 and Decision-Making
    A. How do we consider risk in our decision-making?
    B. How do we perform the technology review?
    C. How do we estimate post-MACT risk 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 effect?
    C. What are the results and proposed decisions based on our
technology review?

    D. What other actions are we proposing?
    E. What compliance dates are we proposing?
V. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
VI. Request for Comments
VII. Submitting Data Corrections
VIII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulation and Controlling
Regulatory Costs
    C. Paperwork Reduction Act (PRA)
    D. Regulatory Flexibility Act (RFA)
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
    K. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. General Information

A. Does this action apply to me?

    Table 1 of this preamble lists the NESHAP and associated regulated
industrial source category that is the subject of this proposal. Table
1 is not intended to be exhaustive, but rather provides a guide for
readers regarding the entities that this proposed action is likely to
affect. The proposed standards, once promulgated, will be directly
applicable to the affected sources. This proposed action will not
affect federal, state, local, and tribal government entities. As
defined in the Initial List of Categories of Sources Under Section
112(c)(1) of the Clean Air Act Amendments of 1990 (see 57 FR 31576,
July 16, 1992) and Documentation for Developing the Initial Source
Category List, Final Report (see EPA-450/3-91-030, July 1992), the POWC
source category is any facility engaged in the coating of paper,
plastic film, metallic foil, and other web surfaces. The category may
include, but is not limited to, decorative coatings on gift wraps or
packaging. The source category does not include printing operations
covered under the Printing and Publishing NESHAP (40 CFR part 63,
subpart KK).

    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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Paper and Other Web Coating.....  Paper and Other     322220, 322121,
                                   Web Coating.        326113, 326112,
                                                       325992, 327993.
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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/paper-and-other-web-coating-national-emission-standards-hazardous-0. 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-2018-0416).

II. Background

A. What is the statutory authority for this action?

    The statutory authority for this action is provided by sections 112
and 301 of the CAA, as amended (42 U.S.C. 7401 et seq.). Section 112 of
the CAA establishes a two-stage regulatory process to develop standards
for emissions of hazardous air pollutants (HAP) from stationary
sources. Generally, the first stage involves establishing technology-
based standards and the second stage involves evaluating those
standards that are based on maximum achievable control technology
(MACT) to determine whether additional standards are needed to address
any remaining risk associated with HAP emissions. This second stage is
commonly referred to as the ``residual risk review.'' In addition to
the residual risk review, the CAA also requires the EPA to review
standards set under CAA section 112 every 8 years to determine if there
are ``developments in practices, processes, or control technologies''
that may be appropriate to incorporate into the standards. This review
is commonly referred to as the ``technology review.'' When the two
reviews are combined into a single rulemaking, it is commonly referred
to as the ``risk and technology review.'' The discussion that follows
identifies the most relevant statutory sections and briefly explains
the contours of the methodology used to implement these statutory
requirements. A more comprehensive discussion appears in the document
titled CAA Section 112 Risk and Technology Reviews: Statutory Authority
and Methodology, in the docket for this rulemaking.
    In the first stage of the CAA section 112 standard setting process,
the EPA promulgates technology-based standards under CAA section 112(d)
for categories of sources identified as emitting one or more of the HAP
listed in CAA section 112(b). Sources of HAP emissions are either major
sources or area sources, and CAA section 112 establishes different
requirements for major source standards and area source standards.
``Major sources'' are those that emit or have the potential to emit 10
tons per year (tpy) or more of a single HAP or 25 tpy or more of any
combination of HAP. All other sources are ``area sources.'' For major
sources, CAA section 112(d)(2) provides that the technology-based
NESHAP must reflect the maximum degree of emission reductions of HAP
achievable (after considering cost, energy requirements, and non-air
quality health and environmental impacts). These standards are commonly
referred to as MACT standards. CAA section 112(d)(3) also establishes a
minimum control level for MACT standards, known as the MACT ``floor.''
The EPA must also consider control options that are more stringent than
the floor. Standards more stringent than the floor are commonly
referred to as beyond-the-floor standards. In certain instances, as
provided in CAA section 112(h), the EPA may set work practice

standards where it is not feasible to prescribe or enforce a numerical
emission standard. For area sources, CAA section 112(d)(5) gives the
EPA discretion to set standards based on generally available control
technologies or management practices (GACT standards) in lieu of MACT
standards.
    The second stage in standard-setting focuses on identifying and
addressing any remaining (i.e., ``residual'') risk according to CAA
section 112(f). For source categories subject to MACT standards,
section 112(f)(2) of the CAA requires the EPA to determine 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
Natural Resources Defense Council (NRDC) v. EPA, 529 F.3d 1077, 1083
(D.C. Cir. 2008).
    The approach incorporated into the CAA and used by the EPA to
evaluate residual risk and to develop standards under CAA section
112(f)(2) is a two-step approach. In the first step, the EPA determines
whether risks are acceptable. This determination ``considers all health
information, including risk estimation uncertainty, and includes a
presumptive limit on maximum individual lifetime [cancer] risk (MIR)
\1\ of approximately 1 in 10 thousand.'' 54 FR 38045, September 14,
1989. If risks are unacceptable, the EPA must determine the emissions
standards necessary to reduce risk 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 to protect public health ``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 or determine that the standards being
reviewed provide an ample margin of safety without any revisions. 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 often than every 8 years. In
conducting this review, which we call the ``technology review,'' the
EPA is not required to recalculate the MACT floor. NRDC v. EPA, 529
F.3d 1077, 1084 (D.C. Cir. 2008). Association of Battery Recyclers,
Inc. v. EPA, 716 F.3d 667 (D.C. Cir. 2013). The EPA may consider cost
in deciding whether to revise the standards pursuant to CAA section
112(d)(6).

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

    The POWC source category includes new and existing facilities that
coat paper and other web substrates that are major sources of HAP
emissions. For purposes of the regulation, a web is defined as a
continuous substrate that is capable of being rolled at any point
during the coating process. Further, a web coating line is any number
of work stations, of which one or more applies a continuous layer of
coating material along the entire width of a continuous web substrate
or any portion of the width of the web substrate, and any associated
curing/drying equipment between an unwind (or feed) station and a
rewind (or cutting) station. Web coating operations covered by other
MACT standards (i.e., Printing and Publishing, 40 CFR part 63, subpart
KK; Magnetic Tape, 40 CFR part 63, subpart EE; Metal Coil Coating, 40
CFR part 63, subpart SSSS; Fabric Coating, 40 CFR part 63, subpart
OOOO), and research and development lines are excluded. In addition,
specific process exclusions include lithography, screen printing,
letterpress, and narrow web flexographic printing.
    All the coating lines at a subject facility are defined as one
affected source. An existing source means any affected source of which
the construction or reconstruction commenced on or before September 13,
2000, and has not since undergone reconstruction. Generally, an
additional line at an existing facility is considered part of the
existing affected source. New affected sources are new lines installed
at new facilities or at a facility with no prior POWC operations.
Affiliated operations such as coating formulation, mixing, handling,
and storage of coatings and solvent, and conveyance and treatment of
wastewater are defined as ``affiliated equipment'' and are part of the
POWC source category but have no requirements in the existing rule.
    This proposal includes both a residual risk assessment and a
technology review of the emission sources subject to the POWC NESHAP.
Facilities subject to the POWC NESHAP must utilize low-solvent
coatings, add-on controls, or a combination of both to meet the organic
HAP emission limits described below:
     No more than 5 percent of the organic HAP applied for each
month (95-percent reduction) at existing affected sources, and no more
than 2 percent of the organic HAP applied for each month (98-percent
reduction) at new affected sources;
     No more than 4 percent of the mass of coating materials
applied for each month at existing affected sources, and no more than
1.6 percent of the mass of coating materials applied for each month at
new affected sources;
     No more than 20 percent of the mass of coating solids
applied for each month at existing affected sources, and no more than 8
percent of the coating solids applied for each month at new affected
sources; or
     If an oxidizer is used to control organic HAP emissions,
the oxidizer must be operated such that an outlet organic HAP
concentration of no greater than 20 parts per million by volume (ppmv)
by compound on a dry basis is achieved and the efficiency of the
capture system is 100 percent.

The NESHAP also includes various operating limits, initial and
continuous

compliance requirements, and recordkeeping and reporting requirements
for the POWC source category. We reviewed these requirements and are
proposing to update them as part of this action in conjunction with
conducting the RTR for this source category.

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

    The EPA collected data from several environmental databases that
included information pertaining to POWC facilities in the United
States. The primary databases were the EPA's Enforcement and Compliance
History Online (ECHO) database, Toxics Release Inventory (TRI), and
National Emissions Inventory (NEI) for 2011 and 2014 (versions 1 and
2). Title V operating permits were obtained from states that have
facilities subject to 40 CFR part 63, subpart JJJJ. See the memorandums
titled Determination of Facilities Subject to 40 CFR part 63, subpart
JJJJ, Paper and Other Web Coating and Preparation of POWC Risk Inputs
File, in the docket for this rulemaking for more information on the
review of these databases (Docket ID No. EPA-HQ-OAR-2018-0416).
Additionally, the EPA conducted several site visits to better
understand POWC processes and how the NESHAP is implemented. Trip
reports drafted from these site visits are available in the docket for
this rulemaking (Docket ID No. EPA-HQ-OAR-2018-0416). EPA did not use
its authority under CAA section 114 to request additional information
from POWC facilities.

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

    In addition to the ECHO, TRI, and NEI databases, the EPA reviewed
the additional information sources listed below and consulted with
stakeholders regulated under the POWC NESHAP to determine if there have
been developments in practices, processes, or control technologies.
These include:
     Permit limits and selected compliance options from permits
collected from state agencies;
     Information on air pollution control options in the POWC
industry from the Reasonably Available Control Technology/Best
Available Control Technology/Lowest Achievable Emission Rate
Clearinghouse (RBLC);
     Information on the most effective ways to control
emissions of volatile organic compounds (VOC) and volatile organic HAP
from sources in various industries, including the POWC industry;
     Communication with trade groups and associations
representing industries in the affected NAICS categories and their
members; and
     Review of on-line information on trade group and
association sites and sites of relevant publications.

III. Analytical Procedures and Decision-Making

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

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 risk within the
exposed populations, cancer incidence, and an evaluation of the
potential for an adverse environmental effect. The scope of the EPA's
risk analysis is consistent with the EPA's response to comments on our
policy under the Benzene NESHAP where the EPA explained that:
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    \2\ The MIR is defined as the cancer risk associated with a
lifetime of exposure at the highest concentration of HAP where
people are likely to live. The HQ is the ratio of the potential HAP
exposure concentration to the noncancer dose-response value; 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 risk. 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 an MIR less than the
presumptively acceptable level is unacceptable in the light of other
health risk factors.'' Id. at 38045. In other words, risks that include
an MIR above 100-in-1 million may be determined to be acceptable, and
risks with an MIR below that level may be determined to be
unacceptable, depending on all of the available health information.
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 the HAP risk 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 risk, 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 an 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\ Recommendations of the SAB Risk and Technology Review
Methods Panel are provided in their report, which is available at:
https://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
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    In response to the SAB recommendations, the EPA incorporates
cumulative risk analyses into its RTR risk assessments, including those
reflected in this action. The Agency (1) conducts facility-wide
assessments, which include source category emission points, as well as
other emission points within the facilities; (2) combines exposures
from multiple sources in the same category that could affect the same
individuals; and (3) for some persistent and bioaccumulative
pollutants, analyzes the ingestion route of exposure. In addition, the
RTR risk assessments consider aggregate cancer risk from all
carcinogens and aggregated noncancer HQs for all noncarcinogens
affecting the same target organ or target organ system.
    Although we are interested in placing source category and facility-
wide HAP risk in the context of total HAP risk from all sources
combined in the vicinity of each source, we are concerned about the
uncertainties of doing so. Estimates of total HAP risk from emission
sources other than those that we have studied in depth during this RTR
review 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, we analyze their technical feasibility,
estimated costs, energy implications, and non-air environmental
impacts. We also consider the emission reductions associated with
applying each development. This analysis informs our decision of
whether it is ``necessary'' to revise the emissions standards. 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
the NESHAP, we review a variety of data sources in our investigation of
potential practices, processes, or controls to consider. See sections
II.C and II. D of this preamble for information on the specific data
sources that were reviewed as part of the technology review.

C. How do we estimate post-MACT risk posed by the source category?

    In this section, we provide a complete description of the types of
analyses that we generally perform during the risk assessment process.
In some cases, we do not perform a specific analysis because it is not
relevant. For example, in the absence of emissions of HAP known to be
persistent and bioaccumulative in the environment (PB-HAP), we would
not perform a multipathway exposure assessment. Where we do not perform
an analysis, we state that we do not and provide the reason. While we
present all of our risk assessment methods, we only present risk
assessment results for the analyses actually conducted (see section
IV.B of this preamble).
    The EPA conducts 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 risk
within the exposed populations, cancer incidence, and an evaluation of
the potential for an adverse environmental effect. The seven sections
that follow this paragraph describe how we estimated emissions and
conducted the risk assessment. The docket for this rulemaking contains
the following document which provides more information on the risk
assessment inputs and models: Residual Risk Assessment for the Paper
and Other Web Coating Source Category in Support of the 2019 Risk and
Technology Review Proposed Rule. The methods used to assess risk (as
described in the seven primary steps below) are consistent with those
described by the EPA in the document reviewed by a panel of the EPA's
SAB

in 2009; \4\ and described in the SAB review report issued in 2010.
They are also consistent with the key recommendations contained in that
report.
---------------------------------------------------------------------------

    \4\ U.S. EPA. 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, June 2009. EPA-452/R-09-006. https://www3.epa.gov/airtoxics/rrisk/rtrpg.html.
---------------------------------------------------------------------------

1. How did we estimate actual emissions and identify the emissions
release characteristics?
    The facilities subject to the POWC NESHAP were identified primarily
by using the ECHO and TRI databases. Review of title V permits and
discussions with state agencies and stakeholders helped to refine the
preliminary list to the final list of 168 facilities subject to the
regulation. The effort to identify facilities subject to the POWC
NESHAP is described in detail in the memorandum titled Determination of
Facilities Subject to 40 CFR part 63, subpart JJJJ, Paper and Other Web
Coating, in the docket for this rulemaking (Docket ID No. EPA-HQ-OAR-
2018-0416). As described in the memorandum, Preparation of POWC Risk
Inputs File, eight of the identified facilities had source category HAP
emissions of zero. These facilities are subject to the POWC NESHAP
because they are major sources of HAP for another source category, even
though their web coating operations do not utilize any HAP-containing
coatings. For example, a paper towel core production line might use a
glue the does not contain any HAP, but the operation is co-located at a
pulp mill, which is a major source of HAP, therefore, the coating
operations are subject to the POWC NESHAP. As a result of the eight
facilities without HAP emissions, a total of 160 facilities were
included in the source-category risk assessment modeling input file.
The communications with state agencies and stakeholders regarding
development of the facility list and the risk input file are documented
in the memorandum titled Communications Regarding the Development of
the Subpart JJJJ Facility List and Risk Modeling File, in the docket
for this rulemaking (Docket ID No. EPA-HQ-OAR-2018-0416).
    Emissions data for facilities subject to the POWC NESHAP were
gathered primarily from the 2011 and 2014 NEI (versions 1 and 2),
supplemented by the TRI. The NEI is a database that contains
information about sources that emit criteria air pollutants, their
precursors, and HAP. The NEI database includes estimates of actual
annual air pollutant emissions from point and volume sources; emission
rate characteristic data such as emission release height, temperature,
stack diameter, exit gas velocity, and exit gas flow rate; and
locational latitude/longitude coordinates. We compared the NEI data for
each facility to title V permits to determine which emission points
listed in the NEI were subject to the POWC NESHAP. We then performed
quality assurance (QA) checks and made corrections when data were
missing from the NEI or appeared to be incorrect. For example, if the
exit gas flow rate for an emission point was missing, we calculated
this release characteristic using the stack velocity and cross-
sectional area of the stack. Each correction we made is discussed in
the memorandum, Preparation of POWC Risk Inputs File, in the docket for
this rulemaking (Docket ID No. EPA-HQ-OAR-2018-0416). The QA procedures
and tools used are described in the memorandum titled QA Procedures and
Criteria Used in Residual Risk Modeling Input File Development, in the
docket for this rulemaking (Docket ID No. EPA-HQ-OAR-2018-0416).
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 allowed under the MACT standards are referred
to as the ``MACT-allowable'' emissions. We discussed the consideration
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 RTR (71 FR 34428, June 14, 2006, and
71 FR 76609, December 21, 2006, respectively). In those actions, we
noted that assessing the risk at the MACT-allowable level is inherently
reasonable since that risk reflects 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.)
    Initially, we reviewed permits for available allowable HAP
emissions information, and two facilities were found to have allowable
HAP emissions limits specified for POWC NESHAP emission sources. For
these two facilities, MACT-allowable emissions were assumed to be equal
to the allowable HAP emissions limits contained in the permits.
Allowable emissions were not available for the remainder of the
emission units in the POWC dataset. Although some permits listed
overall plant HAP emission limits, most did not break down allowable
HAP emissions by process. Therefore, we developed a POWC category
allowable emissions multiplier to estimate allowable emissions based on
actual emissions.
    Allowable emissions are emissions that can be emitted from an
emission unit and still comply with the POWC NESHAP. Because the format
of the POWC NESHAP emission standards are in a HAP-percent of mass of
coating applied, it is difficult to determine the allowable HAP
emissions without production and coating HAP content information for
each facility. Coatings sales information and industry capacity
utilization were the only information readily available to estimate
allowable emissions for this source category. A description of the
methodology used to estimate allowable emissions follows.
    According to chapter 18 of the American Coatings Association 9th
Edition Market Analysis (2014-2019), the volume of paper, paperboard,
film, and foil coating shipments are forecast to increase at an annual
rate of 2 percent per year. This implies that the demand for paper and
other web coated products, as well as the capacity utilization at the
facilities producing the materials, continues to increase. For the
primary NAICS codes associated with the facilities in the risk input
file, the capacity utilization rate was obtained from the U.S. Census
Bureau's Quarterly Survey of Plant Capacity Utilization for 5 years
(2013-2017). All POWC NAICS codes and years were utilized to determine
a 5-year average plant capacity utilization rate (71.3 percent).
Because the sector continues to grow, and additional production
information is not available, we estimate that the maximum allowable
emissions will occur at 100-percent production capacity utilization. A
ratio of the maximum possible capacity utilization (100 percent) to the
5-year average capacity utilization (71.3 percent) results in an
allowable multiplier of 1.4. Thus, allowable emissions for the majority
of emission points in the risk input file were estimated by multiplying
the actual emissions by 1.4. A more detailed description of the
estimation of allowable emissions for the POWC source category is
described in the memorandum, Preparation of POWC

Risk Inputs File, in the docket for this rulemaking (Docket ID No. EPA-
HQ-OAR-2018-0416).
3. How do we conduct dispersion modeling, determine inhalation
exposures, and estimate individual and population inhalation risk?
    Both long-term and short-term inhalation exposure concentrations
and health risk from the source category addressed in this action were
estimated using the Human Exposure Model (HEM-3).\5\ 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 risk using the
exposure estimates and quantitative dose-response information.
---------------------------------------------------------------------------

    \5\ For more information about HEM-3, go to https://www.epa.gov/fera/risk-assessment-and-modeling-human-exposure-model-hem.
---------------------------------------------------------------------------

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.\6\ To perform the dispersion modeling and
to develop the preliminary risk estimates, HEM-3 draws on three data
libraries. The first is a library of meteorological data, which is used
for dispersion calculations. This library includes 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 \7\
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
risk. These are discussed below.
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    \6\ U.S. EPA. Revision to the Guideline on Air Quality Models:
Adoption of a Preferred General Purpose (Flat and Complex Terrain)
Dispersion Model and Other Revisions (70 FR 68218, November 9,
2005).
    \7\ A census block is the smallest geographic area for which
census statistics are tabulated.
---------------------------------------------------------------------------

b. Risk From Chronic Exposure to HAP
    In developing the risk assessment for chronic exposures, we use the
estimated annual average ambient air concentrations of each HAP emitted
by each source in the source category. The HAP air concentrations at
each nearby census block centroid located within 50 km of the facility
are a surrogate for the chronic inhalation exposure concentration for
all the people who reside in that census block. 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.
    For each facility, we calculate the MIR as the cancer risk
associated with a continuous lifetime (24 hours per day, 7 days per
week, 52 weeks per year, 70 years) exposure to the maximum
concentration at the centroid of each inhabited census block. We
calculate individual cancer risk 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 incremental risk 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 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. The pollutant-specific dose-response values used to
estimate health risk are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
    To estimate individual lifetime cancer risks associated with
exposure to HAP emissions from each facility in the source category, we
sum the risks for each of the carcinogenic HAP \8\ emitted by the
modeled facility. We estimate cancer risk at every census block within
50 km of every facility in the source category. The MIR is the highest
individual lifetime cancer risk estimated for any of those census
blocks. In addition to calculating the MIR, we estimate the
distribution of individual cancer risks for the source category by
summing the number of individuals within 50 km of the sources whose
estimated risk falls within a specified risk range. We also estimate
annual cancer incidence by multiplying the estimated lifetime cancer
risk at each census block by the number of people residing in that
block, summing results for all of the census blocks, and then dividing
this result by a 70-year lifetime.
---------------------------------------------------------------------------

    \8\ The EPA's 2005 Guidelines for Carcinogen Risk Assessment
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 risk of these individual compounds to obtain the cumulative
cancer risk 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 https://
yosemite.epa.gov/sab/sabproduct.nsf/
214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf.
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    To assess the risk of noncancer health effects from chronic
exposure to HAP, we calculate either an HQ or a target organ-specific
hazard index (TOSHI). We calculate an HQ when a single noncancer HAP is
emitted. Where more than one noncancer HAP is emitted, we sum the HQ
for each of the HAP that affects a common target organ or target organ
system to obtain a TOSHI. The HQ is the estimated exposure divided by
the chronic noncancer dose-response value, which is a value selected
from one of several sources. The preferred chronic noncancer dose-
response value is the EPA RfC, 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'' (https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glossary). In cases where an RfC
from the EPA's IRIS is not available or where the EPA determines that
using a value other than the RfC is appropriate, the chronic noncancer
dose-response value can be a value from the following prioritized
sources, which define their dose-response values similarly to the EPA:
(1) The Agency for Toxic

Substances and Disease Registry (ATSDR) Minimum Risk Level (https://www.atsdr.cdc.gov/mrls/index.asp); (2) the CalEPA Chronic Reference
Exposure Level (REL) (https://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. The pollutant-specific dose-response values used to
estimate health risks are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
c. 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. In this proposed rulemaking, as part of our efforts
to continually improve our methodologies to evaluate the risks that HAP
emitted from categories of industrial sources pose to human health and
the environment,\9\ we are revising our treatment of meteorological
data to use reasonable worst-case air dispersion conditions in our
acute risk screening assessments instead of worst-case air dispersion
conditions. This revised treatment of meteorological data and the
supporting rationale are described in more detail in Residual Risk
Assessment for Paper and Other Web Coating Source Category in Support
of the 2019 Risk and Technology Review Proposed Rule and in Appendix 5
of the report: Technical Support Document for Acute Risk Screening
Assessment. We will be applying this revision in RTR rulemakings
proposed on or after June 3, 2019.
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    \9\ See, e.g., U.S. EPA. Screening Methodologies to Support Risk
and Technology Reviews (RTR): A Case Study Analysis (Draft Report,
May 2017. https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html).
---------------------------------------------------------------------------

    To assess the potential acute risk to the maximally exposed
individual, we use the peak hourly emission rate for each emission
point,\10\ reasonable worst-case air dispersion conditions (i.e., 99th
percentile), and the point of highest off-site exposure. Specifically,
we assume that peak emissions from the source category and reasonable
worst-case air dispersion conditions co-occur and that a person is
present at the point of maximum exposure.
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    \10\ In the absence of hourly emission data, we develop
estimates of maximum hourly emission rates by multiplying the
average actual annual emissions rates by a factor (either a
category-specific factor or a default factor of 10) to account for
variability. This is documented in Residual Risk Assessment for
Paper and Other Web Coating Source Category in Support of the 2019
Risk and Technology Review Proposed Rule and in Appendix 5 of the
report: Technical Support Document for Acute Risk Screening
Assessment. 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 concentration by the acute dose-response
value. For each HAP for which acute dose-response values are available,
the EPA calculates acute HQs.
    An acute REL is defined as ``the concentration level at or below
which no adverse health effects are anticipated for a specified
exposure duration.'' \11\ Acute RELs are based on the most sensitive,
relevant, adverse health effect reported in the peer-reviewed medical
and toxicological literature. They are designed to protect the most
sensitive individuals in the population through the inclusion of
margins of safety. Because margins of safety are incorporated to
address data gaps and uncertainties, exceeding the REL does not
automatically indicate an adverse health impact. AEGLs represent
threshold exposure limits for the general public and are applicable to
emergency exposures ranging from 10 minutes to 8 hours.\12\ They are
guideline levels for ``once-in-a-lifetime, short-term exposures to
airborne concentrations of acutely toxic, high-priority chemicals.''
Id. at 21. The AEGL-1 is specifically defined as ``the airborne
concentration (expressed as ppm (parts per million) or mg/m\3\
(milligrams per cubic meter)) of a substance above which it is
predicted that the general population, including susceptible
individuals, could experience notable discomfort, irritation, or
certain asymptomatic nonsensory effects. However, the effects are not
disabling and are transient and reversible upon cessation of
exposure.'' The document also notes that ``Airborne concentrations
below AEGL-1 represent exposure levels that can produce mild and
progressively increasing but transient and nondisabling odor, taste,
and sensory irritation or certain asymptomatic, nonsensory effects.''
Id. AEGL-2 are defined as ``the airborne concentration (expressed as
parts per million or milligrams per cubic meter) of a substance above
which it is predicted that the general population, including
susceptible individuals, could experience irreversible or other
serious, long-lasting adverse health effects or an impaired ability to
escape.'' Id.
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    \11\ CalEPA issues acute RELs as part of its Air Toxics Hot
Spots Program, and the 1-hour and 8-hour values are documented in
Air Toxics Hot Spots Program Risk Assessment Guidelines, Part I, The
Determination of Acute Reference Exposure Levels for Airborne
Toxicants, which is available at https://oehha.ca.gov/air/general-info/oehha-acute-8-hour-and-chronic-reference-exposure-level-rel-summary.
    \12\ National Academy of Sciences, 2001. Standing Operating
Procedures for Developing Acute Exposure Levels for Hazardous
Chemicals, page 2. Available at https://www.epa.gov/sites/production/files/2015-09/documents/sop_final_standing_operating_procedures_2001.pdf. Note that the
National Advisory Committee for Acute Exposure Guideline Levels for
Hazardous Substances ended in October 2011, but the AEGL program
continues to operate at the EPA and works with the National
Academies to publish final AEGLs (https://www.epa.gov/aegl).
---------------------------------------------------------------------------

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

    \13\ ERPGs Procedures and Responsibilities. March 2014. American
Industrial Hygiene Association. Available at: https://www.aiha.org/get-involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERPG%20Committee%20Standard%20Operating%20Procedures%20%20-%20March%202014%20Revision%20%28Updated%2010-2-2014%29.pdf.
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    An acute REL for 1-hour exposure durations is typically lower than
its corresponding AEGL-1 and ERPG-1. Even though their definitions are
slightly different, AEGL-1s are often the same as the corresponding
ERPG-1s, and AEGL-2s are often equal to ERPG-2s. The maximum HQs from
our acute inhalation screening risk assessment typically result when we
use the acute REL for a HAP. In cases where the

maximum acute HQ exceeds 1, we also report the HQ based on the next
highest acute dose-response value (usually the AEGL-1 and/or the ERPG-
1).
    For this source category, no short-term emissions data were readily
available for the majority of the sources subject to the POWC NESHAP.
The EPA assumed that a facility's peak 1-hour emission rate could
exceed its annual average hourly emission rate by as much as a factor
of 10, under worst-case meteorological conditions and the presence of a
person at the facility boundary. This peak-to-mean emissions ratio was
used as an acute multiplier for all facilities except one. The permit
for one facility contained allowable short-term VOC emission rates for
POWC NESHAP sources. The acute emissions for this facility were
determined using the allowable short-term VOC emission rate using the
assumption that the VOC emission rate is equal to the HAP emission
rate. For more details, see the memorandum, Preparation of the POWC
Risk Inputs File, in the docket for this rulemaking (Docket ID No. EPA-
HQ-OAR-2018-0416).
    In our acute inhalation screening risk assessment, acute impacts
are deemed negligible for HAP for which acute HQs are less than or
equal to 1, and no further analysis is performed for these HAP. In
cases where an acute HQ from the screening step is greater than 1, we
assess the site-specific data to ensure that the acute HQ is at an off-
site location. For this source category, the data refinements employed
consisted of ensuring that the locations where the maximum HQ occurred
were off facility property and where the public could potentially be
exposed. These refinements are discussed more fully in the Residual
Risk Assessment for the Paper and Other Web Coating Source Category in
Support of the 2019 Risk and Technology Review Proposed Rule, which is
available in the docket for this source category (Docket ID No. EPA-HQ-
OAR-2018-0416).
4. How do we conduct the multipathway exposure and risk screening
assessment?
    The EPA conducts 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 determine
whether any sources in the source category emit any HAP known to be
persistent and bioaccumulative in the environment, as identified in the
EPA's Air Toxics Risk Assessment Library (see Volume 1, Appendix D, at
https://www.epa.gov/fera/risk-assessment-and-modeling-air-toxics-risk-assessment-reference-library).
    For the POWC source category, we identified PB-HAP emissions of
arsenic, cadmium compounds, mercury compounds, polycyclic organic
matter (POM), and lead, so we proceeded to the next step of the
evaluation. Except for lead, the human health risk screening assessment
for PB-HAP consists of three progressive tiers. The POWC source
category only required the completion of Tier 1 for the multipathway
screening assessment. For Tier 1, we determine whether the magnitude of
the facility-specific emissions of PB-HAP warrants further evaluation
to characterize human health risk through ingestion exposure. To
facilitate this step, we evaluate emissions against previously
developed screening threshold emission rates for several PB-HAP that
are based on a hypothetical upper-end screening exposure scenario
developed for use in conjunction with the EPA's Total Risk Integrated
Methodology.Fate, Transport, and Ecological Exposure (TRIM.FaTE) model.
The PB-HAP with screening threshold emission rates are arsenic
compounds, cadmium compounds, chlorinated dibenzodioxins and furans,
mercury compounds, and POM. Based on the EPA estimates of toxicity and
bioaccumulation potential, these pollutants represent a conservative
list for inclusion in multipathway risk assessments for RTR rules. (See
Volume 1, Appendix D at https://www.epa.gov/sites/production/files/2013-08/documents/volume_1_reflibrary.pdf.) In this assessment, we
compare the facility-specific emission rates of these PB-HAP to the
screening threshold emission rates for each PB-HAP to assess the
potential for significant human health risks via the ingestion pathway.
We call this application of the TRIM.FaTE model the Tier 1 screening
assessment. The ratio of a facility's actual emission rate to the Tier
1 screening threshold emission rate is a ``screening value.''
    We derive the Tier 1 screening threshold emission rates for these
PB-HAP (other than lead compounds) to correspond to a maximum excess
lifetime cancer risk of 1-in-1 million (i.e., for arsenic compounds,
polychlorinated dibenzodioxins and furans and POM) or, for HAP that
cause noncancer health effects (i.e., cadmium compounds and mercury
compounds), a maximum HQ of 1. If the emission rate of any one PB-HAP
or combination of carcinogenic PB-HAP in the Tier 1 screening
assessment exceeds the Tier 1 screening threshold emission rate for any
facility (i.e., the screening value is greater than 1), we conduct a
second screening assessment, which we call the Tier 2 screening
assessment. The Tier 2 screening assessment separates the Tier 1
combined fisher and farmer exposure scenario into fisher, farmer, and
gardener scenarios that retain upper-bound ingestion rates.
    In the Tier 2 screening assessment, the location of each facility
that exceeds a Tier 1 screening threshold emission rate is used to
refine the assumptions associated with the Tier 1 fisher and farmer
exposure scenarios at that facility. A key assumption in the Tier 1
screening assessment is that a lake and/or farm is located near the
facility. As part of the Tier 2 screening assessment, we use a U.S.
Geological Survey (USGS) database to identify actual waterbodies within
50 km of each facility and assume the fisher only consumes fish from
lakes within that 50 km zone. We also examine the differences between
local meteorology near the facility and the meteorology used in the
Tier 1 screening assessment. We then adjust the previously-developed
Tier 1 screening threshold emission rates for each PB-HAP for each
facility based on an understanding of how exposure concentrations
estimated for the screening scenario change with the use of local
meteorology and USGS lakes database.
    In the Tier 2 farmer scenario, we maintain an assumption that the
farm is located within 0.5 km of the facility and that the farmer
consumes meat, eggs, dairy, vegetables, and fruit produced near the
facility. We may further refine the Tier 2 screening analysis by
assessing a gardener scenario to characterize a range of exposures,
with the gardener scenario being more plausible in RTR evaluations.
Under the gardener scenario, we assume the gardener consumes home-
produced eggs, vegetables, and fruit products at the same ingestion
rate as the farmer. The Tier 2 screen continues to rely on the high-end
food intake assumptions that were applied in Tier 1 for local fish
(adult female angler at 99th percentile fish consumption of fish \14\)
and locally grown or raised foods (90th percentile consumption of
locally grown or raised foods for the farmer and gardener scenarios
\15\). If PB-HAP emission rates do not result in a Tier 2 screening
value greater than 1, we consider those PB-HAP emissions to pose risks
below a

level of concern. If the PB-HAP emission rates for a facility exceed
the Tier 2 screening threshold emission rates, we may conduct a Tier 3
screening assessment.
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    \14\ Burger, J. 2002. Daily consumption of wild fish and game:
Exposures of high end recreationists. International Journal of
Environmental Health Research 12:343-354.
    \15\ U.S. EPA. Exposure Factors Handbook 2011 Edition (Final).
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/
052F, 2011.
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    There are several analyses that can be included in a Tier 3
screening assessment, depending upon the extent of refinement
warranted, including validating that the lakes are fishable, locating
residential/garden locations for urban and/or rural settings,
considering plume-rise to estimate emissions lost above the mixing
layer, and considering hourly effects of meteorology and plume rise on
chemical fate and transport (a time-series analysis). If necessary, the
EPA may further refine the screening assessment through a site-specific
assessment.
    In evaluating the potential multipathway risk from emissions of
lead compounds, rather than developing a screening threshold emission
rate, we compare maximum estimated chronic inhalation exposure
concentrations to the level of the current National Ambient Air Quality
Standard (NAAQS) for lead.\16\ Values below the level of the primary
(health-based) lead NAAQS are considered to have a low potential for
multipathway risk.
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    \16\ In doing so, the EPA notes that the legal standard for a
primary NAAQS--that a standard is requisite to protect public health
and provide an adequate margin of safety (CAA section 109(b))--
differs from the CAA section 112(f) standard (requiring, among other
things, that the standard provide an ``ample margin of safety to
protect public health''). However, the primary lead NAAQS is a
reasonable measure of determining risk acceptability (i.e., the
first step of the Benzene NESHAP analysis) since it is designed to
protect the most susceptible group in the human population--
children, including children living near major lead emitting
sources. 73 FR 67002/3; 73 FR 67000/3; 73 FR 67005/1. In addition,
applying the level of the primary lead NAAQS at the risk
acceptability step is conservative, since that primary lead NAAQS
reflects an adequate margin of safety.
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    For further information on the multipathway assessment approach,
see the Residual Risk Assessment for the Paper and Other Web Coating
Source Category in Support of the 2019 Risk and Technology Review
Proposed Rule, which is available in the docket for this action (Docket
ID No. EPA-HQ-OAR-2018-0416).
5. How do we conduct the environmental risk screening assessment?
a. Adverse Environmental Effect, Environmental HAP, and Ecological
Benchmarks
    The EPA conducts a screening assessment to examine the potential
for an adverse environmental effect 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, POM, 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, are 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 Paper and Other Web Coating Source Category in
Support of the 2019 Risk and Technology Review Proposed Rule, which is
available in the docket for this action (Docket ID No. EPA-HQ-OAR-2018-
0416).
b. Environmental Risk Screening Methodology
    For the environmental risk screening assessment, the EPA first
determined whether any facilities in the POWC source category emitted
any of the environmental HAP. For the POWC source category, we
identified emissions of arsenic, cadmium compounds, mercury compounds,
POM, and lead. Because one or more of the environmental HAP evaluated
are emitted by at least one facility in the source category, we
proceeded to the second step of the evaluation.
c. PB-HAP Methodology
    The environmental screening assessment includes six PB-HAP, arsenic
compounds, cadmium compounds, dioxins/furans, POM, mercury (both
inorganic mercury and methyl mercury), and lead compounds. With the
exception of lead, the environmental risk screening assessment for PB-
HAP consists of three tiers. The first tier of the environmental risk
screening assessment uses the same health-protective conceptual model
that is used for the Tier 1 human health screening assessment. The POWC
source category only required the completion of Tier 1 for the
multipathway ecological screening assessment. TRIM.FaTE model
simulations were used to back-calculate Tier 1 screening threshold
emission rates. The screening threshold emission rates represent the
emission rate in tons of pollutant per year that results in media
concentrations at the facility that equal the relevant ecological
benchmark. To assess emissions from each facility in the category, the
reported emission rate for each PB-HAP was compared to the Tier 1
screening threshold emission rate for that PB-HAP for each assessment
endpoint and effect level. If emissions from a facility do not exceed
the Tier 1 screening threshold emission rate, the facility ``passes''
the screening assessment, and, therefore, is not evaluated further
under the screening approach. If emissions from a facility exceed the
Tier 1 screening threshold emission rate, we evaluate the facility
further in Tier 2.
    In Tier 2 of the environmental screening assessment, the screening
threshold emission rates are adjusted to

account for local meteorology and the actual location of lakes in the
vicinity of facilities that did not pass the Tier 1 screening
assessment. For soils, we evaluate the average soil concentration for
all soil parcels within a 7.5-km radius for each facility and PB-HAP.
For the water, sediment, and fish tissue concentrations, the highest
value for each facility for each pollutant is used. If emission
concentrations from a facility do not exceed the Tier 2 screening
threshold emission rate, the facility ``passes'' the screening
assessment and typically is not evaluated further. If emissions from a
facility exceed the Tier 2 screening threshold emission rate, we
evaluate the facility further in Tier 3.
    As in the multipathway human health risk assessment, in Tier 3 of
the environmental screening assessment, we examine the suitability of
the lakes around the facilities to support life and remove those that
are not suitable (e.g., lakes that have been filled in or are
industrial ponds), adjust emissions for plume-rise, and conduct hour-
by-hour time-series assessments. If these Tier 3 adjustments to the
screening threshold emission rates still indicate the potential for an
adverse environmental effect (i.e., facility emission rate exceeds the
screening threshold emission rate), we may elect to conduct a more
refined assessment using more site-specific information. If, after
additional refinement, the facility emission rate still exceeds the
screening threshold emission rate, the facility may have the potential
to cause an adverse environmental effect.
    To evaluate the potential for an adverse environmental effect from
lead, we compared the average modeled air concentrations (from HEM-3)
of lead around each facility in the source category to the level of the
secondary NAAQS for lead. The secondary lead NAAQS is a reasonable
means of evaluating environmental risk because it is set to provide
substantial protection against adverse welfare effects which can
include ``effects on soils, water, crops, vegetation, man-made
materials, animals, wildlife, weather, visibility and climate, damage
to and deterioration of property, and hazards to transportation, as
well as effects on economic values and on personal comfort and well-
being.''
d. Acid Gas Environmental Risk Methodology
    The environmental screening assessment for acid gases evaluates the
potential phytotoxicity and reduced productivity of plants due to
chronic exposure to HF and HCl. The environmental risk screening
methodology for acid gases is a single-tier screening assessment that
compares modeled ambient air concentrations (from AERMOD) to the
ecological benchmarks for each acid gas. To identify a potential
adverse environmental effect (as defined in section 112(a)(7) of the
CAA) from emissions of HF and HCl, we evaluate the following metrics:
The size of the modeled area around each facility that exceeds the
ecological benchmark for each acid gas, in acres and km\2\; the
percentage of the modeled area around each facility that exceeds the
ecological benchmark for each acid gas; and the area-weighted average
screening value around each facility (calculated by dividing the area-
weighted average concentration over the 50-km modeling domain by the
ecological benchmark for each acid gas). For further information on the
environmental screening assessment approach, see Appendix 9 of the
Residual Risk Assessment for the Paper and Other Web Coating Source
Category in Support of the Risk and Technology Review 2019 Proposed
Rule, which is available in the docket for this action (Docket ID No.
EPA-HQ-OAR-2018-0416).
6. How do 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 compiled from the 2014 NEI. The source category records
of that NEI dataset were removed, evaluated, and updated as described
in section II.C of this preamble: What data collection activities were
conducted to support this action? Once a quality assured source
category dataset was available, it was placed back with the remaining
records from the NEI for that facility. The facility-wide file was then
used to analyze risks due to the inhalation of HAP that are emitted
``facility-wide'' for the populations residing within 50 km of each
facility, consistent with the methods used for the source category
analysis described above. For these facility-wide risk analyses, the
modeled source category risks were compared to the facility-wide risks
to determine the portion of the facility-wide risks that could be
attributed to the source category addressed in this action. 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 Paper and Other Web Coating Source Category in
Support of the 2019 Risk and Technology Review Proposed Rule, available
through the docket for this action (Docket ID No. EPA-HQ-OAR-2018-
0416), 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 do 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
Paper and Other Web Coating Source Category in Support of the 2019 Risk
and Technology Review Proposed Rule, which is available in the docket
for this action (Docket ID No. EPA-HQ-OAR-2018-0416). 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 an emission adjustment factor
applied to the average annual hourly emission rates, which are intended
to account for emission fluctuations due to normal facility operations.
b. Uncertainties in Dispersion Modeling
    We recognize there is uncertainty in ambient concentration
estimates associated with any model, including the EPA's recommended
regulatory dispersion model, AERMOD. In using a model to estimate
ambient pollutant concentrations, the user chooses certain options to
apply. For RTR assessments, we select some model options that have the
potential to overestimate ambient air concentrations (e.g., not
including plume depletion or pollutant transformation). We select other
model options that have the potential to underestimate ambient impacts
(e.g., not including building downwash). Other options that we select
have the potential to either under- or overestimate ambient levels
(e.g., meteorology and receptor locations). On balance, considering the
directional nature of the uncertainties commonly present in ambient
concentrations estimated by dispersion models, the approach we apply in
the RTR assessments should yield unbiased estimates of ambient HAP
concentrations. We also note that the selection of meteorology dataset
location could have an impact on the risk estimates. As we continue to
update and expand our library of meteorological station data used in
our risk assessments, we expect to reduce this variability.
c. Uncertainties in Inhalation Exposure Assessment
    Although every effort is made to identify all of the relevant
facilities and emission points, as well as to develop accurate
estimates of the annual emission rates for all relevant HAP, the
uncertainties in our emission inventory likely dominate the
uncertainties in the exposure assessment. Some uncertainties in our
exposure assessment include human mobility, using the centroid of each
census block, assuming lifetime exposure, and assuming only outdoor
exposures. For most of these factors, there is neither an under nor
overestimate when looking at the maximum individual risk 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 Guidelines for Carcinogen Risk Assessment;
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'' (the EPA's 2005
Guidelines for Carcinogen Risk Assessment, page 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.\17\
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). In some circumstances, the true risk could be as low
as zero; however, in other circumstances the risk could be greater.\18\
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,\19\ 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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    \17\ IRIS glossary (https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&glossaryName=IRIS%20Glossary).
    \18\ 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.
    \19\ See A Review of the Reference Dose and Reference
Concentration Processes, U.S. EPA, December 2002, and Methods for
Derivation of Inhalation Reference Concentrations and Application of
Inhalation Dosimetry, U.S. EPA, 1994.
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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.
    Although we make every effort to identify appropriate human health
effect dose-response values for all pollutants emitted by the sources
in this risk assessment, some HAP emitted by this source category are
lacking dose-response assessments. Accordingly, these pollutants cannot
be included in the quantitative risk assessment, which could result in
quantitative estimates understating HAP risk. To help to alleviate this
potential underestimate, where we conclude similarity with a HAP for
which a dose-response value is

available, we use that value as a surrogate for the assessment of the
HAP for which no value is available. To the extent use of surrogates
indicates appreciable risk, we may identify a need to increase priority
for an IRIS assessment for that substance. We additionally note that,
generally speaking, HAP of greatest concern due to environmental
exposures and hazard are those for which dose-response assessments have
been performed, reducing the likelihood of understating risk. Further,
HAP not included in the quantitative assessment are assessed
qualitatively and considered in the risk characterization that informs
the risk management decisions, including consideration of HAP
reductions achieved by various control options.
    For a group of compounds that are unspeciated (e.g., glycol
ethers), we conservatively use the most protective dose-response value
of an individual compound in that group to estimate risk. Similarly,
for an individual compound in a group (e.g., ethylene glycol diethyl
ether) that does not have a specified dose-response value, we also
apply the most protective dose-response value from the other compounds
in the group to estimate risk.
e. Uncertainties in Acute Inhalation Screening Assessments
    In addition to the uncertainties highlighted above, there are
several factors specific to the acute exposure assessment that the EPA
conducts as part of the risk review under section 112 of the CAA. The
accuracy of an acute inhalation exposure assessment depends on the
simultaneous occurrence of independent factors that may vary greatly,
such as hourly emissions rates, meteorology, and the presence of a
person. In the acute screening assessment that we conduct under the RTR
program, we assume that peak emissions from the source category and
reasonable worst-case air dispersion conditions (i.e., 99th percentile)
co-occur. We then include the additional assumption that a person is
located at this point at the same time. Together, these assumptions
represent a reasonable worst-case actual exposure scenario. In most
cases, it is unlikely that a person would be located at the point of
maximum exposure during the time when peak emissions and reasonable
worst-case air dispersion conditions occur simultaneously.
f. Uncertainties in the Multipathway and Environmental Risk Screening
Assessments
    For each source category, we generally rely on site-specific levels
of PB-HAP or environmental HAP emissions to determine whether a refined
assessment of the impacts from multipathway exposures is necessary or
whether it is necessary to perform an environmental screening
assessment. This determination is based on the results of a three-
tiered screening assessment that relies on the outputs from models--
TRIM.FaTE and AERMOD--that estimate environmental pollutant
concentrations and human exposures for five PB-HAP (dioxins, POM,
mercury, cadmium, and arsenic) and two acid gases (HF and HCl). For
lead, we use AERMOD to determine ambient air concentrations, which are
then compared to the secondary NAAQS standard for lead. Two important
types of uncertainty associated with the use of these models in RTR
risk assessments and inherent to any assessment that relies on
environmental modeling are model uncertainty and input uncertainty.\20\
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    \20\ In the context of this discussion, the term ``uncertainty''
as it pertains to exposure and risk encompasses both variability in
the range of expected inputs and screening results due to existing
spatial, temporal, and other factors, as well as uncertainty in
being able to accurately estimate the true result.
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    Model uncertainty concerns whether the model adequately represents
the actual processes (e.g., movement and accumulation) that might occur
in the environment. For example, does the model adequately describe the
movement of a pollutant through the soil? This type of uncertainty is
difficult to quantify. However, based on feedback received from
previous EPA SAB reviews and other reviews, we are confident that the
models used in the screening assessments are appropriate and state-of-
the-art for the multipathway and environmental screening risk
assessments conducted in support of RTR.
    Input uncertainty is concerned with how accurately the models have
been configured and parameterized for the assessment at hand. For Tier
1 of the multipathway and environmental screening assessments, we
configured the models to avoid underestimating exposure and risk. This
was accomplished by selecting upper-end values from nationally
representative datasets for the more influential parameters in the
environmental model, including selection and spatial configuration of
the area of interest, lake location and size, meteorology, surface
water, soil characteristics, and structure of the aquatic food web. We
also assume an ingestion exposure scenario and values for human
exposure factors that represent reasonable maximum exposures.
    In Tier 2 of the multipathway and environmental screening
assessments, we refine the model inputs to account for meteorological
patterns in the vicinity of the facility versus using upper-end
national values, and we identify the actual location of lakes near the
facility rather than the default lake location that we apply in Tier 1.
By refining the screening approach in Tier 2 to account for local
geographical and meteorological data, we decrease the likelihood that
concentrations in environmental media are overestimated, thereby
increasing the usefulness of the screening assessment. In Tier 3 of the
screening assessments, we refine the model inputs again to account for
hour-by-hour plume rise and the height of the mixing layer. We can also
use those hour-by-hour meteorological data in a TRIM.FaTE run using the
screening configuration corresponding to the lake location. These
refinements produce a more accurate estimate of chemical concentrations
in the media of interest, thereby reducing the uncertainty with those
estimates. The assumptions and the associated uncertainties regarding
the selected ingestion exposure scenario are the same for all three
tiers.
    For the environmental screening assessment for acid gases, we
employ a single-tiered approach. We use the modeled air concentrations
and compare those with ecological benchmarks.
    For all tiers of the multipathway and environmental screening
assessments, our approach to addressing model input uncertainty is
generally cautious. We choose model inputs from the upper end of the
range of possible values for the influential parameters used in the
models, and we assume that the exposed individual exhibits ingestion
behavior that would lead to a high total exposure. This approach
reduces the likelihood of not identifying high risks for adverse
impacts.
    Despite the uncertainties, when individual pollutants or facilities
do not exceed screening threshold emission rates (i.e., screen out), we
are confident that the potential for adverse multipathway impacts on
human health is very low. On the other hand, when individual pollutants
or facilities do exceed screening threshold emission rates, it does not
mean that impacts are significant, only that we cannot rule out that
possibility and that a refined assessment for the site might be
necessary to obtain a more accurate risk characterization for the
source category.
    The EPA evaluates the following HAP in the multipathway and/or

environmental risk screening assessments, where applicable: Arsenic,
cadmium, dioxins/furans, lead, mercury (both inorganic and methyl
mercury), POM, HCl, and HF. These HAP represent pollutants that can
cause adverse impacts either through direct exposure to HAP in the air
or through exposure to HAP that are deposited from the air onto soils
and surface waters and then through the environment into the food web.
These HAP represent those HAP for which we can conduct a meaningful
multipathway or environmental screening risk assessment. For other HAP
not included in our screening assessments, the model has not been
parameterized such that it can be used for that purpose. In some cases,
depending on the HAP, we may not have appropriate multipathway models
that allow us to predict the concentration of that pollutant. The EPA
acknowledges that other HAP beyond these that we are evaluating may
have the potential to cause adverse effects and, therefore, the EPA may
evaluate other relevant HAP in the future, as modeling science and
resources allow.

IV. Analytical Results and Proposed Decisions

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

1. Chronic Inhalation Risk Assessment Results
    Table 2 of this preamble provides an overall summary of the
inhalation risk results. The results of the chronic baseline inhalation
cancer risk assessment indicate the maximum individual lifetime cancer
risk (MIR) posed by the POWC source category was estimated to be 6-in-1
million based on actual emissions and 7-in-1 million based on allowable
emissions. The risk driver is formaldehyde emissions from web coating
processes. The total estimated cancer incidence from POWC emission
sources based on actual emission levels is 0.005 excess cancer cases
per year, or one case in every 200 years, with emissions from web
coating operations representing 80 percent of the modeled cancer
incidence. Emissions of formaldehyde contributed 90 percent to this
cancer incidence. Based upon actual emissions, 4,300 people were
exposed to cancer risks greater than or equal to 1-in-1 million
compared to 9,900 people from allowable emissions.
    The maximum chronic noncancer HI (TOSHI) values for the source
category, based on actual and allowable emissions, were estimated to be
less than 1 (0.8 based on allowable emissions). Based on actual and
allowable emissions, respiratory risks were driven by acrylic acid
emissions from web coating processes.

                                                  Table 2--POWC Inhalation Risk Assessment Results \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Maximum        Estimated       Estimated
                                                            individual     population at   annual cancer      Maximum
             Risk assessment                 Number of      cancer risk   increased risk     incidence        chronic         Maximum screening acute
                                          facilities \2\  (in 1 million)  of cancer >= 1-   (cases per       noncancer           noncancer HQ \5\
                                                                \3\        in-1 million        year)         TOSHI \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Baseline Actual Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category.........................             160               6           4,300           0.005             0.6  3 (REL).
Facility-Wide \6\.......................             168             300         161,000            0.03              30
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Baseline Allowable Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category.........................             160               7           9,900           0.007             0.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Based on actual and allowable emissions.
\2\ As discussed in section III.C.1 of this preamble, 168 facilities were identified as subject to the POWC NESHAP. Additionally, eight facilities did
  not emit any HAP from their POWC processes, resulting in 160 facilities being modeled for the source-category risk assessment and 168 modeled for the
  facility-wide risk assessment.
\3\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category except for risks from facility-wide emissions.
\4\ Maximum TOSHI. The target organ with the highest TOSHI for the POWC source category is the respiratory system.
\5\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. HQ values
  shown use the lowest available acute threshold value, which in most cases is the REL. The risk driver for acute risks were emissions of formaldehyde
  from web coating processes and affiliated operations.
\6\ The facility-wide risk value estimate of 300-in-1 million and the HI equal to 30 was from trichloroethylene (TCE) emissions from a production
  process outside the source category.

2. Screening Level Acute Risk Assessment Results
    Reasonable worst-case acute HQs were calculated for every HAP for
which there is an acute health benchmark using actual emissions. The
maximum refined off-site acute noncancer HQ values for the source
category were equal to 3 from formaldehyde emissions and 3 from
diethylene glycol monoethyl ether (DGME) emissions based on the acute
(1-hour) REL for these pollutants. The formaldehyde and DGME maximum HQ
values were at separate facilities and no facilities have an HQ based
on AEGL or ERPG greater than 1. No other acute health benchmarks were
exceeded for this source category. For DGME, no other acute dose
benchmark was available besides the 1-hour REL. The acute risks for
these pollutants were from web coating processes with an acute hourly
multiplier of 10 times the annual average hourly emissions rate.
3. Multipathway Risk Screening Results
    Results of the worst-case Tier 1 screening analysis indicate that
PB-HAP emissions (based on estimates of actual emissions) from the
source category did not exceed the screening value of 1 for any
carcinogenic PB-HAP (arsenic and POM compounds). Emissions of dioxins
were not reported by any facilities within the source category.
    The Tier 1 screening analysis for the noncarcinogenic PB-HAP
(cadmium and mercury) was below a screening value of 1. Further
screening or multipathway analysis was not required for any of the
reported PB-HAP based upon our Analytical Procedures discussed in
section III.C.4 of this preamble. Based on this upperbound Tier 1
screening assessment for carcinogens (arsenic and POM) and non-
carcinogens (cadmium and mercury), the emission rates for all
facilities and scenarios were below levels of concern.
    In evaluating the potential for multipathway effects from emissions
of

lead, we compared modeled annual lead concentrations to the secondary
NAAQS for lead (0.15 [mu]g/m\3\). The highest annual average lead
concentration, of 0.001 [mu]g/m\3\, is below the NAAQS for lead,
indicating a low potential for multipathway impacts of concern due to
lead.
4. Environmental Risk Screening Results
    We conducted an environmental risk screening assessment for the
POWC source category for the following pollutants: Arsenic, cadmium,
lead, mercury (methyl mercury and mercuric chloride) and POM.
    In the Tier 1 screening analysis for PB-HAP (other than lead, which
was evaluated differently), arsenic, cadmium, mercury (methyl mercury
and mercuric chloride), and POM emissions had no Tier 1 exceedances for
any ecological benchmark.
    For lead, we did not estimate any exceedances of the secondary lead
NAAQS. Based on the results of the environmental risk screening
analysis, we do not expect an adverse environmental effect as a result
of HAP emissions from this source category.
5. Facility-Wide Risk Results
    Results of the assessment of facility-wide emissions indicate that
of the 168 facilities, 42 facilities have a facility-wide MIR cancer
risk greater than 1-in-1 million. The maximum facility-wide cancer risk
is 300-in-1 million, driven by TCE emissions from emissions outside the
source category. The total estimated cancer incidence from the whole
facility is 0.03 excess cancer cases per year, or one case in every 33
years. Approximately 161,000 people are estimated to have cancer risks
greater than or equal to 1-in-1 million with approximately 30 people
with excess cancer risks greater than or equal to 100-in-1 million. The
maximum facility-wide chronic noncancer TOSHI is estimated to be equal
to 30, driven by emissions of TCE from non-category emission 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 risk 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 risk from the POWC source category
across different demographic groups within the populations living near
facilities.\21\
---------------------------------------------------------------------------

    \21\ Demographic groups included in the analysis are: White,
African American, Native American, other races and multiracial,
Hispanic or Latino, children 17 years of age and under, adults 18 to
64 years of age, adults 65 years of age and over, adults without a
high school diploma, people living below the poverty level, people
living two times the poverty level, and linguistically isolated
people.
---------------------------------------------------------------------------

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

                                 Table 3--POWC Demographic Risk Analysis Results
                         [POWC: Demographic assessment results--50 km study area radius]
----------------------------------------------------------------------------------------------------------------
                                                                                Population
                                                                                with cancer
                                                                                risk greater     Population
                                                                                than or equal      with HI
                                                                                to 1-in-1    greater than 1
                                                                                million
----------------------------------------------------------------------------------------------------------------
                                                                    Nationwide            Source category
                                                                 -----------------------------------------------
Total Population................................................     317,746,049           4,331               0
                                                                 -----------------------------------------------
                                                                           White and Minority by Percent
                                                                 -----------------------------------------------
White...........................................................              62              86               0
Minority........................................................              38              14               0
                                                                 -----------------------------------------------
                                                                                Minority by Percent
                                                                 -----------------------------------------------
African American................................................              12               8               0
Native American.................................................             0.8             0.2               0
Hispanic or Latino (includes white and nonwhite)................              18               3               0
Other and Multiracial...........................................               7               3               0
                                                                 -----------------------------------------------
                                                                                Income by Percent
                                                                 -----------------------------------------------
Below Poverty Level.............................................              14              17               0
Above Poverty Level.............................................              86              83               0
                                                                 -----------------------------------------------
                                                                               Education by Percent
                                                                 -----------------------------------------------
Over 25 and without a High School Diploma.......................              14              14               0
Over 25 and with a High School Diploma..........................              86              86               0
                                                                 -----------------------------------------------
                                                                        Linguistically Isolated by Percent
                                                                 -----------------------------------------------
Linguistically Isolated.........................................               6               1               0
----------------------------------------------------------------------------------------------------------------

    The results of the POWC source category demographic analysis
indicate that emissions from the source category expose approximately
4,300 people to a cancer risk at or above 1-in-1 million and zero
people to a chronic noncancer TOSHI greater than 1. The percentages of
the at-risk population in the demographic groups, White and people
below poverty level, are greater than their respective nationwide
percentages.
    The methodology and the results of the demographic analysis are
presented in a technical report, Risk and Technology Review--Analysis
of Demographic Factors for Populations Living Near Paper and Other Web
Coating Facilities, available in the docket for this action (Docket ID
No. EPA-HQ-OAR-2018-0416).

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

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.' '' See 54 FR 38045, September 14, 1989.
    In this proposal, the EPA estimated risks based on actual and
allowable emissions for 160 facilities in the POWC source category
(i.e., as discussed in section III.C.1 of this preamble, 168 facilities
were determined to be subject to the POWC NESHAP, however eight
facilities did not have POWC source category emissions, therefore, 160
facilities were modeled for source-category risks) In determining
whether risks are acceptable, the EPA considered all available health
information and risk estimation uncertainty, as described above. Table
2 summarizes the risk assessment results from the POWC source category.
The risk results for the POWC source category indicate that both the
actual and allowable inhalation cancer risks to the individual most
exposed are at least 14 times below the presumptive limit of
acceptability of 100-in-1 million (i.e., 1-in-10 thousand). The
residual risk assessment for the POWC source category \22\ estimated
cancer incidence rate at 0.005 cases per year based on actual
emissions. Approximately 4,300 people are exposed to a cancer risk
equal to or above 1-in-1 million from the source category based upon
actual emissions from 11 facilities.
---------------------------------------------------------------------------

    \22\ Residual Risk Assessment for the Paper and Other Web
Coating Source Category in Support of the 2019 Risk and Technology
Review Proposed Rule, EPA-HQ-OAR-2018-0416.
---------------------------------------------------------------------------

    The maximum chronic noncancer TOSHI due to inhalation exposures is
less than 1 for actual and allowable emissions. The results of the
acute screening analysis showed that acute risks were below a level of
concern for the source category considering the conservative
assumptions used that err on the side of overestimating acute risk (as
discussed in section III.C.7.e of this preamble). Multipathway screen
values were below a level of concern for both carcinogenic and non-
carcinogenic PB-HAP as well as emissions of lead compounds.
    Maximum cancer and noncancer risks due to ingestion exposures using
health-protective risk screening assumptions are below the presumptive
limit of acceptability. The maximum estimated excess cancer risk is
below 1-in-1 million and the maximum noncancer HQ for mercury is less
than 1 based upon the Tier 1 farmer/fisher exposure scenario.
    Taking into account all of this information, the EPA proposes that
the risks remaining after implementation of the existing MACT standard
for the POWC source category are acceptable.
2. Ample Margin of Safety Analysis
    Although the EPA is proposing that the risks from this source
category are acceptable for both inhalation and multipathway, risk
estimates for approximately 4,300 people in the exposed population are
above 1-in-1 million, caused primarily by formaldehyde and acetaldehyde
emissions from 11 POWC facilities. The maximum acute risk is an HQ of 3
from two facilities, one based on DGME emissions and the second,
formaldehyde emissions. As a result, we further considered whether the