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EO12866_ChemicalRTR2060-AR02Proposal_20111103

6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA–HQ–OAR–2011–0435; FRL- ]

RIN 2060–AR02

National Emission Standards for Hazardous Air Pollutant 

Emissions: Group IV Polymers and Resins; Pesticide Active 

Ingredient Production; and Polyether Polyols Production 

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: The EPA is proposing amendments to three national 

emission standards for hazardous air pollutants (NESHAP): 

National Emission Standards for Hazardous Air Pollutant 

Emissions: Group IV Polymers and Resins; NESHAP for Pesticide 

Active Ingredient Production; and NESHAP for Polyether Polyols 

Production. For all three of these NESHAP rules, the EPA is 

proposing decisions concerning the following: residual risk 

reviews; technology reviews; emissions during periods of 

startup, shutdown and malfunction; standards for previously 

unregulated hazardous air pollutant emissions; and electronic 

reporting of performance test results.

DATES: Comments. Comments must be received on or before [INSERT 

DATE 60 DAYS FROM DATE OF PUBLICATION IN THE FEDERAL REGISTER]. 

Under the Paperwork Reduction Act, comments on the information 
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collection provisions are best assured of having full effect if 

the Office of Management and Budget (OMB) receives a copy of 

your comments on or before [INSERT DATE 30 DAYS FROM DATE OF 

PUBLICATION IN THE FEDERAL REGISTER].

Public Hearing. If anyone contacts the EPA requesting to 

speak at a public hearing by [INSERT DATE 10 DAYS FROM DATE OF 

PUBLICATION IN THE FEDERAL REGISTER], a public hearing will be 

held on [INSERT DATE 30 DAYS FROM DATE OF PUBLICATION IN THE 

FEDERAL REGISTER].

ADDRESSES: Comments. Submit your comments, identified by Docket 

ID No. EPA-HQ-OAR-2011-0435, by one of the following methods:

 www.regulations.gov: Follow the on-line instructions for 

submitting comments.

 Email: a-and-r-docket@epa.gov. Attention Docket ID No. EPAHQ-OAR-2011-0435.

 Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR2011-0435.

 Mail: U.S. Postal Service, send comments to: EPA Docket 

Center, EPA West (Air Docket), Attention Docket ID No. EPAHQ-OAR-2011-0435, U.S. Environmental Protection Agency, 

Mailcode: 2822T, 1200 Pennsylvania Ave., NW, Washington, DC 

20460. Please include a total of two copies. In addition, 

please mail a copy of your comments on the information 
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collection provisions to the Office of Information and 

Regulatory Affairs, Office of Management and Budget (OMB), 

Attn: Desk Officer for EPA, 725 17th Street, NW, Washington, 

DC 20503. 

 Hand Delivery: U.S. Environmental Protection Agency, EPA 

West (Air Docket), Room 3334, 1301 Constitution Ave., NW, 

Washington, DC 20004. Attention Docket ID No. EPA-HQ-OAR2011-0435. Such deliveries are only accepted during the 

Docket’s normal hours of operation, and special 

arrangements should be made for deliveries of boxed 

information.

Instructions. Direct your comments to Docket ID No. EPA-HQOAR-2011-0435. 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 www.regulations.gov, including any 

personal information provided, unless the comment includes 

information claimed to be confidential business information 

(CBI) or other information whose disclosure is restricted by 

statute. Do not submit information that you consider to be CBI 

or otherwise protected through www.regulations.gov or email. The 

www.regulations.gov website is an “anonymous access” system, 

which means the EPA will not know your identity or contact 

information unless you provide it in the body of your comment. 

If you send an email comment directly to the EPA without going 
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through www.regulations.gov, your email address will be 

automatically captured and included as part of the comment that 

is placed in the public docket and made available on the 

Internet. If you submit an electronic comment, the EPA 

recommends that you include your name and other contact 

information in the body of your comment and with any disk or CDROM 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 avoid the use of special characters, any form of 

encryption, and be free of any defects or viruses. For 

additional information about the EPA’s public docket, visit the 

EPA Docket Center homepage at 

http://www.epa.gov/epahome/dockets.htm.

Docket. The EPA has established a docket for this 

rulemaking under Docket ID No. EPA-HQ-OAR-2011-0435. All 

documents in the docket are listed in the www.regulations.gov

index. Although listed in the index, some information is not 

publicly available, e.g., CBI or other information whose 

disclosure is restricted by statute. Certain other material, 

such as copyrighted material, is not placed on the Internet and 

will be publicly available only in hard copy. Publicly available 

docket materials are available either electronically in 

www.regulations.gov or in hard copy at the EPA Docket Center, 
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EPA West, Room 3334, 1301 Constitution Ave., NW, Washington, DC. 

The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., 

Monday through Friday, excluding legal holidays. The telephone 

number for the Public Reading Room is (202) 566-1744, and the 

telephone number for the EPA Docket Center is (202) 566-1742.

Public Hearing. If a public hearing is held, it will begin 

at 10 a.m. on [INSERT DATE 30 DAYS FROM DATE OF PUBLICATION IN 

THE FEDERAL REGISTER] and will be held at the EPA’s campus in 

Research Triangle Park, North Carolina, or at an alternate 

facility nearby. Persons interested in presenting oral testimony 

or inquiring as to whether a public hearing is to be held should 

contact Ms. Mary Tom Kissell, Sector Policies and Programs 

Division (E143-01), Office of Air Quality Planning and 

Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, NC 27711, telephone number: (919) 541–4516. If a

public hearing will be held, a notification will be posted on 

the following website: http://www.epa.gov/ttn/oarpg/t3main.html.

FOR FURTHER INFORMATION CONTACT: For questions about this 

proposed action, contact Mr. Nick Parsons, Sector Policies and 

Programs Division (E143-01), Office of Air Quality Planning and 

Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, NC 27711; telephone number: (919) 541-5372; fax 

number: (919) 541-0246; email address: parsons.nick@epa.gov. For 

specific information regarding the risk modeling methodology, 
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contact Ms. Elaine Manning, Health and Environmental Impacts 

Division (C159-02), Office of Air Quality Planning and 

Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, NC 27711; telephone number: (919) 541-5499; fax 

number: (919) 541-0840; email address: manning.elaine@epa.gov. 

For information about the applicability of these three national 

emission standards for hazardous air pollutants (NESHAP) to a 

particular entity, contact the appropriate person listed in 

Table 1 to this preamble.

Table 1. List of the EPA Contacts for the Rules Addressed in 

This Proposed Action

NESHAP OECA Contact1 OAQPS Contact2

NESHAP for 

Group IV 

Polymers and 

Resins 

Tavara Culpepper

(202) 564-0902

culpepper.tavara@epa.gov

Nick Parsons

(919) 541-5372

parsons.nick@epa.gov

NESHAP for 

Pesticide 

Active 

Ingredient 

Production 

Tavara Culpepper

(202) 564-0902

culpepper.tavara@epa.gov

Andrea Siefers

(919) 541-1185

siefers.andrea@epa.gov

NESHAP for 

Polyether 

Polyols 

Tavara Culpepper

(202) 564-0902

culpepper.tavara@epa.gov

Andrea Siefers

(919) 541-1185

siefers.andrea@epa.gov

1 OECA stands for the EPA’s Office of Enforcement and Compliance Assurance.

2 OAQPS stands for the EPA’s Office of Air Quality Planning and Standards.

SUPPLEMENTARY INFORMATION:

Preamble Acronyms and Abbreviations

Several acronyms and terms used to describe industrial 

processes, data inventories and risk modeling are included in 
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this preamble. While this may not be an exhaustive list, to ease 

the reading of this preamble and for reference purposes, the 

following terms and acronyms are defined here:

ABS - Acrylonitrile Butadiene Styrene Resin

ADAF - Age-Dependent Adjustment Factors

AERMOD – Air Dispersion Model used by the HEM-3 Model

AEGL - Acute Exposure Guideline Levels 

ASA/AMSAN - Acrylonitrile Styrene Resin/Alpha Methyl

Styrene Acrylonitrile Resin

BACT - Best Available Control Technology 

CalEPA – California Environmental Protection Agency

CAA – Clean Air Act

CBI – Confidential Business Information

CDX - Central Data Exchange 

CEDRI - Compliance and Emissions Data Reporting Interface

CFR – Code of Federal Regulations

EPA – Environmental Protection Agency

ERPG - Emergency Response Planning Guidelines 

ERT - Electronic Reporting Tool 

HAP – Hazardous Air Pollutants

HCl – Hydrochloric Acid

HI – Hazard Index

HEM-3 – Human Exposure Model, Version 3

HON – National Emission Standards for Organic Hazardous Air 
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Pollutants From the Synthetic Organic Chemical Manufacturing 

Industry

HQ – Hazard Quotient

ICR – Information Collection Request

IRIS – Integrated Risk Information System

km – Kilometer

LAER - Lowest Achievable Emission Rate

LDAR – Leak Detection and Repair

MACT – Maximum Achievable Control Technology

MACT Code – Code within the NEI used to Identify Processes 

Included in a Source Category

MBS - Methyl Methacrylate Butadiene Styrene 

MIR – Maximum Individual Risk

NAAQS - National Ambient Air Quality Standards 

NAICS – North American Industry Classification System

NAS - National Academy of Sciences

NATA - National Air Toxics Assessment

NESHAP – National Emissions Standards for Hazardous Air 

Pollutants

NEI – National Emissions Inventory

NRC – National Research Council

NTTAA - National Technology Transfer and Advancement Act

OECA – Office of Enforcement and Compliance Assurance

OMB – Office of Management and Budget
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P&R IV - National Emission Standards for Hazardous Air 

Pollutant Emissions: Group IV Polymers and Resins

PAI - Pesticide Active Ingredient 

PB-HAP – Hazardous Air Pollutants known to be Persistent 

and Bio-Accumulative in the Environment

PCB - Polychlorinated Biphenyls

PCCT – Process Contact Cooling Tower

PEPO - Polyether Polyols 

PET - Poly (Ethylene Terephthalate) Resin

PM – Particulate Matter

POM – Polycyclic Organic Matter

PRD – Pressure Relief Device

RACT - Reasonably Available Control Technology

RBLC - RACT/BACT/LAER Clearinghouse

REL - CalEPA Chronic Reference Exposure Level

RFA - Regulatory Flexibility Act

RfC – Reference Concentration

RfD – Reference Dose

RTR – Residual Risk and Technology Review

SAB - Science Advisory Board

SAN - Styrene Acrylonitrile Resin 

SCC – Source Classification Codes

SOCMI - Synthetic Organic Chemical Manufacturing Industry 

SOP – Standard Operating Procedures
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SSM – Startup, Shutdown and Malfunction

THF - Tetrahydrofuran

TOSHI – Target Organ-Specific Hazard Index

TPA - Terephthalic Acid

tpy – Tons Per Year

TRIM – Total Risk Integrated Modeling System

TRIM.FaTE - EPA’s Total Risk Integrated Methodology Fate, 

Transport and Ecological Exposure Model

TTN – Technology Transfer Network

UF - Uncertainty Factor

UMRA - Unfunded Mandates Reform Act

URE – Unit Risk Estimate

VOC – Volatile Organic Compounds

WWW – World Wide Web

Organization of this Document. The information in this preamble 

is organized as follows: 

I. General Information

A. What is the statutory authority for this action?

B. Does this action apply to me?

C. Where can I get a copy of this document and other 

related information?

D. What should I consider as I prepare my comments for the 

EPA?

II. Background

A. What are the source categories addressed by this action?

B. What data collection activities were conducted to 

support this proposed action?

III. Analyses Performed

A. How did we address unregulated emissions sources?

B. How did we estimate risks posed by the source category?

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

D. How did we perform the technology review?

E. What other issues are we addressing in this proposal?

IV. Analytical Results and Proposed Decisions for the Group IV 

Polymers and Resins Source Categories

A. Acrylonitrile butadiene styrene resin (ABS)

B. Styrene acrylonitrile resin (SAN)

C. Methyl methacrylate butadiene styrene (MBS)

D. Polystyrene resin

E. Poly (ethylene terephthalate) resin (PET)

V. Analytical Results and Proposed Decisions for Pesticide 

Active Ingredient Production

A. What are the results of the risk assessments?

B. What are the results of the technology review?

C. What other actions are we proposing?

VI. Analytical Results and Proposed Decisions for Polyether 

Polyols Production

A. What are the results of the risk assessments?

B. What are the results of the technology review?

C. What other actions are we proposing?

VII. Compliance Dates

VIII. 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?

IX. Request for Comments

X. Submitting Data Corrections

XI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review 

and Executive Order 13563: Improving Regulation and Regulatory 

Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination 

with Indian Tribal Governments

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks

H. Executive Order 13211: Actions Concerning Regulations 

That Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations
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A red-line version of the regulatory language that incorporates 

the proposed changes in this action is available in the docket.

I. General Information

A. What is the statutory authority for this action?

Section 112 of the Clean Air Act (CAA) establishes a twostage regulatory process to address emissions of hazardous air 

pollutants (HAP) from stationary sources. In the first stage, 

after the EPA has identified categories of sources emitting one 

or more of the HAP listed in CAA section 112(b), CAA section 

112(d) calls for us to promulgate technology-based NESHAP for 

those sources. “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. For major sources, 

these technology-based standards must reflect the maximum degree 

of emissions reductions of HAP achievable (after considering 

cost, energy requirements and non-air quality health and 

environmental impacts) and are commonly referred to as maximum 

achievable control technology (MACT) standards.

MACT standards must require the maximum degree of emissions 

reduction achievable through the application of measures, 

processes, methods, systems or techniques, including, but not 

limited to, measures that: (1) reduce the volume of or eliminate 

pollutants through process changes, substitution of materials or 
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other modifications; (2) enclose systems or processes to 

eliminate emissions; (3) capture or treat pollutants when 

released from a process, stack, storage or fugitive emissions 

point; (4) are design, equipment, work practice or operational 

standards (including requirements for operator training or 

certification); or (5) are a combination of the above. CAA 

section 112(d)(2)(A)-(E). The MACT standards may take the form 

of design, equipment, work practice or operational standards 

where the EPA first determines either that: (1) a pollutant 

cannot be emitted through a conveyance designed and constructed 

to emit or capture the pollutants or that any requirement for, 

or use of, such a conveyance would be inconsistent with law; or 

(2) the application of measurement methodology to a particular 

class of sources is not practicable due to technological and 

economic limitations. CAA sections 112(h)(1)-(2).

The MACT “floor” is the minimum control level allowed for 

MACT standards promulgated under CAA section 112(d)(3) and may 

not be based on cost considerations. For new sources, the MACT 

floor cannot be less stringent than the emissions control that 

is achieved in practice by the best-controlled similar source. 

The MACT floors for existing sources can be less stringent than 

floors for new sources, but they cannot be less stringent than 

the average emissions limitation achieved by the best-performing 

12 percent of existing sources in the category or subcategory 
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(or the best-performing five sources for categories or 

subcategories with fewer than 30 sources). In developing MACT 

standards, we must also consider control options that are more 

stringent than the floor. We may establish standards more 

stringent than the floor based on considerations of the cost of 

achieving the emissions reductions, any non-air quality health 

and environmental impacts and energy requirements.

The EPA is then required to review these technology-based 

standards and revise them “as necessary (taking into account 

developments in practices, processes, and control technologies)” 

no less frequently than every 8 years, under CAA section 

112(d)(6). In conducting this review, the EPA is not obliged to 

completely recalculate the prior MACT determination. NRDC v. 

EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008). 

The second stage in standard-setting focuses on reducing 

any remaining (i.e., “residual”) risk according to CAA section 

112(f). This provision requires, first, that the EPA prepare a 

Report to Congress discussing (among other things) methods of 

calculating the risks posed (or potentially posed) by sources 

after implementation of the MACT standards, the public health 

significance of those risks and the EPA’s recommendations as to 

legislation regarding such remaining risk. The EPA prepared and 

submitted this report (Residual Risk Report to Congress, EPA–

453/R–99–001) in March 1999. Congress did not act in response to 
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the report, thereby triggering the EPA’s obligation under CAA 

section 112(f)(2) to analyze and address residual risk.

CAA section 112(f)(2) requires the EPA to determine, for 

source categories subject to certain MACT standards, whether 

those emissions standards provide an ample margin of safety to 

protect public health. If the MACT standards for HAP “classified 

as a known, probable, or possible human carcinogen do not reduce 

lifetime excess cancer risks to the individual most exposed to 

emissions from a source in the category or subcategory to less 

than one in one million,” the EPA must promulgate residual risk 

standards for the source category (or subcategory), as necessary 

to provide an ample margin of safety to protect public health. 

In doing so, the EPA may adopt standards equal to existing MACT 

standards if the EPA determines that the existing standards are 

sufficiently protective. NRDC v. EPA, 529 F.3d at 1083 (“If EPA 

determines that the existing technology-based standards provide 

an ‘ample margin of safety,’ then the agency is free to readopt 

those standards during the residual risk rulemaking.”). The EPA 

must also adopt more stringent standards, if necessary, to 

prevent an adverse environmental effect1 but must consider cost, 

 

1 “Adverse environmental effect” is defined in CAA section 

112(a)(7) as any significant and widespread adverse effect, 

which may be reasonably anticipated to wildlife, aquatic life or 

natural resources, including adverse impacts on populations of 

endangered or threatened species or significant degradation of 
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energy, safety and other relevant factors in doing so. 

Section 112(f)(2) of the CAA expressly preserves our use of 

the two-step process for developing standards to address any 

residual risk and our interpretation of “ample margin of safety” 

developed in the National 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 first step in 

this process is the determination of acceptable risk. The second 

step provides for an ample margin of safety to protect public 

health, which is the level at which the standards are to be set 

(unless an even more stringent standard is necessary to prevent, 

taking into consideration costs, energy, safety and other 

relevant factors, an adverse environmental effect).

The terms “individual most exposed,” “acceptable level” and 

“ample margin of safety” are not specifically defined in the 

CAA. However, CAA section 112(f)(2)(B) preserves the EPA’s 

interpretation set out in the Benzene NESHAP, and the United 

States Court of Appeals for the District of Columbia Circuit in 

NRDC v. EPA, 529 F.3d 1077, concluded that the EPA’s 

interpretation of subsection 112(f)(2) is a reasonable one. See 

 

environmental qualities over broad areas.
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NRDC v. EPA, 529 F.3d at 1083 (“[S]ubsection 112(f)(2)(B) 

expressly incorporates EPA’s interpretation of the Clean Air Act 

from the Benzene standard, complete with a citation to the 

Federal Register.”). See also, A Legislative History of the 

Clean Air Act Amendments of 1990, volume 1, p. 877 (Senate 

debate on Conference Report). We also notified Congress in the 

Residual Risk Report to Congress that we intended to use the 

Benzene NESHAP approach in making CAA section 112(f) residual 

risk determinations (EPA–453/R–99–001, p. ES–11).

In the Benzene NESHAP, we stated as an overall objective:

* * * in protecting public health with an ample margin of 

safety, we strive to provide maximum feasible protection 

against risks to health from hazardous air pollutants by 

(1) protecting the greatest number of persons possible to 

an individual lifetime risk level no higher than 

approximately 1-in-1 million; and (2) limiting to no higher 

than approximately 1-in-10 thousand [i.e., 100-in-1 

million] the estimated risk that a person living near a 

facility would have if he or she were exposed to the 

maximum pollutant concentrations for 70 years. 

The agency also stated that, “The EPA also considers 

incidence (the number of persons estimated to suffer cancer or 

other serious health effects as a result of exposure to a 

pollutant) to be an important measure of the health risk to the 

exposed population. Incidence measures the extent of health 

risks to the exposed population as a whole, by providing an 

estimate of the occurrence of cancer or other serious health 

effects in the exposed population.” The agency went on to 
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conclude that “estimated incidence would be weighed along with 

other health risk information in judging acceptability.” As 

explained more fully in our Residual Risk Report to Congress, 

the EPA does not define “rigid line[s] of acceptability,” but 

rather considers broad objectives to be weighed with a series of 

other health measures and factors (EPA–453/R–99–001, p. ES–11). 

The determination of what represents an “acceptable” risk is 

based on a judgment of “what risks are acceptable in the world 

in which we live,” (Residual Risk Report to Congress, p. 178, 

quoting NRDC v. EPA, 824 F.2d 1146, 1165 (D.C. Cir. 1987) (Vinyl 

Chloride Decision)) recognizing that our world is not risk-free.

In the Benzene NESHAP, we stated that the “EPA will 

generally presume that if the risk to [the maximum exposed] 

individual is no higher than approximately one in 10 thousand, 

that risk level is considered acceptable.” 54 FR 38045. We 

discussed the maximum individual lifetime cancer risk (or 

maximum individual risk (MIR)) as being “the estimated risk that 

a person living near a plant would have if he or she were 

exposed to the maximum pollutant concentrations for 70 years.” 

Id. We explained that this measure of risk “is an estimate of 

the upper bound of risk based on conservative assumptions, such 

as continuous exposure for 24 hours per day for 70 years.” Id. 

We acknowledge that maximum individual lifetime cancer risk 

“does not necessarily reflect the true risk, but displays a 
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conservative risk level which is an upper-bound that is unlikely 

to be exceeded.” Id.

Understanding that there are both benefits and limitations 

to using maximum individual lifetime cancer risk as a metric for 

determining acceptability, we acknowledged in the 1989 Benzene 

NESHAP that “consideration of maximum individual risk * * * must 

take into account the strengths and weaknesses of this measure 

of risk.” Id. Consequently, the presumptive risk level of 100 in 

one million (one in 10 thousand) “provides a benchmark for 

judging the acceptability of maximum individual lifetime cancer 

risk (MIR), but does not constitute a rigid line for making that 

determination.” Id. Further, in the Benzene NESHAP, we noted 

that, “Particular attention will also be accorded to the weight 

of evidence presented in the risk assessment of potential 

carcinogenicity or other health effects of a pollutant. While 

the same numerical risk may be estimated for an exposure to a 

pollutant judged to be a known human carcinogen, and to a 

pollutant considered a possible human carcinogen based on 

limited animal test data, the same weight cannot be accorded to 

both estimates. In considering the potential public health 

effects of the two pollutants, the Agency’s judgment on 

acceptability, including the MIR, will be influenced by the 

greater weight of evidence for the known human carcinogen.” Id. 

at 38046.
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The agency also explained in the 1989 Benzene NESHAP the 

following: “In establishing a presumption for MIR, rather than a 

rigid line for acceptability, the Agency intends to weigh it 

with a series of other health measures and factors. These 

include the overall incidence of cancer or other serious health 

effects within the exposed population, the numbers of persons 

exposed within each individual lifetime risk range and 

associated incidence within, typically, a 50-kilometer (km) 

exposure radius around facilities, the science policy 

assumptions and estimation uncertainties associated with the 

risk measures, weight of the scientific evidence for human 

health effects, other quantified or unquantified health effects, 

effects due to co-location of facilities, and co-emissions of 

pollutants.” Id. 

In some cases, these health measures and factors taken 

together may provide a more realistic description of the 

magnitude of risk in the exposed population than that provided 

by maximum individual lifetime cancer risk alone. As explained 

in the Benzene NESHAP, “[e]ven though the risks judged 

‘acceptable’ by EPA in the first step of the Vinyl Chloride 

inquiry are already low, the second step of the inquiry, 

determining an ‘ample margin of safety,’ again includes 

consideration of all of the health factors, and whether to 

reduce the risks even further. [...] Beyond that information, 
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additional factors relating to the appropriate level of control 

will also be considered, including costs and economic impacts of 

controls, technological feasibility, uncertainties and any other 

relevant factors. Considering all of these factors, the agency 

will establish the standard at a level that provides an ample 

margin of safety to protect the public health as required by CAA 

section 112.”

In NRDC v. EPA, 529 F.3d 1077, 1082 (D.C. Cir. 2008), the 

Court of Appeals held that CAA section 112(f)(2) “incorporates 

EPA’s ‘interpretation’ of the Clean Air Act from the Benzene 

Standard, and the text of this provision draws no distinction 

between carcinogens and non-carcinogens.” Additionally, the 

Court held there is nothing on the face of the statute that 

limits the Agency’s section 112(f) assessment of risk to 

carcinogens. Id. at 1081 – 82. In the NRDC case, the petitioners 

argued, among other things, that CAA section 112(f)(2)(B) 

applied only to non-carcinogens. The D.C. Circuit rejected this 

position, holding that the text of that provision “draws no 

distinction between carcinogens and non-carcinogens,” Id., and 

that Congress’ incorporation of the Benzene standard applies 

equally to carcinogens and non-carcinogens.

In the ample margin of safety decision process, the agency 

again considers all of the health risks and other health 

information considered in the first step. Beyond that 
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information, additional factors relating to the appropriate 

level of control will also be considered, including costs and 

economic impacts of controls, technological feasibility, 

uncertainties and any other relevant factors. Considering all of 

these factors, the agency will establish the standard at a level 

that provides an ample margin of safety to protect the public 

health, as required by CAA section 112(f). 54 FR 38046.

B. Does this action apply to me?

The NESHAP and associated regulated industrial source 

categories that are the subject of this proposal are listed in 

Table 2 to this preamble. Table 2 is not intended to be 

exhaustive, but rather provides a guide for readers regarding 

entities likely to be affected by the proposed action for the 

industrial source categories listed. These standards, and any 

changes considered in this rulemaking, would be directly 

applicable to sources as a federal program. Thus, federal, 

state, local and tribal government entities are not affected by 

this proposed action. The regulated categories affected by this 

proposed action include:

Table 2. NESHAP and Industrial Source Categories Affected by 

This Proposed Action

NESHAP and Source Category NAICS 

Code1 MACT Code2

Group IV 

Polymers 

Acrylic-Butadiene-Styrene 

Production 325211 1302
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and Resins Methyl MethacrylateAcrylonitrile-ButadieneStyrene Production3

325211 1317

Methyl MethacrylateButadiene-Styrene 

Production 

325211 1318

Nitrile Resins Production3 325211 1342

Polyethylene Terephthalate 

Production 325211 1328

Polystyrene Production 325211 1331

Styrene-Acrylonitrile 

Production 325211 1338

Pesticide Active Ingredient Production 325199, 

325320 0911

Polyether Polyols Production 325199 1625

1 North American Industry Classification System.

2 Maximum Achievable Control Technology.

3 There are no longer any operating facilities in either the Methyl 

Methacrylate-Acrylonitrile-Butadiene-Styrene Production or Nitrile Resins 

Production source categories, and none are anticipated to begin operation in 

the future. Therefore, this proposal does not address these source 

categories.

C. Where can I get a copy of this document and other related 

information?

In addition to being available in the docket, an electronic 

copy of this proposal will also be available on the World Wide 

Web (WWW) through the Technology Transfer Network (TTN). 

Following signature by the EPA Administrator, a copy of this 

proposed action will be posted on the TTN’s policy and guidance 

page for newly proposed or promulgated rules at the following 

address: http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. The TTN 

provides information and technology exchange in various areas of 
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air pollution control.

Additional information is available on the residual risk 

and technology review (RTR) web page at 

http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. This information 

includes source category descriptions and detailed emissions and 

other data that were used as inputs to the risk assessments.

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

Submitting CBI. Do not submit information containing CBI to 

the EPA through www.regulations.gov or email. Clearly mark the 

part or all of the information that you claim to be CBI. For CBI 

information on a disk or CD ROM that you mail to the EPA, mark 

the outside of the disk or CD ROM as CBI and then identify 

electronically within the disk or CD ROM the specific 

information that is claimed as CBI. In addition to one complete 

version of the comment that includes information claimed as CBI, 

a copy of the comment that does not contain the information 

claimed as CBI must be submitted for inclusion in the public 

docket. If you submit a CD ROM or disk that does not contain 

CBI, mark the outside of the disk or CD ROM clearly that it does 

not contain CBI. Information not marked as CBI will be included 

in the public docket and the EPA’s electronic public docket 

without prior notice. Information marked as CBI will not be 

disclosed except in accordance with procedures set forth in 40 

CFR part 2. Send or deliver information identified as CBI only 
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to the following address: Nick Parsons, c/o OAQPS Document 

Control Officer (C404-02), Office of Air Quality Planning and 

Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, NC 27711, Attn: Docket ID No. EPA-HQ-OAR-2011-

0435.

II. Background

A. What are the source categories addressed by this action?

1. Group IV Polymers and Resins Production Source Categories

The National Emission Standards for Hazardous Air Pollutant 

Emissions: Group IV Polymers and Resins were promulgated on 

September 12, 1996 (61 FR 48208), and codified at 40 CFR part 

63, subpart JJJ. The Group IV Polymers and Resins MACT standards 

apply to major sources and regulate HAP emissions from seven 

source categories: acrylonitrile butadiene styrene resin (ABS), 

styrene acrylonitrile resin (SAN), methyl methacrylate 

acrylonitrile butadiene styrene resin (MABS), methyl 

methacrylate butadiene styrene resin (MBS), polystyrene resin, 

poly (ethylene terephthalate) resin (PET) and nitrile resin. 

The Group IV Polymers and Resins MACT standards regulate 

HAP emissions resulting from the production of thermoplastics. A 

thermoplastic is a resin that softens with heat and rehardens to 

a rigid material upon cooling, without generally showing any 

change in the physical properties of the thermoplastic, even 

with repeated heating and cooling. Thermoplastics are composed 
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of high-molecular-weight polymers which are synthesized from 

monomers; the thermoplastics covered in these seven source 

categories, with one exception, use styrene monomer as the basic 

feedstock. The thermoplastics included in these source 

categories are produced via a polymerization/copolymerization 

process, in which monomers undergo intermolecular chemical bond 

formation to form a very large polymer molecule. Generally, the 

production of these polymers entails four processes: (1) raw 

material (i.e., solvent) storage and refining; (2) polymer 

formation in a reactor (either via the solution process, where 

monomers are dissolved in an organic solvent, or the emulsion 

process, where monomers are dispersed in water using a soap 

solution); (3) material recovery; and (4) finishing (i.e., 

blending, aging, coagulation, washing and drying). 

Sources of HAP emissions from thermoplastics production 

include raw material storage vessels, continuous and batch 

process vents, wastewater operations, heat exchangers and 

equipment leaks. The Group IV Polymers and Resins MACT standards 

include a combination of equipment standards and emission limits 

for the various emission sources, which vary in stringency in 

some cases among the source categories.

To meet the requirements of the Group IV Polymers and

Resins MACT standards, the typical control devices used to 

reduce organic HAP emissions from process vents include flares, 
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incinerators, absorbers, carbon adsorbers and condensers. In 

addition, emissions of hydrochloric acid (HCl) are controlled 

using scrubbers. Emissions from storage vessels are controlled 

by fixed roofs with closed vent systems routed to a control 

device. Emissions from wastewater are controlled by a variety of 

methods, including equipment modifications (e.g., fixed roofs on 

storage vessels and oil water separators; covers on surface 

impoundments, containers and drain systems), treatment to remove 

the HAP (steam stripping, biological treatment), control devices 

and work practices. Emissions from equipment leaks and heat 

exchangers are typically reduced by leak detection and repair 

(LDAR) work practice programs and, in some cases, by equipment 

modifications. Each of the five Group IV Polymers and Resins 

source categories addressed in this proposal are discussed 

further below. Two of the Group IV Polymers and Resins source 

categories, MABS and nitrile resins, no longer have any 

operating facilities in the U.S. and we do not anticipate any 

will begin to operate in the future. Therefore, this proposal 

does not address these source categories.2

a. Acrylonitrile butadiene styrene resin (ABS)

 

2 It is the EPA’s practice in these circumstances to not conduct 

unnecessary risk and technology reviews for source categories 

that will no longer have sources operating in the U.S. See, 

e.g., 75 FR 65068, 65075, n.5 (Oct. 21, 2010) and 76 FR 22566, 

22575, n.5 (Apr. 21, 2011). 
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ABS consist of a terpolymer of acrylonitrile, butadiene and 

styrene and can be synthesized by emulsion, suspension and 

continuous mass polymerization. The majority of ABS resin 

production is by batch emulsion. Typical products made from ABS 

resins are piping, refrigerator door liners and food 

compartments, automotive components, telephones, luggage and 

cases, toys, mobile homes and margarine tubs.

We identified five currently operating ABS facilities 

subject to the Group IV Polymers and Resins MACT standards. 

Styrene, acrylonitrile and 1,3-butadiene account for the 

majority of the HAP emissions from the ABS production processes 

at these facilities (approximately 156 tpy and 76 percent of the 

total HAP emissions by mass). These facilities also reported 

relatively small emissions of 23 other HAP. We estimate that the 

MACT-allowable emissions (i.e., the maximum emission levels 

allowed if in compliance with the MACT standards) from this 

source category are approximately equal to the reported, actual 

emissions. For more detail about this estimate of the ratio of 

actual to MACT-allowable emissions and the estimation of MACTallowable emission levels and associated risks and impacts, see 

the memorandum, MACT Allowable Emissions and Risks for the 

Pesticide Active Ingredient, Polyether Polyols, and Polymers and 

Resins IV Production Source Categories, in the docket for this 

rulemaking.
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b. Styrene acrylonitrile resin (SAN)

SAN resins are copolymers of styrene and acrylonitrile, and 

they may be synthesized by emulsion, suspension and continuous 

mass polymerization; however, the majority of production is by 

batch emulsion. Typical uses include automobile instrument 

panels and interior trim and housewares.

We identified two currently operating SAN facilities 

subject to the Group IV Polymers and Resins MACT standards. 

Ethyl benzene and styrene account for the majority of the HAP 

emissions from the SAN production processes at these facilities 

(approximately 2 tpy and 82 percent of the total HAP emissions 

by mass). These facilities also reported relatively small 

emissions of methylene chloride and acrylonitrile. We estimate 

that the MACT-allowable emissions (i.e., the maximum emission 

levels allowed if in compliance with the MACT standards) from 

this source category are approximately equal to the reported, 

actual emissions. For more detail about this estimate of the 

ratio of actual to MACT-allowable emissions and the estimation 

of MACT-allowable emission levels and associated risks and

impacts, see the memorandum, MACT Allowable Emissions and Risks 

for the Pesticide Active Ingredient, Polyether Polyols, and 

Polymers and Resins IV Production Source Categories, in the 

docket for this rulemaking.

c. Methyl methacrylate butadiene styrene resin (MBS)
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MBS resins are prepared by grafting methyl methacrylate and 

styrene onto a styrene-butadiene rubber in an emulsion process. 

The product is a two-phase polymer used as an impact modifier 

for rigid polyvinyl chloride products. These products are used 

for applications in packaging, building and construction. 

We identified two currently operating MBS facilities 

subject to the Group IV Polymers and Resins MACT standards. 

Methyl methacrylate and 1,3-butadiene account for the majority 

of the HAP emissions from the MBS production processes at these 

facilities (approximately 4 tpy and 75 percent of the total HAP 

emissions by mass). These facilities also reported relatively 

small emissions of ethyl acrylate, methanol, styrene and HCl. We 

estimate that the MACT-allowable emissions (i.e., the maximum 

emission levels allowed if in compliance with the MACT 

standards) from this source category are approximately equal to 

the reported, actual emissions. For more detail about this 

estimate of the ratio of actual to MACT-allowable emissions and 

the estimation of MACT-allowable emission levels and associated 

risks and impacts, see the memorandum, MACT Allowable Emissions 

and Risks for the Pesticide Active Ingredient, Polyether 

Polyols, and Polymers and Resins IV Production Source 

Categories, in the docket for this rulemaking.

d. Polystyrene resin

Polystyrene resins are those produced by the polymerization 
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of styrene monomer. This type of resin can be produced by three 

methods: (1) suspension polymerization (operated in batch mode); 

(2) mass (operated in a continuous mode); and (3) emulsion 

process (operated in a continuous mode). The mass and suspension 

methods are the most commercially significant, whereas use of 

the emulsion process has decreased significantly since the mid1940s. The uses for polystyrene resin include packaging and onetime use, expandable polystyrene beads, electronics, resellers 

and compounding, consumer and institutional products and 

furniture, building or construction uses. A wide variety of 

consumer and construction products are made from polystyrene 

resins, including disposable dinnerware, shower doors, light 

diffusers, soap dishes, insulation board, food containers, drain 

pipes, audio and video tape, picnic coolers, loose fill 

packaging and tubing.

We identified 11 currently operating polystyrene resin 

facilities subject to the Group IV Polymers and Resins MACT 

standards. Styrene accounts for the majority of the HAP 

emissions from the polystyrene resin production processes at 

these facilities (approximately 85 tpy and 94 percent of the 

total HAP emissions by mass). These facilities also reported 

relatively small emissions of eight other HAP. We estimate that 

the MACT-allowable emissions (i.e., the maximum emission levels 

allowed if in compliance with the MACT standards) from this 
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source category are approximately equal to the reported, actual 

emissions. For more detail about this estimate of the ratio of 

actual to MACT-allowable emissions and the estimation of MACTallowable emission levels and associated risks and impacts, see 

the memorandum, MACT Allowable Emissions and Risks for the 

Pesticide Active Ingredient, Polyether Polyols, and Polymers and 

Resins IV Production Source Categories, in the docket for this 

rulemaking.

e. Poly (ethylene terephthalate) resin (PET)

Three different types of resins are made by sources covered 

by the PET source category: solid-state resins (PET bottle grade 

resins), polyester film and engineering resins. They are all 

thermoplastic linear condensation polymers based on dimethyl 

terephthalate or terephthalic acid (TPA). PET meltphase polymer 

is used in the production of all three of these resins. PET 

production can occur via either a batch or continuous process. 

The most common use of PET solid-state resins is in soft drink 

bottles, and some industrial fiber-graded polyester (e.g., for 

tire cord) is also produced from PET solid-state resins. The 

most common uses of PET film are photographic film and magnetic 

media. PET is used extensively in the manufacture of synthetic 

fibers (i.e., polyester fibers), which compose the largest 

segment of the synthetic fiber industry. The most common uses of 

polyester fibers are apparel, home furnishings, carpets, 
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fiberfill and other industrial processes. 

We identified 15 currently operating PET facilities subject 

to the Group IV Polymers and Resins MACT standards. Ethylene 

glycol, acetaldehyde and methanol account for the majority of 

the HAP emissions from the PET production processes at these 

facilities (approximately 1,048 tpy and 89 percent of the total 

HAP emissions by mass). These facilities also reported 

relatively small emissions of 34 other HAP. We estimate that the 

MACT-allowable emissions (i.e., the maximum emission levels 

allowed if in compliance with the MACT standards) from this 

source category are approximately equal to the reported, actual 

emissions. For more detail about this estimate of the ratio of 

actual to MACT-allowable emissions and the estimation of MACTallowable emission levels and associated risks and impacts, see 

the memorandum, MACT Allowable Emissions and Risks for the 

Pesticide Active Ingredient, Polyether Polyols, and Polymers and 

Resins IV Production Source Categories, in the docket for this 

rulemaking.

2. Pesticide Active Ingredient Production

The National Emission Standards for Hazardous Air 

Pollutants for Pesticide Active Ingredient Production were 

promulgated on June 23, 1999 (64 FR 33549), and codified at 40 

CFR part 63, subpart MMM. The Pesticide Active Ingredient (PAI) 

MACT standards apply to major sources and regulate HAP emissions 
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resulting from the production of active ingredients in 

insecticides, herbicides, fungicides and related products. 

Typically, the active ingredients subject to the PAI MACT 

standards are subsequently formulated with inert ingredients to 

create end-product pesticides for application. The MACT 

standards do not apply to the formulation of end-product 

pesticides or to other types of active ingredients, such as 

biocides.

PAI are made from a number of raw materials in a variety of 

processes. A process often consists of several steps, which may 

include reaction, crystallization, washing, solvent extraction, 

distillation and/or drying.

The HAP emission sources at PAI production facilities 

include storage vessels, process vents, equipment leaks,

wastewater systems, heat exchange systems, bag dumps and product 

dryers. In the production of PAI, HAP are used primarily as 

reactants or extraction solvents; some of the PAI products are 

also HAP. The MACT standards for PAI production include a 

combination of equipment standards and emission limits for the 

various emission sources.

To meet the requirements of the PAI MACT standards, the 

typical control devices used to reduce emissions from process 

vents include flares, incinerators, absorbers, carbon adsorbers 

and condensers. In addition, emissions of HCl are controlled 
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using scrubbers. Emissions from storage vessels are controlled 

by fixed roofs with closed vent systems routed to a control 

device. Emissions from wastewater are controlled by a variety of 

methods, including equipment modifications (e.g., fixed roofs on 

storage vessels and oil water separators; covers on surface 

impoundments, containers and drain systems), treatment to remove 

the HAP (steam stripping, biological treatment), control devices 

and work practices. Emissions from equipment leaks and heat 

exchangers are typically reduced by LDAR work practice programs 

and, in some cases, by equipment modifications. Fabric filters 

are used to control particulate matter (PM) emissions from 

product dryers and bag dumps.

We identified 17 currently operating facilities subject to 

the PAI MACT standards. Toluene, methanol and methylene chloride 

account for the majority of the HAP emissions from the PAI 

production processes at these facilities (approximately 177 tpy 

and 51 percent of the total HAP emissions by mass). A variety of 

chemicals are used in the production of PAI, and these 

facilities also reported emissions of 67 other HAP. We estimate 

that the actual emissions level is representative of the MACTallowable level (i.e., the maximum emission levels allowed if in 

compliance with the MACT standards) for all emissions sources 

except process vents. As it is possible that the capture systems 

and control devices used at some facilities achieve greater 
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emission reductions than what is required by the NESHAP for 

process vents, the MACT-allowable level for organic HAP 

emissions could be up to five times the actual emissions and the 

MACT-allowable level for chlorine and HCl emissions could be up 

to six times the actual emissions from this source category. For 

more detail about this estimate of the ratio of actual to MACTallowable emissions and the estimation of MACT-allowable 

emission levels and associated risks and impacts, see the 

memorandum, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, in the docket for this rulemaking.

3. Polyether Polyols Production

The National Emission Standards for Hazardous Air Pollutant 

Emissions for Polyether Polyols Production were promulgated on 

June 1, 1999 (64 FR 29419), and codified at 40 CFR part 63, 

subpart PPP. The Polyether Polyols (PEPO) MACT standards apply 

to major sources and regulate HAP emissions resulting from the 

production of chemical products with repeating ether linkages 

(i.e., -R-O-R-) formed by the reaction of ethylene oxide, 

propylene oxide or other cyclic ethers with compounds having one 

or more reactive hydrogens. (This definition excludes materials 

regulated as glycols or glycol ethers under the National 

Emission Standards for Organic Hazardous Air Pollutants From the 

Synthetic Organic Chemical Manufacturing Industry (HON).) PEPO 
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do not have significant uses of their own but are used to make a 

variety of other products. Urethane grade PEPO (i.e., those that 

are free of water) are used as raw material in the production of 

polyurethanes, including slabstock and molded flexible foams, 

rigid foams and other polyurethanes, including microcellular 

products, surface coatings, elastomers, fibers, adhesives and 

sealants. Nonurethane PEPO are used as surfactants, lubricants, 

degreasing agents, hydraulic fluids, cosmetics and 

pharmaceuticals.

PEPO can be produced by either polymerization of epoxides 

(i.e., a three-membered cyclic ether, such as ethylene oxide or 

propylene oxide) or tetrahydrofuran (THF). The former process is 

usually conducted as a batch process, while production of 

polyols using THF is generally a continuous process. Ethylene 

oxide and propylene oxide are both HAP, but THF is not. For the 

MACT regulation, two subcategories of PEPO were created based on 

the use of either epoxides or THF in polymerization.

The HAP emission sources at PEPO production facilities 

include process vents, storage vessels, equipment leaks and 

wastewater, and some facilities have cooling towers or other 

heat exchangers. In the production of PEPO, HAP are used 

primarily as reactants or extraction solvents; some of the PEPO 

products are also HAP compounds. The MACT standards for PEPO 

production include emission limits for process vents, a 
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combination of equipment standards and work practices for 

storage vessels, wastewater and equipment leaks, and work 

practice standards for cooling towers.

To meet the requirements of the PEPO MACT standards, the 

typical control devices used to reduce emissions from storage 

vessels are fixed roofs with closed vent systems routed to a 

control device. Emissions from wastewater are controlled by a 

variety of methods, including equipment modifications (e.g., 

fixed roofs on storage vessels and oil water separators; covers 

on surface impoundments, containers and drain systems), 

treatment to remove the HAP (steam stripping, biological 

treatment), control devices and work practices. Emissions from 

equipment leaks and heat exchangers are typically reduced by 

LDAR work practice programs and, in some cases, by equipment 

modifications. Controls for process vents for facilities that 

use THF as a reactant generally use scrubbers. Epoxide emissions 

from process vents are typically controlled by scrubbers or 

combustion devices, but some facilities use extended cookout as 

a pollution prevention technique. Extended cookout reduces the 

amount of unreacted ethylene oxide and/or propylene oxide 

(epoxides) in the reactor. This is accomplished by allowing the 

product to react for a longer time period, thereby having less 

unreacted epoxides and reducing epoxides emissions that may have 

otherwise occurred. Emissions from catalyst extraction and other 
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processes are generally vented to the same control device as the 

epoxide emissions or are minimal if the extended cookout 

practice is used.

We identified 23 currently operating facilities subject to 

the PEPO MACT standards. Ethylene glycol, ethylene oxide and 

propylene oxide account for the majority of the HAP emissions 

from the PEPO production processes at these facilities 

(approximately 269 tpy and 61 percent of the total HAP emissions 

by mass). A variety of chemicals are used in the production of 

PEPO, and these facilities also reported emissions of 81 other 

HAP. We estimate that the actual emissions level is 

representative of the MACT-allowable level (i.e., the maximum 

emission levels allowed if in compliance with the MACT 

standards) for all emissions sources except batch process vents 

and process vents that use organic HAP in catalyst extraction at 

units producing PEPO products using epoxides. As it is possible 

that the capture systems and control devices used at some 

facilities achieve greater emission reductions in the organic 

non-epoxide HAP than what is required by the NESHAP for these 

process vents, the MACT-allowable level for organic non-epoxide 

HAP emissions could be up to five times the actual emissions 

from this source category. For more detail about this estimate 

of the ratio of actual to MACT-allowable emissions and the 

estimation of MACT-allowable emission levels and associated 
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risks and impacts, see the memorandum, MACT Allowable Emissions 

and Risks for the Pesticide Active Ingredient, Polyether 

Polyols, and Polymers and Resins IV Production Source 

Categories, in the docket for this rulemaking.

B. What data collection activities were conducted to support 

this proposed action?

To perform the risk assessments for these source 

categories, we developed data sets for these seven source 

categories (five Group IV Polymers and Resins categories, PAI 

and PEPO) based on information in the 2005 National Emissions 

Inventory (NEI) (available at 

http://www.epa.gov/chief/net/2005inventory.html). The NEI is a 

database that contains information about sources that emit 

criteria air pollutants, their precursors and HAP. The database 

includes estimates of annual air pollutant emissions from point, 

nonpoint and mobile sources in the 50 states, the District of 

Columbia, Puerto Rico and the Virgin Islands. The EPA collects 

this information and releases an updated version of the NEI 

database every 3 years. We reviewed the NEI data and made 

changes where necessary to ensure the proper facilities were 

included and to ensure the proper processes were allocated to 

each source category. We also reviewed the emissions and other 

data to identify data anomalies that could affect risk 

estimates, such as whether a pollutant was expected to be 
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emitted from facilities in a source category or whether an 

emission point was located within a facility’s fenceline. The 

NEI data were also reviewed by industry trade groups, including 

the American Chemistry Council and the Society of Chemical 

Manufacturers and Affiliates. Where the EPA received new 

information in response to these data review by industry, 

including updated emissions data and process information, 

facility closure information and information that some 

facilities were not subject to the PAI, PEPO or Group IV 

Polymers and Resins MACT standards, we revised the NEI data 

where we concluded the comments supported such adjustment. We 

obtained updated emissions data and process information, found 

that some facilities had closed and that others were no longer 

subject to the PAI, PEPO or Group IV Polymers and Resins MACT 

standards. In general, we found that emissions from these source 

categories had decreased from the values reported in the 2005 

NEI, due to factors such as the installation of additional 

controls at the facility, duplication of emissions in the 

inventory, or emissions misappropriated to the wrong source 

category. We used this reviewed and revised data set to conduct 

the risk assessment and other analyses for each source category. 

Due to the uncertainties in the data (e.g., most emission 

estimates in the data set are the result of emission factors 

rather than test data), along with our general finding that 
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emissions were less than those reported in the 2005 NEI, we 

believe that the data set provides a conservative estimate of 

the risk from these source categories. Further details on the 

changes made to the 2005 NEI data can be found in the 

memorandum, Emissions Data and Acute Risk Factor Used in 

Residual Risk Modeling: Pesticide Active Ingredients, Polyether 

Polyols, and Group IV Polymers and Resins, which is in the 

docket for this rulemaking.

To conduct the technology review, we primarily relied on 

information downloaded from the reasonably available control 

technology (RACT)/best available control technology 

(BACT)/lowest achievable emission rate (LAER) Clearinghouse 

(RBLC) for processes in Agricultural Chemical Manufacturing (for 

PAI controls), Polymer and Resin Production (for Group IV 

Polymers and Resins controls) and the Synthetic Organic Chemical 

Manufacturing Industry (SOCMI) (for PAI, PEPO and Group IV 

Polymers and Resins controls) with permits dating back to the 

promulgation dates of each MACT regulation.

To evaluate unregulated emission points in the Group IV 

Polymers and Resins MACT standards, we relied on existing data 

submitted to the EPA during development of the MACT, information 

submitted after proposal of the MACT standards and information 

submitted with requests for reconsideration of standards.

III. Analyses Performed
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A. How did we address unregulated emissions sources?

For the Group IV Polymers and Resins source categories, we 

identified one subcategory - PET sources using a continuous TPA 

high viscosity multiple end finisher process - consisting of one 

facility that was not subject to standards for process contact 

cooling towers (PCCT) or equipment leaks. While the promulgated 

rule includes provisions for PCCT for this subcategory, the 

facility is not required to comply with these provisions due to 

an indefinite stay in the compliance date provisions issued by 

the EPA in response to a request to reconsider the emission 

limits for this equipment. For this facility, we also identified 

the absence of a standard for equipment leaks, which in the 

absence of an enforceable standard is a potential significant 

emissions source for this facility, even though its operators 

currently voluntarily conduct their own LDAR program. For the 

one facility in this subcategory, we are proposing to set 

standards for PCCT and equipment leaks under CAA section 

112(d)(2) and (d)(3) in this action. The results and proposed 

decisions based on the analyses performed pursuant to CAA 

section 112(d)(2) and 112(d)(3) are presented in section IV.E.1 

of this preamble. While we also identified the absence of a 

standard for wastewater for the acrylonitrile styrene 

resin/alpha methyl styrene acrylonitrile resin (ASA/AMSAN) 

subcategory of the SAN source category, the only facility in 
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this subcategory has permanently closed, and no new ASA/AMSAN 

operations are expected to begin operation in the United States. 

As stated previously and as established in prior risk and 

technology review rulemakings, it is not EPA’s practice to 

unnecessarily conduct risk and technology reviews for source 

categories that will no longer have sources operating in the 

United States. Therefore, we are not addressing this emission 

point in this proposed action. 

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

The EPA conducted risk assessments that provided estimates 

of the MIR posed by the HAP emissions from each source in each 

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. The assessments 

also provided estimates of the distribution of cancer risks 

within the exposed populations, cancer incidence and an 

evaluation of the potential for adverse environmental effects 

for each source category. The risk assessments consisted of 

seven primary steps, as discussed below. The docket for this 

rulemaking contains the following document which provides more 

information on the risk assessment inputs and models: Draft 

Residual Risk Assessment for 7 Source Categories. The methods 

used to assess risks (as described in the seven primary steps 
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below) are consistent with those peer-reviewed by a panel of the 

EPA’s Science Advisory Board (SAB) in 2009 and described in 

their peer review report issued in 2010; they are also 

consistent with the key recommendations contained in that 

report.

1. Establishing the Nature and Magnitude of Actual Emissions and 

Identifying the Emissions Release Characteristics.

As discussed in section II.B, we created the preliminary 

data sets for the seven source categories using data in the 2005 

NEI, supplemented by data collected from industry or industry 

trade associations when available.

2. Establishing the Relationship Between Actual Emissions and 

MACT-Allowable Emissions Levels

The available emissions data in the NEI and from other 

sources typically represent the mass of HAP actually emitted 

during the specified annual time period. These “actual” emission 

levels can be lower than the emission levels a facility might be 

allowed to emit and still comply with the MACT standards. The 

emissions level allowed to be emitted by the MACT standards is 

referred to as the “MACT-allowable” emissions level. This 

represents the highest emissions level that could be emitted by 

facilities without violating the MACT standards.

We discussed the use of both MACT-allowable and actual 

emissions in the final Coke Oven Batteries residual risk rule 
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(70 FR 19998–19999, April 15, 2005) and in the proposed and 

final HON residual risk rules (71 FR 34428, June 14, 2006, and 

71 FR 76609, December 21, 2006, respectively). In those previous 

actions, we noted that assessing the risks at the MACT-allowable 

level is inherently reasonable because these risks reflect the 

maximum level sources could emit and still comply with national 

emission standards. We continue to take this view, for the 

reasons presented in those discussions. But we also explained 

that it is reasonable to consider actual emissions, where such 

data are available, in both steps of the risk analysis, in 

accordance with the Benzene NESHAP. (54 FR 38044, September 14, 

1989.) We also continue to take this view, for the reasons 

explained in those prior discussions.

As described above, the actual emissions data were compiled 

based on the NEI and information gathered from facilities 

through industrial trade associations. To estimate emissions at 

the MACT-allowable level, we developed a ratio of MACT-allowable 

to actual emissions for each emissions source type in each 

source category, based on the level of control required by the 

MACT standards compared to the level of reported actual 

emissions and available information on the level of control 

achieved by the emissions controls in use. For example, if there 

was information to suggest several facilities in a source 

category were controlling storage tank emissions by 98 percent,
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while the MACT standards required only 92-percent control, we 

would estimate that MACT-allowable emissions from these emission 

points could be as much as four times higher (8-percent 

allowable emissions compared with 2 percent actually emitted), 

and the ratio of MACT-allowable to actual would be 4:1 for this 

emission point type at the facilities in this source category. 

After developing these ratios for each emission point type in 

each source category, we next applied these ratios on a 

facility-by-facility basis to the maximum chronic risk values 

from the inhalation risk assessment to obtain facility-specific 

maximum risk values based on MACT-allowable emissions. Further 

explanation of this evaluation is provided in the technical 

document, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, which is available in the docket 

for this action.

3. Conducting Dispersion Modeling, Determining Inhalation 

Exposures, and Estimating Individual and Population Inhalation 

Risks

Both long-term and short-term inhalation exposure 

concentrations and health risks from each facility in the source 

categories addressed in this proposal were estimated using the 

Human Exposure Model (HEM) (Community and Sector HEM–3 version 

1.1.0). The HEM–3 performs three of the primary risk assessment 
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activities listed above: (1) conducting dispersion modeling to 

estimate the concentrations of HAP in ambient air; (2) 

estimating long-term and short-term inhalation exposures to 

individuals residing within 50 km of the modeled sources; and 

(3) estimating individual and population-level inhalation risks 

using the exposure estimates and quantitative dose-response 

information.

The dispersion model used by HEM–3 is AERMOD, which is one 

of the EPA’s preferred models for assessing pollutant 

concentrations from industrial facilities.3 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 (1991) of hourly 

surface and upper air observations for 189 meteorological 

stations, selected to provide coverage of the United States and 

Puerto Rico. A second library of United States Census Bureau 

census block4 internal point locations and populations provides 

the basis of human exposure calculations (U.S. Census, 2000). In 

 

3 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).

4 A census block is generally the smallest geographic area for 

which census statistics are tabulated.
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addition, the census library includes the elevation and 

controlling hill height for each census block, which are also 

used in dispersion calculations. A third library of pollutant 

unit risk factors and other health benchmarks is used to 

estimate health risks. These risk factors and health benchmarks 

are the latest values recommended by the EPA for HAP and other 

toxic air pollutants. These values are available at 

http://www.epa.gov/ttn/atw/toxsource/summary.html and are 

discussed in more detail later in this section.

In developing the risk assessment for chronic exposures, we 

used the estimated annual average ambient air concentration of 

each of the HAP emitted by each source for which we have 

emissions data in the source category. The air concentrations at 

each nearby census block centroid were used as a surrogate for 

the chronic inhalation exposure concentration for all people who 

reside in that census block. We calculated the MIR for each 

facility as the cancer risk associated with a continuous 

lifetime (24 hours per day, 7 days per week and 52 weeks per 

year for a 70-year period) exposure to the maximum concentration 

at the centroid of inhabited census blocks. Individual cancer 

risks were calculated by multiplying the estimated lifetime 

exposure to the ambient concentration of each of the HAP (in 

micrograms per cubic meter (μg/m3)) by its unit risk estimate 

(URE), which is an upper bound estimate of an individual’s 
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probability of contracting cancer over a lifetime of exposure to 

a concentration of 1 microgram of the pollutant per cubic meter 

of air. For residual risk assessments, we generally use URE 

values from the EPA’s Integrated Risk Information System (IRIS).5

For carcinogenic pollutants without EPA IRIS values, we look to 

other reputable sources of cancer dose-response values, often 

using California EPA (CalEPA) URE values, where available. In 

cases where new, scientifically credible dose response values 

have been developed in a manner consistent with EPA guidelines 

and have undergone a peer review process similar to that used by 

the EPA, we may use such dose-response values in place of, or in 

addition to, other values, if appropriate.

We note here that several carcinogens have a mutagenic mode 

of action.6 Of these compounds, polycyclic organic matter (POM) 

is emitted by facilities in the PEPO and PET source categories, 

and vinyl chloride is emitted by facilities in the PEPO and the 

PAI source categories. For these compounds, the age-dependent 

adjustment factors (ADAF) described in the EPA’s Supplemental 

Guidance for Assessing Susceptibility from Early-Life Exposure 

 

5 The IRIS information is available at http://www.epa.gov/IRIS.

6 U.S. EPA, 2006. Performing risk assessments that include 

carcinogens described in the Supplemental Guidance as having a 

mutagenic mode of action. Science Policy Council Cancer 

Guidelines Implementation Workgroup Communication II: Memorandum 

from W.H. Farland, dated June 14, 2006. 

http://epa.gov/osa/spc/pdfs/CGIWGCommunication_II.pdf. 
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to Carcinogens

7 were applied. This adjustment has the effect of 

increasing the estimated lifetime risks for these pollutants by 

a factor of 1.6.8 In addition, the EPA expresses carcinogenic 

potency for compounds in the POM group in terms of 

benzo[a]pyrene equivalence, based on evidence that carcinogenic 

POM have the same mutagenic mechanism of action as does 

benzo[a]pyrene. For this reason, the EPA’s Science Policy 

Council9 recommends applying the Supplemental Guidance to all 

carcinogenic polycyclic aromatic hydrocarbons for which risk 

estimates are based on relative potency. Accordingly, we have 

applied the ADAF to benzo[a]pyrene equivalent portion of all POM 

mixtures. 

Incremental individual lifetime cancer risks associated 

with emissions from the source categories were estimated as the 

sum of the risks for each of the carcinogenic HAP (including 

those classified as carcinogenic to humans, likely to be 

carcinogenic to humans, and suggestive evidence of carcinogenic 

 

7 U.S. EPA, 2005. Supplemental Guidance for Assessing Early-Life 

Exposure to Carcinogens. EPA/630/R-03/003F. 

http://www.epa.gov/ttn/atw/childrens_supplement_final.pdf.

8 Only one of these mutagenic compounds, benzo[a]pyrene, is 

emitted by any of the sources covered by this proposal.

9 U.S. EPA, 2005. Science Policy Council Cancer Guidelines 

Implementation Workgroup Communication I: Memorandum from W.H. 

Farland, dated October 4, 2005, to Science Policy Council. 

http://www.epa.gov/osa/spc/pdfs/canguid1.pdf.
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potential10) emitted by the modeled sources. Cancer incidence and 

the distribution of individual cancer risks for the population 

within 50 km of any source were also estimated for the source 

categories as part of these assessments by summing individual 

risks. A distance of 50 km is consistent with both the analysis 

supporting the 1989 Benzene NESHAP (54 FR 38044) and the 

limitations of Gaussian dispersion models, including AERMOD. 

To assess risk of noncancer health effects from chronic 

exposures, we summed the HQ for each of the HAP that affects a 

common target organ system to obtain the HI for that target 

organ system (or target organ-specific HI, TOSHI). The HQ is the 

estimated exposure divided by the chronic reference level, which 

is either the EPA reference concentration (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 

 

10 These classifications also coincide with the terms "known 

carcinogen, probable carcinogen, and possible carcinogen," 

respectively, which are the terms advocated in the EPA's 

previous Guidelines for Carcinogen Risk Assessment, published in 

1986 (51 FR 33992, September 24, 1986). Summing the risks of 

these individual compounds to obtain the cumulative cancer risks

is an approach that was recommended by the EPA's SAB in their 

2002 peer review of the EPA's National Air Toxics Assessment 

(NATA) entitled, NATA - Evaluating the National-scale Air Toxics 

Assessment 1996 Data -- an SAB Advisory, available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/214C6E915BB04E1485257

0CA007A682C/$File/ecadv02001.pdf.
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without an appreciable risk of deleterious effects during a 

lifetime,” or, in cases where an RfC from the EPA’s IRIS 

database is not available, a value from the following 

prioritized sources for chronic dose-response values: (1) the 

Agency for Toxic Substances and Disease Registry Minimum Risk 

Level, which is defined as “an estimate of daily human exposure 

to a substance that is likely to be without an appreciable risk 

of adverse effects (other than cancer) over a specified duration 

of exposure”; (2) the CalEPA Chronic Reference Exposure Level 

(REL), which is defined as “the concentration level at or below 

which no adverse health effects are anticipated for a specified 

exposure duration”; 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, in place of or 

in concert with other values.

Screening estimates of acute exposures and risks were also 

evaluated for each of the HAP at the point of highest off-site 

exposure for each facility (i.e., not just the census block 

centroids), assuming that a person is located at this spot at a 

time when both the peak (hourly) emission rates from each 

emission point at the facility and worst-case dispersion 

conditions occur. The acute HQ is the estimated acute exposure 

divided by the acute dose-response value. In each case, acute HQ 
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values were calculated using best available, short-term health 

threshold values. These acute dose-response values, which are 

described below, include the acute REL, acute exposure guideline 

levels (AEGL) and emergency response planning guidelines (ERPG) 

for 1-hour exposure durations. As discussed below, we used 

conservative assumptions for emission rates, meteorology and 

exposure location for our acute analysis. 

As described in the CalEPA’s Air Toxics Hot Spots Program 

Risk Assessment Guidelines, Part I, The Determination of Acute 

Reference Exposure Levels for Airborne Toxicants, an acute REL 

value (http://www.oehha.ca.gov/air/pdf/acuterel.pdf) is defined 

as “the concentration level at or below which no adverse health 

effects are anticipated for a specified exposure duration.” 

Acute REL values are based on the most sensitive, relevant, 

adverse health effect reported in the medical and toxicological 

literature. Acute REL values are designed to protect the most 

sensitive sub-populations (e.g., asthmatics) by the inclusion of 

margins of safety. Because margins of safety are incorporated to 

address data gaps and uncertainties, exceeding the REL value 

does not automatically indicate an adverse health impact.

AEGL values were derived in response to recommendations 

from the National Research Council (NRC). As described in 

Standing Operating Procedures (SOP) of the National Advisory 

Committee on Acute Exposure Guideline Levels for Hazardous 
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Substances (http://www.epa.gov/opptintr/aegl/pubs/sop.pdf),11

“the NRC’s previous name for acute exposure levels — community 

emergency exposure levels — was replaced by the term AEGL to 

reflect the broad application of these values to planning, 

response and prevention in the community, the workplace, 

transportation, the military and the remediation of Superfund 

sites.” This document also states that AEGL values “represent 

threshold exposure limits for the general public and are 

applicable to emergency exposures ranging from 10 minutes to 8 

hours.” The document lays out the purpose and objectives of AEGL 

by stating (page 21) that “the primary purpose of the AEGL 

program and the National Advisory Committee for Acute Exposure 

Guideline Levels for Hazardous Substances is to develop 

guideline levels for once-in-a-lifetime, short-term exposures to 

airborne concentrations of acutely toxic, high-priority 

chemicals.” In detailing the intended application of AEGL 

values, the document states (page 31) that ”[i]t is anticipated 

that the AEGL values will be used for regulatory and 

nonregulatory purposes by U.S. federal and state agencies and, 

possibly, the international community in conjunction with 

chemical emergency response, planning and prevention programs. 

 

11 NAS, 2001. Standing Operating Procedures for Developing Acute 

Exposure Levels for Hazardous Chemicals, page 2.
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More specifically, the AEGL values will be used for conducting 

various risk assessments to aid in the development of emergency 

preparedness and prevention plans, as well as real-time 

emergency response actions, for accidental chemical releases at 

fixed facilities and from transport carriers.”

The AEGL–1 value is then specifically defined as “the 

airborne concentration of a substance above which it is 

predicted that the general population, including susceptible 

individuals, could experience notable discomfort, irritation or 

certain asymptomatic nonsensory effects. However, the effects 

are not disabling and are transient and reversible upon 

cessation of exposure.” The document also notes (page 3) that, 

“Airborne concentrations below AEGL–1 represent exposure levels 

that can produce mild and progressively increasing but transient 

and nondisabling odor, taste, and sensory irritation or certain 

asymptomatic, nonsensory effects.” Similarly, the document 

defines AEGL–2 values as “the airborne concentration (expressed 

as ppm or milligrams per cubic meter (mg/m3) of a substance above 

which it is predicted that the general population, including 

susceptible individuals, could experience irreversible or other 

serious, long-lasting adverse health effects or an impaired 

ability to escape.”

ERPG values are derived for use in emergency response, as 

described in the American Industrial Hygiene Association’s 
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document titled, Emergency Response Planning Guidelines (ERPG) 

Procedures and Responsibilities

(http://www.aiha.org/1documents/committees/ERPSOPs2006.pdf), 

which states that, “Emergency Response Planning Guidelines were 

developed for emergency planning and are intended as healthbased guideline concentrations for single exposures to 

chemicals.”12 The ERPG–1 value is defined as “the maximum 

airborne concentration below which it is believed that nearly 

all individuals could be exposed for up to 1 hour without 

experiencing other than mild transient adverse health effects or 

without perceiving a clearly defined, objectionable odor.” 

Similarly, the ERPG–2 value is defined as “the maximum airborne 

concentration below which it is believed that nearly all 

individuals could be exposed for up to 1 hour without 

experiencing or developing irreversible or other serious health 

effects or symptoms which could impair an individual’s ability 

to take protective action.”

As can be seen from the definitions above, the AEGL and 

ERPG values include the similarly-defined severity levels 1 and 

2. For many chemicals, a severity level 1 value AEGL or ERPG has 

not been developed because the types of effects for these 

 

12 ERP Committee Procedures and Responsibilities. 1 November, 

2006. American Industrial Hygiene Association.
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chemicals are not consistent with the AEGL-1/ERPG-1 definitions; 

in these instances, higher severity level AEGL–2 or ERPG–2 

values are compared to our modeled exposure levels to screen for 

potential acute concerns. When AEGL-1/ERPG-1 values are 

available, they are used in our acute risk assessments.

Acute REL values for 1-hour exposure durations are 

typically lower than their corresponding AEGL–1 and ERPG–1 

values. Even though their definitions are slightly different, 

AEGL–1 values are often similar to the corresponding ERPG–1 

values, and AEGL–2 values are often similar to ERPG–2 values. 

Maximum HQ values from our acute screening risk assessments 

typically result when basing them on the acute REL value for a 

particular pollutant. In cases where our maximum acute HQ value 

exceeds 1, we also report the HQ value based on the next highest 

acute dose-response value (usually the AEGL–1 and/or the ERPG–1 

value).

To develop screening estimates of acute exposures in the 

absence of hourly emissions data, generally we first develop 

estimates of maximum hourly emissions rates by multiplying the 

average actual annual hourly emission rates by a default factor 

to cover routinely variable emissions. We choose the factor to 

use based on process knowledge and engineering judgment and with 

awareness of a Texas study of short-term emissions variability, 

which showed that most peak emission events in a heavily-
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industrialized 4-county area (Harris, Galveston, Chambers and 

Brazoria Counties, Texas) were less than twice the annual 

average hourly emission rate. The highest peak emissions event 

was 74 times the annual average hourly emission rate, and the 

99th percentile ratio of peak hourly emissions rate to the annual 

average hourly emissions rate was 9.13 This analysis is provided 

in the Draft Residual Risk Assessment for 7 Source Categories

report, which is available in the docket for this action. 

Considering this analysis, to account for more than 99 percent 

of the peak hourly emissions, we apply a conservative screening 

multiplication factor of 10 to the average annual hourly 

emissions rate in our acute exposure screening assessments as 

our default approach. However, we use a factor other than 10 if 

we have information that indicates that a different factor is 

appropriate for a particular source category. For these source 

categories, a factor of 10 was applied to all emissions, with 

two exceptions. For certain facilities with volatile organic 

compound (VOC) emissions greater than 876 tpy and for several 

facilities with emissions from equipment leaks, a factor of two 

was applied. A further discussion of why this factor was chosen 

can be found in the memorandum, Emissions Data and Acute Risk 

 

13 See 

http://www.tceq.state.tx.us/compliance/field_ops/eer/index.html 

or docket to access the source of these data.
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Factor Used in Residual Risk Modeling: Pesticide Active 

Ingredients, Polyether Polyols, and Group IV Polymers and 

Resins, available in the docket for this rulemaking.

As part of our acute risk assessment process, for cases 

where acute HQ values from the screening step were less than or 

equal to 1, acute impacts were deemed negligible and no further 

analysis was performed. In the cases where an acute HQ from the 

screening step was greater than 1, additional site-specific data 

were considered to develop a more refined estimate of the 

potential for acute impacts of concern. The data refinements 

considered include using a peak-to-mean hourly emissions ratio 

based on source category-specific knowledge or data (rather than 

the default factor of 10) and using the site-specific facility 

layout to distinguish facility property from an area where the 

public could be exposed. Ideally, we would prefer to have 

continuous measurements over time to see how the emissions vary 

by each hour over an entire year. Having a frequency 

distribution of hourly emission rates over a year would allow us 

to perform a probabilistic analysis to estimate potential 

threshold exceedances and their frequency of occurrence. Such an 

evaluation could include a more complete statistical treatment 

of the key parameters and elements adopted in this screening 

analysis. However, we recognize that having this level of data 

is rare, hence our use of the multiplier approach. 
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To better characterize the potential health risks 

associated with estimated acute exposures to HAP, and in 

response to a key recommendation from the SAB’s peer review of 

the EPA’s RTR risk assessment methodologies,14 we generally 

examine a wider range of available acute health metrics (e.g., 

REL, AEGL) than we do for our chronic risk assessments. This is 

in response to the SAB’s acknowledgement that there are 

generally more data gaps and inconsistencies in acute reference 

values than there are in chronic reference values. In some 

cases, when Reference Value Arrays15 for HAP have been developed, 

we consider additional acute values (i.e., occupational and 

international values) to provide a more complete risk 

characterization.

4. Conducting Multipathway Exposure and Risk Screening

The potential for significant human health risks due to 

exposures via routes other than inhalation (i.e., multipathway 

exposures) and the potential for adverse environmental impacts 

 

14 The SAB peer review of RTR Risk Assessment Methodologies is 

available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A85257

71F00668381/$File/EPA-SAB-10-007-unsigned.pdf.

15 U.S. EPA. (2009) Chapter 2.9 Chemical Specific Reference 

Values for Formaldehyde in Graphical Arrays of Chemical-Specific 

Health Effect Reference Values for Inhalation Exposures (Final 

Report). U.S. Environmental Protection Agency, Washington, DC, 

EPA/600/R-09/061, and available on-line at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
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were evaluated in a two-step process. In the first step, we 

determined whether any facilities emitted any HAP known to be 

persistent and bio-accumulative in the environment (PB-HAP). 

There are 14 PB-HAP compounds or compound classes identified for 

this screening in the EPA’s Air Toxics Risk Assessment Library 

(available at http://www.epa.gov/ttn/fera/risk_atra_vol1.html). 

They are cadmium compounds, chlordane, chlorinated 

dibenzodioxins and furans, dichlorodiphenyldichloroethylene, 

heptachlor, hexachlorobenzene, hexachlorocyclohexane, lead 

compounds, mercury compounds, methoxychlor, polychlorinated 

biphenyls (PCB), POM, toxaphene and trifluralin. 

In the second step of the screening process, we determined 

whether the facility-specific emission rates of each of the 

emitted PB–HAP were large enough to create the potential for 

significant non-inhalation human or environmental risks under 

reasonable worst-case conditions. To facilitate this step, we 

have developed emission rate thresholds for several of these PB–

HAP using a hypothetical worst-case 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 hypothetical screening scenario was 

subjected to a sensitivity analysis to ensure that its key 

design parameters were established such that environmental media 

concentrations were not underestimated (i.e., to minimize the 
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occurrence of false negatives or results that suggest that risks 

might be acceptable when, in fact, actual risks are high) and to 

also minimize the occurrence of false positives for human health 

endpoints. We call this application of the TRIM.FaTE model TRIMScreen. The facility-specific emission rates of each of the PB–

HAP in each source category were compared to the TRIM-Screen 

emission threshold values for each of these PB–HAP to assess the 

potential for significant human health risks or environmental 

risks via non-inhalation pathways. 

5. Assessing Risks Considering Emissions Control Options

In addition to assessing baseline inhalation risks and 

screening for potential multipathway risks, for some source 

categories, we also estimated risks considering the potential 

emission reductions that would be achieved by the particular 

control options under consideration. In these cases, the 

expected emissions reductions were applied to the specific HAP 

and emission points in the source category dataset to develop 

corresponding estimates of risk reductions.

6. Conducting Other Risk-related Analyses: Facility-wide 

Assessments

To put the source category risks in context, we examined 

the risks from the entire “facility,” where the facility 

includes all HAP-emitting operations within a contiguous area 

and under common control. In other words, for each facility that 
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includes one or more sources from a source category under 

review, we examined the HAP emissions not only from that source 

category, but also emissions of HAP from all other emission 

sources at the facility. The emissions data for generating these 

“facility-wide” risks were obtained from the 2005 NEI. We 

analyzed risks due to the inhalation of HAP that are emitted 

“facility-wide” for the populations residing within 50 km of 

each facility, consistent with the methods used for the source 

category analysis described above. For these facility-wide risk 

analyses, the modeled source category risks were compared to the 

facility-wide risks to determine the portion of facility-wide 

risks that could be attributed to each of the seven source 

categories addressed in this proposal. We 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 risk documentation 

available through the docket for this action provides all 

facility-wide risks and the percentage of source category 

contribution for all source categories assessed.

The methodology and results of the facility-wide analyses 

for each source category are included in the residual risk 

documentation as referenced in sections IV though VI of this 

preamble, which is available in the docket for this action.

7. Considering Uncertainties in Risk Assessment
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Uncertainty and the potential for bias are inherent in all 

risk assessments, including those performed for the source 

categories addressed in this proposal. Although uncertainty 

exists, we believe the approach taken, which used conservative 

tools and assumptions, ensures that our decisions are healthprotective. A brief discussion of the uncertainties in the 

emissions data sets, dispersion modeling, inhalation exposure 

estimates and dose-response relationships follows below. A more 

thorough discussion of these uncertainties is included in the 

risk assessment documentation (Draft Residual Risk Assessment 

for 7 Source Categories (September 2011)), which is available in 

the docket for this action.

a. Uncertainties in the Emissions Data Sets

Although the development of the RTR data sets involved 

quality assurance/quality control processes, the accuracy of 

emissions values will vary depending on the source of the data, 

the degree to which data are incomplete or missing, the degree 

to which assumptions made to complete the data sets are 

accurate, errors in estimating emissions values and other 

factors. The emission values considered in this analysis 

generally are annual totals that do not reflect short-term 

fluctuations during the course of a year or variations from year 

to year. In contrast, the estimates of peak hourly emission 

rates for the acute effects screening assessment were based on 
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emission adjustment factors applied to the average annual hourly 

emission rates (the default factor is 10 for the initial 

screening), which are intended to account for emission 

fluctuations due to normal facility operations. In some cases, 

more refined estimates, using lower emission adjustment factors 

that reflected consideration of category-specific information, 

were used for source categories where the screening estimates 

did not “screen out” all sources and more specific information 

was available.

b. Uncertainties in Dispersion Modeling

While the analysis employed the EPA’s recommended 

regulatory dispersion model, AERMOD, we recognize that there is 

uncertainty in ambient concentration estimates associated with 

any model, including AERMOD. Where possible, model options 

(e.g., rural/urban, plume depletion, chemistry) were selected to 

provide an overestimate of ambient air concentrations of the HAP 

rather than underestimates. However, because of practicality and 

data limitation reasons, some factors (e.g., meteorology, 

building downwash) have the potential in some situations to 

overestimate or underestimate ambient impacts. For example, 

meteorological data were taken from a single year (1991), and 

facility locations can be a significant distance from the site 

where these data were taken. Despite these uncertainties, we 

believe that at off-site locations and census block centroids, 
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the approach considered in the dispersion modeling analysis 

should generally yield overestimates of ambient HAP 

concentrations.

c. Uncertainties in Inhalation Exposure

The effects of human mobility on exposures were not 

included in the assessment. Specifically, short-term mobility 

and long-term mobility between census blocks in the modeling 

domain were not considered.16 Not considering short or long-term 

population mobility does not bias the estimate of the 

theoretical MIR, nor does it affect the estimate of cancer 

incidence because the total population number remains the same. 

It does, however, affect the shape of the distribution of 

individual risks across the affected population, shifting it 

toward higher estimated individual risks at the upper end and 

reducing the number of people estimated to be at lower risks, 

thereby increasing the estimated number of people at specific 

high risk levels (e.g., 1-in-1 million). 

In addition, the assessment predicted the chronic exposures 

at the centroid of each populated census block as surrogates for 

the exposure concentrations for all people living in that block. 

 

16 Short-term mobility is movement from one microenvironment to 

another over the course of hours or days. Long-term mobility is 

movement from one residence to another over the course of a 

lifetime.
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Using the census block centroid to predict chronic exposures 

tends to over-predict exposures for people in the census block 

who live farther from the facility and under-predict exposures 

for people in the census block who live closer to the facility. 

Thus, using the census block centroid to predict chronic 

exposures may lead to a potential understatement or 

overstatement of the true maximum impact, but it is an unbiased 

estimate of average risk and incidence.

The assessments evaluate the cancer inhalation risks 

associated with continuous pollutant exposures over a 70-year 

period, which is the assumed lifetime of an individual. In 

reality, both the length of time that modeled emissions sources 

at facilities actually operate (i.e., more or less than 70 

years) and the domestic growth or decline of the modeled 

industry (i.e., the increase or decrease in the number or size 

of United States facilities) will influence the risks posed by a 

given source category. Depending on the characteristics of the 

industry, these factors will, in most cases, result in an 

overestimate both in individual risk levels and in the total 

estimated number of cancer cases. However, in rare cases, where 

a facility maintains or increases its emission levels beyond 70 

years, residents live beyond 70 years at the same location, and 

the residents spend most of their days at that location, then 

the risks could potentially be underestimated. Annual cancer 
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incidence estimates from exposures to emissions from these 

sources would not be affected by uncertainty in the length of 

time emissions sources operate. 

The exposure estimates used in these analyses assume 

chronic exposures to ambient levels of pollutants. Because most 

people spend the majority of their time indoors, actual 

exposures may not be as high, depending on the characteristics 

of the pollutants modeled. For many HAP, indoor levels are 

roughly equivalent to ambient levels, but for very reactive 

pollutants or larger particles, these levels are typically 

lower. This factor has the potential to result in an 

overstatement of 25 to 30 percent of exposures.17

In addition to the uncertainties highlighted above, there 

are several other factors specific to the acute exposure 

assessment. The accuracy of an acute inhalation exposure 

assessment depends on the simultaneous occurrence of independent 

factors that may vary greatly, such as hourly emissions rates, 

meteorology and human activity patterns. In this assessment, we 

assume that individuals remain for 1 hour at the point of 

maximum ambient concentration as determined by the co-occurrence 

of peak emissions and worst-case meteorological conditions. 

 

17 U.S. EPA. National-Scale Air Toxics Assessment for 1996. (EPA 

453/R–01–003; January 2001; page 85.)
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These assumptions would tend to be worst-case actual exposures, 

as it is unlikely that a person would be located at the point of 

maximum exposure during the time of worst-case impact.

d. Uncertainties in Dose-Response Relationships

There are uncertainties inherent in the development of the 

reference values used in our risk assessments for cancer effects 

from chronic exposures and noncancer effects from both chronic 

and acute exposures. Some uncertainties may be considered 

quantitatively and others generally are expressed in qualitative 

terms. We note as a preface to this discussion a point on doseresponse uncertainty that is brought out in the EPA’s 2005 

Cancer Guidelines; namely, that “the primary goal of EPA actions 

is protection of human health; accordingly, as an Agency policy, 

risk assessment procedures, including default options that are 

used in the absence of scientific data to the contrary, should 

be health protective.” (EPA 2005 Cancer Guidelines, pages 1–7.) 

This is the approach followed here as summarized in the next 

several paragraphs. A complete detailed discussion of 

uncertainties and variabilities in dose-response relationships 

is given in the residual risk documentation, which is available 

in the docket for this action. 

Cancer URE values used in our risk assessments are those 

that have been developed to generally provide an upper bound 

estimate of risk. That is, they represent a “plausible upper 
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limit to the true value of a quantity” (although this is usually 

not a true statistical confidence limit).18 In some 

circumstances, the true risk could be as low as zero; however, 

in other circumstances the risk could be greater.19 When 

developing an upper bound estimate of risk and to provide risk 

values that do not underestimate risk, health-protective default 

approaches are generally used. To err on the side of ensuring 

adequate health protection, the EPA typically uses the upper 

bound estimates rather than lower bound or central tendency 

estimates in our risk assessments, an approach that may have 

limitations for other uses (e.g., priority-setting or expected 

benefits analysis). 

Chronic noncancer reference (RfC) and reference dose (RfD) 

values represent chronic exposure levels that are intended to be 

health-protective levels. Specifically, these values provide an 

estimate (with uncertainty spanning perhaps an order of 

magnitude) of daily oral exposure (RfD) or of a continuous 

inhalation exposure (RfC) to the human population (including 

sensitive subgroups) that is likely to be without an appreciable 

risk of deleterious effects during a lifetime. To derive values 

 

18 IRIS glossary (http://www.epa.gov/NCEA/iris/help_gloss.htm).

19 An exception to this is the URE for benzene, which is 

considered to cover a range of values, each end of which is 

considered to be equally plausible, and which is based on 

maximum likelihood estimates.
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that are intended to be “without appreciable risk,” the 

methodology relies upon an uncertainty factor (UF) approach 

(U.S. EPA, 1993, 1994), which includes consideration of both 

uncertainty and variability. The UF are applied to derive 

reference values that are intended to protect against 

appreciable risk of deleterious effects. The UF are commonly 

default values,20 e.g., factors of 10 or 3, used in the absence 

of compound-specific data; where data are available, UF may also 

be developed using compound-specific information. When data are 

limited, more assumptions are needed and more UF are used. Thus, 

there may be a greater tendency to overestimate risk in the 

sense that further study might support development of reference 

values that are higher (i.e., less potent), because fewer 

 

20 According to the NRC report, Science and Judgment in Risk 

Assessment (NRC, 1994) “[Default] options are generic 

approaches, based on general scientific knowledge and policy 

judgment, that are applied to various elements of the risk 

assessment process when the correct scientific model is unknown 

or uncertain.” The 1983 NRC report, Risk Assessment in the 

Federal Government: Managing the Process, defined default option 

as “the option chosen on the basis of risk assessment policy 

that appears to be the best choice in the absence of data to the 

contrary” (NRC, 1983a, p. 63). Therefore, default options are 

not rules that bind the agency; rather, the agency may depart 

from them in evaluating the risks posed by a specific substance 

when it believes this to be appropriate. In keeping with the 

EPA’s goal of protecting public health and the environment, 

default assumptions are used to ensure that risk to chemicals is 

not underestimated (although defaults are not intended to 

overtly overestimate risk). See EPA 2004, An examination of EPA 

Risk Assessment Principles and Practices, EPA/100/B–04/001, 

available at: http://www.epa.gov/osa/pdfs/ratf-final.pdf.
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default assumptions are needed. However, for some pollutants it 

is possible that risks may be underestimated.

While collectively termed “UF,” these factors account for a 

number of different quantitative considerations when using 

observed animal (usually rodent) or human toxicity data in the 

development of the RfC. The UF are intended to account for: (1) 

variation in susceptibility among the members of the human 

population (i.e., inter-individual variability); (2) uncertainty 

in extrapolating from experimental animal data to humans (i.e., 

interspecies differences); (3) uncertainty in extrapolating from 

data obtained in a study with less-than-lifetime exposure (i.e., 

extrapolating from sub-chronic to chronic exposure); (4) 

uncertainty in extrapolating the observed data to obtain an 

estimate of the exposure associated with no adverse effects; and 

(5) uncertainty when the database is incomplete or there are 

problems with the applicability of available studies. Many of 

the UF used to account for variability and uncertainty in the 

development of acute reference values are quite similar to those 

developed for chronic durations, but they more often use 

individual UF values that may be less than 10. UF are applied 

based on chemical-specific or health effect-specific information 

(e.g., simple irritation effects do not vary appreciably between 

human individuals, hence a value of 3 is typically used), or 

based on the purpose for the reference value (see the following 
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paragraph). The UF applied in acute reference value derivation 

include: (1) heterogeneity among humans; (2) uncertainty in 

extrapolating from animals to humans; (3) uncertainty in lowest 

observed adverse effect (exposure) level to no observed adverse 

effect (exposure) level adjustments; and (4) uncertainty in 

accounting for an incomplete database on toxic effects of 

potential concern. Additional adjustments are often applied to 

account for uncertainty in extrapolation from observations at 

one exposure duration (e.g., 4 hours) to derive an acute 

reference value at another exposure duration (e.g., 1 hour). 

Not all acute reference values are developed for the same 

purpose and care must be taken when interpreting the results of 

an acute assessment of human health effects relative to the 

reference value or values being exceeded. Where relevant to the 

estimated exposures, the lack of short-term dose-response values 

at different levels of severity should be factored into the risk 

characterization as potential uncertainties.

Although every effort is made to identify peer-reviewed 

reference values for cancer and noncancer effects for all 

pollutants emitted by the sources included in this assessment, 

some pollutants have no peer-reviewed reference values for 

cancer, chronic noncancer or acute effects. Since exposures to 

these pollutants cannot be included in a quantitative risk 

estimate, an understatement of risk for these pollutants at 
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environmental exposure levels is possible. For a group of 

compounds that are either unspeciated or do not have reference 

values for every individual compound (e.g., glycol ethers) we 

conservatively use the most protective reference value to 

estimate risk from individual compounds in the group of 

compounds.

Additionally, chronic reference values for several of the 

compounds included in this assessment are currently under EPA 

IRIS review, and revised assessments may determine that these 

pollutants are more or less potent than the current value. We 

may re-evaluate residual risks for the final rulemaking if these 

reviews are completed prior to our taking final action for these 

source categories and if a dose-response metric changes enough 

to indicate that the risk assessment supporting this notice may 

significantly understate human health risk.

e. Uncertainties in the Multipathway and Environmental Effects 

Screening Assessment

We generally assume that when exposure levels are not 

anticipated to adversely affect human health, they also are not 

anticipated to adversely affect the environment. For each source 

category, we generally rely on the site-specific levels of PBHAP emissions to determine whether a full assessment of the 

multipathway and environmental effects is necessary. Our 

screening methods use worst-case scenarios to determine whether 
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multipathway impacts might be important. The results of such a 

process are biased high for the purpose of screening out 

potential impacts. Thus, when individual pollutants or 

facilities screen out, we are confident that the potential for 

multipathway impacts is negligible. On the other hand, when 

individual pollutants or facilities do not screen out, it does 

not mean that multipollutant impacts are significant, only that 

we cannot rule out that possibility.

C. How did we consider the risk results in making decisions for 

this proposal?

As discussed in the previous section of this preamble, we 

apply a two-step process for determining whether to develop 

standards to address residual risk. 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 level on maximum 

individual lifetime [cancer] risk (MIR)21 of approximately one in 

10 thousand [i.e., 100-in-1 million].” 54 FR 38045. In the 

second step of the process, the EPA determines what level of the 

standard is needed to provide an ample margin of safety “in 

 

21 Although defined as “maximum individual risk,” MIR refers only 

to cancer risk. MIR, one metric for assessing cancer risk, is 

the estimated risk were an individual exposed to the maximum 

level of a pollutant for a lifetime.
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consideration of all health information, including the number of 

persons at risk levels higher than approximately one in one 

million, as well as other relevant factors, including costs and 

economic impacts, technological feasibility, and other factors 

relevant to each particular decision.” Id.

In past residual risk actions, the EPA presented and 

considered a number of human health risk metrics associated with 

emissions from the category under review, including: the MIR; 

the numbers of persons in various risk ranges; cancer incidence; 

the maximum noncancer HI; and the maximum acute noncancer 

hazard. See, e.g., 75 FR 65068, 65072-74 (Oct. 21, 2010), and 76 

FR 22566, 22575 (Apr. 21, 2011). In estimating risks, the EPA 

considered sources under review that are located near each other 

and that affect the same population. The EPA developed risk 

estimates based on the actual emissions from the source category 

under review as well as based on the maximum emissions allowed 

pursuant to the source category MACT standards. The EPA also 

discussed and considered risk estimation uncertainties. The EPA 

is providing this same type of information in support of these 

actions.

The agency is considering all available health information 

to inform our determinations of risk acceptability and ample 

margin of safety under CAA section 112(f). Specifically, as 

explained in the Benzene NESHAP, “the first step judgment on 
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acceptability cannot be reduced to any single factor” and thus 

“[t]he Administrator believes that the acceptability of risk 

under [previous] section 112 is best judged on the basis of a 

broad set of health risk measures and information.” 54 FR 38046. 

Similarly, with regard to making the ample margin of safety 

determination, as stated in the Benzene NESHAP “[i]n the ample 

margin decision, 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 agency acknowledges that the Benzene NESHAP provides 

flexibility regarding what factors the EPA might consider in 

making our determinations and how they might be weighed for each 

source category. In responding to comment on our policy under 

the Benzene NESHAP, the EPA explained that: “The policy chosen 

by the Administrator permits consideration of multiple measures 

of health risk. Not only can the MIR figure be considered, but 

also incidence, the presence of noncancer health effects and the 

uncertainties of the risk estimates. In this way, the effect on 

the most exposed individuals can be reviewed as well as the 

impact on the general public. These factors can then be weighed 

in each individual case. This approach complies with the Vinyl 
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Chloride mandate that the Administrator ascertain an acceptable 

level of risk to the public by employing [her] expertise to 

assess available data. It also complies with the Congressional 

intent behind the CAA, which did not exclude the use of any 

particular measure of public health risk from the EPA's 

consideration with respect to CAA section 112 regulations and, 

thereby, implicitly permits consideration of any and all 

measures of health risk which the Administrator, in [her] 

judgment, believes are appropriate to determining what will 

‘protect the public health.’” 54 FR 38057.

Thus, the level of the MIR is only one factor to be weighed 

in determining acceptability of risks. The Benzene NESHAP 

explains “an MIR of approximately one in 10 thousand should 

ordinarily be the upper end of the range of acceptability. As 

risks increase above this benchmark, they become presumptively 

less acceptable under CAA section 112, and would be weighed with 

the other health risk measures and information in making an 

overall judgment on acceptability. Or, the agency may find, in a 

particular case, that a risk that includes MIR less than the 

presumptively acceptable level is unacceptable in the light of 

other health risk factors.” Id. at 38045. Similarly, with regard 

to the ample margin of safety analysis, the Benzene NESHAP 

states that: “EPA believes the relative weight of the many 

factors that can be considered in selecting an ample margin of 
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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.

D. How did we perform the technology review?

Our technology review is focused on the identification and 

evaluation of “developments in practices, processes, and control 

technologies.” If a review of available information identifies 

such developments, then we conduct an analysis of the technical 

feasibility of requiring the implementation of these 

developments, along with the impacts (costs, emission 

reductions, risk reductions, etc.). We then make a decision on 

whether it is necessary to amend the regulation to require 

compliance with revised standards in light of these 

developments. This has become our standard practice in 

conducting technology reviews. See, e.g., 75 FR 65068, 65083 

(October 21, 2010).

Based on specific knowledge of each source category, we 

began by identifying known developments in practices, processes 

and control technologies. For the purpose of this exercise, we 

considered any of the following to be a “development”:

 Any add-on control technology or other equipment that was 

not identified and considered during MACT development; 

 Any improvements in add-on control technology or other 
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equipment (that was identified and considered during MACT 

development) that could result in significant additional 

emission reduction;

 Any work practice or operational procedure that was not 

identified and considered during MACT development; and

 Any process change or pollution prevention alternative that 

could be broadly applied that was not identified and 

considered during MACT development.

In addition to looking back at practices, processes or 

control technologies reviewed at the time we developed the MACT 

standards, we reviewed a variety of sources of data to aid in 

our evaluation of whether there were additional practices, 

processes or controls to consider. One of these sources of data 

was subsequent air toxics rules. Since the promulgation of the 

MACT standards for the source categories addressed in this 

proposal, the EPA has developed air toxics regulations for a 

number of additional source categories. In these subsequent air 

toxic regulatory actions, we consistently evaluated any new 

practices, processes and control technologies. We reviewed the 

regulatory requirements and/or technical analyses associated 

with these subsequent regulatory actions to identify any 

practices, processes and control technologies considered in 

these efforts that could possibly be applied to emission sources 

in the source categories under this current RTR review.
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We also consulted the EPA’s RBLC. The terms “RACT,” “BACT” 

and “LAER” are acronyms for different program requirements under 

the CAA provisions addressing the national ambient air quality 

standards. Control technologies classified as RACT, BACT or LAER 

apply to stationary sources depending on whether the sources are 

existing or new and on the size, age and location of the 

facility. BACT and LAER (and sometimes RACT) are determined on a 

case-by-case basis, usually by state or local permitting 

agencies. The EPA established the RBLC to provide a central data 

base of air pollution technology information (including 

technologies required in source-specific permits) to promote the 

sharing of information among permitting agencies and to aid in 

identifying future possible control technology options that 

might apply broadly to numerous sources within a category or 

apply only on a source-by-source basis. The RBLC contains over 

5,000 air pollution control permit determinations that can help 

identify appropriate technologies to mitigate many air pollutant 

emission streams. We searched this database to determine whether 

any practices, processes or control technologies are included 

for the types of processes used for emission sources (e.g., 

tanks or vents) in the source categories under consideration in 

this proposal.

We also reviewed other information sources, such as state 

or local permitting agency databases and industry-supported 
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databases.

E. What other issues are we addressing in this proposal?

In addition to the RTR performed regarding the NESHAP, we 

are also proposing revisions to the NESHAP to address emissions 

during periods of startup, shutdown and malfunction (SSM) and 

revisions to require electronic reporting of emissions test 

results.

1. Startup, Shutdown and Malfunction (SSM)

The United States Court of Appeals for the District of 

Columbia Circuit vacated portions of two provisions in the EPA’s 

CAA Section 112 regulations governing the emissions of HAP 

during periods of SSM. Sierra Club v. EPA, 551 F.3d 1019 (D.C. 

Cir. 2008), cert. denied, 130 S. Ct. 1735 (U.S. 2010). 

Specifically, the Court vacated the SSM exemption contained in 

40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), that are part of a 

regulation, commonly referred to as the “General Provisions 

Rule,” that the EPA promulgated under section 112 of the CAA. 

When incorporated into CAA section 112(d) regulations for 

specific source categories, these two provisions exempt sources 

from the requirement to comply with the otherwise applicable CAA 

section 112(d) emission standard during periods of SSM.

As we have done in other recent risk and technology review 

rulemakings, we are proposing the elimination of the SSM 

exemption in each of the three MACT standards addressed by this 
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rule. See, e.g., 76 FR 22568, 22573 (Apr. 21, 2011). Consistent 

with Sierra Club v. EPA, the EPA is proposing standards in these 

rules that apply at all times. We are also proposing several 

revisions to the General Provisions Applicability table in each 

of the MACT standards. For example, we are proposing to 

eliminate the incorporation of the General Provisions’ 

requirement that the source develop an SSM plan. We also are 

proposing to eliminate or revise certain recordkeeping and 

reporting related to the SSM exemption. The EPA has attempted to 

ensure that we have not included in the proposed regulatory 

language any provisions that are inappropriate, unnecessary or 

redundant in the absence of the SSM exemption. We are 

specifically seeking comment on whether there are any such 

provisions that we have inadvertently incorporated or 

overlooked. 

In proposing the standards in these rules, the EPA has 

taken into account startup and shutdown periods and has not 

proposed different standards for those periods because we expect 

the difference in emission levels during periods of startup and 

shutdown are insignificant and that facilities in these source 

categories should be able to comply with the standards during 

these times. 

Periods of startup, normal operation and shutdown are all 

predictable and routine aspects of a source’s operations. 
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However, by contrast, malfunction is defined as a “sudden, 

infrequent, and not reasonably preventable failure of air 

pollution control and monitoring equipment, process equipment or 

a process to operate in a normal or usual manner * * *” (40 CFR 

63.2). The EPA has determined that CAA section 112 does not 

require that emissions that occur during periods of malfunction 

be factored into development of CAA section 112 standards. Under 

section 112, emissions standards for new sources must be no less 

stringent than the level “achieved” by the best controlled 

similar source and for existing sources generally must be no 

less stringent than the average emission limitation “achieved” 

by the best performing 12 percent of sources in the category. 

There is nothing in section 112 that directs the agency to 

consider malfunctions in determining the level “achieved” by the 

best performing or best controlled sources when setting emission 

standards. Moreover, while the EPA accounts for variability in 

setting emissions standards consistent with the CAA section 112 

caselaw, nothing in that caselaw requires the agency to consider 

malfunctions as part of that analysis. Section 112 uses the 

concept of “best controlled” and “best performing” unit in 

defining the level of stringency that CAA section 112 

performance standards must meet. Applying the concept of “best 

controlled” or “best performing” to a unit that is 

malfunctioning presents significant difficulties, as 
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malfunctions are sudden and unexpected events. 

Further, accounting for malfunctions would be difficult, if 

not impossible, given the myriad different types of malfunctions 

that can occur across all sources in the category and given the 

difficulties associated with predicting or accounting for the 

frequency, degree and duration of various malfunctions that 

might occur. As such, the performance of units that are 

malfunctioning is not “reasonably” foreseeable. See, e.g., 

Sierra Club v. EPA, 167 F. 3d 658, 662 (D.C. Cir. 1999) (The EPA 

typically has wide latitude in determining the extent of datagathering necessary to solve a problem. We generally defer to an 

agency's decision to proceed on the basis of imperfect 

scientific information, rather than to "invest the resources to

conduct the perfect study."). See also, Weyerhaeuser v. Costle, 

590 F.2d 1011, 1058 (D.C. Cir. 1978) (“In the nature of things, 

no general limit, individual permit, or even any upset provision 

can anticipate all upset situations. After a certain point, the 

transgression of regulatory limits caused by ‘uncontrollable 

acts of third parties,’ such as strikes, sabotage, operator 

intoxication or insanity, and a variety of other eventualities, 

must be a matter for the administrative exercise of case-by-case 

enforcement discretion, not for specification in advance by 

regulation.”). In addition, the goal of a best controlled or 

best performing source is to operate in such a way as to avoid 
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malfunctions of the source and accounting for malfunctions could 

lead to standards that are significantly less stringent than 

levels that are achieved by a well-performing non-malfunctioning 

source. The EPA’s approach to malfunctions is consistent with 

section 112 and is a reasonable interpretation of the statute. 

In the event that a source fails to comply with the 

applicable CAA section 112(d) standards as a result of a 

malfunction event, the EPA would determine an appropriate 

response based on, among other things, the good faith efforts of 

the source to minimize emissions during malfunction periods, 

including preventative and corrective actions, as well as root 

cause analyses to ascertain and rectify excess emissions. The 

EPA would also consider whether the source's failure to comply 

with the CAA section 112(d) standard was, in fact, “sudden, 

infrequent, not reasonably preventable” and was not instead 

“caused in part by poor maintenance or careless operation.” 40 

CFR 63.2 (definition of malfunction).

Finally, the EPA recognizes that even equipment that is 

properly designed and maintained can sometimes fail and that 

such failure can sometimes cause an exceedance of the relevant 

emission standard. (See, e.g., State Implementation Plans: 

Policy Regarding Excessive Emissions During Malfunctions, 

Startup, and Shutdown (Sept. 20, 1999); Policy on Excess 

Emissions During Startup, Shutdown, Maintenance, and 
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Malfunctions (Feb. 15, 1983)). The EPA is, therefore, proposing 

to follow its recently established practice (see, e.g., 76 FR 

22566, 22573-74 (Apr. 21, 2011)) and add to the rules an 

affirmative defense to civil penalties for exceedances of 

emission limits that are caused by malfunctions. See proposed 40 

CFR 63.1312 (Group IV Polymers and Resins), 40 CFR 63.1361 (PAI) 

and 40 CFR 63.1423 (PEPO). The regulations define “affirmative 

defense” to mean, in the context of an enforcement proceeding, a 

response or defense put forward by a defendant, regarding which 

the defendant has the burden of proof, and the merits of which 

are independently and objectively evaluated in a judicial or 

administrative proceeding. We also are proposing other 

regulatory provisions to specify the elements that are necessary 

to establish this affirmative defense; the source must prove by 

a preponderance of the evidence that it has met all of the 

elements set forth in proposed 40 CFR 63.1310(k) (Group IV 

Polymers and Resins), 40 CFR 63.1360(k) (PAI) and 40 CFR 

63.1420(i) (PEPO). (See 40 CFR 22.24). The criteria ensure that 

the affirmative defense is available only where the event that 

causes an exceedance of the emission limit meets the narrow 

definition of malfunction in 40 CFR 63.2 (sudden, infrequent, 

not reasonable preventable and not caused by poor maintenance 

and or careless operation). For example, to successfully assert 

the affirmative defense, the source must prove by a 
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preponderance of the evidence that excess emissions “[w]ere 

caused by a sudden, infrequent, and unavoidable failure of air 

pollution control and monitoring equipment, process equipment, 

or a process to operate in a normal or usual manner....” The 

criteria also are designed to ensure that steps are taken to 

correct the malfunction, to minimize emissions in accordance 

with proposed 40 CFR 63.1310(j)(4) (Group IV Polymers and 

Resins), 40 CFR 63.1362(i) (PAI) and 40 CFR 63.1420(h)(4) (PEPO) 

and to prevent future malfunctions. For example, the source must 

prove by a preponderance of the evidence that “[r]epairs were 

made as expeditiously as possible when the applicable emission 

limitations were being exceeded...” and that “[a]ll possible steps 

were taken to minimize the impact of the excess emissions on 

ambient air quality, the environment and human health....” In any 

judicial or administrative proceeding, the Administrator may 

challenge the assertion of the affirmative defense and, if the 

respondent has not met its burden of proving all of the 

requirements in the affirmative defense, appropriate penalties 

may be assessed in accordance with section 113 of the CAA (see 

also 40 CFR Part 22.27). 

The EPA included an affirmative defense in these proposed 

rules in an attempt to balance a tension, inherent in many types 

of air regulation, to ensure adequate compliance while 

simultaneously recognizing that despite the most diligent of 
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efforts, emission limits may be exceeded under circumstances 

beyond the control of the source. The EPA must establish 

emission standards that “limit the quantity, rate, or 

concentration of emissions of air pollutants on a continuous 

basis.” 42 U.S.C. § 7602(k)(defining “emission limitation and 

emission standard”). See generally, Sierra Club v. EPA, 551 F.3d 

1019, 1021 (D.C. Cir. 2008). Thus, the EPA is required to ensure 

that section 112 emissions limitations are continuous. The 

affirmative defense for malfunction events meets this 

requirement by ensuring that even where there is a malfunction, 

the emission limitation is still enforceable through injunctive 

relief. While “continuous” limitations, on the one hand, are 

required, there is also caselaw indicating that in many 

situations it is appropriate for the EPA to account for the 

practical realities of technology. For example, in Essex 

Chemical v. Ruckelshaus, 486 F.2d 427, 433 (D.C. Cir. 1973), the 

District of Columbia Circuit acknowledged that, in setting 

standards under CAA section 111, “variant provisions” such as 

provisions allowing for upsets during startup, shutdown and 

equipment malfunction “appear necessary to preserve the 

reasonableness of the standards as a whole and that the record 

does not support the ‘never to be exceeded’ standard currently 

in force.” See also, Portland Cement Association v. Ruckelshaus, 

486 F.2d 375 (D.C. Cir. 1973). Though intervening caselaw such 
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as Sierra Club v. EPA and the CAA 1977 amendments undermine the 

relevance of these cases today, they support the EPA’s view that 

a system that incorporates some level of flexibility is 

reasonable. The affirmative defense simply provides for a 

defense to civil penalties for excess emissions that are proven 

to be beyond the control of the source. By incorporating an 

affirmative defense, EPA has formalized its approach to upset 

events. In a Clean Water Act setting, the Ninth Circuit required 

this type of formalized approach when regulating “upsets beyond 

the control of the permit holder.” Marathon Oil Co. v. EPA, 564 

F.2d 1253, 1272-73 (9th Cir. 1977). See, Weyerhaeuser Co. v. 

Costle, 590 F.2d 1011, 1057-58 (D.C. Cir. 1978) (holding that an 

informal approach is adequate). The affirmative defense 

provisions give the EPA the flexibility to both ensure that its 

emission limitations are “continuous” as required by 42 U.S.C. 

section 7602(k), and account for unplanned upsets and thus 

support the reasonableness of the standard as a whole.

In addition to these changes in the provisions related to 

SSM, we are also proposing that there be no discharge to the 

atmosphere from any pressure relief device (PRD) on any 

equipment in HAP service within the process units for these 

seven source categories. To ensure compliance with this 

requirement, facility owners or operators would be required to 

install electronic indicators on each PRD that would be able to 
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identify and record the time and duration of each pressure 

release and notify operators that a pressure release has 

occurred. While pressure release events may be associated with 

unplanned, nonroutine discharges that result from operator 

error, malfunctions or other unexpected causes that require 

immediate venting of gas from process equipment in order to 

avoid safety hazards or equipment damage, we are concerned that 

a large number of these releases that occur may emit large 

quantities of HAP, may not be identified and controlled in a 

timely manner and may be due to repeat problems that have not 

been corrected. These proposed provisions will clarify that such 

release events would be violations of the emissions standards of 

these rules. If any pressure release events that occur are 

related to a process or control device malfunction, the owner or 

operator could claim the affirmative defense described above. 

2. Electronic Reporting

We are proposing to add electronic reporting requirements 

to the PAI, PEPO and the Group IV Polymers and Resin Production 

NESHAP. The EPA must have performance test data to conduct 

effective reviews of CAA section 112 standards, as well as for 

many other purposes including compliance determinations, 

emission factor development and annual emission rate 

determinations. In conducting these required reviews, the EPA 

has found it ineffective and time consuming, not only for us, 
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but also for regulatory agencies and source owners and 

operators, to locate, collect and submit performance test data 

because of varied locations for data storage and varied data 

storage methods. In recent years, though, stack testing firms 

have typically collected performance test data in electronic 

format, making it possible to move to an electronic data 

submittal system that would increase the ease and efficiency of 

data submittal and improve data accessibility.

Through this proposal, the EPA is presenting a step to 

increase the ease and efficiency of data submittal and improve 

data accessibility. Specifically, the EPA is proposing that 

owners and operators of PAI, PEPO and Group IV Polymers and 

Resins facilities submit electronic copies of required 

performance test reports to the EPA’s WebFIRE database. The 

WebFIRE database was constructed to store performance test data 

for use in developing emission factors. A description of the 

WebFIRE database is available at 

http://cfpub.epa.gov/oarweb/index.cfm?action=fire.main.

As proposed above, data entry would be through an 

electronic emissions test report structure called the Electronic 

Reporting Tool (ERT). The ERT would generate electronic report 

which would be submitted using the Compliance and Emissions Data 

Reporting Interface (CEDRI). The submitted report would be 

transmitted through the EPA’s Central Data Exchange (CDX) 
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network for storage in the WebFIRE database making submittal of 

data very straightforward and easy. A description of the ERT can 

be found at http://www.epa.gov/ttn/chief/ert/index.html and 

CEDRI can be accessed through the CDX website (www.epa.gov/cdx).

The proposal to submit performance test data electronically 

to the EPA would apply only to those performance tests conducted 

using test methods that will be supported by the ERT. The ERT 

contains a specific electronic data entry form for most of the 

commonly used EPA reference methods. A listing of the pollutants 

and test methods supported by the ERT is available at 

http://www.epa.gov/ttn/chief/ert/index.html. We believe that 

industry would benefit from this proposed approach to electronic 

data submittal. Having these data, the EPA would be able to 

develop improved emission factors, make fewer information 

requests and promulgate better regulations.

One major advantage of the proposed submittal of 

performance test data through the ERT is a standardized method 

to compile and store much of the documentation required to be 

reported by this rule. Another advantage is that the ERT clearly 

states what testing information would be required. Another 

important proposed benefit of submitting these data to the EPA 

at the time the source test is conducted is that it should 

substantially reduce the effort involved in data collection 

activities in the future. When the EPA has performance test data 
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in hand, there will likely be fewer or less substantial data 

collection requests in conjunction with prospective required 

residual risk assessments or technology reviews. This would 

result in a reduced burden on both affected facilities (in terms 

of reduced manpower to respond to data collection requests) and 

the EPA (in terms of preparing and distributing data collection 

requests and assessing the results).

State, local and tribal agencies could also benefit from 

more streamlined and accurate review of electronic data 

submitted to them. The ERT would allow for an electronic review 

process rather than a manual data assessment making review and 

evaluation of the source provided data and calculations easier 

and more efficient. Finally, another benefit of the proposed 

data submittal to WebFIRE electronically is that these data 

would greatly improve the overall quality of existing and new 

emissions factors by supplementing the pool of emissions test 

data for establishing emissions factors and by ensuring that the 

factors are more representative of current industry operational 

procedures. A common complaint heard from industry and 

regulators is that emission factors are outdated or not 

representative of a particular source category. With timely 

receipt and incorporation of data from most performance tests, 

the EPA would be able to ensure that emission factors, when 

updated, represent the most current range of operational 
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practices. In summary, in addition to supporting regulation 

development, control strategy development and other air 

pollution control activities, having an electronic database 

populated with performance test data would save industry, state, 

local, tribal agencies and the EPA significant time, money and 

effort while also improving the quality of emission inventories 

and, as a result, air quality regulations.

IV. Analytical Results and Proposed Decisions for Group IV 

Polymers and Resins Source Categories

A. Acrylonitrile butadiene styrene resin (ABS)

1. What are the results of the risk assessments?

a. Inhalation Risk Assessment Results

Table 3 provides an overall summary of the inhalation risk 

assessment results for the source category.

Table 3. ABS Inhalation Risk Assessment Results

Number of 

Facilities1

Maximum

individual

cancer risk

(in 1 million)2 Population

at risk ≥ 

1-in-1 

million

Annual

cancer

incidence 

(cases 

per year)

Maximum

chronic noncancer

TOSHI3 Maximum offsite acute 

noncancer 

HQ4

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

5 30 30 32,000 0.003 0.2 0.2

HQREL = 2 

acetaldehyde

HQERPG-1 = 

0.04 

acetaldehyde

1 Number of facilities evaluated in the risk analysis.

2 Maximum individual excess lifetime cancer risk.

3 Maximum TOSHI. The target organ with the highest TOSHI for the ABS source 

category is the reproductive system. 

4 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 
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REL. When HQ values exceed 1, we also show HQ values using the next lowest 

available dose-response value. See section III.B.3 of this preamble for 

explanation of acute dose-response values.

The inhalation risk modeling was performed using actual 

emissions level data. As shown in Table 3, the results of the 

inhalation risk assessment indicated the maximum lifetime 

individual cancer risk could be up to 30-in-1 million, the 

maximum chronic noncancer TOSHI value could be up to 0.2, and 

the maximum off-facility site acute HQ value could be up to 2, 

based on the actual emissions level and the REL value for 

acetaldehyde. The total estimated national cancer incidence from 

these facilities, based on actual emission levels, is 0.003 

excess cancer cases per year or one case in every 333 years.

Based on our analysis, we believe that actual emissions 

approximate emissions allowable under the MACT standards. 

Therefore, the risk results for MACT-allowable emissions are 

approximately equal to those for actual emissions. For more 

detail about this estimate of the ratio of actual to MACTallowable emissions and the estimation of MACT-allowable 

emission levels and associated risks and impacts, see the 

memorandum, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, in the docket for this rulemaking.

There were no reported emissions of PB–HAP; therefore, we 

do not expect potential for human health multipathway risks or 
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adverse environmental impacts as a result of PB-HAP.

b. Facility-wide Risk Assessment Results

Table 4 displays the results of the facility-wide risk 

assessment. This assessment was conducted based on actual 

emission levels. For detailed facility-specific results, see 

Appendix 4 of the Draft Residual Risk Assessment for 7 Source 

Categories in the docket for this rulemaking.

Table 4. ABS Facility-Wide Risk Assessment Results

Number of facilities analyzed 5

Cancer Risk:

 Estimated maximum facilitywide individual cancer risk (in 

1 million)

30

 Number of facilities with 

estimated facility-wide 

individual cancer risk of 100-

in-1 million or more

0

 Number of facilities at 

which the ABS source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risks of 100-in-1 

million or more

0

 Number of facilities at 

which the ABS source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risk of 1-in-1 million 

or more

4

Chronic Noncancer Risk:

 Maximum facility-wide 

chronic noncancer TOSHI

<1
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 Number of facilities with 

facility-wide maximum noncancer 

TOSHI greater than 1

0

 Number of facilities at 

which the ABS source category 

contributes 50 percent or more 

to the facility-wide maximum 

noncancer TOSHI of 1 or more

0

The facility-wide MIR from all HAP emissions at a facility 

that contains sources subject to the Group IV Polymers and 

Resins MACT standards for ABS resins is estimated to be 30-in-1 

million, based on actual emissions. Of the 5 facilities included 

in this analysis, none have a facility-wide MIR of 100-in-1 

million. There are 4 facilities with facility-wide MIR of 1-in-1 

million or greater (MIR ranging from 10 to 30 in a million). 

Each of these facilities has ABS production operations that 

contribute greater than 50 percent to the facility-wide risks. 

The facility-wide maximum individual chronic noncancer 

TOSHI is estimated to be less than 1, based on actual emissions. 

Of the 5 facilities included in this analysis, none have 

facility-wide maximum chronic noncancer TOSHI values greater 

than 1. 

c. What is our proposed decision regarding risk acceptability?

As noted in section III.C of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the number of persons in various cancer and 
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noncancer risk ranges; cancer incidence; the maximum noncancer 

HI; the maximum acute noncancer HQ; the extent of noncancer 

risks; the potential for adverse environmental effects; 

distribution of cancer and noncancer risks in the exposed 

population; and risk estimation uncertainty (54 FR 38044, 

September 14, 1989).

For the ABS source category, the risk analysis we performed 

indicates that the cancer risks to the individual most exposed 

could be up to 30-in-1 million due to both actual and allowable 

emissions. This value is considerably less than 100-in-1 

million, which is the presumptive level of acceptability. The 

risk analysis also shows low cancer incidence (1 in every 333 

years), no potential for human health multipathway effects, and 

that chronic noncancer health impacts are unlikely. 

We estimate that the worst-case acute HQ value could exceed 

a value of 1 for one HAP, acetaldehyde, with a potential maximum 

HQ up to 2 based on the acute REL dose-response value. Only one 

of the five facilities in this source category had an estimated 

HQ greater than 1 (REL of 2 for acetaldehyde). All other 

facilities modeled had an HQ less than 1. The maximum HQ based 

on an AEGL-1 or ERPG-1 dose-response value is 0.04 for 

acetaldehyde based on the ERPG-1. As described earlier in this 

preamble, the acute assessment includes some conservative 

assumptions and some uncertainties. Moreover, the REL are 
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protective and designed to protect the most sensitive 

individuals in the population by inclusion of margins of safety 

and exposures above the REL do not necessarily indicate that 

adverse effects will occur. Considering the improbable 

assumption that worst-case meteorological conditions are present 

at the same time that maximum hourly emissions of acetaldehyde 

exceed the average hourly emission rate by a factor of 10 at all 

emission points simultaneously, coincident with individuals 

being in the location of maximum impact, and considering the low 

acute HQ values based on the AEGL-1 and ERPG-1 dose-response 

values collectively with the REL value, we believe it is 

unlikely that HAP emissions from this source category would 

result in acute health effects.

Our additional analysis of facility-wide risks showed that 

the maximum facility-wide cancer risk is 30-in-1 million and 

that the maximum chronic exposures are expected to be without 

appreciable risk of adverse noncancer health effects.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the risks from the ABS source category are 

acceptable. 

d. What is our proposed decision regarding ample margin of 

safety?
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We considered whether the MACT standards provide an ample 

margin of safety to protect public health. In this analysis, we 

investigated available emissions control options that might 

reduce the risk associated with emissions from the source 

category and considered this information along with all of the 

health risks and other health information considered in the risk 

acceptability determination.

For the ABS source category, we identified only one control 

option to further address risks from equipment leaks. This 

control option would require sources to install leakless valves 

to prevent leaks from those components. While approximately 15 

percent of the emissions from this source category are due to 

equipment leaks, these emissions do not contribute to the 

maximum individual cancer risks estimated for the source 

category.

We estimated HAP reduction resulting from this control 

option is approximately 6 tpy from the baseline actual emissions 

level. We estimated that achieving these reductions would 

involve a capital cost of approximately $11,000,000, a total 

annualized cost of about $1,500,000 and a cost effectiveness of 

$244,000 per ton of HAP emissions reduced. The additional 

control requirement would not achieve a reduction in the maximum 

individual cancer risks. We estimate that the MACT allowable 

emissions from this source category are approximately equal to 
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the reported, actual emissions. Therefore, the estimated 

emission reduction, risk reduction and costs discussed above 

would also be applicable to the MACT allowable emissions level. 

We believe that the costs of this option are not reasonable, 

given the level of emission and risk reduction.

In accordance with the approach established in the Benzene 

NESHAP, the EPA weighed all health risk measures and information 

considered in the risk acceptability determination, along with 

the costs and economic impacts of emissions controls, 

technological feasibility, uncertainties and other relevant 

factors in making our ample margin of safety determination. 

Considering the health risk information and the unreasonable 

cost effectiveness of the option identified, we propose that the 

existing MACT standards provide an ample margin of safety to 

protect public health and prevent an adverse environmental 

effect.

2. What are the results of the technology review?

In the decade since the Group IV Polymers and Resins MACT 

standards were promulgated, the EPA has developed 19 air toxics 

regulations for source categories that emit organic HAP from the 

same type of emissions sources that are present in the five 

Group IV Polymers and Resins source categories addressed in this 

proposed action. We reviewed the regulatory requirements and/or 

technical analyses for these 19 regulations for new practices, 
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processes and control technologies. We also conducted a search 

of the RBLC for controls for VOC-SOCMI categories with permits 

dating back to 1997. 

We identified no advancements in practices, processes, and 

control technologies applicable to the emission sources in the 

Group IV Polymers and Resins source categories in our technology 

review.

3. What other actions are we proposing?

a. SSM Provisions

We are proposing to eliminate the SSM exemption in the 

Group IV Polymers and Resins MACT standards. Consistent with 

Sierra Club v. EPA, the EPA is proposing that standards in this 

rule would apply at all times. We are proposing several 

revisions to 40 CFR part 63, subpart JJJ. Specifically, we are 

proposing to revise Table 1 to indicate that the requirements of 

40 CFR 63.6(e) of the General Provisions do not apply. The 40 

CFR 63.6(e) requires the owner or operator to act according to 

the general duty to “operate and maintain any affected source, 

including associated air pollution control equipment and 

monitoring equipment, in a manner consistent with safety and 

good air pollution control practices for minimizing emissions.” 

We are separately proposing to incorporate this general duty to 

minimize into 40 CFR 63.1310(j)(4). The 40 CFR 63.6(e) also 

requires the owner or operator of an affected source to develop 
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a written SSM plan. We are proposing to remove the SSM plan 

requirement. We are proposing to remove the explanation of 

applicability of emissions standards during periods SSM in 40 

CFR 63.1310(j); remove the malfunction plan from 40 CFR 

63.1335(b); clarify that representative conditions do not 

include periods of SSM throughout the rule; remove references to 

periods of SSM in monitoring; remove the provisions for excused 

excursions from 40 CFR 63.1334(g); and revise the SSM-associated 

recordkeeping and reporting requirements in 40 CFR 63.1335(b) to 

require reporting and recordkeeping for periods of malfunction. 

We are also proposing to revise Table 1 to indicate that SSMrelated provisions in 40 CFR 63.6(e)(1), 63.6(e)(3), 63.6(f)(1); 

40 CFR 63.7(e)(1); 40 CFR 63.8(c)(1); and 40 CFR 63.10(d)(5) of 

the General Provisions do not apply. We are also proposing to 

add requirements in 40 CFR 63.1331(a)(9)) to clarify that PRD 

releases to the atmosphere are violations of the emissions 

standards and to require pressure release alarms and to add 

requirements in 40 CFR 63.1335(e)(9) to require reporting of any 

pressure device releases to the atmosphere with the periodic 

report. In addition, we are proposing to promulgate an 

affirmative defense against civil penalties for exceedances of 

emission standards caused by malfunctions, as well as criteria 

for establishing the affirmative defense.

b. Electronic Reporting
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To increase the ease and efficiency of data submittal and 

improve data accessibility, we are proposing to require the 

submission of electronic copies of required performance tests 

for test methods that are supported by the ERT to EPA’s WebFIRE 

database. These provisions are added in 40 CFR 63.1335(e)(10).

B. Styrene acrylonitrile resin (SAN)

1. What are the results of the risk assessments?

a. Inhalation Risk Assessment Results

Table 5 provides an overall summary of the inhalation risk 

assessment results for the source category.

Table 5. SAN Inhalation Risk Assessment Results

Number of 

Facilities1

Maximum

individual

cancer risk

(in 1 million)2 Population

at risk ≥ 

1-in-1 

million

Annual

cancer

incidence 

(cases 

per year)

Maximum

chronic noncancer

TOSHI3

Maximum 

off-site 

acute 

noncancer 

HQ4

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

2 0.03 0.03 0 0.000006 0.0002 0.0002

HQREL = 

0.007 

methylene 

chloride

1 Number of facilities evaluated in the risk analysis.

2 Maximum individual excess lifetime cancer risk.

3 Maximum TOSHI. The target organ with the highest TOSHI for the SAN source 

category is the respiratory system. 

4 The maximum estimated acute exposure concentration was divided by available 

short-term threshold values to develop an array of HQ values. HQ values shown 

use the lowest available acute threshold value, which, in most cases, is the 

REL. When HQ values exceed 1, we also show HQ values using the next lowest 

available acute dose-response value. See section III.B.3 of this preamble for 

explanation of acute dose-response values.

The inhalation risk modeling was performed using actual 

emissions level data. As shown in Table 5, the results of the 
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inhalation risk assessment indicated the maximum lifetime 

individual cancer risk could be up to 0.03-in-1 million, the 

maximum chronic noncancer TOSHI value could be up to 0.0002, and 

the maximum off-facility site acute HQ value could be up to

0.007, based on the actual emissions level and the REL value for 

methylene chloride. The total estimated national cancer 

incidence from these facilities based on actual emission levels 

is 0.000006 excess cancer cases per year or one case in every 

166,666 years.

Based on our analysis, we believe that actual emissions 

approximate emissions allowable under the MACT standards. 

Therefore, the risk results for MACT-allowable emissions are 

approximately equal to those for actual emissions. For more 

detail about this estimate of the ratio of actual to MACTallowable emissions and the estimation of MACT-allowable 

emission levels and associated risks and impacts, see the 

memorandum, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, in the docket for this rulemaking.

There were no reported emissions of PB–HAP; therefore, we 

do not expect potential for human health multipathway risks or 

adverse environmental impacts as a result of PB-HAP.

b. Facility-wide Risk Assessment Results

Table 6 displays the results of the facility-wide risk 
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assessment. This assessment was conducted based on actual 

emission levels. For detailed facility-specific results, see 

Appendix 4 of the Draft Residual Risk Assessment for 7 Source 

Categories in the docket for this rulemaking.

Table 6. SAN Facility-Wide Risk Assessment Results

Number of facilities analyzed 2

Cancer Risk:

 Estimated maximum facilitywide individual cancer risk (in 

1 million)

20

 Number of facilities with 

estimated facility-wide 

individual cancer risk of 100-

in-1 million or more

0

 Number of facilities at 

which the SAN source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risks of 100-in-1 

million or more

0

 Number of facilities at 

which the SAN source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risk of 1-in-1 million 

or more

0

Chronic Noncancer Risk:

 Maximum facility-wide 

chronic noncancer TOSHI

2

 Number of facilities with 

facility-wide maximum noncancer 

TOSHI greater than 1

1

 Number of facilities at 

which the SAN source category 

contributes 50 percent or more 

0
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to the facility-wide maximum 

noncancer TOSHI of 1 or more

The facility-wide MIR from all HAP emissions at a facility 

that contains sources subject to the Group IV Polymers and 

Resins MACT standards for SAN resins is estimated to be 20-in-1 

million, based on actual emissions. Of the 2 facilities included 

in this analysis, none have a facility-wide MIR of 100-in-1 

million. There are 2 facilities with facility-wide MIR of 1-in-1 

million or greater (MIR of 20 and 10 in a million). Neither of 

these facilities have SAN production operations that contribute 

greater than 50 percent to the facility-wide risks. 

The facility-wide maximum individual chronic noncancer 

TOSHI is estimated to be 2, based on actual emissions. Of the 2 

facilities included in this analysis, only one facility has a 

facility-wide maximum chronic noncancer TOSHI value greater than 

1 (TOSHI of 2).

c. What is our proposed decision regarding risk acceptability?

As noted in section III.C of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the number of persons in various cancer and 

noncancer risk ranges; cancer incidence; the maximum noncancer 

HI; the maximum acute noncancer HQ; the extent of noncancer 

risks; the potential for adverse environmental effects; 

distribution of cancer and noncancer risks in the exposed 
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population; and risk estimation uncertainty (54 FR 38044, 

September 14, 1989).

For the SAN source category, the risk analysis we performed 

indicates that the cancer risks to the individual most exposed 

could be up to 0.03-in-1 million due to both actual and 

allowable emissions. This value is less than 1-in-1 million. The 

risk analysis also shows low cancer incidence (1 in every 

166,666 years), no potential for human health multipathway 

effects and that chronic noncancer and acute health effects are 

unlikely.

Our additional analysis of facility-wide risks showed that 

the maximum facility-wide cancer risk is 20-in-1 million. The 

maximum chronic noncancer TOSHI is estimated to be 2, but the 

source category contributes less than 1 percent to the maximum 

facility-wide TOSHI.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the risks from the SAN source category are 

acceptable.

d. What is our proposed decision regarding ample margin of 

safety?

The SAN source category emits HAP which are known, probable 

or possible carcinogens. The EPA evaluated the emissions of 
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these HAP and determined that the cancer risks to the individual 

most exposed are less than 1-in-1 million. Our analysis 

demonstrated that chronic noncancer risks are expected to be 

low, based on actual and MACT allowable emissions. We determined 

that emissions from the SAN source category would result in a 

chronic noncancer TOSHI less than 1 and an acute HQ less than 1 

for the individual most exposed. The EPA undertook further 

analysis to assess whether environmental effects might result 

from emissions from this source category. We assume that human 

toxicity values for the inhalation pathway are generally 

protective of terrestrial mammals and plants, and thus, we do 

not anticipate that actual or MACT allowable emissions would 

result in acute or chronic noncancer health effects to these 

mammals. While we believe this to be generally true, we 

acknowledge that there is some associated uncertainty with this 

assumption. In addition, this source category had no reported 

emissions of PB-HAP and, therefore, no potential for an adverse 

environment effect via multipathway exposures was identified as 

a result of PB-HAP.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the existing MACT standards for the SAN source 

category provide an ample margin of safety to protect public 
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health and prevent an adverse environmental effect.

2. What are the results of the technology review?

The results of the technology review for the Group IV 

Polymers and Resins MACT standards are discussed above in 

section IV.A.2. We identified no advancements in practices, 

processes, and control technologies applicable to the emission 

sources in the Group IV Polymers and Resins source categories in 

our technology review.

3. What other actions are we proposing?

a. SSM Provisions

The proposed changes to the SSM provisions for the Group IV 

Polymers and Resins MACT standards, which apply to the SAN 

source category, are discussed above in section IV.A.3.a.

b. Electronic Reporting

The proposed addition of electronic reporting requirements 

for performance tests for the Group IV Polymers and Resins MACT 

standards, which apply to the SAN source category, is discussed 

above in section IV.A.3.b.

C. Methyl methacrylate butadiene styrene resin (MBS)

1. What are the results of the risk assessments?

a. Inhalation Risk Assessment Results

Table 7 provides an overall summary of the inhalation risk 

assessment results for the source category.

Table 7. MBS Inhalation Risk Assessment Results
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Number of 

Facilities1

Maximum

individual

cancer risk

(in 1 million)2 Population

at risk ≥ 

1-in-1 

million

Annual

cancer

incidence 

(cases 

per year)

Maximum

chronic noncancer

TOSHI3

Maximum 

off-site 

acute 

noncancer 

HQ4

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

2 0.4 0.4 0 0.00003 0.007 0.007

HQERPG-1 = 

9 ethyl 

acrylate

HQAEGL-1 = 

0.01 

ethyl 

acrylate

1 Number of facilities evaluated in the risk analysis.

2 Maximum individual excess lifetime cancer risk.

3 Maximum TOSHI. The target organ with the highest TOSHI for the MBS source 

category is the reproductive system. 

4 The maximum estimated acute exposure concentration was divided by available 

short-term threshold values to develop an array of HQ values. HQ values shown 

use the lowest available acute threshold value, which, in most cases, is the 

REL. When HQ values exceed 1, we also show HQ values using the next lowest 

available acute threshold. For this source category, the maximum acute values 

were based on the ERPG-1 HQ for ethyl acrylate, and no REL value was 

available for this HAP. See section III.B.3 of this preamble for explanation 

of acute dose-response values.

The inhalation risk modeling was performed using actual 

emissions level data. As shown in Table 7, the results of the 

inhalation risk assessment indicated the maximum lifetime 

individual cancer risk could be up to 0.4-in-1 million, the 

maximum chronic noncancer TOSHI value could up to 0.007 and the 

maximum off-facility site acute HQ value could be up to 9, based 

on the actual emissions level and the ERPG-1 value for ethyl 

acrylate. The total estimated national cancer incidence from 

these facilities, based on actual emission levels is 0.00003 

excess cancer cases per year or one case in every 33,333 years.

Based on our analysis, we believe that actual emissions 
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approximate emissions allowable under the MACT standards. 

Therefore, the risk results for MACT-allowable emissions are 

approximately equal to those for actual emissions. For more 

detail about this estimate of the ratio of actual to MACTallowable emissions and the estimation of MACT-allowable 

emission levels and associated risks and impacts, see the 

memorandum, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, in the docket for this rulemaking.

There were no reported emissions of PB–HAP; therefore, we 

do not expect potential for human health multipathway risks or 

adverse environmental impacts as a result of PB-HAP.

b. Facility-wide Risk Assessment Results

Table 8 displays the results of the facility-wide risk 

assessment. This assessment was conducted based on actual 

emission levels. For detailed facility-specific results, see 

Appendix 4 of the Draft Residual Risk Assessment for 7 Source 

Categories in the docket for this rulemaking.

Table 8. MBS Facility-Wide Risk Assessment Results

Number of facilities analyzed 2

Cancer Risk:

 Estimated maximum facilitywide individual cancer risk (in 

1 million)

2

 Number of facilities with 

estimated facility-wide 

0
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individual cancer risk of 100-

in-1 million or more

 Number of facilities at 

which the MBS source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risks of 100-in-1 

million or more

0

 Number of facilities at 

which the MBS source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risk of 1-in-1 million 

or more

0

Chronic Noncancer Risk:

 Maximum facility-wide 

chronic noncancer TOSHI

<1

 Number of facilities with 

facility-wide maximum noncancer 

TOSHI greater than 1

0

 Number of facilities at 

which the MBS source category 

contributes 50 percent or more 

to the facility-wide maximum 

noncancer TOSHI of 1 or more

0

The facility-wide MIR from all HAP emissions at a facility 

that contains sources subject to the Group IV Polymers and 

Resins MACT standards for MBS resins is estimated to be 2-in-1 

million, based on actual emissions. Of the 2 facilities included 

in this analysis, none have a facility-wide MIR of 100-in-1 

million. There is 1 facility with a facility-wide MIR of 1-in-1 

million or greater (MIR of 2 in a million). The facility with an 

MIR greater than 1-in-1 million does not have MBS production 
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operations that contribute greater than 50 percent to the 

facility-wide risks.

The facility-wide maximum individual chronic noncancer 

TOSHI is estimated to be less than 1, based on actual emissions. 

Of the 2 facilities included in this analysis, neither have 

facility-wide maximum chronic noncancer TOSHI values greater 

than 1.

c. What is our proposed decision regarding risk acceptability?

As noted in section III.C of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the number of persons in various cancer and 

noncancer risk ranges; cancer incidence; the maximum noncancer 

HI; the maximum acute noncancer HQ; the extent of noncancer 

risks; the potential for adverse environmental effects; 

distribution of cancer and noncancer risks in the exposed 

population; and risk estimation uncertainty (54 FR 38044, 

September 14, 1989).

For the MBS source category, the risk analysis we performed 

indicates that the cancer risks to the individual most exposed 

could be up to 0.4-in-1 million due to both actual and allowable 

emissions. This value is less than 1-in-1 million. The risk 

analysis also shows low cancer incidence (1 in every 33,333 

years), no potential for human health multipathway effects and 

that chronic noncancer health impacts are unlikely.
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We estimate that the worst-case acute HQ value could exceed 

a value of 1 for one HAP, ethyl acrylate, with a potential 

maximum HQ up to 9 based on the acute ERPG-1 dose-response 

value. One of the two facilities in this source category had an 

estimated HQ greater than 1 (ERPG-1 of 9 for ethyl acrylate). 

All other facilities modeled had an HQ less than 1. The maximum 

HQ based on an AEGL-1 dose-response value is 0.01 for ethyl 

acrylate. For ethyl acrylate, the ERPG-1 value is indicative of 

the odor recognition threshold, while the AEGL-1 value is 

indicative of a level which could result in eye irritation. 

This suggests that, at this worst-case exposure level, a person 

might smell the pollutant, but not experience any eye 

irritation. As described earlier in this preamble, the acute 

assessment includes some conservative assumptions and some 

uncertainties. Considering the improbable assumption that worstcase meteorological conditions are present at the same time that 

maximum hourly emissions of ethyl acrylate exceed the average 

hourly emission rate by a factor of 10 at all emission points 

simultaneously, coincident with individuals being in the 

location of maximum impact and considering the low acute HQ 

value based on the AEGL-1 dose-response value collectively with 

the ERPG-1 value, we believe it is unlikely that HAP emissions 

from this source category would result in acute health effects.

Our additional analysis of facility-wide risks showed that 
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the maximum facility-wide cancer risk is 2-in-1 million and that 

the maximum chronic exposures are expected to be without 

appreciable risk of adverse noncancer health effects.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the risks from the MBS source category are 

acceptable.

d. What is our proposed decision regarding ample margin of 

safety?

The MBS source category emits HAP which are known, probable 

or possible carcinogens. The EPA evaluated the emissions of 

these HAP and determined that the cancer risks to the individual 

most exposed are less than 1-in-1 million. Our analysis 

demonstrated that chronic noncancer risks are expected to be 

low, based on actual and MACT allowable emissions. We determined 

that emissions from the MBS source category would result in a 

chronic noncancer TOSHI less than 1 for the individual most 

exposed. While the assessment for acute impacts suggests that 

short-term ethyl acrylate concentrations at one facility could 

exceed the ERPG-1 dose-response value, we believe it unlikely 

that acute impacts would occur due to the conservative 

assumptions and uncertainties associated with the acute 

analysis. These assumptions include having worst-case 
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meteorological conditions present at the same time that maximum 

hourly emissions of ethyl acrylate exceed the average hourly 

emission rate by a factor of 10, coincident with individuals 

being in the location of maximum impact. The EPA undertook 

further analysis to assess whether environmental effects might 

result from emissions from this source category. We assume that 

human toxicity values for the inhalation pathway are generally 

protective of terrestrial mammals and plants and, thus, we do 

not anticipate that actual or MACT allowable emissions would 

result in acute or chronic noncancer health effects to these 

mammals. While we believe this to be generally true, we 

acknowledge that there is some associated uncertainty with this 

assumption. In addition, this source category had no reported 

emissions of PB-HAP and, therefore, no potential for an adverse 

environmental effect via multipathway exposures was identified.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the existing MACT standards for the MBS source 

category provide an ample margin of safety to protect public 

health and prevent an adverse environmental effect.

2. What are the results of the technology review?

The results of the technology review for the Group IV 

Polymers and Resins MACT standards are discussed above in 
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section IV.A.2. We identified no advancements in practices, 

processes and control technologies applicable to the emission 

sources in the Group IV Polymers and Resins source categories in 

our technology review.

3. What other actions are we proposing?

a. SSM Provisions

The proposed changes to the SSM provisions for the Group IV 

Polymers and Resins MACT standards, which apply to the MBS 

source category, are discussed above in section IV.A.3.a.

b. Electronic Reporting

The proposed addition of electronic reporting requirements 

for performance tests for the Group IV Polymers and Resins MACT 

standards, which apply to the MBS source category, are discussed 

above in section IV.A.3.b.

D. Polystyrene resin

1. What are the results of the risk assessments?

a. Inhalation Risk Assessment Results

Table 9 provides an overall summary of the inhalation risk 

assessment results for the source category.

Table 9. Polystyrene Resins Inhalation Risk Assessment Results

Number of 

Facilities1

Maximum

individual

cancer risk

(in 1 million)2 Population

at risk ≥ 

1-in-1 

million

Annual

cancer

incidence 

(cases 

per year)

Maximum

chronic noncancer

TOSHI3

Maximum 

off-site 

acute 

noncancer 

HQ4

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

Actual 

Emissions 

Level

Allowable 

Emissions 

Level
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11 2 2 180 0.00003 0.004 0.004

HQREL = 

0.3 

styrene

1 Number of facilities evaluated in the risk analysis.

2 Maximum individual excess lifetime cancer risk.

3 Maximum TOSHI. The target organ with the highest TOSHI for the polystyrene 

resin source category is the nervous system. 

4 The maximum estimated acute exposure concentration was divided by available 

short-term threshold values to develop an array of HQ values. HQ values shown 

use the lowest available acute threshold value, which, in most cases, is the 

REL. When HQ values exceed 1, we also show HQ values using the next lowest 

available acute dose-response value. See section III.B.3 of this preamble for 

explanation of acute dose-response values.

The inhalation risk modeling was performed using actual 

emissions level data. As shown in Table 9, the results of the 

inhalation risk assessment indicated the maximum lifetime 

individual cancer risk could be up to 2-in-1 million, the 

maximum chronic noncancer TOSHI value could be up to 0.004, and 

the maximum off-facility site acute HQ value could be up to 0.3, 

based on the actual emissions level and the REL value for 

styrene. The total estimated national cancer incidence from 

these facilities, based on actual emission levels, is 0.00003 

excess cancer cases per year, or one case in every 33,333 years.

Based on our analysis, we believe that actual emissions 

approximate emissions allowable under the MACT standards. 

Therefore, the risk results for MACT-allowable emissions are 

approximately equal to those for actual emissions. For more 

detail about this estimate of the ratio of actual to MACTallowable emissions and the estimation of MACT-allowable 

emission levels and associated risks and impacts, see the 
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memorandum, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, in the docket for this rulemaking.

There were no reported emissions of PB–HAP; therefore, we 

do not expect potential for human health multipathway risks or 

adverse environmental impacts as a result of PB-HAP.

b. Facility-wide Risk Assessment Results

Table 10 displays the results of the facility-wide risk 

assessment. This assessment was conducted based on actual 

emission levels. For detailed facility-specific results, see 

Appendix 4 of the Draft Residual Risk Assessment for 7 Source 

Categories in the docket for this rulemaking.

Table 10. Polystyrene Resins Facility-Wide Risk Assessment 

Results

Number of facilities analyzed 11

Cancer Risk:

 Estimated maximum facilitywide individual cancer risk (in 

1 million)

10

 Number of facilities with 

estimated facility-wide 

individual cancer risk of 100-

in-1 million or more

0

 Number of facilities at 

which the polystyrene resin 

source category contributes 50 

percent or more to the 

facility-wide individual cancer 

risks of 100-in-1 million or 

more

0
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 Number of facilities at 

which the polystyrene resin 

source category contributes 50 

percent or more to the 

facility-wide individual cancer 

risk of 1-in-1 million or more

1

Chronic Noncancer Risk:

 Maximum facility-wide 

chronic noncancer TOSHI

<1

 Number of facilities with 

facility-wide maximum noncancer 

TOSHI greater than 1

0

 Number of facilities at 

which the Polystyrene Resin 

source category contributes 50 

percent or more to the 

facility-wide maximum noncancer 

TOSHI of 1 or more

0

The facility-wide MIR from all HAP emissions at a facility 

that contains sources subject to the Group IV Polymers and 

Resins MACT standards for polystyrene resins is estimated to be 

10-in-1 million, based on actual emissions. Of the 11 facilities 

included in this analysis, none have a facility-wide MIR of 100-

in-1 million. There are 2 facilities with facility-wide MIR of 

1-in-1 million or greater (MIR of 10 and 2 in a million). One of 

these facilities has polystyrene resin production operations 

that contribute greater than 50 percent to the facility-wide 

risks.

The facility-wide maximum individual chronic noncancer 

TOSHI is estimated to be less than 1, based on actual emissions. 
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Of the 11 facilities included in this analysis, none have 

facility-wide maximum chronic noncancer TOSHI values greater 

than 1.

c. What is our proposed decision regarding risk acceptability?

As noted in section III.C of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the number of persons in various cancer and 

noncancer risk ranges; cancer incidence; the maximum noncancer 

HI; the maximum acute noncancer HQ; the extent of noncancer 

risks; the potential for adverse environmental effects; 

distribution of cancer and noncancer risks in the exposed 

population; and risk estimation uncertainty (54 FR 38044, 

September 14, 1989).

For the Polystyrene Resin source category, the risk 

analysis we performed indicates that the cancer risks to the 

individual most exposed could be up to 2-in-1 million due to 

both actual and allowable emissions. This value is considerably 

less than 100-in-1 million, which is the presumptive level of 

acceptability. The risk analysis also shows low cancer incidence 

(1 in every 33,333 years), no potential for human health 

multipathway effects and that acute and chronic noncancer health 

impacts are unlikely.

Our additional analysis of facility-wide risks showed that 

the maximum facility-wide cancer risk is 10-in-1 million and 
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that the maximum chronic exposures are expected to be without 

appreciable risk of adverse noncancer health effects.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the risks from the Polystyrene Resin source 

category are acceptable.

d. What is our proposed decision regarding ample margin of 

safety?

We considered whether the MACT standards provide an ample 

margin of safety to protect public health. In this analysis, we 

investigated available emissions control options that might

reduce the risk associated with emissions from the source 

category and considered this information along with all of the 

health risks and other health information considered in the risk 

acceptability determination.

For the Polystyrene Resin source category, we identified 

only one control option to further address risks from equipment 

leaks, which were shown to contribute 100 percent to the maximum 

individual cancer risks for this source category. This control 

option would require sources to install leakless valves to 

prevent leaks from those components.

We estimated HAP reduction resulting from this control 

option is approximately 5 tpy from the baseline actual emissions 
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level. We estimated that achieving these reductions would 

involve a capital cost of approximately $9,000,000, a total 

annualized cost of about $1,300,000 and a cost effectiveness of 

$244,000 per ton of HAP emissions reduced. The additional 

control requirement would achieve approximately 20-percent 

reduction in baseline risks at a very high cost. We estimate 

that the MACT allowable emissions from this source category are 

approximately equal to the reported, actual emissions. 

Therefore, the estimated emission reduction, risk reduction and 

costs discussed above would also be applicable to the MACT 

allowable emissions level. We believe that the costs of this 

option are not reasonable, given the level of emission and risk 

reduction.

In accordance with the approach established in the Benzene 

NESHAP, the EPA weighed all health risk measures and information 

considered in the risk acceptability determination, along with 

the costs and economic impacts of emissions controls, 

technological feasibility, uncertainties and other relevant 

factors in making our ample margin of safety determination. 

Considering the health risk information and the unreasonable 

cost effectiveness of the option identified, we propose that the 

existing MACT standards provide an ample margin of safety to 

protect public health and prevent an adverse environmental 

effect.
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2. What are the results of the technology review?

The results of the technology review for the Group IV 

Polymers and Resins MACT standards are discussed above in 

section IV.A.2. We identified no advancements in practices, 

processes and control technologies applicable to the emission 

sources in the Group IV Polymers and Resins source categories in 

our technology review.

3. What other actions are we proposing?

a. SSM Provisions

The proposed changes to the SSM provisions for the Group IV 

Polymers and Resins MACT standards, which apply to the 

polystyrene resin source category, are discussed above in 

section IV.A.3.a.

b. Electronic Reporting

The proposed addition of electronic reporting requirements 

for performance tests for the Group IV Polymers and Resins MACT 

standards, which apply to the polystyrene resin source category, 

are discussed above in section IV.A.3.b.

E. Poly (ethylene terephthalate) resin (PET)

1. What are the results of our analyses and proposed decisions 

regarding unregulated HAP and/or emissions sources?

a. Equipment leaks

We identified the absence of a limit for a potentially 

significant emissions source within the provisions of the Group 
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IV Polymers and Resins MACT standards that apply to the PET 

continuous TPA high viscosity multiple end finisher subcategory. 

Specifically, there are no regulations for equipment leaks for 

this source subcategory.22 As these processes are potentially 

major sources of emissions for the one facility in the source 

category, we are proposing to set a work practice standard for 

equipment leaks under CAA section 112(d)(2) and (d)(3) in this 

action. CAA section 112(h)(1) states that the Administrator may 

prescribe a work practice standard or other requirements, 

consistent with the provisions of CAA sections 112(d) or (f), in 

those cases where, in the judgment of the Administrator, it is 

not feasible to enforce an emission standard. CAA section 

112(h)(2) defines the phrase “not feasible to prescribe or 

enforce an emission standard” as follows:

[A]ny situation in which the Administrator determines that 

(A) a hazardous air pollutant or pollutants cannot be 

emitted through a conveyance designed and constructed to 

emit or capture such pollutant, or that any requirement 

for, or use of, such a conveyance would be inconsistent 

with any Federal, State, or local law, or (B) the 

application of measurement methodology to a particular 

 

22 Note that these uncontrolled emissions were included in the 

risk assessment for the PET source category.
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class of sources is not practicable due to technological 

and economic limitations.

The work practice standards in this proposed rule are 

consistent with CAA section 112(h)(2)(B), because applying a 

measurement methodology to this class of sources is not

technologically and economically feasible due to the number of 

openings and possible emissions points and because the fugitive 

emissions cannot be routed to a conveyance designed to capture 

such emissions.

As there is only one facility in the source subcategory, 

the emissions level currently being achieved by this facility 

represents the MACT floor. However, emissions from equipment 

leaks are intermittent and fugitive in nature and, therefore, it 

is not feasible to fully measure the mass emission rate from

numerous potential leaks at this facility or to route such 

emissions through a conveyance designed and constructed to emit 

or capture such fugitive pollutants. For this reason, under CAA 

section 112(h), we are proposing to establish the MACT floor for 

this source subcategory, based on the work practices this 

facility currently performs to limit emissions from equipment 

leaks. The work practices this facility follows are to perform a 

2- to 3-hour leak check upon startup following an outage where 

changes have been made to the facility’s esterification 

equipment, which is the only area of the facility that has 
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equipment in gas/vapor service. This is conducted by introducing 

hot ethylene g1yco1 vapors into the system. Any leaks identified 

are repaired by tightening flange bolts before introducing new 

materials into the process. The other equipment components at 

the facility are in vacuum or heavy liquid service, which are 

not monitored due to the low vapor pressure of predominant HAP, 

ethylene glycol and the low potential for equipment leak 

emissions from these components.

As part of our beyond-the-floor analysis, we considered 

alternatives more stringent than the MACT floor option. We 

identified the HON LDAR program as one such option, which is the 

required level of control for other facilities subject to the 

Group IV Polymers and Resins MACT standards. The HON requires 

the use of sensory monitoring for pumps, valves, agitators and 

connectors in heavy liquid service; the use of EPA Method 21 of 

40 CFR part 60, Appendix A, for instrument monitoring of 

equipment in gas/vapor service; and equipment in vacuum service 

is not required to be monitored. Based on previous information 

prepared to examine the equipment leak costs for facilities in 

the PET source category,23 the capital costs of this option are 

estimated to be approximately $13,000 and the total annual costs 

 

23 Memorandum to Group IV Resins Docket, A-92-45, from Ken 

Meardon, Pacific Environmental Services, Inc. Re-Evaluation of 

Equipment Leak Emissions and Costs at PET Facilities.
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are estimated to be approximately $13,000. The estimated HAP 

decrease is 1.27 tpy, with a cost effectiveness of approximately 

$11,000/ton. Table 11 summarizes the cost and emission reduction 

impacts of the proposed options. Because the HAP reduced would 

be ethylene glycol, which does not contribute to the cancer risk 

estimate for the PET source category, the MIR for the source 

category would remain at 9. Any impact on the magnitude of the 

HI resulting from ethylene glycol emission reductions due to 

this control option would be negligible as ethylene glycol 

contributes minimally to the chronic noncancer TOSHI of 0.5. 

These risk values are discussed further in section IV.E.2 below.

Table 11. PET Continuous TPA High Viscosity Equipment Leaks 

Options Impacts

Regulatory 

alternatives

HAP 

emissions 

(tpy)

Capital 

cost ($)

Annual cost 

($)

Cost 

effectiveness 

($/ton HAP 

removed)

Baseline 1.43 ----- ----- -----

1 (MACT 

floor) 1.43 0 0 -----

2 (Beyondthe-floor) 0.16 13,000 13,000 11,000

We believe that the costs of this beyond-the-floor option 

are not reasonable, given the level of emission reduction. 

Therefore, we are proposing an emission standard that reflects 

the MACT floor option, which is a work practice standard.

We are requesting comment on this analysis and these

options.
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b. Changes to PCCT Provisions in Response to a Petition for 

Reconsideration

We identified a potentially significant emissions source 

that is currently effectively unregulated within the provisions 

of the Group IV Polymers and Resins MACT standards that apply to 

the sources producing PET using the continuous TPA high 

viscosity multiple end finisher process. Specifically, sources 

have not been required to comply with the previously promulgated 

provisions addressing emissions from PCCT within this source 

subcategory. We originally promulgated standards for PCCT in 

this subcategory in the September 12, 1996, Federal Register

publication of NESHAP for Group IV Polymer and Resin source 

categories. On August 29, 2000, the EPA took action to 

indefinitely stay the compliance date for the PCCT provisions 

for this subcategory because the EPA was in the process of 

responding to a request to reconsider portions of the Group IV 

Polymers and Resins MACT standards that could result in changes 

to the emission limitation for PCCT in this subcategory (65 FR 

52319-23). As PCCT are potentially major sources of emissions 

for the one facility in the PET continuous TPA high viscosity 

multiple end finisher subcategory, we have reconsidered the 

emissions and cost data available and we are proposing MACT 

standards for PCCT under CAA section 112(d)(2) and (d)(3) in 

this action.
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As there is only one facility in the source subcategory, 

the emissions level currently being achieved by this facility 

represents the MACT floor. The facility is currently regulated 

by the Polymers Manufacturing New Source Performance Standards, 

which requires the facility to maintain an ethylene glycol 

concentration in the PCCT at or below 6.0 percent by weight, 

averaged on a daily basis over a rolling 14-day period of 

operating days. We are proposing to establish the MACT floor for 

this source subcategory, based on the 6.0 percent by weight 

ethylene glycol concentration limit this facility is required to 

achieve.

As part of our beyond-the-floor analysis, we considered 

alternatives more stringent than the MACT floor option. The 

original PCCT regulations promulgated in the Group IV Polymer 

and Resin NESHAP established an ethylene glycol concentration 

limit of 4.0 percent by weight for PCCT in this source 

subcategory, based on the information available on controls and 

costs, but the source has never been required to achieve this 

limit, in light of our August 29, 2000, indefinite stay of the 

compliance date. We identified this 4.0-percent concentration 

limit as a beyond-the-floor option for our revised analysis. To 

achieve the beyond-the-floor option, the facility would need to 

modify its existing ethylene glycol recovery system and increase 

the amount of steam used to strip ethylene glycol from the 
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contaminated water. Based on information received from the only 

facility in the subcategory after promulgation of the Group IV 

Polymers and Resins MACT standards, the capital costs of this 

option are estimated to be approximately $8.7 million and the 

total annual costs are estimated to be approximately $4.2 

million. The estimated HAP decrease is 49.0 tpy, with a cost 

effectiveness of approximately $86,000/ton. Table 12 summarizes 

the cost and emission reduction impacts of the proposed options. 

Because the HAP reduced would be ethylene glycol, which does not 

contribute to the cancer risk estimate for the PET source 

category, the MIR for the source category would remain at 9. Any 

impact on the magnitude of the HI resulting from ethylene glycol 

emission reductions due to this control option would be 

negligible as ethylene glycol contributes minimally to the

chronic noncancer TOSHI of 0.5. These risk values are discussed 

further in section IV.E.2 below. Further information regarding 

this analysis can be found in the memorandum, Impacts Assessment 

for Process Contact Cooling Towers for the PET Continuous TPA 

High Viscosity Multiple End Finisher Subcategory, available in 

the docket for this action.

Table 12. PET Continuous TPA High Viscosity Multiple End 

Finisher Subcategory Process Contact Cooling Towers Options 

Impacts

Regulatory 

alternatives HAP 

emissions 

Capital 

cost ($)

Annual cost 

($)

Cost 

effectiveness 

($/ton HAP 
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(tpy) removed)

Baseline 147.0 ----- ----- -----

1 (MACT 

floor)

147.0 0 0 -----

2 (Beyondthe-floor)

98.0 8,800,000 4,200,000 86,000

We believe that the costs of this beyond-the-floor option 

are not reasonable, given the level of emission reduction. 

Therefore, we are proposing to re-set the previously stayed MACT 

standard as an emission standard that reflects the MACT floor 

option, which is the ethylene glycol concentration limit of 6.0 

weight percent.

We are requesting comment on this analysis and these 

options.

2. What are the results of the risk assessments?

a. Inhalation Risk Assessment Results

Table 13 provides an overall summary of the inhalation risk 

assessment results for the source category.

Table 13. PET Inhalation Risk Assessment Results

Number of 

Facilities1

Maximum

individual

cancer risk

(in 1 million)2 Population

at risk ≥ 

1-in-1 

million

Annual

cancer

incidence 

(cases 

per year)

Maximum

chronic noncancer

TOSHI3 Maximum offsite acute 

noncancer 

HQ4

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

15 9 9 4,200 0.002 0.5 0.5

HQREL = 8 

acetaldehyde

HQERPG-1 = 1 
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acetaldehyde

HQAEGL-1 = 0.2 

acetaldehyde

1 Number of facilities evaluated in the risk analysis.

2 Maximum individual excess lifetime cancer risk.

3 Maximum TOSHI. The target organ with the highest TOSHI for the PET source 

category is the respiratory system. 

4 The maximum estimated acute exposure concentration was divided by available 

short-term threshold values to develop an array of HQ values. HQ values shown 

use the lowest available acute threshold value, which, in most cases, is the 

REL. When HQ values exceed 1, we also show HQ values using the next lowest 

available acute dose-response value. See section III.B.3 of this preamble for 

explanation of acute dose-response values.

The inhalation risk modeling was performed using actual 

emissions level data. As shown in Table 13, the results of the 

inhalation risk assessment indicated the maximum lifetime 

individual cancer risk could be up to 9-in-1 million, the 

maximum chronic noncancer TOSHI value could be up to 0.5, and 

the maximum off-facility site acute HQ value could be up to 8, 

based on the actual emissions level and the REL value for 

acetaldehyde. The total estimated national cancer incidence from 

these facilities based on actual emission levels is 0.002 excess 

cancer cases per year or one case in every 500 years.

Based on our analysis, we believe that actual emissions 

approximate emissions allowable under the MACT standards. 

Therefore, the risk results for MACT-allowable emissions are 

approximately equal to those for actual emissions. For more 

detail about this estimate of the ratio of actual to MACTallowable emissions and the estimation of MACT-allowable 

emission levels and associated risks and impacts, see the 

memorandum, MACT Allowable Emissions and Risks for the Pesticide 
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Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, in the docket for this rulemaking.

One facility reported emissions of PB-HAP, including 

cadmium compounds, lead compounds and POM. Therefore, we 

compared the facility-specific emission rates of each of these 

PB–HAP to the TRIM–Screen emission threshold values to assess 

the potential for significant human health risks or 

environmental risks via non-inhalation pathways. The emission 

rates were less than the emission threshold values; therefore, 

we do not expect potential for human health multipathway risks 

or adverse environmental impacts as a result of PB-HAP.

b. Facility-wide Risk Assessment Results

Table 14 displays the results of the facility-wide risk 

assessment. This assessment was conducted based on actual 

emission levels. For detailed facility-specific results, see 

Appendix 4 of the Draft Residual Risk Assessment for 7 Source 

Categories in the docket for this rulemaking.

Table 14. PET Facility-Wide Risk Assessment Results

Number of facilities analyzed 15

Cancer Risk:

 Estimated maximum facilitywide individual cancer risk (in 

1 million)

9

 Number of facilities with 

estimated facility-wide 

individual cancer risk of 100-

0
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in-1 million or more

 Number of facilities at 

which the PET source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risks of 100-in-1 

million or more

0

 Number of facilities at 

which the PET source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risk of 1-in-1 million 

or more

6

Chronic Noncancer Risk:

 Maximum facility-wide 

chronic noncancer TOSHI

1

 Number of facilities with 

facility-wide maximum noncancer 

TOSHI greater than 1

1

 Number of facilities at 

which the PET source category 

contributes 50 percent or more 

to the facility-wide maximum 

noncancer TOSHI of 1 or more

0

The facility-wide MIR from all HAP emissions at a facility 

that contains sources subject to the Group IV Polymers and 

Resins MACT standards for PET is estimated to be 9-in-1 million, 

based on actual emissions. Of the 15 facilities included in this 

analysis, none have a facility-wide MIR of 100-in-1 million. 

There are 8 facilities with facility-wide MIR of 1-in-1 million 

or greater (MIR ranging from 2 to 9 in a million). Six of these 

facilities have PET production operations that contribute 

greater than 50 percent to the facility-wide risks.
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The facility-wide maximum individual chronic noncancer 

TOSHI is estimated to be 1, based on actual emissions. Of the 15 

facilities included in this analysis, one has a facility-wide 

maximum chronic noncancer TOSHI value of 1.

c. What is our proposed decision regarding risk acceptability?

As noted in section III.C of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the number of persons in various cancer and 

noncancer risk ranges; cancer incidence; the maximum noncancer 

HI; the maximum acute noncancer HQ; the extent of noncancer 

risks; the potential for adverse environmental effects; 

distribution of cancer and noncancer risks in the exposed 

population; and risk estimation uncertainty (54 FR 38044, 

September 14, 1989).

For the PET source category, the risk analysis we performed 

indicates that the cancer risks to the individual most exposed 

could be up to 9-in-1 million due to both actual and allowable 

emissions. This value is considerably less than 100-in-1 

million, which is the presumptive level of acceptability. The 

risk analysis also shows low cancer incidence (1 in every 500 

years), no potential for human health multipathway effects and 

that chronic noncancer health impacts are unlikely.

We estimate that the worst-case acute HQ value could exceed 

a value of 1 for one HAP, acetaldehyde, with a potential maximum 
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HQ up to 8 based on the acute REL dose-response value. Seven of 

the 15 facilities in this source category had an estimated acute 

HQ greater than 1 (REL for acetaldehyde ranging from 3 to 8). 

All other facilities modeled had an acute HQ less than 1. The 

maximum acute HQs based on ERPG-1 and AEGL-1 dose-response 

values for acetaldehyde are 1 and 0.2, respectively. As 

described earlier in this preamble, the acute assessment 

includes some conservative assumptions and some uncertainties. 

Considering the improbable assumption that worst-case 

meteorological conditions are present at the same time that 

maximum hourly emissions of acetaldehyde exceed the average 

hourly emission rate by a factor of 10 at all emission points 

simultaneously, coincident with individuals being in the 

location of maximum impact and considering the low acute HQ 

values, based on the ERPG-1 and AEGL-1 dose-response values 

collectively with the REL value, we believe it is unlikely that 

HAP emissions from this source category would result in acute 

health effects.

Our screening level evaluation of the potential health 

risks associated with emissions of PB-HAP did not indicate 

potential for adverse multipathway impacts due to emissions of 

the any of the PB-HAP associated with the source category.

Our additional analysis of facility-wide risks showed that 

the maximum facility-wide cancer risk is 9-in-1 million. The 
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maximum chronic noncancer TOSHI is estimated to be 1, but the 

source category contributes only 5 percent to the maximum 

facility-wide TOSHI.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the risks from the PET source category are 

acceptable.

d. What is our proposed decision regarding ample margin of 

safety?

We considered whether the MACT standards provide an ample 

margin of safety to protect public health. In this analysis, we 

investigated available emissions control options that might 

reduce the risk associated with emissions from the source 

category and considered this information along with all of the 

health risks and other health information considered in the risk 

acceptability determination.

For the PET source category, we identified only one control 

option to further address risks from equipment leaks, which were 

shown to contribute 100 percent to the maximum individual cancer 

risks for this source category. This control option would 

require sources to install leakless valves to prevent leaks from 

those components.

We estimated HAP reduction resulting from this control 
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option is approximately 123 tpy from the baseline actual 

emissions level. We estimated that achieving these reductions 

would involve a capital cost of approximately $220,000,000, a 

total annualized cost of about $30,000,000 and a cost 

effectiveness of $244,000 per ton of HAP emissions reduced. The 

additional control requirement would achieve approximately 20-

percent reduction in baseline risks at a very high cost. We 

estimate that the MACT allowable emissions from this source 

category are approximately equal to the reported, actual 

emissions. Therefore, the estimated emission reduction, risk 

reduction and costs discussed above would also be applicable to 

the MACT allowable emissions level. We believe that the costs of 

this option are not reasonable, given the level of emission and 

risk reduction.

In accordance with the approach established in the Benzene 

NESHAP, the EPA weighed all health risk measures and information 

considered in the risk acceptability determination, along with 

the costs and economic impacts of emissions controls, 

technological feasibility, uncertainties and other relevant 

factors in making our ample margin of safety determination. 

Considering the health risk information and the unreasonable 

cost effectiveness of the option identified, we propose that the 

existing MACT standards provide an ample margin of safety to 

protect public health and prevent an adverse environmental 
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effect.

3. What are the results of the technology review?

The results of the technology review for the Group IV 

Polymers and Resins MACT standards are discussed above in 

section IV.A.2. We identified no advancements in practices, 

processes and control technologies applicable to the emission 

sources in the Group IV Polymers and Resins source categories in 

our technology review.

4. What other actions are we proposing?

a. SSM Provisions

The proposed changes to the SSM provisions for the Group IV 

Polymers and Resins MACT standards, which apply to the PET 

source category, are discussed above in section IV.A.3.a.

b. Electronic Reporting

The proposed addition of electronic reporting requirements 

for performance tests for the Group IV Polymers and Resins MACT 

standards, which apply to the PET source category, are discussed 

above in section IV.A.3.b.

V. Analytical Results and Proposed Decisions for Pesticide 

Active Ingredient Production

A. What are the results of the risk assessments?

1. Inhalation Risk Assessment Results

Table 16 provides an overall summary of the inhalation risk 

assessment results for the source category.
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Table 16. PAI Inhalation Risk Assessment Results

Number of 

Facilities1

Maximum

individual

cancer risk

(in 1 million)2 Population

at risk ≥ 

1-in-1 

million

Annual

cancer

incidence 

(cases 

per year)

Maximum

chronic noncancer

TOSHI3

Maximum 

off-site 

acute 

noncancer 

HQ4

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

17 7 7 11,000 0.001 0.7 3

HQREL = 8 

ethylene 

glycol 

ethyl 

ether

HQERPG-1 = 

0.3 

chlorine

1 Number of facilities evaluated in the risk analysis.

2 Maximum individual excess lifetime cancer risk.

3 Maximum TOSHI. The target organ with the highest TOSHI for the PAI source 

category is the respiratory system. 

4 The maximum estimated acute exposure concentration was divided by available 

short-term threshold values to develop an array of HQ values. HQ values shown 

use the lowest available acute threshold value, which, in most cases, is the 

REL. When HQ values exceed 1, we also show HQ values using the next lowest 

available acute dose-response value. See section III.B.3 of this preamble for 

explanation of acute dose-response values.

The inhalation risk modeling was performed using actual 

emissions level data. As shown in Table 16, the results of the 

inhalation risk assessment indicated the maximum lifetime

individual cancer risk could be up to 7-in-1 million, the 

maximum chronic noncancer TOSHI value could be up to 0.7, and 

the maximum off-facility site acute HQ value could be up to 8, 

based on the actual emissions level and the REL value for 

ethylene glycol ethyl ethers. The total estimated national 

cancer incidence from these facilities, based on actual emission 

levels is 0.001 excess cancer cases per year or one case in 

every 1,000 years.
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Based on our analysis, we estimate that the MACT-allowable 

emissions levels from process vents for organic HAP emissions 

could be up to five times the actual emissions and the MACTallowable level for chlorine and HCl emissions could be up to

six times the actual emissions from this source category. 

However, the highest cancer risks are caused by fugitive 

emissions and the application of the factor of five to the 

organic HAP emissions from point sources did not result in 

cancer risks in excess of the levels resulting from actual 

fugitive source emissions. Therefore, the cancer risk results 

for MACT-allowable emissions are approximately equal to those 

for actual emissions. The highest TOSHI at the MACT-allowable 

level is approximately 3. For more detail about this estimate of 

the ratio of actual to MACT-allowable emissions and the 

estimation of MACT-allowable emission levels and associated 

risks and impacts, see the memorandum, MACT Allowable Emissions 

and Risks for the Pesticide Active Ingredient, Polyether 

Polyols, and Polymers and Resins IV Production Source 

Categories, in the docket for this rulemaking.

Three facilities reported emissions of PB-HAP, including 

lead compounds, PCBs and hexachlorobenzene. We typically would 

compare the facility-specific emission rates of each of these 

PB–HAP to the TRIM–Screen emission threshold values to assess 

the potential for significant human health risks or 
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environmental risks via non-inhalation pathways. However, while 

lead is a PB-HAP, the National Ambient Air Quality Standards 

(NAAQS) value (which was used for the chronic noncancer risk 

assessment) takes into account air-related multipathway 

exposures, so a separate multipathway screening value was not 

developed here. Since we did not estimate any exceedances of the 

NAAQS in our chronic noncancer risk assessment, we do not expect 

any unacceptable multipathway exposure and risk of concern due 

to lead emissions from these facilities. In addition, there is 

currently not a screening value for PCBs or hexachlorobenzene, 

and they were not evaluated for potential non-inhalation risks.

2. Facility-wide Risk Assessment Results

Table 17 displays the results of the facility-wide risk 

assessment. This assessment was conducted based on actual 

emission levels. For detailed facility-specific results, see 

Appendix 4 of the Draft Residual Risk Assessment for 7 Source 

Categories in the docket for this rulemaking.

Table 17. PAI Facility-Wide Risk Assessment Results

Number of facilities analyzed 17

Cancer Risk:

 Estimated maximum facilitywide individual cancer risk (in 

1 million)

20

 Number of facilities with 

estimated facility-wide 

individual cancer risk of 100-

0
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in-1 million or more

 Number of facilities at 

which the PAI source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risks of 100-in-1 

million or more

0

 Number of facilities at 

which the PAI source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risk of 1-in-1 million 

or more

4

Chronic Noncancer Risk:

 Maximum facility-wide 

chronic noncancer TOSHI

2

 Number of facilities with 

facility-wide maximum noncancer 

TOSHI greater than 1

1

 Number of facilities at 

which the PAI source category 

contributes 50 percent or more 

to the facility-wide maximum 

noncancer TOSHI of 1 or more

0

The facility-wide MIR from all HAP emissions at a facility 

that contains sources subject to the PAI MACT standards is 

estimated to be 20-in-1 million, based on actual emissions. Of 

the 17 facilities included in this analysis, none have a 

facility-wide MIR of 100-in-1 million. There are 12 facilities 

with facility-wide MIR of 1-in-1 million or greater (2 

facilities with an MIR of 20 in a million and 2 facilities with

an MIR of 10 in a million; the remaining 8 facilities have an

MIR below 10 in a million). Four of these facilities have PAI 
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production operations that contribute greater than 50 percent to 

the facility-wide risks.

The facility-wide maximum individual chronic noncancer 

TOSHI is estimated to be 2, based on actual emissions. Of the 17 

facilities included in this analysis, one has a facility-wide 

maximum chronic noncancer TOSHI values greater than 1 (TOSHI of 

2).

3. What is our proposed decision regarding risk acceptability?

As noted in section III.C of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the number of persons in various cancer and 

noncancer risk ranges; cancer incidence; the maximum noncancer 

HI; the maximum acute noncancer HQ; the extent of noncancer 

risks; the potential for adverse environmental effects; 

distribution of cancer and noncancer risks in the exposed 

population; and risk estimation uncertainty (54 FR 38044, 

September 14, 1989).

For the PAI source category, the risk analysis we performed 

indicates that the cancer risks to the individual most exposed 

could be up to 7-in-1 million due to both actual and allowable 

emissions. This value is considerably less than 100-in-1 

million, which is the presumptive level of acceptability. The 

risk analysis also shows low cancer incidence (1 in every 1,000 

years) and that chronic noncancer health impacts are unlikely at 
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the actual emissions levels. 

We estimate that the worst-case acute HQ value could exceed 

a value of 1 for six HAP: ethylene glycol ethyl ethers (one 

facility); acrolein (one facility); chloroform (one facility); 

nickel compounds (one facility); chlorine (one facility); and 

formaldehyde (one facility). One facility had acute HQ greater 

than 1 for three HAP (ethyl glycol ethyl ether, acrolein and 

nickel). The potential maximum HQ is up to 8, based on the acute 

REL dose-response value for ethylene glycol ethyl ether. Four of 

the 17 facilities in this source category had an estimated HQ 

greater than 1. All other facilities modeled had an HQ less than 

1. The maximum HQ based on an ERPG-1 or AEGL-1 dose-response 

value is 0.3, based on the AEGL-1 for chlorine. As described 

earlier in this preamble, the acute assessment includes some 

conservative assumptions and some uncertainties. Considering the 

improbable assumption that worst-case meteorological conditions 

are present at the same time that maximum hourly emissions of 

ethylene glycol ethyl ether exceed the average hourly emission

rate by a factor of 10 at all emission points simultaneously for 

three of these four facilities or a factor of 2 at all emission 

points simultaneously for the other facility, coincident with 

individuals being in the location of maximum impact and 

considering the low acute HQ values, based on the AEGL-1 and 

ERPG-1 dose-response values collectively with the REL values, we 
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believe it is unlikely that HAP emissions from this source 

category would result in acute health effects.

Our screening level evaluation of the potential health 

risks associated with emissions of PB-HAP did not indicate 

potential for adverse multipathway impacts due to emissions of 

lead. While there are no screening values for PCB and 

hexachlorobenzene, these HAP are not emitted in appreciable 

quantities and are not expected to cause multipathway impacts of 

concern.

Our additional analysis of facility-wide risks showed that 

the maximum facility-wide cancer risk is 20-in-1 million. The 

maximum chronic noncancer TOSHI is estimated to be 2, but the 

source category contributes less than 5 percent to the maximum 

facility-wide TOSHI.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the risks from the PAI source category are 

acceptable.

4. What is our proposed decision regarding ample margin of 

safety?

We considered whether the MACT standards provide an ample 

margin of safety to protect public health. In this analysis, we 

investigated available emissions control options that might 
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reduce the risk associated with emissions from the source 

category and considered this information along with all of the 

health risks and other health information considered in the risk 

acceptability determination.

For the PAI source category, we identified only one control 

option to further address risks from equipment leaks, which were 

shown to contribute 100 percent to the maximum individual cancer 

risks for this source category. This control option would 

require sources to install leakless valves to prevent leaks from 

those components.

We estimated HAP reduction resulting from this control 

option is approximately 101 tpy from the baseline actual 

emissions level. We estimated that achieving these reductions 

would involve a capital cost of approximately $180,000,000, a 

total annualized cost of about $25,000,000 and a cost 

effectiveness of $244,000 per ton of HAP emissions reduced. The 

additional control requirement would achieve approximately 60-

percent reduction in baseline risks at a very high cost. We 

estimate that the MACT allowable emissions from equipment leaks 

at this source category are approximately equal to the reported, 

actual emissions. Therefore, the estimated emission reduction, 

risk reduction and costs discussed above would also be 

applicable to the MACT allowable emissions level. We believe 

that the costs of this option are not reasonable, given the 
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level of emission and risk reduction.

In accordance with the approach established in the Benzene 

NESHAP, the EPA weighed all health risk measures and information 

considered in the risk acceptability determination, along with 

the costs and economic impacts of emissions controls, 

technological feasibility, uncertainties and other relevant 

factors in making our ample margin of safety determination. 

Considering the health risk information and the unreasonable 

cost effectiveness of the option identified, we propose that the 

existing MACT standards provide an ample margin of safety to 

protect public health and prevent an adverse environmental 

effect.

B. What are the results of the technology review?

In the decade since the PAI NESHAP was promulgated, the EPA 

has developed 19 air toxics regulations for source categories 

that emit organic HAP from the same type of emissions sources 

that are present in the PAI source category. We reviewed the 

regulatory requirements and/or technical analyses for these 19 

regulations for new practices, processes and control 

technologies. We also conducted a search of the RBLC for 

controls for VOC- and HAP-emitting processes in the Agricultural 

Chemical Manufacturing and the SOCMI categories with permits 

dating back to 1997.

We identified no advancements in practices, processes and 
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control technologies applicable to the emission sources in the 

PAI source category in our technology review.

C. What other actions are we proposing?

1. SSM Provisions

As we have done in other recent risk and technology 

rulemakings, we are proposing to eliminate the SSM exemption in 

the PAI MACT standards. Consistent with Sierra Club v. EPA, the 

EPA is proposing that standards in this rule would apply at all 

times. We are proposing several revisions to 40 CFR part 63, 

subpart MMM. Specifically, we are proposing to revise Table 1 to 

indicate that the requirements of 40 CFR 63.6(e) of the General 

Provisions do not apply. The 40 CFR 63.6(e) requires owner or 

operators to act according to the general duty to “operate and 

maintain any affected source, including associated air pollution 

control equipment and monitoring equipment, in a manner 

consistent with safety and good air pollution control practices 

for minimizing emissions.” We are separately proposing to 

incorporate this general duty to minimize into 40 CFR 

63.1360(e). The 40 CFR 63.6(e) also requires the owner or 

operator of an affected source to develop a written SSM plan. We 

are proposing to remove the SSM plan requirement. We are 

proposing to remove the explanation of applicability of 

emissions standards during periods SSM in 40 CFR 63.1360(e); 

remove the malfunction plan from 40 CFR 63.1367(a); clarify that 
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representative conditions do not include periods of SSM 

throughout the rule; remove references to periods of SSM in 

monitoring; and revise the SSM-associated recordkeeping and 

reporting requirements in 40 CFR 63.1367(a) to require reporting 

and recordkeeping for periods of malfunction. We are also 

proposing to revise Table 1 to indicate that SSM-related 

provisions in 40 CFR 63.6(e)(1), 63.6(e)(3), 63.6(f)(1); 40 CFR 

63.7(e)(1); 40 CFR 63.8(c)(1) – (3); 40 CFR 63.10(c)(10), (11), 

and (15); and 40 CFR 63.10(d)(5) of the General Provisions do 

not apply. We are also proposing to add requirements in 40 CFR 

63.1363(b)(4) to clarify that PRD releases to the atmosphere are 

violations of the emissions standards and to require pressure 

release alarms and to add requirements in 40 CFR 63.1463(h)(4) 

to require reporting of any pressure device releases to the 

atmosphere with the periodic report. In addition, following our 

recently established practice in other risk and technology 

review rulemakings, we are proposing to promulgate an 

affirmative defense against civil penalties for exceedances of 

emission standards caused by malfunctions, as well as criteria 

for establishing the affirmative defense.

2. Electronic Reporting

To increase the ease and efficiency of data submittal and 

improve data accessibility, we are proposing to require the 

submission of electronic copies of required performance tests 
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for test methods that are supported by the ERT to EPA’s WebFIRE 

database. These provisions are added in 40 CFR 63.1368(p).

VI. Analytical Results and Proposed Decisions for Polyether 

Polyols Production

A. What are the results of the risk assessments?

1. Inhalation Risk Assessment Results

Table 19 provides an overall summary of the inhalation risk 

assessment results for the source category.

Table 19. PEPO Inhalation Risk Assessment Results

Number of 

Facilities1

Maximum

individual

cancer risk

(in 1 million)2 Population

at risk ≥ 

1-in-1 

million

Annual

cancer

incidence 

(cases 

per year)

Maximum

chronic noncancer

TOSHI3

Maximum 

off-site 

acute 

noncancer 

HQ4

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

Actual 

Emissions 

Level

Allowable 

Emissions 

Level

23 30 30 160,000 0.02 0.8 0.8

HQREL = 6 

glycol 

ethers

HQAEGL-1 = 

0.1 

acrolein

1 Number of facilities evaluated in the risk analysis.

2 Maximum individual excess lifetime cancer risk.

3 Maximum TOSHI. The target organ with the highest TOSHI for the PEPO source 

category is the respiratory system. 

4 The maximum estimated acute exposure concentration was divided by available 

short-term threshold values to develop an array of HQ values. HQ values shown 

use the lowest available acute threshold value, which, in most cases, is the 

REL. When HQ values exceed 1, we also show HQ values using the next lowest 

available acute dose-response value. See section III.B.3 of this preamble for 

explanation of acute dose-response values.

The inhalation risk modeling was performed using actual 

emissions level data. As shown in Table 19, the results of the 

inhalation risk assessment indicated the maximum lifetime 

individual cancer risk could be up to 30-in-1 million, the 
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maximum chronic noncancer TOSHI value could be up to 0.8 and the 

maximum off-facility site acute HQ value could be up to 6, based 

on the actual emissions level and the REL value for glycol 

ethers. The total estimated national cancer incidence from these 

facilities, based on actual emission levels is 0.02 excess 

cancer cases per year or one case in every 50 years.

Based on our analysis, we estimate that the MACT-allowable 

emissions level for organic non-epoxide HAP emissions from 

certain process vents could be up to five times the actual 

emissions from this source category. However, the highest cancer 

risks are caused by epoxide emissions, and the application of 

the factor of five to the non-epoxide organic HAP emissions from 

point sources did not result in cancer risks in excess of the 

levels resulting from actual epoxide emissions. Therefore, the 

cancer risk results for MACT-allowable emissions are 

approximately equal to those for actual emissions. For more 

detail about this estimate of the ratio of actual to MACTallowable emissions and the estimation of MACT-allowable 

emission levels and associated risks and impacts, see the 

memorandum, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV 

Production Source Categories, in the docket for this rulemaking.

Two facilities reported emissions of PB-HAP, including 

fluoranthene (a POM HAP) and lead compounds. We typically 
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compare the facility-specific emission rates of PB–HAP to the 

TRIM–Screen emission threshold values to assess the potential 

for significant human health risks or environmental risks via 

non-inhalation pathways. However, while lead is a PB-HAP, the 

NAAQS value (which was used for the chronic noncancer risk 

assessment) takes into account multipathway exposures, so a 

separate multipathway screening value was not developed. Since 

we did not estimate any exceedances of the NAAQS in our chronic 

noncancer risk assessment, we do not expect any significant 

multipathway exposure and risk due to lead emissions from these 

facilities. For fluoranthene emissions, one facility emits this 

PB-HAP and the emissions exceed the screening-level threshold 

level for POM by a factor of four. Based on this screening 

analysis, we cannot rule out the potential for multipathway 

impacts of concern due to emissions of fluoranthene from the one 

facility. However, we do not expect fluoranthene emissions from 

PEPO processes, and we specifically request data regarding these 

emissions.

2. Facility-wide Risk Assessment Results

Table 20 displays the results of the facility-wide risk 

assessment. This assessment was conducted based on actual 

emission levels. For detailed facility-specific results, see 

Appendix 4 of the Draft Residual Risk Assessment for 7 Source 

Categories in the docket for this rulemaking.
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Table 20. PEPO Facility-Wide Risk Assessment Results

Number of facilities analyzed 23

Cancer Risk:

 Estimated maximum facilitywide individual cancer risk (in 

1 million)

30

 Number of facilities with 

estimated facility-wide 

individual cancer risk of 100-

in-1 million or more

0

 Number of facilities at 

which the PEPO source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risks of 100-in-1 

million or more

0

 Number of facilities at 

which the PEPO source category 

contributes 50 percent or more 

to the facility-wide individual 

cancer risk of 1-in-1 million 

or more

14

Chronic Noncancer Risk:

 Maximum facility-wide 

chronic noncancer TOSHI

2

 Number of facilities with 

facility-wide maximum noncancer 

TOSHI greater than 1

1

 Number of facilities at 

which the PEPO source category 

contributes 50 percent or more 

to the facility-wide maximum 

noncancer TOSHI of 1 or more

0

The facility-wide MIR from all HAP emissions at a facility 

that contains sources subject to the PEPO MACT standards is 
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estimated to be 30-in-1 million, based on actual emissions. Of 

the 23 facilities included in this analysis, none have a 

facility-wide MIR of 100-in-1 million. There are 20 facilities 

with a facility-wide MIR of 1-in-1 million or greater (10 of 

these facilities have a facility-wide MIR equal to or greater 

than 10 in a million). Fourteen of these facilities have PEPO 

production operations that contribute greater than 50 percent to 

the facility-wide risks.

The facility-wide maximum individual chronic noncancer 

TOSHI is estimated to be 2 based on actual emissions. Of the 23 

facilities included in this analysis, one has facility-wide

maximum chronic noncancer TOSHI values greater than 1 (TOSHI of 

2).

3. What is our proposed decision regarding risk acceptability?

As noted in section III.C of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the number of persons in various cancer and 

noncancer risk ranges; cancer incidence; the maximum noncancer 

HI; the maximum acute noncancer HQ; the extent of noncancer 

risks; the potential for adverse environmental effects; 

distribution of cancer and noncancer risks in the exposed 

population; and risk estimation uncertainty (54 FR 38044, 

September 14, 1989).

For the PEPO source category, the risk analysis we 
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performed indicates that the cancer risks to the individual most 

exposed could be up to 30-in-1 million due to both actual and 

allowable emissions. This value is considerably less than 100-

in-1 million, which is the presumptive level of acceptability. 

The risk analysis also shows low cancer incidence (1 in every 50 

years). The chronic noncancer TOSHI is estimated to be 1 due to 

emissions of chlorine.

We estimate that the worst-case acute HQ value could exceed 

a value of 1 for two HAP, glycol ethers and acrolein, with a 

potential maximum acute HQ up to 6, based on the acute REL doseresponse value for glycol ethers. For glycol ethers, we used the 

lowest acute REL of any of the glycol ethers with such health 

values (i.e., ethylene glycol monomethyl ether) to assess the 

other glycol ethers without such values. Two of the 23 

facilities in this source category had an estimated acute HQ 

greater than 1. All other facilities modeled had an acute HQ 

less than 1. The maximum acute HQ (based on the AEGL-1 doseresponse value for acrolein) is 0.1.. As described earlier in 

this preamble, the acute assessment includes some conservative

assumptions and some uncertainties. Considering the improbable 

assumption that worst-case meteorological conditions are present 

at the same time that maximum hourly emissions of glycol ethers 

exceed the average hourly emission rate by a factor of 2 at all

emission points simultaneously for both of these facilities and 
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coincident with individuals being in the location of maximum 

impact, and considering the low acute HQ values, based on the 

AEGL-1 and ERPG-1 dose-response values collectively with the REL 

values, we believe it is unlikely that HAP emissions from this 

source category would result in acute health effects.

Our screening level evaluation of the potential health 

risks associated with emissions of PB-HAP did not indicate 

potential for adverse multipathway impacts due to emissions of 

lead. The screening level evaluation indicated that the one 

facility that reported fluoranthene emissions exceeded the 

screening-level threshold for POM by a factor of 4; however, as 

explained in section III.B.7.e, our screening methods use worstcase scenarios and the results are biased high.

Our additional analysis of facility-wide risks showed that 

the maximum facility-wide cancer risk is 30-in-1 million. The 

maximum chronic noncancer TOSHI is estimated to be 3, but the 

source category contributes less than one-third to the maximum 

facility-wide TOSHI.

The EPA has weighed the various health risk measures and 

health factors, including risk estimation uncertainty, discussed 

above and in section III.B.7 of this preamble, and we are 

proposing that the risks from the PEPO source category are 

acceptable.

4. What is our proposed decision regarding ample margin of 
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safety?

We considered whether the MACT standards provide an ample 

margin of safety to protect public health. In this analysis, we 

investigated available emissions control options that might 

reduce the risk associated with emissions from the source 

category and considered this information along with all of the 

health risks and other health information considered in the risk 

acceptability determination.

For the PEPO source category, we identified only one 

control option to further address risks from equipment leaks, 

which were shown to contribute approximately 47 percent to the 

maximum individual cancer risks for this source category. This 

control option would require sources to install leakless valves 

to prevent leaks from those components.

We estimated HAP reduction resulting from this control 

option is approximately 59 tpy from the baseline actual 

emissions level. We estimated that achieving these reductions 

would involve a capital cost of about $104,000,000, a total 

annualized cost of about $14,000,000 and a cost effectiveness of 

$244,000 per ton of HAP emissions reduced. The additional 

control requirement would achieve approximately 30-percent 

reduction in baseline risks at a very high cost. We estimate 

that the MACT allowable emissions from equipment leaks at this 

source category are approximately equal to the reported, actual 
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emissions. Therefore, the estimated emission reduction, risk 

reduction and costs discussed above would also be applicable to 

the MACT allowable emissions level. We believe that the costs of 

this option are not reasonable, given the level of emission and 

risk reduction.

In accordance with the approach established in the Benzene 

NESHAP, the EPA weighed all health risk measures and information 

considered in the risk acceptability determination, along with 

the costs and economic impacts of emissions controls, 

technological feasibility, uncertainties and other relevant 

factors in making our ample margin of safety determination. 

Considering the health risk information and the unreasonable 

cost effectiveness of the option identified, we propose that the 

existing MACT standards provide an ample margin of safety to 

protect public health and prevent an adverse environmental 

effect.

B. What are the results of the technology review?

In the decade since the PEPO NESHAP was promulgated, EPA 

has developed 19 air toxics regulations for source categories 

that emit organic HAP from the same type of emissions sources 

that are present in the PEPO source category. We reviewed the 

regulatory requirements and/or technical analyses for these 19 

regulations for new practices, processes and control 

technologies. We also conducted a search of the RBLC for 
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controls for VOC- and HAP-emitting processes in the SOCMI 

categories with permits dating back to 1997.

We identified no advancements in practices, processes and 

control technologies applicable to the emission sources in the 

PEPO source category in our technology review.

C. What other actions are we proposing?

1. SSM Provisions

As we have done in other recent risk and technology review 

rulemakings, we are proposing to eliminate the SSM exemption in 

the PEPO MACT standards. Consistent with Sierra Club v. EPA, the 

EPA is proposing that standards in this rule would apply at all 

times. We are proposing several revisions to 40 CFR part 63, 

subpart PPP. Specifically, we are proposing to revise Table 1 to 

indicate that the requirements of 40 CFR 63.6(e) of the General 

Provisions do not apply. The 40 CFR 63.6(e) requires owners or 

operators to act according to the general duty to “operate and 

maintain any affected source, including associated air pollution 

control equipment and monitoring equipment, in a manner 

consistent with safety and good air pollution control practices 

for minimizing emissions.” We are separately proposing to 

incorporate this general duty to minimize into 40 CFR 

63.1420(h). The 40 CFR 63.6(e) also requires the owner or 

operator of an affected source to develop a written SSM plan. We 

are proposing to remove the SSM plan requirement. We are 
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proposing to remove the explanation of applicability of 

emissions standards during periods SSM in 40 CFR 63.1420(h);

remove the malfunction plan from 40 CFR 63.1439(b); clarify that 

representative conditions do not include periods of SSM 

throughout the rule; remove references to periods of SSM in 

monitoring; remove the provisions for excused excursions in 40 

CFR 63.1438(g) and revise the SSM-associated recordkeeping and 

reporting requirements in 40 CFR 63.1439(b) to require reporting 

and recordkeeping for periods of malfunction. We are also 

proposing to revise Table 1 to indicate that SSM-related 

provisions in 40 CFR 63.6(e)(1), 63.6(e)(3), 63.6(f)(1); 40 CFR 

63.7(e)(1); 40 CFR 63.8(c)(1); 40 CFR 63.10(c)(10), (11) and 

(15); and 40 CFR 63.10(d)(5) of the General Provisions do not 

apply. We are also proposing to add requirements in 40 CFR 

63.1434(c) to clarify that PRD releases to the atmosphere are 

violations of the emissions standards and to require pressure 

release alarms and to add requirements in 40 CFR 63.1439(e)(9) 

to require reporting of any pressure device releases to the 

atmosphere with the periodic report. In addition, following our 

practice established in other risk and technology review 

rulemakings, we are proposing to promulgate an affirmative 

defense against civil penalties for exceedances of emission 

standards caused by malfunctions, as well as criteria for 

establishing the affirmative defense.
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2. Electronic Reporting

To increase the ease and efficiency of data submittal and 

improve data accessibility, we are proposing to require the 

submission of electronic copies of required performance tests 

for test methods that are supported by the ERT to EPA’s WebFIRE 

database. These provisions are added in 40 CFR 63.1439(e)(10).

VII. Compliance Dates

For the three MACT standards being addressed in this 

action, the proposed compliance date for the revised SSM 

requirements and electronic reporting requirements is the 

effective date of the promulgated revised standards. We are 

proposing these compliance dates because these requirements 

should be immediately implementable by the facilities upon the 

next occurrence of a malfunction or the performance of a 

performance test that is required to be submitted to the ERT. We 

also believe that the facilities should already be able to 

comply with the existing standards during periods of startup and 

shutdown.

In accordance with CAA section 112(i)(3), the compliance 

date for PRD monitoring is 3 years from the effective date of 

the promulgated standards. This time period will allow 

facilities to purchase, install and test the equipment.

For the facility in the PET continuous TPA high viscosity 

multiple end finisher subcategory subject to the Group IV 
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Polymers and Resins MACT standards, the proposed compliance date 

for the new MACT standards applicable to equipment leaks and 

PCCT is the effective date of the promulgated standards. Since 

this facility is already performing the proposed equipment leak 

requirements and meeting the proposed PCCT standards, the 

facility should be able to comply immediately with the 

promulgated rule provisions. It should be feasible for the 

facility to conduct any additional recordkeeping required upon 

the promulgation date and information required in the next 

periodic report for these requirements would only reflect the 

period of time between the promulgation date and the periodic 

report due date.

Beyond the revised SSM and electronic reporting 

requirements, there are no changes to the PAI and PEPO MACT 

standards.

VIII. Summary of Cost, Environmental and Economic Impacts

A. What are the affected sources?

We anticipate that each facility in these seven source 

categories will be affected by these proposed amendments. We 

estimate there are 17 existing facilities subject to the PAI 

MACT standards, 23 existing facilities subject to the PEPO MACT 

standards and 30 existing facilities subject to the Group IV 

Polymers and Resins MACT standards. We do not know of any new 

facilities that are expected to be constructed in the 
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foreseeable future. Therefore, our impact analysis is focused on 

the existing sources affected by the MACT standards for these 

source categories.

B. What are the air quality impacts?

No quantifiable air quality impacts are expected to result 

from the proposed amendments to these three MACT standards for 

seven source categories. For the two emissions sources, we are 

proposing new emissions standards for equipment leaks and PCCT 

in the PET continuous TPA high viscosity multiple end finisher 

subcategory regulated by the Group IV Polymers and Resins MACT 

standards, we are proposing to establish the MACT floor at the 

current emissions levels for the one facility in this 

subcategory. As a result, no additional emission reduction will 

be realized, although increases in emissions in the future will 

be prevented. For the proposed revisions to the MACT standards 

regarding SSM, while these changes may result in fewer emissions 

during these periods or less frequent periods of startup, 

shutdown or malfunction, these possible emission reductions are 

difficult to quantify and are not included in our assessment of 

air quality impacts.

C. What are the cost impacts?

Under the proposed amendments, facilities in all seven 

source categories are expected to incur initial capital and 

annual operation and maintenance costs for the installation of 
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PRD monitoring systems. The capital costs for each facility were 

estimated, based on data collected for other EPA projects. The 

memorandum, Draft Cost Impacts of the Revised NESHAP for 7 

Source Categories, includes a complete description of the cost 

estimate methods used for this analysis and is available in the 

docket.

Table 21. Cost Impacts of the Proposed PRD Monitoring 

Requirements

Source Category

Total Capital Costs 

(million 2010 $)

Total Annual Costs 

(million 2010 

$/year)

PAI 3.2 0.5

PEPO 4.7 0.7

P&R IV

 ABS 0.9 0.1

 MBS 0.4 0.05

 Polystyrene Resins 2.0 0.3

 PET 2.8 0.4

 SAN 0.4 0.05

D. What are the economic impacts?

We estimate that there will be no more than a 0.5-percent 

price change and a similar reduction in output associated with 

the proposal. This is based on the costs of the rule and 

responsiveness of producers and consumers based on supply and 

demand elasticities for the industries affected by this 

proposal. The impacts to affected firms will be low because the 
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annual compliance costs are quite small when compared to the 

annual revenues for the affected parent firms (much less than 1 

percent for each). The impacts to affected consumers should also 

be quite small. Thus, there will not be any significant impacts 

on affected firms and their consumers as a result of this 

proposal.

E. What are the benefits?

No quantifiable monetized benefits are expected to result 

from the proposed amendments to these three MACT standards for 

seven source categories. As explained in the air quality impacts 

section, there are no quantifiable emission reductions 

associated with the proposed amendments for these MACT standards 

and, therefore, there are no quantifiable health benefits to 

associate with reduced emissions. 

IX. Request for Comments

We are soliciting comments on this proposed action. All 

comments received during the comment period will be considered. 

In addition to general comments on the proposed actions, we are 

also interested in any additional data that may help to reduce 

the uncertainties inherent in the risk assessments. Such data 

should include supporting documentation in sufficient detail to 

allow characterization of the quality and representativeness of 

the data or information. Please see the following section for 

more information on submitting data.
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X. Submitting Data Corrections

The facility-specific data used in the source category risk 

analyses and facility-wide analyses for each source category 

subject to this action are available for download on the RTR Web 

page at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. These data 

files include detailed information for each HAP emissions 

release point at each facility included in the source category 

and all other HAP emissions sources at these facilities 

(facility-wide emissions sources). However, it is important to 

note that the source category risk analysis included only those 

emissions tagged with the MACT code associated with the source 

category subject to the risk analysis.

If you believe the data are not representative or are 

inaccurate, please identify the data in question, provide your 

reason for concern, and provide the data that you believe are 

more accurate, if available. When you submit data, we request 

that you provide documentation of the basis for the revised 

values to support your suggested changes. To submit comments on 

the data downloaded from the RTR Web page, complete the 

following steps:

1. Within this downloaded file, enter suggested revisions 

to the data fields appropriate for that information. The data 

fields that may be revised include the following:
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Data Element Definition

Control Measure

Are control measures in place? 

(yes or no)

Control Measure Comment

Select control measure from 

list provided, and briefly 

describe the control measure

Delete

Indicate here if the facility 

or record should be deleted

Delete Comment

Describes the reason for 

deletion

Emission Calculation 

Method Code For Revised 

Emissions

Code description of the method 

used to derive emissions. For 

example, continuous emission 

monitoring, material balance, 

stack test, etc.

Emission Process Group

Enter the general type of 

emission process associated 

with the specified emission 

point

Fugitive Angle

Enter release angle (clockwise 

from true North); orientation 

of the y-dimension relative to 

true North, measured positive 

for clockwise starting at 0 

degrees (maximum 89 degrees)

Fugitive Length

Enter dimension of the source 

in the east-west (x-) 

direction, commonly referred

to as length (ft)

Fugitive Width

Enter dimension of the source 

in the north-south (y-) 

direction, commonly referred 

to as width (ft)
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Data Element Definition

Malfunction Emissions

Enter total annual emissions 

due to malfunctions (tpy)

Malfunction Emissions Max 

Hourly

Enter maximum hourly 

malfunction emissions here 

(lb/hr)

North American Datum

Enter datum for 

latitude/longitude coordinates 

(NAD27 or NAD83); if left 

blank, NAD83 is assumed

Process Comment

Enter general comments about 

process sources of emissions

REVISED Address

Enter revised physical street 

address for MACT facility here

REVISED City Enter revised city name here

REVISED County Name Enter revised county name here

REVISED Emission Release 

Point Type

Enter revised Emission Release 

Point Type here

REVISED End Date Enter revised End Date here

REVISED Exit Gas Flow Rate

Enter revised Exit Gas 

Flowrate here (ft3/sec)

REVISED Exit Gas 

Temperature 

Enter revised Exit Gas 

Temperature here (F)

REVISED Exit Gas Velocity 

Enter revised Exit Gas 

Velocity here (ft/sec)

REVISED Facility Category 

Code

Enter revised Facility 

Category Code here, which 

indicates whether facility is 

a major or area source

REVISED Facility Name

Enter revised Facility Name 

here
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Data Element Definition

REVISED Facility Registry 

Identifier

Enter revised Facility 

Registry Identifier here, 

which is an ID assigned by the 

EPA Facility Registry System

REVISED HAP Emissions 

Performance Level Code

Enter revised HAP Emissions 

Performance Level here

REVISED Latitude 

Enter revised Latitude here 

(decimal degrees)

REVISED Longitude 

Enter revised Longitude here 

(decimal degrees)

REVISED MACT Code Enter revised MACT Code here

REVISED Pollutant Code

Enter revised Pollutant Code 

here

REVISED Routine Emissions

Enter revised routine 

emissions value here (tpy)

REVISED SCC Code Enter revised SCC Code here

REVISED Stack Diameter 

Enter revised Stack Diameter 

here (ft)

REVISED Stack Height

Enter revised Stack Height 

here (Ft)

REVISED Start Date Enter revised Start Date here

REVISED State Enter revised State here

REVISED Tribal Code Enter revised Tribal Code here

REVISED Zip Code Enter revised Zip Code here

Shutdown Emissions

Enter total annual emissions 

due to shutdown events (tpy)

Shutdown Emissions Max 

Hourly

Enter maximum hourly shutdown 

emissions here (lb/hr)
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Data Element Definition

Stack Comment

Enter general comments about 

emission release points

Startup Emissions

Enter total annual emissions 

due to startup events (tpy)

Startup Emissions Max 

Hourly

Enter maximum hourly startup 

emissions here (lb/hr)

Year Closed

Enter date facility stopped 

operations

2. Fill in the commenter information fields for each 

suggested revision (i.e., commenter name, commenter 

organization, commenter email address, commenter phone number 

and revision comments).

3. Gather documentation for any suggested emissions 

revisions (e.g., performance test reports, material balance 

calculations, etc.).

4. Send the entire downloaded file with suggested revisions 

in Microsoft® Access format and all accompanying documentation 

to Docket ID No. EPA-HQ-OAR-2011-0435 (through one of the 

methods described in the ADDRESSES section of this preamble). To 

expedite review of the revisions, it would also be helpful if 

you submitted a copy of your revisions to the EPA directly at 

RTR@epa.gov in addition to submitting them to the docket.

5. If you are providing comments on a facility with 

multiple source categories, you need only submit one file for 
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that facility, which should contain all suggested changes for 

all source categories at that facility. We request that all data 

revision comments be submitted in the form of updated Microsoft® 

Access files, which are provided on the 

http://www.epa.gov/ttn/atw/rrisk/rtrpg.html Web page.

XI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and 

Executive Order 13563: Improving Regulation and Regulatory 

Review

Under Executive Order 12866 (58 FR 51735, October 4, 1993), 

this action is a significant regulatory action because it raises 

novel legal and policy issues. Accordingly, the EPA submitted 

this action to OMB for review under Executive Order 12866 and 

Executive Order 13563 (76 FR 3821, January 21, 2011) and any 

changes made in response to OMB recommendations have been 

documented in the docket for this action.

B. Paperwork Reduction Act

The information collection requirements in this proposed 

rule have been submitted for approval to OMB under the Paperwork 

Reduction Act, 44 U.S.C. 3501, et seq. The information 

collection requirements are not enforceable until OMB approves 

them. The information requirements are based on notification, 

recordkeeping and reporting requirements in the NESHAP General 

Provisions (40 CFR part 63, subpart A), which are mandatory for 
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all operators subject to national emissions standards. These 

recordkeeping and reporting requirements are specifically 

authorized by CAA section 114 (42 U.S.C. 7414). All information 

submitted to the EPA pursuant to the recordkeeping and reporting 

requirements for which a claim of confidentiality is made is 

safeguarded according to agency policies set forth in 40 CFR 

part 2, subpart B.

The OMB has previously approved the information collection 

requirements contained in the existing regulations being amended 

with this proposed rule (i.e., 40 CFR part 63, subparts JJJ, 

MMM, and PPP) under the provisions of the Paperwork Reduction 

Act, 44 U.S.C. 3501, et seq. The OMB control numbers for the 

EPA’s regulations in 40 CFR are listed in 40 CFR part 9. Burden 

is defined at 5 CFR 1320.3(b).

For these proposed rules, the EPA is adding affirmative 

defense to the estimates of burden in the ICR for these rules. 

To provide the public with an estimate of the relative magnitude 

of the burden associated with an assertion of the affirmative 

defense position adopted by a source, the EPA has provided 

administrative adjustments to this ICR to show what the 

notification, recordkeeping and reporting requirements 

associated with the assertion of the affirmative defense might 

entail. The EPA’s estimate for the required notification, 

reports and records for any individual incident, including the 
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root cause analysis, totals $1,459 annually per MACT standard 

and is based on the time and effort required of a source to 

review relevant data, interview plant employees and document the 

events surrounding a malfunction that has caused an exceedance 

of an emissions limit. The estimate also includes time to 

produce and retain the record and reports for submission to the 

EPA. The EPA provides this illustrative estimate of this burden 

because these costs are only incurred if there has been a 

violation and a source chooses to take advantage of the 

affirmative defense.

Given the variety of circumstances under which malfunctions 

could occur, as well as differences among sources' operation and 

maintenance practices, we cannot reliably predict the severity 

and frequency of malfunction-related excess emissions events for 

a particular source. It is important to note that the EPA has no 

basis currently for estimating the number of malfunctions that 

would qualify for an affirmative defense. Current historical 

records would be an inappropriate basis, as source owners or 

operators previously operated their facilities in recognition 

that they were exempt from the requirement to comply with 

emissions standards during malfunctions. Of the number of excess 

emissions events reported by source operators, only a small 

number would be expected to result from a malfunction (based on 

the definition above) and only a subset of excess emissions 
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caused by malfunctions would result in the source choosing to 

assert the affirmative defense. Thus, we believe the number of 

instances in which source operators might be expected to avail 

themselves of the affirmative defense will be extremely small. 

For this reason, we estimate no more than 1 or 2 such 

occurrences for all sources subject to subparts JJJ, MMM and PPP 

over the 3-year period covered by this ICR. We expect to gather 

information on such events in the future and will revise this 

estimate as better information becomes available.

1. Group IV Polymers and Resins MACT Standards

The ICR document prepared by the EPA for the amendments to 

the Group IV Polymers and Resins MACT standards has been 

assigned EPA ICR number 1737.01. Burden changes associated with 

these amendments would result from new recordkeeping and 

reporting requirements associated with the cooling towers and 

equipment leak provisions for one facility and PRD monitoring 

systems and affirmative defense provisions for all facilities 

subject to the MACT standards.

We estimate 30 regulated facilities are currently subject 

to 40 CFR part 63, subpart JJJ. The annual monitoring, reporting 

and recordkeeping burden for this collection (averaged over the 

first 3 years after the effective date of the standards) for 

these amendments to subpart JJJ is estimated to be 327 labor 

hours at a cost of $19,947 per year. There is no estimated 
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change in annual burden to the federal government for these 

amendments. 

2. Pesticide Active Ingredient Production MACT Standards

The ICR document prepared by the EPA for the amendments to 

the PAI MACT standards has been assigned EPA ICR number 1807.05. 

Burden changes associated with these amendments would result 

from new recordkeeping and reporting requirements associated 

with PRD monitoring systems and affirmative defense provisions 

for all facilities subject to the MACT standards.

We estimate 17 regulated facilities are currently subject 

to 40 CFR part 63, subpart MMM. The annual monitoring, reporting 

and recordkeeping burden for this collection (averaged over the 

first 3 years after the effective date of the standards) for 

these amendments to subpart MMM is estimated to be 187 labor 

hours at a cost of $11,433 per year. There is no estimated 

change in annual burden to the federal government for these 

amendments. 

3. Polyether Polyols Production MACT Standards

The ICR document prepared by the EPA for the amendments to 

the PEPO MACT standards has been assigned EPA ICR number 

1811.06. Burden changes associated with these amendments would 

result from new recordkeeping and reporting requirements 

associated with PRD monitoring systems and affirmative defense 

provisions for all facilities subject to the MACT standards. 
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We estimate 23 regulated facilities are currently subject 

to 40 CFR part 63, subpart PPP. The annual monitoring, reporting 

and recordkeeping burden for this collection (averaged over the 

first 3 years after the effective date of the standards) for 

these amendments to subpart PPP is estimated to be 253 labor 

hours at a cost of $15,433 per year. There is no estimated 

change in annual burden to the federal government for these 

amendments. 

An agency may not conduct or sponsor, and a person is not 

required to respond to, a collection of information unless it 

displays a currently valid OMB control number. The OMB control 

numbers for the EPA's regulations in 40 CFR are listed in 40 CFR 

part 9. When these ICR are approved by OMB, the agency will 

publish a technical amendment to 40 CFR part 9 in the Federal 

Register to display the OMB control numbers for the approved 

information collection requirements contained in the final 

rules.

To comment on the agency's need for this information, the 

accuracy of the provided burden estimates and any suggested 

methods for minimizing respondent burden, the EPA has 

established a public docket for this rule, which includes this 

ICR, under Docket ID number EPA-HQ-OAR-2011-0435. Submit any 

comments related to the ICR to the EPA and OMB. See the 

ADDRESSES section at the beginning of this notice for where to 
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submit comments to the EPA. Send comments to OMB at the Office 

of Information and Regulatory Affairs, Office of Management and 

Budget, 725 17th Street, NW, Washington, DC 20503, Attention: 

Desk Office for EPA. Because OMB is required to make a decision 

concerning the ICR between 30 and 60 days after [INSERT DATE OF 

PUBLICATION IN THE FEDERAL REGISTER], a comment to OMB is best 

assured of having its full effect if OMB receives it by [INSERT 

DATE 30 DAYS FROM DATE OF PUBLICATION IN THE FEDERAL REGISTER]. 

The final rule will respond to any OMB or public comments on the 

information collection requirements contained in this proposal.

C. Regulatory Flexibility Act

The Regulatory Flexibility Act generally requires an agency 

to prepare a regulatory flexibility analysis of any rule subject 

to notice and comment rulemaking requirements under the 

Administrative Procedure Act or any other statute unless the 

agency certifies that the rule will not have a significant 

economic impact on a substantial number of small entities. Small 

entities include small businesses, small organizations and small 

governmental jurisdictions. 

For purposes of assessing the impacts of this proposed rule 

on small entities, small entity is defined as: (1) a small 

business as defined by the Small Business Administration’s (SBA) 

regulations at 13 CFR 121.201; (2) a small governmental 

jurisdiction that is a government of a city, county, town, 
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school district or special district with a population of less 

than 50,000; and (3) a small organization that is any not-forprofit enterprise that is independently owned and operated and 

is not dominant in its field. According to the SBA small 

business standards definitions, for the Group IV Polymers and 

Resins source categories, which have the NAICS code of 325211 

(i.e., Plastics Material and Resin Manufacturing), the SBA small 

business size standard is 750 employees. For the PEPO source 

category, which has the NAICS code of 325199 (i.e., All Other 

Basic Organic Chemical Manufacturing), the SBA small business 

size standard is 1,000 employees. For the PAI source category, 

which has the NAICS codes of 325199 (i.e., All Other Basic 

Organic Chemical Manufacturing) and 325320 (i.e., Pesticide and 

Other Agricultural Chemical Manufacturing), the SBA small 

business size standards are 1,000 employees and 500 employees, 

respectively.

After considering the economic impacts of this proposed 

rule on small entities, I certify that this action will not have 

a significant economic impact on a substantial number of small 

entities. Only one small business in the PAI source category is 

impacted and only one small business in the Group IV Polymers 

and Resins source categories is impacted. For each affected 

small business, the impact of this proposal is an annual 

compliance cost of less than 1 percent of the parent firm’s 
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revenues. There are no affected small businesses in the PEPO 

source category. All of the other companies affected by this 

rule are generally large integrated corporations that are not 

considered to be small entities per the definitions provided in 

this section. 

We continue to be interested in the potential impacts of 

the proposed rule on small entities and welcome comments on 

issues related to such impacts.

D. Unfunded Mandates Reform Act

This proposed rule does not contain a federal mandate under 

the provisions of Title II of the Unfunded Mandates Reform Act 

of 1995 (UMRA), 2 U.S.C. 1531-1538 for state, local or tribal 

governments or the private sector. The proposed rule would not 

result in expenditures of $100 million or more for state, local 

and tribal governments, in aggregate, or the private sector in 

any 1 year. This proposed rule would require the use of PRD 

monitoring systems, but the nationwide annualized costs of this 

proposed requirement are estimated to be approximately $2 

million for affected sources. Thus, this proposed rule is not 

subject to the requirements of sections 202 or 205 of the UMRA.

This proposed rule is also not subject to the requirements 

of section 203 of UMRA because it contains no regulatory 

requirements that might significantly or uniquely affect small 

governments because it contains no requirements that apply to 
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such governments nor does it impose obligations upon them.

E. Executive Order 13132: Federalism

This proposed rule does not have federalism implications. 

It will not have substantial direct effects on the states, on 

the relationship between the national government and the states, 

or on the distribution of power and responsibilities among the 

various levels of government, as specified in Executive Order 

13132. The burden to the respondents and the states is 

approximately $2,000,000 for the three MACT standards addresses 

in this proposed rule. Thus, Executive Order 13132 does not 

apply to this proposed rule. 

In the spirit of Executive Order 13132 and consistent with 

EPA policy to promote communications between the EPA and state 

and local governments, the EPA specifically solicits comment on 

this proposed rule from state and local officials. 

F. Executive Order 13175: Consultation and Coordination with 

Indian Tribal Governments

This proposed rule does not have tribal implications, as 

specified in Executive Order 13175 (65 FR 67249, November 9, 

2000). Thus, Executive Order 13175 does not apply to this 

action.

The EPA specifically solicits additional comment on this 

proposed action from tribal officials.
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G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks

This proposed rule is not subject to Executive Order 13045 

(62 FR 19885, April 23, 1997) because it is not economically 

significant, as defined in Executive Order 12866, and because 

the EPA does not believe the environmental health or safety 

risks addressed by this action present a disproportionate risk 

to children. This action would not cause appreciable increases 

in emissions or emissions-related health risks. The EPA’s risk 

assessments (included in the docket for this proposed rule) 

demonstrate that the existing regulations are associated with an 

acceptable level of risk and provide an ample margin of safety 

to protect public health and prevent adverse environmental 

effects.

H. Executive Order 13211: Actions Concerning Regulations That 

Significantly Affect Energy Supply, Distribution, or Use

This action is not a “significant energy action,” as 

defined under Executive Order 13211, (66 FR 28355, May 22, 

2001), because it is not likely to have significant adverse 

effect on the supply, distribution or use of energy. This action 

will not create any new requirements and, therefore, no 

additional costs for sources in the energy supply, distribution 

or use sectors.

I. National Technology Transfer and Advancement Act
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Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (NTTAA), Public Law No. 104-113 (15 

U.S.C. 272 note) directs the EPA to use voluntary consensus 

standards (VCS) in its regulatory activities, unless to do so 

would be inconsistent with applicable law or otherwise 

impractical. VCS are technical standards (e.g., materials 

specifications, test methods, sampling procedures and business 

practices) that are developed or adopted by VCS bodies. NTTAA 

directs the EPA to provide Congress, through OMB, explanations 

when the agency decides not to use available and applicable VCS. 

This proposed rulemaking involves technical standards. The 

EPA proposes to use ASTM D2908–74 or 91 and ASTM D3370–76 or 96a 

for the PCCT at the one Group IV Polymers and Resins facility in 

the PET continuous TPA high viscosity multiple end finisher 

subcategory. No applicable VCS were identified for these 

methods.

The EPA welcomes comments on this aspect of this proposed 

rulemaking and, specifically, invites the public to identify 

potentially-applicable VCS and to explain why such standards 

should be used in this regulation.

Under section 63.7(f) and section 63.8(f) of Subpart A of 

the General Provisions, a source may apply to the EPA for 

permission to use alternative test methods or alternative 

monitoring requirements in place of any required testing 
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methods, performance specifications or procedures in the 

proposed rule.

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations

Executive Order 12898 (59 FR 7629, February 16, 1994) 

establishes federal executive policy on environmental justice. 

Its main provision directs federal agencies, to the greatest 

extent practicable and permitted by law, to make environmental 

justice part of their mission by identifying and addressing, as 

appropriate, disproportionately high and adverse human health or 

environmental effects of their programs, policies and activities 

on minority populations and low-income populations in the United 

States. 

To examine the potential for any environmental justice 

issues that might be associated with the level of the standards 

for each source category, we performed a comparative analysis of 

the demographics of the population within the vicinity of the 

facilities in these source categories (i.e., within a 3-mile 

radius) and the national average demographic distributions. The 

results of this analysis show that most demographic categories 

are within 2 percentage points of national averages, except for

the African American population, which exceeds the national 

average by 6 percentage points (18 percent versus 12 percent). 
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The EPA has determined that the current health risks posed by 

emissions from these source categories are acceptable and 

provide an ample margin of safety to protect public health and 

prevent adverse environmental effects. The proposed rule will 

not have disproportionately high and adverse human health or 

environmental effects on minority or low-income populations 

because it maintains the level of environmental protection for 

all affected populations.
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National Emission Standards for Hazardous Air Pollutant 

Emissions: Group IV Polymers and Resins; Pesticide Active 

Ingredient Production; and Polyether Polyols Production--

Page 190 of 253

List of Subjects for 40 CFR Part 63

Environmental protection, Administrative practice and 

procedures, Air pollution control, Hazardous substances, 

Intergovernmental relations, Reporting and recordkeeping 

requirements.

______________

Dated: 

________________________

Lisa P. Jackson,

Administrator.
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For the reasons stated in the preamble, the Environmental 

Protection Agency (EPA) proposes to amend Title 40, chapter I, 

of the Code of Federal Regulations (CFR) as follows:

PART 63—[AMENDED]

1. The authority citation for part 63 continues to read 

as follows:

Authority: 42 U.S.C. 7401, et seq.

Subpart JJJ--[AMENDED]

2. Section 63.1310 is amended by: 

a. Revising paragraphs (a)(4), (a)(4)(iv) and (a)(4)(vi);

b. Revising paragraphs (c)(1) and (d);

c. Revising paragraphs (j) and (j)(1) through (j)(4); and

d. Adding paragraph (k) to read as follows:

§63.1310 Applicability and designation of affected sources.

(a) * * *

(4) Emission points and equipment. The affected source also 

includes the emission points and components specified in 

paragraphs (a)(4)(i) through (vi) of this section that are 

associated with each applicable group of one or more TPPU

constituting an affected source.

* * * * *

(iv) Each process contact cooling tower used in the 

manufacture of poly (ethylene terephthalate) resin (PET) that is 

associated with a new affected source.
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* * * * *

(vi) Components required by or utilized as a method of 

compliance with this subpart, which may include control devices 

and recovery devices.

* * * * *

(c) * * *

(1) Components and equipment that do not contain organic 

HAP and is located within a TPPU that is part of an affected 

source;

* * * * *

(d) Processes excluded from the affected source. The 

processes specified in paragraphs (d)(1) through (5) of this 

section are not part of the affected source and are not subject 

to the requirements of both this subpart and subpart A of this 

part:

* * * * *

(j) Applicability of this subpart.

(1) The emission limitations set forth in this subpart and 

the emission limitations referred to in this subpart shall apply 

at all times except during periods of non-operation of the 

affected source (or specific portion thereof) resulting in 

cessation of the emissions to which this subpart applies.

(2) The emission limitations set forth in subpart H of this 

part, as referred to in §63.1331, shall apply at all times 
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except during periods of non-operation of the affected source 

(or specific portion thereof) in which the lines are drained and 

depressurized, resulting in cessation of the emissions to which 

§63.1331 applies.

(3) The owner or operator shall not shut down items of 

equipment that are required or utilized for compliance with this

subpart during times when emissions (or, where applicable, 

wastewater streams or residuals) are being routed to such items 

of equipment, if the shutdown would contravene requirements of 

this subpart applicable to such items of equipment

(4) General duty. At all times, the owner or operator must 

operate and maintain any affected source, including associated 

air pollution control equipment and monitoring equipment, in a 

manner consistent with safety and good air pollution control 

practices for minimizing emissions. Determination of whether 

such operation and maintenance procedures are being used will be 

based on information available to the Administrator, which may 

include, but is not limited to, monitoring results, review of 

operation and maintenance procedures, review of operation and 

maintenance records and inspection of the source.

(k) Affirmative defense for exceedance of emission limit 

during malfunction. In response to an action to enforce the 

standards set forth in this subpart, the owner or operator may 

assert an affirmative defense to a claim for civil penalties for 
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exceedances of such standards that are caused by malfunction, as 

defined at §63.2. Appropriate penalties may be assessed, 

however, if the owner or operator fails to meet their burden of 

proving all of the requirements in the affirmative defense. The 

affirmative defense shall not be available for claims for 

injunctive relief.

(1) To establish the affirmative defense in any action to 

enforce such a limit, the owner or operator must timely meet the 

notification requirements in paragraph (k)(2) of this section, 

and must prove by a preponderance of evidence that:

(i) The excess emissions: 

(A) Were caused by a sudden, infrequent and unavoidable 

failure of air pollution control and monitoring equipment, 

process equipment or a process to operate in a normal or usual 

manner; and 

(B) Could not have been prevented through careful planning, 

proper design or better operation and maintenance practices; and

(C) Did not stem from any activity or event that could have 

been foreseen and avoided or planned for; and

(D) Were not part of a recurring pattern indicative of 

inadequate design, operation or maintenance; and

(ii) Repairs were made as expeditiously as possible when 

the applicable emission limitations were being exceeded. Offshift and overtime labor were used to the extent practicable to 
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make these repairs; and

(iii) The frequency, amount and duration of the excess 

emissions (including any bypass) were minimized to the maximum 

extent practicable during periods of such emissions; and

(iv) If the excess emissions resulted from a bypass of 

control equipment or a process, then the bypass was unavoidable 

to prevent loss of life, personal injury or severe property 

damage; and

(v) All possible steps were taken to minimize the impact of 

the excess emissions on ambient air quality, the environment and 

human health; and

(vi) All emissions monitoring and control systems were kept 

in operation if at all possible, consistent with safety and good 

air pollution control practices; and

(vii) All of the actions in response to the excess 

emissions were documented by properly signed, contemporaneous 

operating logs; and

(viii) At all times, the affected source was operated in a 

manner consistent with good practices for minimizing emissions; 

and

(ix) A written root cause analysis has been prepared, the 

purpose of which is to determine, correct and eliminate the 

primary causes of the malfunction and the excess emissions 

resulting from the malfunction event at issue. The analysis 
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shall also specify, using best monitoring methods and 

engineering judgment, the amount of excess emissions that were 

the result of the malfunction.

(2) Notification. The owner or operator of the affected 

source experiencing an exceedance of its emission limit(s) 

during a malfunction shall notify the Administrator by telephone 

or facsimile (FAX) transmission as soon as possible, but no 

later than 2 business days after the initial occurrence of the 

malfunction, if it wishes to avail itself of an affirmative 

defense to civil penalties for that malfunction. The owner or 

operator seeking to assert an affirmative defense shall also 

submit a written report to the Administrator within 45 days of 

the initial occurrence of the exceedance of the standard in this 

subpart to demonstrate, with all necessary supporting 

documentation, that it has met the requirements set forth in 

paragraph (k)(1) of this section. The owner or operator may seek 

an extension of this deadline for up to 30 additional days by 

submitting a written request to the Administrator before the 

expiration of the 45-day period. Until a request for an 

extension has been approved by the Administrator, the owner or 

operator is subject to the requirement to submit such report 

within 45 days of the initial occurrence of the exceedance.

3. Section 63.1311 is amended by revising “Notthstanding” 

to read “Notwithstanding” in paragraph (d)(6) to read as 
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follows:

§63.1311 Compliance dates and relationship of this subpart to 

existing applicable rules.

* * * * *

(d) * * *

(6) Notwithstanding paragraphs (d)(1) through (5) of this 

section, existing affected sources whose primary product, as 

determined using the procedures specified in §63.1310(f), is PET 

shall be in compliance with §63.1331 no later than August 6, 

2002.

* * * * *

4. Section 63.1312 is amended by:

a. Removing the term “Start-up, shutdown, and malfunction 

plan (§63.101)” in paragraph (a); and

b. Adding the definition for “Affirmative defense” in 

paragraph (b) to read as follows:

§63.1312 Definitions.

* * * * *

(b) * * *

Affirmative defense means, in the context of an enforcement 

proceeding, a response or defense put forward by a defendant, 

regarding which the defendant has the burden of proof, and the 

merits of which are independently and objectively evaluated in a 

judicial or administrative proceeding.
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* * * * *

5. Section 63.1319 is amended by revising “Lfimits” to read 

“limits” in paragraph (c) to read as follows:

§63.1319 PET and polystyrene affected sources—recordkeeping 

provisions.

* * * * *

(c) Records demonstrating compliance with temperature 

limits for final condensers. * * *

6. Section 63.1324 is amended by revising paragraph 

(c)(4)(ii)(C) to read as follows:

§63.1324 Batch process vents—monitoring equipment.

* * * * *

(c) * * *

(4) * * *

(ii) * * *

(C) The owner or operator may prepare and implement a gas 

stream flow determination plan that documents an appropriate 

method which will be used to determine the gas stream flow. The 

plan shall require determination of gas stream flow by a method 

which will at least provide a value for either a representative 

or the highest gas stream flow anticipated in the scrubber 

during representative operating conditions other than 

malfunctions. * * *

* * * * *
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7. Section 63.1329 is amended by:

a. Revising paragraph (c); and

b. Redesignating paragraph (c)(2) as (c)(2)(i) and adding 

paragraphs (c)(2)(ii) and (iii) to read as follows:

§63.1329 Process contact cooling towers provisions.

* * * * *

(c) Existing affected source requirements. The owner or 

operator of an existing affected source subject to this section 

who manufactures PET using a continuous terephthalic acid high 

viscosity multiple end finisher process and who is subject or 

becomes subject to 40 CFR part 60, subpart DDD, shall maintain 

an ethylene glycol concentration in the process contact cooling 

tower at or below 6.0 percent by weight averaged on a daily 

basis over a rolling 14-day period of operating days. * * *

* * * * *

(2)(i) Measuring an alternative parameter, such as carbon 

oxygen demand or biological oxygen demand, that is demonstrated 

to be directly proportional to the ethylene glycol concentration 

shall be allowed. Such parameter shall be measured during the 

initial 14-day performance test during which the facility is 

shown to be in compliance with the ethylene glycol concentration 

standard whereby the ethylene glycol concentration is determined 

using the procedures described in paragraph (c)(1) of this 

section. The alternative parameter shall be measured on a daily 
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basis and the average value of the alternative parameter shall 

be calculated on a daily basis over a rolling 14-day period of 

operating days. Each daily average value of the alternative 

parameter constitutes a performance test.

(ii) Where 40 CFR 60.564(j)(1) requires the use of ASTM 

D2908–74 or 91, “Standard Practice for Measuring Volatile 

Organic Matter in Water by Aqueous-Injection Gas 

Chromatography,” ASTM D2908—91(2011), D2908-91(2005), D2908-

91(2001), D2908-91 or D2908–74 may be used.

(iii) Where 40 CFR 60.564(j)(1)(i) requires the use of ASTM 

D3370–76 or 96a, “Standard Practices for Sampling Water,” ASTM 

D3370-10, D3370-08, D3370-07, D3370-96a or D3370-76 may be used.

8. Section 63.1331 is amended by:

a. Revising paragraph (a)(9);

b. Adding paragraphs (a)(9)(i) through (a)(9)(iii);

c. Redesignating paragraph (c) as (c)(1); and

d. Adding paragraphs (c)(2) through (c)(4) to read as 

follows:

§63.1331 Equipment leak provisions.

(a) * * *

(9) Requirements for pressure relief devices. For pressure 

relief devices, the owner or operator must meet the requirements 

of this paragraph. Any release to the atmosphere from a pressure 

relief device in organic HAP service constitutes a violation of 
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this rule. The owner or operator must install, maintain and 

operate release indicators as specified in paragraphs (a)(9)(i) 

and (ii) of this section unless the pressure relief routes to a 

closed vent system and control device designed and operated in 

accordance with the requirements of this subpart. For any 

pressure relief devices, the owner or operator must comply with 

the recordkeeping and reporting provisions in this paragraph (a) 

and §63.1335(e)(9). For any release, the owner or operator must 

submit the report specified in §63.1335(e)(9), as described in 

paragraph (a)(9)(iii) of this section.

(i) A release indicator must be properly installed on each 

pressure relief device in such a way that it will indicate when 

an emission release has occurred.

(ii) Each indicator must be equipped with an alert system 

that will notify an operator immediately and automatically when 

the pressure relief device is open. The alert must be located 

such that the signal is detected and recognized easily by an 

operator.

(iii) For any instance that the release indicator indicates 

that a pressure relief device is open, the owner or operator 

must notify the Administrator that a pressure release has 

occurred and submit to the Administrator the report specified in 

§63.1335(e)(9). This report is required even if the owner or 

operator elects to follow the procedures specified in 
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§63.1310(k) to establish an affirmative defense.

* * * * *

(c)(1) Each affected source producing PET using a 

continuous TPA high viscosity multiple end finisher process 

shall monitor for leaks upon startup following an outage where 

changes have been made to equipment in gas/vapor or light liquid 

service. This leak check shall consist of the introduction of 

hot ethylene glycol vapors into the system for a period of no 

less than 2 hours during which time sensory monitoring of the 

equipment shall be conducted. 

(2) A leak is determined to be detected if there is 

evidence of a potential leak found by visual, audible or 

olfactory means. 

(3) When a leak is detected, it shall be repaired as soon 

as practical, but not later than 15 days after it is detected, 

except as provided in §63.171.

(i) The first attempt at repair shall be made no later than 

5 days after each leak is detected.

(ii) Repaired shall mean that the visual, audible, 

olfactory or other indications of a leak have been eliminated; 

that no bubbles are observed at potential leak sites during a 

leak check using soap solution; or that the system will hold a 

test pressure.

(4) When a leak is detected, the following information 
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shall be recorded and kept for 2 years and reported in the next 

periodic report:

(i) The instrument and the equipment identification number 

and the operator name, initials or identification number.

(ii) The date the leak was detected and the date of first 

attempt to repair the leak.

(iii) The date of successful repair of the leak.

9. Section 63.1332 is amended by:

a. Removing and reserving paragraph (f)(1); and

b. Revising paragraph (f)(2) to read as follows:

§63.1332 Emissions averaging provisions.

* * * * *

(f) * * *

(1) [Removed and Reserved]

(2) Emissions during periods of monitoring excursions, as 

defined in §63.1334(f). For these periods, the calculation of 

monthly credits and debits shall be adjusted as specified in 

paragraphs (f)(2)(i) through (f)(2)(iii) of this section.

* * * * *

10. Section 63.1333 is amended by revising paragraph (a) to 

read as follows:

§63.1333 Emissions averaging provisions.

(a) Performance testing shall be conducted under such 

conditions as the Administrator specifies to the owner or 
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operator based on representative performance of the affected 

source for the period being tested and in accordance with 

§63.7(a)(1), (a)(3), (d), (e)(2), (e)(4), (g) and (h), with the 

exceptions specified in paragraphs (a)(1) through (5) of this 

section and the additions specified in paragraphs (b) through 

(d) of this section. Upon request, the owner or operator shall 

make available to the Administrator such records as may be 

necessary to determine the conditions of performance tests. 

Sections 63.1314 through 63.1330 also contain specific testing 

requirements.

* * * * *

11. Section 63.1334 is amended by:

a. Removing and reserving paragraphs (f)(1)(v)(B) through 

(D);

b. Removing and reserving paragraphs (f)(2)(ii)(B)(2) 

through (4);

c. Removing and reserving paragraphs (f)(5)(ii) through 

(iv);

d. Removing and reserving paragraphs (f)(6)(ii) through 

(iv); and

e. Removing and reserving paragraph (g) to read as follows:

§63.1334 Parameter monitoring levels and excursions.

* * * * *

(f) * * *
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(1) * * *

(v) * * *

(B) [Removed and Reserved]

(C) [Removed and Reserved]

(D) [Removed and Reserved]

* * * * *

(2) * * *

(ii) * * *

(B) * * *

(2) [Removed and Reserved]

(3) [Removed and Reserved]

(4) [Removed and Reserved]

* * * * *

(5) * * *

(ii) [Removed and Reserved]

(iii) [Removed and Reserved]

(iv ) [Removed and Reserved] 

* * * * *

(6) * * *

(ii) [Removed and Reserved]

(iii) [Removed and Reserved]

(iv ) [Removed and Reserved] 

* * * * *

(g) [Removed and Reserved]
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12. Section 63.1335 is amended by:

a. Revising paragraphs (b)(1), (b)(1)(i), and (b)(1)(i)(A) 

– (B);

b. Removing and reserving paragraph ((b)(1)(i)(C);

c. Revising paragraph (b)(1)(ii);

d. Revising paragraph (d)(7)(i);

e. Removing and reserving paragraphs (d)(7)(ii) - (iv)

f. Revising paragraphs (e), (e)(3) and (e)(3)(v);

g. Removing and reserving paragraph (e)(3)(viii);

h. Revising paragraph (e)(3)(ix)(B)

i. Revising paragraphs (e)(6), (e)(6)(iii)(E), 

(e)(6)(xii)(A)(1), and (e)(6)(xii)(D);

j. Adding paragraphs (e)(9) and (e)(10);

k. Revising paragraph (h)(1)(i);

l. Removing and reserving paragraph (h)(1)(ii)(C);

m. Revising paragraph (h)(1)(iii);

n. Revising paragraphs (h)(2)(iii) – (iv); and

o. Removing paragraphs (h)(2)(iv)(A) – (B) to read as 

follows:

§63.1335 General recordkeeping and reporting provisions. 

* * * * *

(b) * * *

(1) Malfunction recordkeeping and reporting. (i) Records of 

malfunctions. The owner or operator shall keep the records 
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specified in paragraphs (b)(1)(i)(A) through (b)(1)(i)(C) of 

this section.

(A) Records of the occurrence and duration of each 

malfunction of operation of process equipment or control devices 

or recovery devices or continuous monitoring systems used to 

comply with this subpart, and an estimate of the excess 

emissions released.

(B) Records of actions taken during periods of malfunction 

to minimize emissions in accordance with §63.1420(h)(4), 

including corrective actions to restore malfunctioning process 

and air pollution control and monitoring equipment to its normal 

or usual manner of operation.

(C) [Removed and Reserved]

(ii) Reports of malfunctions. For the purposes of this 

subpart, reports of malfunctions shall be submitted on the same 

schedule as the Periodic Reports required under paragraph (e)(6) 

of this section. If a malfunction occurred during the reporting 

period, the report must include the number, duration, excess 

emissions estimate and a brief description for each type of 

malfunction which occurred during the reporting period and which 

caused or may have caused any applicable emission limitation to 

be exceeded. The report must also include a description of 

actions taken by an owner or operator during a malfunction of an 

affected source to minimize emissions in accordance with 
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§63.1420(h)(4), including actions taken to correct a 

malfunction.

* * * * *

(d) * * *

(7) * * *

(i) Monitoring system malfunctions, breakdowns, repairs, 

calibration checks and zero (low-level) and high-level 

adjustments;

(ii) [Removed and Reserved]

(iii) [Removed and Reserved]

(iv) [Removed and Reserved]

* * * * *

(e) Reporting and notification. In addition to the reports 

and notifications required by subpart A of this part as 

specified in Table 1 of this subpart, the owner or operator of 

an affected source shall prepare and submit the reports listed 

in paragraphs (e)(3) through (10) of this section, as 

applicable. * * *

* * * * *

(3) Precompliance Report. Owners or operators of affected 

sources requesting an extension for compliance; requesting 

approval to use alternative monitoring parameters, alternative 

continuous monitoring and recordkeeping or alternative controls; 

requesting approval to use engineering assessment to estimate 
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emissions from a batch emissions episode, as described in 

§63.1323(b)(6)(i)(C); or wishing to establish parameter 

monitoring levels according to the procedures contained in 

§63.1334(c) or (d), shall submit a Precompliance Report 

according to the schedule described in paragraph (e)(3)(i) of 

this section. * * *

* * * * *

(v) The owner or operator shall report the intent to use 

alternative emissions standards to comply with the provisions of 

this subpart in the Precompliance Report. The Administrator may 

deem alternative emissions standards to be equivalent to the 

standard required by the subpart, under the procedures outlined 

in §63.6(g).

* * * * *

(viii) [Removed and Reserved]

* * * * *

(ix) * * *

(B) Supplements to the Precompliance Report may be 

submitted to request approval to use alternative monitoring 

parameters, as specified in paragraph (e)(3)(iii) of this 

section; to use alternative continuous monitoring and 

recordkeeping, as specified in paragraph (e)(3)(iv) of this 

section; to use alternative controls, as specified in paragraph 

(e)(3)(v) of this section; to use engineering assessment to 
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estimate emissions from a batch emissions episode, as specified 

in paragraph (e)(3)(vi) of this section; to establish parameter 

monitoring levels according to the procedures contained in 

§63.1334(c) or (d), as specified in paragraph (e)(3)(vii) of 

this section.

* * * * *

(6) Periodic Reports. For existing and new affected 

sources, the owner or operator shall submit Periodic Reports as 

specified in paragraphs (e)(6)(i) through (e)(6)(xi) of this 

section. In addition, for equipment leaks subject to §63.1331, 

with the exception of §63.1331(c), the owner or operator shall 

submit the information specified in §63.182(d) under the 

conditions listed in §63.182(d), and for heat exchange systems 

subject to §63.1328, the owner or operator shall submit the 

information specified in §63.104(f)(2) as part of the Periodic 

Report required by this paragraph (e)(6). * * *

* * * * *

(iii) * * *

(E) The information in paragraph (b)(1)(ii) of this section 

for reports of malfunctions.

* * * * *

(xii) * * *

(A) * * *
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(1) A control or recovery device for a particular emission 

point or process section has one or more excursions, as defined 

in §63.1334(f), for a semiannual reporting period; or

* * * * *

(D) After quarterly reports have been submitted for an 

emission point for 1 year without one or more excursions 

occurring (during that year), the owner or operator may return 

to semiannual reporting for the emission point or process 

section.

* * * * *

(9) Pressure relief device deviation report. If any 

pressure relief device in organic HAP service or any piece of 

equipment or closed vent system has discharged to the 

atmosphere, as specified in §63.1331(a)(9), the owner or 

operator must submit to the Administrator in the next Periodic 

Report:

(i) The source, nature and cause of the discharge.

(ii) The date, time and duration of the discharge.

(iii) An estimate of the quantity of total organic HAP 

emitted during the discharge and the method used for determining 

this quantity.

(iv) The actions taken to prevent this discharge. 

(v) The measures adopted to prevent future such discharges.

(10) Electronic reporting. (i) Within 60 days after the 
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date of completing each performance test (defined in §63.2), as 

required in this subpart, the owner or operator must transmit 

the results of the performance tests required by this subpart to 

EPA’s WebFIRE database by using the Compliance and Emissions 

Data Reporting Interface (CEDRI) that is accessed through the 

EPA’s Central Data Exchange (CDX) (see www.epa.gov/cdx). 

Performance test data must be submitted in the file format 

generated through use of EPA’s Electronic Reporting Tool (ERT) 

(see http://www.epa.gov/ttn/chief/ert/index.html). Only data 

collected using test methods on the ERT website are subject to 

this requirement for submitting reports electronically to 

WebFIRE. Owners or operators who claim that some of the 

information being submitted for performance tests is 

confidential business information (CBI) must submit a complete 

ERT file including information claimed to be CBI on a compact 

disk or other commonly used electronic storage media (including, 

but not limited to, flash drives) to EPA. The electronic media 

must be clearly marked as CBI and mailed to U.S. EPA/OAPQS/CORE 

CBI Office, Attention: WebFIRE Administrator, MD C404-02, 4930 

Old Page Rd., Durham, NC 27703. The same ERT file with the CBI 

omitted must be submitted to EPA via CDX as described earlier in 

this paragraph. At the discretion of the delegated authority, 

you must also submit these reports, including the confidential 

business information, to the delegated authority in the format 
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specified by the delegated authority.

(ii) All reports required by this subpart not subject to 

the requirements in paragraphs (e)(10)(i) and (ii) of this 

section must be sent to the Administrator at the appropriate 

address listed in §63.13. The Administrator or the delegated 

authority may request a report in any form suitable for the 

specific case (e.g., by commonly used electronic media such as 

Excel spreadsheet, on CD or hard copy). The Administrator 

retains the right to require submittal of reports subject to 

paragraph (e)(10)(i) and (ii) of this section in paper format.

* * * * *

(h) * * *

(1) * * *

(i) The monitoring system is capable of detecting

unrealistic or impossible data during periods of operation 

(e.g., a temperature reading of −200 °C on a boiler), and will 

alert the operator by alarm or other means. The owner or 

operator shall record the occurrence. All instances of the alarm 

or other alert in an operating day constitute a single 

occurrence.

* * * * *

(ii) * * *

(C) [Removed and Reserved]

(iii) The monitoring system is capable of detecting 
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unchanging data during periods of operation , except in 

circumstances where the presence of unchanging data is the 

expected operating condition based on past experience (e.g., pH 

in some scrubbers), and will alert the operator by alarm or 

other means. * * *

* * * * *

(2) * * *

(iii) The owner or operator shall retain the records 

specified in paragraphs (h)(1)(i) through (h)(1)(iii) of this 

section, for the duration specified in paragraph (h) of this 

section. For any calendar week, if compliance with paragraphs 

(h)(1)(i) through (h)(1)(iv) of this section does not result in

retention of a record of at least one occurrence or measured 

parameter value, the owner or operator shall record and retain 

at least one parameter value during a period of operation.

(iv) For purposes of paragraph (h) of this section, an 

excursion means that the daily average (or batch cycle daily 

average) value of monitoring data for a parameter is greater 

than the maximum, or less than the minimum established value.

13. Table 1 to Part JJJ of Subpart 63 is amended by:

a. Revising entries 63.6(e), 63.6(e)(1)(i), and 

63.6(e)(1)(ii);

b. Removing entries 63.6(e)(3)(i) through 63.6(e)(3)(ix);

c. Adding entries 63.6(e)(3) and 63.6(f)(1);
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d. Revising entry 63.7(e)(1);

e. Revising entries 63.8(c)(i) and 63.8(c)(1)(iii);

f. Removing entries 63.10(d)(5)(i) and 63.10(d)(5)(ii);

g. Adding entry 63.10(d)(5);

h. Removing footnote (a).

The revisions and additions read as follows:

Table 1 to Subpart JJJ of Part 63—Applicability of general 

provisions to subpart JJJ affected sources

Reference

Applies 

to

Subpart 

JJJ Explanation

* * * * * * *

§63.6(e) Yes Except as otherwise specified for 

individual paragraphs.

§63.6(e)(1)(i) No See §63.1310(j)(4) for general duty 

requirement.

§63.6(e)(1)(ii) No

* * * * * * *

§63.6(e)(3) No

§63.6(f)(1) No

* * * * * * *

§63.7(e)(1) No See §63.1333(a).

* * * * * * *

§63.8(c)(1)(i) No

* * * * * * *

§63.8(c)(1)(iii)No

* * * * * * *

§63.10(d)(5) No See §63.1335(b)(1)(ii) for malfunction 

reporting requirements.
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* * * * * * *

* * * * *

Subpart MMM—[AMENDED]

14. Section 63.1360 is amended by: 

a. Revising paragraphs (e) and (e)(1);

b. Removing paragraphs (e)(1)(i) and (ii);

c. Revising paragraphs (e)(3) and (e)(4);

d. Adding paragraph (k).

The revisions and addition read as follows:

§63.1360 Applicability.

* * * * *

(e) Applicability of this subpart. (1) Each provision set 

forth in this subpart shall apply at all times.

(i) [Removed]

(ii) [Removed]

(2) * * *

(3) The owner or operator shall not shut down items of 

equipment that are required or utilized for compliance with the 

emissions limitations of this subpart during times when 

emissions (or, where applicable, wastewater streams or 

residuals) are being routed to such items of equipment, if the 

shutdown would contravene emissions limitations of this subpart 

applicable to such items of equipment.
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(4) General duty. At all times, the owner or operator must 

operate and maintain any affected source, including associated 

air pollution control equipment and monitoring equipment, in a 

manner consistent with safety and good air pollution control 

practices for minimizing emissions. Determination of whether 

such operation and maintenance procedures are being used will be 

based on information available to the Administrator, which may 

include, but is not limited to, monitoring results, review of 

operation and maintenance procedures, review of operation and 

maintenance records, and inspection of the source.

* * * * *

(k) Affirmative defense for exceedance of emission limit 

during malfunction. In response to an action to enforce the 

standards set forth in this subpart, the owner or operator may 

assert an affirmative defense to a claim for civil penalties for 

exceedances of such standards that are caused by malfunction, as 

defined at §63.2. Appropriate penalties may be assessed, 

however, if the owner or operator fails to meet their burden of 

proving all of the requirements in the affirmative defense. The 

affirmative defense shall not be available for claims for 

injunctive relief.

(1) To establish the affirmative defense in any action to 

enforce such a limit, the owner or operator must timely meet the 

notification requirements in paragraph (k)(2) of this section, 
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and must prove by a preponderance of evidence that:

(i) The excess emissions: 

(A) Were caused by a sudden, infrequent, and unavoidable 

failure of air pollution control and monitoring equipment, 

process equipment, or a process to operate in a normal or usual 

manner, and 

(B) Could not have been prevented through careful planning, 

proper design or better operation and maintenance practices; and

(C) Did not stem from any activity or event that could have 

been foreseen and avoided, or planned for; and

(D) Were not part of a recurring pattern indicative of 

inadequate design, operation, or maintenance; and

(ii) Repairs were made as expeditiously as possible when 

the applicable emission limitations were being exceeded. Offshift and overtime labor were used, to the extent practicable to 

make these repairs; and

(iii) The frequency, amount and duration of the excess 

emissions (including any bypass) were minimized to the maximum 

extent practicable during periods of such emissions; and

(iv) If the excess emissions resulted from a bypass of 

control equipment or a process, then the bypass was unavoidable 

to prevent loss of life, personal injury, or severe property 

damage; and

(v) All possible steps were taken to minimize the impact of 
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the excess emissions on ambient air quality, the environment and 

human health; and

(vi) All emissions monitoring and control systems were kept 

in operation if at all possible, consistent with safety and good 

air pollution control practices; and

(vii) All of the actions in response to the excess 

emissions were documented by properly signed, contemporaneous 

operating logs; and

(viii) At all times, the affected source was operated in a 

manner consistent with good practices for minimizing emissions; 

and

(ix) A written root cause analysis has been prepared, the 

purpose of which is to determine, correct, and eliminate the 

primary causes of the malfunction and the excess emissions 

resulting from the malfunction event at issue. The analysis 

shall also specify, using best monitoring methods and 

engineering judgment, the amount of excess emissions that were 

the result of the malfunction.

(2) Notification. The owner or operator of the affected 

source experiencing an exceedance of its emission limit(s) 

during a malfunction shall notify the Administrator by telephone 

or facsimile (FAX) transmission as soon as possible, but no 

later than two business days after the initial occurrence of the 

malfunction, if it wishes to avail itself of an affirmative 
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defense to civil penalties for that malfunction. The owner or 

operator seeking to assert an affirmative defense shall also 

submit a written report to the Administrator within 45 days of 

the initial occurrence of the exceedance of the standard in this 

subpart to demonstrate, with all necessary supporting 

documentation, that it has met the requirements set forth in 

paragraph (k)(1) of this section. The owner or operator may seek 

an extension of this deadline for up to 30 additional days by 

submitting a written request to the Administrator before the 

expiration of the 45 day period. Until a request for an 

extension has been approved by the Administrator, the owner or 

operator is subject to the requirement to submit such report 

within 45 days of the initial occurrence of the exceedance.

15. Section 63.1361 is amended by:

a. Adding the definition for “Affirmative defense”.

b. Correcting a typographical error in the definition of 

“Group 1 process vent” by correcting “hydogen” to read 

“hydrogen;

The correction and addition read as follows:

§63.1361 Definitions.

* * * * *

Affirmative defense means, in the context of an enforcement 

proceeding, a response or defense put forward by a defendant, 

regarding which the defendant has the burden of proof, and the 
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merits of which are independently and objectively evaluated in a 

judicial or administrative proceeding.

Group 1 process vent means any process vent from a process 

at an existing or new affected source for which the uncontrolled 

organic HAP emissions from the sum of all process vents are 

greater than or equal to 0.15 Mg/yr and/or the uncontrolled 

hydrogen chloride (HCl) and chlorine emissions from the sum of 

all process vents are greater than or equal to 6.8 Mg/yr.

* * * * *

16. Section 63.1362 is amended by revising paragraph (i) to 

read as follows:

§ 63.1362 Standards.

(i) Opening of a safety device. The owner or operator that 

opens a safety device, as defined in §63.1361, is not exempt 

from applicable standards in order to avoid unsafe conditions. 

If opening a safety device results in the failure to meet any 

applicable standard, the owner or operator must still comply 

with the general duty to minimize emissions. If opening a safety 

device results in a deviation or excess emissions, such events 

must be reported as specified in §63.1368(i). If the owner or 

operator attributes the event to a malfunction and intends to 

assert an affirmative defense, the owner or operator is subject 

to §63.1360(k).

* * * * *
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17. Section 63.1363 is amended by:

a. Revising paragraph (b);

b. Adding paragraph (b)(4);

c. Revising paragraph (g)(4)(v)(A);

d. Revising paragraphs (h)(1) and (h)(1)(i);

e. Adding paragraph (h)(1)(iii);

f. Adding paragraph (h)(4).

The additions and revisions read as follows:

§63.1363 Standards for equipment leaks.

* * * * *

(b) References. The owner or operator shall comply with the 

provisions of subpart H of this part as specified in paragraphs 

(b)(1) through (3) of this section and with paragraph (b)(4) of 

this section for pressure relief device monitoring. * * *

* * * * *

(4) Requirements for pressure relief devices. For pressure 

relief devices, the owner or operator must meet the requirements 

of this paragraph. Any release to the atmosphere from a pressure 

relief device in organic HAP service constitutes a violation of 

this rule. The owner or operator must install, maintain, and 

operate release indicators as specified in paragraphs (b)(4)(i) 

and (ii) of this section unless the pressure relief routes to a 

closed vent system and control device designed and operated in 

accordance with the requirements of this subpart. For any 
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pressure relief devices, the owner or operator must comply with 

the recordkeeping provisions in paragraph (g) of this section 

and the reporting provisions in this paragraph (h) of this 

section. For any release, the owner or operator must submit the 

report specified in paragraph (h)(4) of this section, as 

described in paragraph (b)(4)(iii) of this section.

(i) A release indicator must be properly installed on each 

pressure relief device in such a way that it will indicate when 

an emission release has occurred.

(ii) Each indicator must be equipped with an alert system 

that will notify an operator immediately and automatically when 

the pressure relief device is open. The alert must be located 

such that the signal is detected and recognized easily by an 

operator.

(iii) For any instance that the release indicator indicates 

that a pressure relief device is open, the owner or operator 

must notify the Administrator that a pressure release has 

occurred and submit to the Administrator the report specified in 

paragraph (h)(4) of this section. This report is required even 

if the owner or operators elects to follow the procedures 

specified in §63.1360(k) to establish an affirmative defense.

* * * * *

(g) * * *

(4) * * *
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(v) * * *

(A) The owner or operator may develop a written procedure 

that identifies the conditions that justify a delay of repair. 

The written procedures must be maintained at the plant site. 

Reasons for delay of repair may be documented by citing the 

relevant sections of the written procedure.

(h) * * * (1) Each owner or operator of a source 

subject to this section shall submit the reports listed in 

paragraphs (h)(1)(i) through (iii) of this section.

(i) A Notification of Compliance Status report described in 

paragraph (h)(2) of this section.

(ii) * * *

(iii) A pressure relief device deviation report described 

in paragraph (h)(4) of this section.

* * * * *

(4) Pressure relief device deviation report. If any 

pressure relief device in organic HAP service or any piece of 

equipment or closed vent system has discharged to the atmosphere 

as specified in paragraph (b)(4) of this section, the owner or 

operator must submit to the Administrator in the next Periodic 

Report:

(i) The source, nature, and cause of the discharge.

(ii) The date, time, and duration of the discharge.

(iii) An estimate of the quantity of total organic HAP 
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emitted during the discharge and the method used for determining 

this quantity.

(iv) The actions taken to prevent this discharge. 

(v) The measures adopted to prevent future such discharges.

18. Section 63.1365 is amended by:

a. Revising paragraph (b); 

b. Removing and reserving paragraph (h)(3).

The revisions read as follows:

§63.1365 Test methods and initial compliance procedures.

* * * * *

(b) Test methods and conditions. When testing is conducted 

to measure emissions from an affected source, the test methods 

specified in paragraphs (b)(1) through (9) of this section shall 

be used. Compliance and performance tests shall be performed 

under such conditions as the Administrator specifies to the 

owner or operator based on representative performance of the 

affected source for the period being tested and as specified in 

paragraphs (b)(10) and (11) of this section. Upon request, the 

owner or operator shall make available to the Administrator such 

records as may be necessary to determine the conditions of 

performance tests.

* * * * *

(h) * * *

(3) [Removed and Reserved]
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* * * * *

19. Section 63.1366 is amended by:

a. Removing and reserving paragraph (b)(8)(iv) to read as 

follows:

§63.1366 Monitoring and inspection requirements.

* * * * *

(b) * * *

(8) * * *

(iv) [Removed and Reserved]

* * * * *

20. Section 63.1367 is amended by:

a. Revising paragraphs (a)(3), (a)(3)(i), and (a)(3)(ii);

b. Removing paragraph (a)(3)(iii).

The revisions read as follows:

§63.1367 Recordkeeping requirements.

(a) * * *

(3) Records of malfunctions. (i) The owner or operator of 

an affected source subject to this subpart shall maintain 

records of the occurrence and duration of each malfunction of 

operation (i.e., process equipment), air pollution control 

equipment, or monitoring equipment, and an estimate of the 

excess emissions released.

(ii) The owner or operator shall maintain records of 

actions taken during periods of malfunction to minimize 
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emissions in accordance with §63.1360(e)(4), including 

corrective actions to restore malfunctioning process and air 

pollution control and monitoring equipment to its normal or 

usual manner of operation.

* * * * *

21. Section 63.1368 is amended by:

a. Revising paragraph (i);

b. Adding paragraphs (p).

The revisions and addition read as follows:

§63.1368 Reporting requirements.

* * * * *

(i) Reports of malfunctions. For the purposes of this 

subpart, reports of malfunctions shall be submitted on the same 

schedule as the Periodic reports required under paragraph (g) of 

this section instead of the schedule specified in 

§63.10(d)(5)(i) of subpart A of this part. If a malfunction 

occurred during the reporting period, the report must include 

the number, duration, excess emissions estimate, and a brief 

description for each type of malfunction which occurred during 

the reporting period and which caused or may have caused any 

applicable emission limitation to be exceeded. The report must 

also include a description of actions taken by an owner or 

operator during a malfunction of an affected source to minimize 

emissions in accordance with §63.1360(e)(4), including actions 
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taken to correct a malfunction.

(p) Electronic reporting. (1) Within 60 days after the date 

of completing each performance test (defined in §63.2) as 

required in this subpart, the owner or operator must transmit 

the results of the performance tests required by this subpart to 

EPA’s WebFIRE database by using the Compliance and Emissions 

Data Reporting Interface (CEDRI) that is accessed through EPA’s 

Central Data Exchange (CDX) (see www.epa.gov/cdx). Performance 

test data must be submitted in the file format generated through 

use of EPA’s Electronic Reporting Tool (ERT) (see 

http://www.epa.gov/ttn/chief/ert/index.html). Only data 

collected using test methods on the ERT website are subject to 

this requirement for submitting reports electronically to 

WebFIRE. Owners or operators who claim that some of the 

information being submitted for performance tests is 

confidential business information (CBI) must submit a complete 

ERT file including information claimed to be CBI on a compact 

disk or other commonly used electronic storage media (including, 

but not limited to, flash drives) to EPA. The electronic media 

must be clearly marked as CBI and mailed to U.S. EPA/OAPQS/CORE 

CBI Office, Attention: WebFIRE Administrator, MD C404-02, 4930 

Old Page Rd., Durham, NC 27703. The same ERT file with the CBI 

omitted must be submitted to EPA via CDX as described earlier in 

this paragraph. At the discretion of the delegated authority, 
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you must also submit these reports, including the confidential 

business information, to the delegated authority in the format 

specified by the delegated authority.

(2) All reports required by this subpart not subject to the 

requirements in paragraphs (p)(1) and (2) of this section must 

be sent to the Administrator at the appropriate address listed 

in §63.13. The Administrator or the delegated authority may 

request a report in any form suitable for the specific case 

(e.g., by commonly used electronic media such as Excel 

spreadsheet, on CD or hard copy). The Administrator retains the 

right to require submittal of reports subject to paragraph 

(p)(1) and (2) of this section in paper format.

22. Table 1 to subpart MMM of part 63 is amended by:

a. Removing entry 63.6(e);

b. Adding entries 63.6(e)(1)(i), 63.6(e)(1)(ii), 

63.6(e)(1)(iii), and 63.6(e)(3);

c. Removing entry 63.6(f);

d. Adding entries 63.6(f)(1) and 63.6(f)(2)-(3);

e. Revising entry 63.7(e)(1);

f. Removing entry 63.8(b)(3)-(c)(3);

g. Adding entries 63.8(b)(3), 63.8(c)(1)(i), 

63.8(c)(1)(ii), 63.8(c)(1)(iii), and 63.8(c)(2)-(3);

h. Revising entry 63.8(d)-(f)(3);

i. Removing entry 63.10(c);
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j. Adding entries 63.10(c)(1)-(8), 63.10(c)(10-(11), 

63.10(c)(12)-(14), and 63.10(c)(15);

k. Revising entry 63.10(d)(5).

The revisions and additions read as follows:

Table 1 to Subpart MMM of Part 63—General Provisions

Applicability to Subpart MMM

Reference to 

subpart A

Applies 

to

subpart 

MMM Explanation

* * * * * * *

63.6(e)(1)(i) No See §63.1360(e)(4) for general duty 

requirement.

§63.6(e)(1)(ii) No

§63.6(e)(1)(iii) Yes

§63.6(e)(3) No

§63.6(f)(1) No

§63.6(f)(2)-(3) Yes

* * * * * * *

§63.7(e)(1) No See §63.1365(b).

* * * * * * *

§63.8(b)(3) Yes

§63.8(c)(1)(i) No
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§63.8(c)(1)(ii) Yes

§63.8(c)(1)(iii) No

§63.8(c)(2)-(3) Yes

* * * * * * *

§63.8(d)–(f)(3) Yes Except the last sentence of 

§63.8(d)(3), which refers to an SSM 

plan. SSM plans are not required.

* * * * * * *

§63.10(c)(1)-(8) Yes

§63.10(c)(10)-

(11)

No See §63.1367(a)(3) for malfunction 

recordkeeping requirements.

§63.10(c)(12)-

(14)

Yes

§63.10(c)(15) No

* * * * * * *

§63.10(d)(5) No See §63.1368(i) for malfunction 

reporting requirements.

* * * * * * *

* * * * *

Subpart PPP—[AMENDED]

23. Section 63.1420 is amended by: 

a. Revising paragraphs (a)(4) and (a)(4)(iv);

b. Revising paragraphs (c)(1), (d), and (e(8);
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c. Revising paragraphs (h), and (h)(1) through (h)(4);

d. Adding paragraph (i).

The revisions read as follows:

§63.1420 Applicability and designation of affected sources.

(a) * * *

(4) The affected source also includes the emission points 

and components specified in paragraphs (a)(4)(i) through (vi) of 

this section that are associated with a PMPU (or a group of 

PMPUs) making up an affected source, as defined in §63.1423.

* * * * *

(iv) Components required by or utilized as a method of 

compliance with this subpart which may include control 

techniques and recovery devices.

* * * * *

(c) * * *

(1) Components and equipment that do not contain organic 

HAP or that contains organic HAP as impurities only and is 

located at a PMPU that is part of an affected source.

* * * * *

(d) Processes excluded from the affected source. The 

processes specified in paragraphs (d)(1) through (3) of this 

section are not part of the affected source and are not subject 

to the requirements of both this subpart and subpart A of this 

part.
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* * * * *

(e) * * *

(8) Requirements for flexible process units that are not 

PMPU. * * *

* * * * *

(h) Applicability of this subpart. (1) The emission 

limitations set forth in this subpart and the emission 

limitations referred to in this subpart shall apply at all times 

except during periods of nonoperation of the affected source (or 

specific portion thereof) resulting in cessation of the 

emissions to which this subpart applies.

(2) The emission limitations set forth in 40 CFR part 63, 

subpart H, as referred to in the equipment leak provisions in 

§63.1434, shall apply at all times except during periods of nonoperation of the affected source (or specific portion thereof) 

in which the lines are drained and depressurized resulting in 

cessation of the emissions to which §63.1434 applies.

(3) The owner or operator shall not shut down items of 

equipment that are required or utilized for compliance with this 

subpart during times when emissions (or, where applicable, 

wastewater streams or residuals) are being routed to such items 

of equipment if the shutdown would contravene requirements 

applicable to such items of equipment.

(4) General duty. At all times, the owner or operator must 
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operate and maintain any affected source, including associated 

air pollution control equipment and monitoring equipment, in a 

manner consistent with safety and good air pollution control 

practices for minimizing emissions. Determination of whether 

such operation and maintenance procedures are being used will be 

based on information available to the Administrator, which may 

include, but is not limited to, monitoring results, review of 

operation and maintenance procedures, review of operation and 

maintenance records, and inspection of the source.

(i) Affirmative defense for exceedance of emission limit 

during malfunction. In response to an action to enforce the 

standards set forth in this subpart, the owner or operator may 

assert an affirmative defense to a claim for civil penalties for 

exceedances of such standards that are caused by malfunction, as 

defined at §63.2. Appropriate penalties may be assessed, 

however, if the owner or operator fails to meet their burden of 

proving all of the requirements in the affirmative defense. The 

affirmative defense shall not be available for claims for 

injunctive relief.

(1) To establish the affirmative defense in any action to 

enforce such a limit, the owner or operator must timely meet the 

notification requirements in paragraph (i)(2) of this section, 

and must prove by a preponderance of evidence that:

(i) The excess emissions: 
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(A) Were caused by a sudden, infrequent, and unavoidable 

failure of air pollution control and monitoring equipment, 

process equipment, or a process to operate in a normal or usual 

manner, and 

(B) Could not have been prevented through careful planning, 

proper design or better operation and maintenance practices; and

(C) Did not stem from any activity or event that could have 

been foreseen and avoided, or planned for; and

(D) Were not part of a recurring pattern indicative of 

inadequate design, operation, or maintenance; and

(ii) Repairs were made as expeditiously as possible when 

the applicable emission limitations were being exceeded. Offshift and overtime labor were used, to the extent practicable to 

make these repairs; and

(iii) The frequency, amount and duration of the excess 

emissions (including any bypass) were minimized to the maximum 

extent practicable during periods of such emissions; and

(iv) If the excess emissions resulted from a bypass of 

control equipment or a process, then the bypass was unavoidable 

to prevent loss of life, personal injury, or severe property 

damage; and

(v) All possible steps were taken to minimize the impact of 

the excess emissions on ambient air quality, the environment and 

human health; and
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(vi) All emissions monitoring and control systems were kept 

in operation if at all possible, consistent with safety and good 

air pollution control practices; and

(vii) All of the actions in response to the excess 

emissions were documented by properly signed, contemporaneous 

operating logs; and

(viii) At all times, the affected source was operated in a 

manner consistent with good practices for minimizing emissions; 

and

(ix) A written root cause analysis has been prepared, the 

purpose of which is to determine, correct, and eliminate the 

primary causes of the malfunction and the excess emissions 

resulting from the malfunction event at issue. The analysis 

shall also specify, using best monitoring methods and 

engineering judgment, the amount of excess emissions that were 

the result of the malfunction.

(2) Notification. The owner or operator of the affected 

source experiencing an exceedance of its emission limit(s) 

during a malfunction shall notify the Administrator by telephone 

or facsimile (FAX) transmission as soon as possible, but no 

later than two business days after the initial occurrence of the 

malfunction, if it wishes to avail itself of an affirmative 

defense to civil penalties for that malfunction. The owner or 

operator seeking to assert an affirmative defense shall also 
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submit a written report to the Administrator within 45 days of 

the initial occurrence of the exceedance of the standard in this 

subpart to demonstrate, with all necessary supporting 

documentation, that it has met the requirements set forth in 

paragraph (i)(1) of this section. The owner or operator may seek 

an extension of this deadline for up to 30 additional days by 

submitting a written request to the Administrator before the 

expiration of the 45 day period. Until a request for an 

extension has been approved by the Administrator, the owner or 

operator is subject to the requirement to submit such report 

within 45 days of the initial occurrence of the exceedance.

24. Section 63.1423 is amended by:

a. Revising paragraph (a) by removing the term “Start-up, 

shutdown, and malfunction plan (subpart F)”; 

b. Revising paragraph (b) and adding the term “Affirmative 

defense” to read as follows:

§63.1423 Definitions.

(a) The following terms used in this subpart shall have the 

meaning given them in subparts A (§63.2), F (§63.101), G 

(§63.111), and H (§63.161) as specified after each term:

Act (subpart A)

Administrator (subpart A)

Automated monitoring and recording system (subpart G)

Boiler (subpart G)
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Bottoms receiver (subpart H)

By-product (subpart F)

Car-seal (subpart G)

Closed-vent system (subpart G)

Combustion device (subpart G)

Commenced (subpart A)

Compliance date (subpart A)

Continuous monitoring system (subpart A)

Emission standard (subpart A)

EPA (subpart A)

Equipment (subpart H)

Flow indicator (subpart G)

Fuel gas (subpart F)

Fuel gas system (subpart F)

Hard-piping (subpart G)

Heat exchange system (subpart F)

Impurity (subpart F)

Incinerator (subpart G)

Major source (subpart A)

Malfunction (subpart A)

Oil-water separator or organic-water separator (subpart G)

Open-ended valve or line (subpart H)

Operating permit (subpart F)

Organic monitoring device (subpart G)
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Owner or operator (subpart A)

Performance evaluation (subpart A)

Performance test (subpart A)

Permitting authority (subpart A)

Plant site (subpart F)

Potential to emit (subpart A)

Primary fuel (subpart G)

Process heater (subpart G)

Process unit shutdown (subpart H)

Reactor (subpart G)

Recapture device (subpart G)

Relief valve (subpart G)

Research and development facility (subpart F)

Responsible official (subpart A)

Run (subpart A)

Secondary fuel (subpart G)

Sensor (subpart H)

Specific gravity monitoring device (subpart G)

State (subpart A) 

* * * * *

(b) All other terms used in this subpart shall have the 

meaning given to them in this section.

Affirmative defense means, in the context of an enforcement 

proceeding, a response or defense put forward by a defendant, 
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regarding which the defendant has the burden of proof, and the 

merits of which are independently and objectively evaluated in a 

judicial or administrative proceeding.

* * * * *

25. Section 63.1430 is amended by revising paragraph 

(d)(2)(i) to read as follows:

§63.1430 Process vent reporting and recordkeeping requirements.

* * * * *

(d) * * *

(2) * * *

(i) Monitoring data recorded during periods of monitoring 

system breakdowns, repairs, calibration checks, and zero (lowlevel) and high-level adjustments shall not be included in 

computing the daily averages. In addition, monitoring data 

recorded during periods of non-operation of the process (or 

specific portion thereof) resulting in cessation of organic HAP 

emissions shall not be included in computing the daily averages.

26. Section 63.1434 is amended by revising paragraphs (c) 

and (c)(1) through (c)(4) to read as follows:

§63.1434 Equipment leak provisions.

* * * * *

(c) Requirements for pressure relief devices. For pressure 

relief devices, the owner or operator must meet the requirements 

of this paragraph. Any release to the atmosphere from a pressure 
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relief device in organic HAP service constitutes a violation of 

this rule. The owner or operator must install, maintain, and 

operate release indicators as specified in paragraphs (c)(1) and 

(2) of this section unless the pressure relief routes to a 

closed vent system and control device designed and operated in 

accordance with the requirements of this subpart. For any 

pressure relief devices, the owner or operator must comply with 

the recordkeeping and reporting provisions in §§63.1439(c) and 

(e)(9). For any release, the owner or operator must submit the 

report specified in §63.1439(e)(9), as described in paragraph 

(c)(3) of this section.

(1) A release indicator must be properly installed on each 

pressure relief device in such a way that it will indicate when 

an emission release has occurred.

(2) Each indicator must be equipped with an alert system 

that will notify an operator immediately and automatically when 

the pressure relief device is open. The alert must be located 

such that the signal is detected and recognized easily by an 

operator.

(3) For any instance that the release indicator indicates 

that a pressure relief device is open, the owner or operator 

must notify the Administrator that a pressure release has 

occurred and submit to the Administrator the report specified in 

§63.1439(e)(9). This report is required even if the owner or 
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operator elects to follow the procedures specified in 

§63.1420(k) to establish an affirmative defense.

* * * * *

27. Section 63.1437 is amended by revising paragraphs (a) 

and (a)(1) to read as follows:

§63.1437 Additional requirements for performance testing.

(a) Performance testing shall be conducted in accordance 

with §63.7(a)(1), (a)(3), (d), (e)(2), (e)(4), (g), and (h), 

with the exceptions specified in paragraphs (a)(1) through (4) 

of this section and the additions specified in paragraph (b) of 

this section. Performance tests shall be conducted under such 

conditions as the Administrator specifies to the owner or 

operator based on representative performance of the affected 

source for the period being tested. Upon request, the owner or 

operator shall make available to the Administrator such records 

as may be necessary to determine the conditions of performance 

tests.

(1) Performance tests shall be conducted according to the 

general provisions' performance testing requirements in 

§63.7(e)(2), except that for all emission sources except process 

vents from batch unit operations, performance tests shall be 

conducted during maximum representative operating conditions for 

the process achievable during one of the time periods described 

in paragraph (a)(1)(i) of this section, without causing any of 
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the situations described in paragraph (a)(1)(ii) or (iii) of 

this section to occur. * * *

* * * * *

28. Section 63.1438 is amended by:

a. Revising paragraphs (e)(1) and (e)(2);

b. Removing and reserving paragraphs (f)(1)(v)(A) through 

(C), (f)(3)(ii)(B)(1) through (3), and (g).

The revisions read as follows:

§63.1438 Parameter monitoring levels and excursions.

(e) * * * (1) Each excursion, as defined in paragraphs 

(f)(1)(i), (f)(2)(i)(A), (f)(2)(ii), (f)(3)(i), and (f)(4) of 

this section, constitutes a violation of the provisions of this 

subpart in accordance with paragraph (e)(1)(i), (ii), or (iii) 

of this section.

* * * * *

(2) Each excursion, as defined in paragraphs (f)(1)(ii), 

(f)(1)(iii), (f)(2)(i)(B), and (f)(3)(ii) of this section 

constitutes a violation of the operating limit.

(f) * * *

(1) * * *

(v) * * *

(A) [Removed and Reserved]

(B) [Removed and Reserved]

(C) [Removed and Reserved]
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* * * * *

(f) * * *

(3) * * *

(ii) * * *

(B) * * *

(1) [Removed and Reserved]

(2) [Removed and Reserved]

(3) [Removed and Reserved]

* * * * *

(g) [Removed and Reserved]

29. Section 63.1439 is amended by:

a. Revising paragraphs (b)(1) and (b)(1)(i);

b. Revising paragraphs (b)(1)(i)(A) and (B);

c. Revising paragraph (b)(1)(ii);

d. Removing and reserving paragraphs (d)(7)(ii) through 

(iv);

e. Revising paragraphs (e),(e)(4), and (e)(4)(v);

f. Removing and reserving paragraph (e)(4)(vi);

g. Revising paragraph (e)(4)(vii)(B);

h. Revising paragraphs (e)(6)(iii)(E), (e)(6)(viii)(A)(1), 

and (e)(6)(viii)(D);

i. Adding paragraphs (e)(9) and (e)(10);

j. Revising paragraph (h)(1)(i);

k. Removing and reserving paragraph (h)(1)(ii)(C);
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l. Revising paragraph (h)(1)(iii);

m. Revising paragraph (h)(2)(iii) – (iv);

n. Removing paragraphs (h)(2)(iv))(A) – (B).

The additions and revisions read as follows:

§63.1439 General recordkeeping and reporting provisions.

* * * * *

(b) * * *

(1) Malfunction recordkeeping and reporting. (i) Records of 

malfunctions. The owner or operator shall keep the records 

specified in paragraphs (b)(1)(i)(A) and (B) of this section.

(A) Records of the occurrence and duration of each malfunction 

of operation of process equipment or combustion, recovery, or 

recapture devices or continuous monitoring systems used to 

comply with this subpart, and an estimate of the excess 

emissions released.

(B) Records of actions taken during periods of malfunction 

to minimize emissions in accordance with §63.1420(h)(4), 

including corrective actions to restore malfunctioning process 

and air pollution control and monitoring equipment to its normal 

or usual manner of operation.

(ii) Reports of malfunctions. For the purposes of this 

subpart, reports of malfunctions shall be submitted on the same 

schedule as the Periodic Reports required under paragraph (e)(6) 

of this section. If a malfunction occurred during the reporting 
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period, the report must include the number, duration, excess 

emissions estimate, and a brief description for each type of 

malfunction which occurred during the reporting period and which 

caused or may have caused any applicable emission limitation to 

be exceeded. The report must also include a description of 

actions taken by an owner or operator during a malfunction of an 

affected source to minimize emissions in accordance with 

§63.1420(h)(4), including actions taken to correct a 

malfunction.

* * * * *

(d) * * *

(7) * * *

(ii) [Removed and Reserved]

(iii) [Removed and Reserved]

(iv) [Removed and Reserved]

* * * * *

(e) Reporting and notification. In addition to the reports 

and notifications required by 40 CFR part 63, subpart A, as 

specified in this subpart, the owner or operator of an affected 

source shall prepare and submit the reports listed in paragraphs 

(e)(3) through (10) of this section, as applicable. All reports 

required by this subpart, and the schedule for their submittal, 

are listed in Table 8 of this subpart.

* * * * *
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(4) Precompliance Report. The owner or operator of an 

affected source requesting an extension for compliance; 

requesting approval to use alternative monitoring parameters, 

alternative continuous monitoring and recordkeeping, or 

alternative controls; or requesting approval to establish 

parameter monitoring levels according to the procedures 

contained in §63.1438(c) or (d) shall submit a Precompliance 

Report according to the schedule described in paragraph 

(e)(4)(i) of this section. The Precompliance Report shall 

contain the information specified in paragraphs (e)(4)(ii) 

through (viii) of this section, as appropriate.

* * * * *

(v) The owner or operator shall report the intent to use an 

alternative emissions standard to comply with the provisions of 

this subpart in the Precompliance Report. The Administrator may 

deem an alternative emissions standard to be equivalent to the 

standard required by the subpart, under the procedures outlined 

in the General Provisions' requirements for use of an 

alternative nonopacity emission standard, in §63.6(g).

(vi) [Removed and Reserved]

(vii) * * *

(B) Supplements to the Precompliance Report may be 

submitted to request approval to use alternative monitoring 

parameters, as specified in paragraph (e)(4)(iii) of this 
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section; to use alternative continuous monitoring and 

recordkeeping, as specified in paragraph (e)(4)(iv) of this 

section; or to use alternative controls, as specified in 

paragraph (e)(4)(v) of this section.

* * * * *

(6) * * *

(iii) * * *

(E) The information in paragraph (b)(1)(ii) of this section 

for reports of malfunctions.

* * * * *

(viii) * * *

(A) * * *

(1) A combustion, recovery, or recapture device for a 

particular emission point or process section has one or more 

excursions, as defined in §63.1438(f) for a semiannual reporting 

period; or

* * * * *

(D) After quarterly reports have been submitted for an 

emission point for 1 year without one or more excursions 

occurring (during that year), the owner or operator may return 

to semiannual reporting for the emission point or process 

section

* * * * *

(9) Pressure relief device deviation report. If any 
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pressure relief device in organic HAP service or any piece of 

equipment or closed vent system has discharged to the atmosphere 

as specified in §63.1434(c), the owner or operator must submit 

to the Administrator in the next Periodic Report:

(i) The source, nature, and cause of the discharge.

(ii) The date, time, and duration of the discharge.

(iii) An estimate of the quantity of total organic HAP 

emitted during the discharge and the method used for determining 

this quantity.

(iv) The actions taken to prevent this discharge. 

(v) The measures adopted to prevent future such discharges.

(10) Electronic reporting. (i) Within 60 days after the 

date of completing each performance test (defined in §63.2) as 

required in this subpart, the owner or operator must transmit 

the results of the performance tests required by this subpart to 

EPA’s WebFIRE database by using the Compliance and Emissions 

Data Reporting Interface (CEDRI) that is accessed through EPA’s 

Central Data Exchange (CDX) (see www.epa.gov/cdx). Performance 

test data must be submitted in the file format generated through 

use of EPA’s Electronic Reporting Tool (ERT) (see 

http://www.epa.gov/ttn/chief/ert/index.html). Only data 

collected using test methods on the ERT website are subject to 

this requirement for submitting reports electronically to 

WebFIRE. Owners or operators who claim that some of the 
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information being submitted for performance tests is 

confidential business information (CBI) must submit a complete 

ERT file including information claimed to be CBI on a compact 

disk or other commonly used electronic storage media (including, 

but not limited to, flash drives) to EPA. The electronic media 

must be clearly marked as CBI and mailed to U.S. EPA/OAPQS/CORE 

CBI Office, Attention: WebFIRE Administrator, MD C404-02, 4930 

Old Page Rd., Durham, NC 27703. The same ERT file with the CBI 

omitted must be submitted to EPA via CDX as described earlier in 

this paragraph. At the discretion of the delegated authority, 

you must also submit these reports, including the confidential 

business information, to the delegated authority in the format 

specified by the delegated authority.

(ii) All reports required by this subpart not subject to 

the requirements in paragraphs (e)(10)(i) and (ii) of this 

section must be sent to the Administrator at the appropriate 

address listed in §63.13. The Administrator or the delegated 

authority may request a report in any form suitable for the 

specific case (e.g., by commonly used electronic media such as 

Excel spreadsheet, on CD or hard copy). The Administrator 

retains the right to require submittal of reports subject to 

paragraph (e)(10)(i) and (ii) of this section in paper format.

* * * * *

(h) * * *
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(1) * * *

(i) The monitoring system is capable of detecting 

unrealistic or impossible data during periods of operation 

(e.g., a temperature reading of −200 °C on a boiler), and will 

alert the operator by alarm or other means. * * *

(ii) * * *

(C) [Reserved]

(iii) The monitoring system is capable of detecting 

unchanging data during periods of operation, except in 

circumstances where the presence of unchanging data are the 

expected operating condition based on past experience (e.g., pH 

in some scrubbers), and will alert the operator by alarm or 

other means. The owner or operator shall record the occurrence. 

All instances of the alarm or other alert in an operating day 

constitute a single occurrence.

(h) * * *

(2) * * *

(iii) The owner or operator shall retain the records 

specified in paragraph (h)(1) of this section, for the duration 

specified in paragraph (h) of this section. For any calendar 

week, if compliance with paragraphs (h)(1)(i) through (iv) of 

this section does not result in retention of a record of at 

least one occurrence or measured parameter value, the owner or 

operator shall record and retain at least one parameter value 
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during a period of operation.

(iv) For the purposes of paragraph (h) of this section, an 

excursion means that the daily average of monitoring data for a 

parameter is greater than the maximum, or less than the minimum 

established value.

(A) [Removed]

(B) [Removed]

* * * * *

30. Table 1 to Subpart PPP of part 63 is amended by:

a. Revising entries 63.6(e)(1)(i) and 63.6(e)(1)(ii);

b. Adding entry 63.6(e)(3);

c. Removing entries 63.6(e)(3)(i) through 63.6(e)(3)(ix);

d. Revising entries 63.6(f)(1), 63.7(e)(1), 63.8(c)(1)(i), 

63.8(c)(1)(iii), and 63.10(d)(5);

e. Removing entries 63.10(d)(5)(i) and 63.10(d)(5)(ii).

The revisions and addition read as follows:

Table 1 of Subpart PPP of Part 63—Applicability of General 

Provisions to Subpart PPP Affected Sources

Reference

Applies to

subpart 

PPP Explanation

* * * * * * *

63.6(e)(1)(i) No See §63.1420(h)(4) for general duty 

requirement.
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63.6(e)(1)(ii) No.

* * * * * * *

63.6(e)(3) No.

63.6(f)(1) No.

* * * * * * *

63.7(e)(1) No. See §§63.1436(h) and 63.1437(a).

* * * * * * *

63.8(c)(1)(i) No.

* * * * * * *

63.8(c)(1)(iii)No.

* * * * * * *

63.10(d)(5) No.

* * * * * * *

31. Table 2 to Subpart PPP of part 63 is amended by

revising the title to read as follows:

Table 2 of Subpart PPP of Part 63—Applicability of HON 

Provisions to Subpart PPP Affected Sources