January 31, 2014

National Emission Standards for Hazardous Air 

Pollutant Emissions: Group IV Polymers and Resins; 

Pesticide Active Ingredient Production; and Polyether 

Polyols Production

Summary of Public Comments and Responses 

on Proposed Rule (77 FR 1268, January 9, 2012)

U.S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Sector Policies and Programs Division

Research Triangle Park, NC 27711
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FOREWORD

This document provides responses to public comments on the U.S. Environmental Protection 

Agency’s (EPA’s) proposed “National Emission Standards for Hazardous Air Pollutant 

Emissions: Group IV Polymers and Resins; Pesticide Active Ingredient Production; and 

Polyether Polyols Production.” The EPA Docket contains all comment letters submitted and are 

available for viewing at the EPA Docket Center Reading Room, or electronically through 

http://www.regulations.gov by searching Docket ID No. EPA-HQ-OAR-2011-0435 by docket 

number.

This document provides a summary of the public comments entered into the docket regarding 

specific issues and topics related to the development of the proposed amendments to the subject 

rules and the EPA’s responses to those comments. Within each comment summary, the EPA 

provides in parentheses one or more Docket ID numbers for commenters who raised particular 

issues. However, the list of commenter ID numbers is not meant to be exhaustive. The EPA does 

not individually identify each and every commenter who made a certain point in all instances, 

particularly in cases where multiple commenters express essentially identical arguments. 

Although portions of the preamble to the final rule are paraphrased in this document, to the 

extent any ambiguity is introduced by paraphrasing, the preamble itself remains the definitive 

statement of the rationale for the final rule.
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TABLE OF CONTENTS

FOREWORD............................................................................................................................ iii

TABLE OF CONTENTS .......................................................................................................... iv

ACRONYMS AND ABBREVIATIONS ....................................................................................v

1.0 Background..........................................................................................................................1

2.0 Risk-Related Assessment and Standards...............................................................................3

2.1 Risk Assessment Data and Methodology.......................................................................3

2.2 Consideration of Risks from Entire Facilities, Industrial Clusters, and Other Sources in 

Risk Assessment .........................................................................................................17

2.3 Consideration of Demographics in Risk Assessment ...................................................19

2.4 Additional Standards to Address Risks........................................................................21

3.0 Technology Review Assessment and Standards..................................................................26

4.0 Startup, Shutdown, and Malfunction Exemption/Affirmative Defense Provisions...............29

4.1 Startup, Shutdown, and Malfunction Exemption..........................................................29

4.2 Affirmative Defense Provisions...................................................................................33

5.0 Electronic Reporting Requirements....................................................................................44

6.0 Pressure Relief Device Provisions......................................................................................46

7.0 Source Category Specific Comments..................................................................................50

7.1 Source Category Specific Comments – Group IV Polymers and Resins.......................50

7.2 Source Category Specific Comments – Pesticide Active Ingredient Production ...........52

7.3 Source Category Specific Comments – Polyether Polyols Production..........................53

8.0 Other Comments................................................................................................................55
v

ACRONYMS AND ABBREVIATIONS

Acronym/

Abbreviation Definition

Act or CAA Clean Air Act

ABS Acrylonitrile Butadiene Styrene

ACA American Coatings Association

ACC American Chemistry Council

ACT Achievable Control Technology

AEGL Acute Exposure Guideline Level

AMOS Ample Margin of Safety

AN Acrylonitrile

BBDR Biologically-Based Dose-Response

Cal OEHHA California Office of Environmental Health Hazard Assessment

CBI Confidential Business Information

CDX Central Data Exchange

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CFR Code of Federal Regulations

CHIEF Clearinghouse for Emission Inventories and Emissions Factors

CIIT Chemical Industry Institute of Toxicology 

CMAS Chemical Manufacturing Area Source

CRWI Coalition for Responsible Waste Incineration

EJ Environmental Justice

EJSEAT Environmental Justice Strategic Enforcement Assessment Tool

EO Executive Order

EPA U.S. Environmental Protection Agency

EPCRA Emergency Planning and Community Right-to-Know Act

ERPG Emergency Response Planning Guideline

ERT Electronic Reporting Tool

FOIA Freedom of Information Act

FR Federal Register

HAP Hazardous Air Pollutants

HCl Hydrogen Chloride

HF Hydrogen Fluoride

HON National Emission Standards for Organic Hazardous Air Pollutants From the 

Synthetic Organic Chemical Manufacturing Industry

HQ Hazard Quotient

ICR Information Collection Request

IRIS Integrated Risk Information System

LDAR Leak Detection and Repair

MACT Maximum Achievable Control Technology

NAAQS National Ambient Air Quality Standards

NACAA National Association of Clean Air Agencies 
vi

Acronym/

Abbreviation Definition

NAS National Academy of Sciences

NATA National Air Toxics Assessment

NEI National Emissions Inventory

NESHAP National Emission Standards for Hazardous Air Pollutants

NRDC Natural Resources Defense Council

PAI Pesticide Active Ingredient Production

P&R IV Group IV Polymers and Resins

PB Persistent and Bioaccumulative

PEPO Polyether Polyols Production

PET Polyethylene Terephthalate

POM Polycyclic Organic Matter

ppmv Parts Per Million by Volume

PRD Pressure Release Device

REL Reference Exposure Level

RfC Reference Concentration

RfD Reference Dose

RQ Reportable Quantity

RTR Risk and Technology Review

SAB Science Advisory Board

SAN Styrene Acrylonitrile Resin

SARA Superfund Amendments and Reauthorization Act

SCAQMD South Coast Air Quality Management District

SISNOSE Significant Economic Impact on a Substantial Number of Small Entities

SOCMA Society of Chemical Manufacturers and Affiliates

SOCMI Synthetic Organic Chemical Manufacturing Industry

SSM Startup, Shutdown, and Malfunction

TOSHI Target Organ-Specific Hazard Index

TPA Thermal Polyaspartic Acid

tpy Tons Per Year

URE Unit Risk Estimate
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1.0 Background

On January 9, 2012 (77 FR 1268), the U.S. Environmental Protection Agency (EPA) 

proposed to revise the National Emission Standards for Hazardous Air Pollutants (NESHAP) for 

Group IV Polymers and Resins (P&R IV); Pesticide Active Ingredient Production (PAI); and 

Polyether Polyols Production (PEPO), under the authority of section 112 of the Clean Air Act 

(CAA). This document presents summaries of the comments that were submitted in response to 

this action and our responses to those comments. The comments to which we are responding 

were submitted in 21 letters from industry representatives, governmental entities, environmental 

advocacy groups, and citizens during the public comment period. In addition, the EPA received 

three comment letters and sets of materials from industry and environmental advocacy group 

commenters following the close of the comment period. Although the EPA is not required to 

respond to these late comments, to the extent practicable, the EPA often attempts to respond to 

late comments and our responses to such comments are also presented in this document. A list of 

the commenters, their affiliations, and the EPA docket number assigned to their correspondence 

is presented in Table 1-1. 

TABLE 1-1. LIST OF COMMENTERS ON PROPOSED NATIONAL EMISSION 

STANDARDS FOR HAZARDOUS AIR POLLUTANTS 

Docket Number a b Commenter and Affiliation

26 K. Watts, private citizen

28 Vinson Hellwig and Robert Colby, National 

Association of Clean Air Agencies (NACAA) 

Air Toxics Committee

29 & 39 Russell Wozniak, The Dow Chemical 

Company

30 & 42 David Darling and Timothy Serie, American 

Coatings Association (ACA)

31 Melvin Keener, Coalition for Responsible 

Waste Incineration (CRWI)

32 Ann Mason, American Chemistry Council 

(ACC)

33 Tom Herman, Zeon Chemicals, L.P.

34 Colleen Greene, private citizen

37 Steven Silz-Carson, private citizen

38 Chris Manley, Eastman Chemical Company

41 Lorraine Krupa Gershman, ACC

44 Russell Frye, SSM Coalition

45 Frederick Fedri, Occidental Chemical 

Corporation

46 Daniel Moss, Society of Chemical 

Manufacturers and Affiliates (SOCMA)
2

47 Brady Wassom, Croda Inc.

48 John Dege, DuPont

49 Matthew Todd, Residual Risk Coalition

50 Andrew Jaques, The Acrylonitrile (AN) Group

51 (Part 1 of 6)

52 (Part 2 of 6)

53 (Part 3 of 6)

54 (Part 4 of 6)

55 (Part 5 of 6)

56 (Part 6 of 6)

Neil Carman, et.al., Sierra Club, Earthjustice, 

Clean Air Muscatine, California Communities 

Against Air Toxics, Ohio Valley 

Environmental Coalition, Del Amo Action 

Committee, Air Alliance Houston, Coalition 

for a Safe Environment, and California Safe 

Schools

57

(Late Comment)

Emma Cheuse and James Pew, Earthjustice on 

behalf of the Sierra Club and California 

Communities Against Toxics

60

(Late Comment)

Lorraine Krupa Gershman, ACC

61

(Late Comment)

Liane Platt, The Dow Chemical Company

a Document ID identifies comments found in Docket No. EPA-HQ-OAR-2011-0435 by 

document number.

b

Individual comments from the public (and attachments submitted with comments) 

submitted to the docket are assigned a unique 4-digit docket number that follows the base 

docket number (i.e., EPA-HQ-OAR-2011-0435-XXXX, where “XXXX” represents the 

unique 4-digit document docket number). The unique document docket numbers presented 

in this table and document represent that unique docket number without the preceding 0s. 

For example, docket number EPA-HQ-OAR-2011-0435-0026 is presented as 26 in this 

table and within the text of this document. 

The following sections provide a summary of the comments received on the proposed 

standards for the P&R IV, PAI, and PEPO NESHAP, as well as the EPA’s responses to these 

comments. Nineteen commenters are represented by 26 public comment submission entries 

represented in the docket and submitted on the proposal within the public comment period. We 

also received three comment submission entries from three commenters that had also submitted 

comments on the proposal within the public comment period. Some of the comment submission 

entries include several file attachments. For example, one commenter submission (docketed 

under 6 Docket IDs, or comment submission entries) includes a total of 110 files (one 108-page 

comment letter and 109 attachments). For the purpose of orderly presentation, the comments 

have been categorized under the following topics:

Section 2: Risk-Related Assessment and Standards

Section 3: Technology Review Assessment and Standards

Section 4: Startup, Shutdown, and Malfunction Exemption/Affirmative Defense 

Provisions

Section 5: Electronic Reporting Requirements

Section 6: Pressure Relief Device Provisions

Section 7: Source Category Specific Comments

Section 8: Other Comments
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2.0 Risk-Related Assessment and Standards

2.1 Risk Assessment Data and Methodology 

Comment 2.1.1: Commenter 28 is pleased to see the EPA placing increasing reliance on 

CalEPA Chronic Reference Exposure Level (REL) acute exposure threshold values and 

recommends continuing the use of RELs over Acute Exposure Guideline Level (AEGL) and 

Emergency Response Planning Guideline (ERPG) values, which the commenter does not feel are 

appropriate for assessing daily human exposure scenarios. 

Response 2.1.1: As discussed in the preamble to the proposed rule (77 FR 1278), the 

EPA considers various acute health effect reference values, including the California acute REL, 

and AEGL and ERPG values, in assessing the potential for risks from acute exposures. The REL 

is one of the preferred acute values for use in risk and technology reviews (RTR), as endorsed by 

the EPA’s Science Advisory Board (SAB).

Comment 2.1.2: Commenters 32 and 49 urge the EPA to use the Chemical Industry 

Institute of Toxicology (CIIT) cancer dose-response value for formaldehyde established in 1999 

rather than the 1991 Integrated Risk Information System (IRIS) dose-response value, in keeping 

with the Information Quality Act and Executive Order 13563, which states that the regulatory 

system must “be based on the best available science.” Commenter 38 states that the CIIT 

formaldehyde value is a biologically based dose-response (BBDR) model, which they claim 

better reflects the available science than the allegedly outdated and overly conservative IRIS 

value. Both commenters also point out that the use of the CIIT BBDR model would fit with the 

recommendations of an expert panel of the National Academy of Science (NAS) that reviewed 

the formaldehyde values in 2011. 

In contrast, commenter 51 supports the EPA in its decision to use the current IRIS values 

for formaldehyde and methanol while reviews of the health benchmark values for chemicals are 

undertaken. 

Response 2.1.2: In 2004, the EPA determined that the CIIT cancer dose-response value 

for formaldehyde (5.5 x 10-9 per μg/m3) was based on better science than the IRIS cancer doseresponse value (1.3 x 10-5 per μg/m3

), and we switched from using the IRIS value to the CIIT 

value in risk assessments supporting regulatory actions. Subsequent research published by the 

EPA suggested that the CIIT model was not appropriate and, in 2010, the EPA returned to using 

the 1991 IRIS value. The EPA has been working on revising the formaldehyde IRIS assessment 

and the NAS completed its review of the EPA’s draft assessment in April of 2011.1The EPA will 

follow the NAS Report recommendations and will present results obtained by implementing the 

BBDR model for formaldehyde. The EPA will compare these estimates with those currently 

presented in the External Review draft of the assessment and will discuss their strengths and 

weaknesses. As recommended by the NAS committee, appropriate sensitivity and uncertainty 

analyses will be an integral component of implementing the BBDR model. In the interim, we will 

present findings using the 1991 IRIS value as a primary estimate and the EPA may also consider 

other information as the science evolves. 

We note that, except in the case of the PAI source category, formaldehyde was not 

generally a primary driver of the risks for these source categories, and risks due to formaldehyde 

 

1

http://www.nap.edu/catalog.php?record_id=13142
4

emissions did not change our decisions about acceptability and ample margin of safety of the 

risks associated with any of these source categories, or about our technology reviews for them. 

Therefore, in this rulemaking the choice between using the IRIS value or the CIIT value makes 

no difference in the regulatory outcome.

Comment 2.1.3: Commenter 50 states that the EPA is using an allegedly outdated cancer 

unit risk estimate (URE) value for acrylonitrile (AN) from IRIS, which leads to a claimed 

overstatement of risks, even though those risk values are already at “acceptable” levels for the 

source categories in this proposal. The commenter states that use of that value is a violation of 

the Information Quality Act guidelines and President Obama’s directive on scientific integrity 

and regulatory review in Executive Order 13563. The commenter notes several data updates and 

peer reviewed evaluations of AN and states that the EPA should use this information rather than 

waiting for an updated IRIS assessment, particularly a review conducted by the North Carolina 

Science Advisory Board that was completed in 2009. While an updated AN IRIS assessment was 

released by the EPA in June 2011 for comment, the commenter states there are significant 

concerns with the draft IRIS assessment. The commenter opines that if the EPA considers the 

updated IRIS assessment before the final rule, then the EPA should also consider the comments 

made by the AN Group and others on the draft assessment. 

Response 2.1.3: The EPA acrylonitrile IRIS assessment is currently under review (for 

detailed information on the new schedule see the IRIS Track website available online at 

http://cfpub.epa.gov/ncea/iristrac/index.cfm?fuseaction=viewChemical.showChemical&sw_id=1

017). As part of the AN assessment review, the EPA will consider all scientific data available, 

comments from the public (including those that may be submitted by the AN Group) and 

recommendations made by the NAS in the 2009 report referred by the commenter. However, 

until completion of the IRIS AN assessment (projected posting date is the second quarter of 

2014), the current EPA URE is considered to be the best-available science and has therefore 

been used in assessing cancer risk for this rulemaking. Because the updated EPA AN IRIS 

assessment released in June 2011 is still in draft form and undergoing peer review, it will not be 

considered for this rulemaking. As noted by the commenter, the EPA’s risk assessment for these 

categories shows that residual risks are already at acceptable levels and that the standards 

provide an ample margin of safety to protect public health. Therefore, the use of the URE for AN, 

even if the commenter were correct that it might overstate risks, did not drive any regulatory 

decisions in this rulemaking that would affect the commenter.

Comment 2.1.4: Commenter 51 states that the EPA cannot assume that hazardous air 

pollutants (HAP) with no peer-reviewed reference values for cancer or non-cancer effects have 

zero risk. The commenter states that the EPA must select health protective values based on the 

information it has or, at a minimum, add an uncertainty factor to the risk estimates. The 

commenter also requests that the EPA clearly state which HAP emitted by these source 

categories have no health reference values. The commenter states that the EPA must set a 

regulatory deadline no later than 8 years from the finalization of these rules to review the current 

residual risk analysis and perform another residual risk rulemaking to incorporate new toxicity 

information for HAP with toxicity information currently under review and HAP that currently 

lack reference values.

Response 2.1.4: This issue was addressed by the EPA’s SAB in its May 10, 2010 (EPASAB-10-007) response to the EPA Administrator; 
5

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA

-SAB-10-007-unsigned.pdf. In that response, the SAB Panel recommended that, for HAP that do 

not have dose-response values from the EPA’s hierarchy list, the EPA should consider and 

utilize, as appropriate, additional sources for such values that have undergone adequate and 

rigorous scientific peer review. The SAB panel further recommended that the inclusion of 

additional sources of dose-response values into the EPA’s hierarchy should be adequately 

documented in a transparent manner in any residual risk assessment case study. We agree with 

this approach and have considered other sources of dose-response data when conducting our 

risk determinations under RTR. However, in some instances no sources of information beyond 

the EPA’s hierarchy are available. 

The EPA disagrees that we must set an 8-year regulatory deadline to review the current 

residual risk analysis and perform another residual risk rulemaking to incorporate new toxicity 

information for HAP with toxicity information currently under review or lacking reference 

values. Pursuant to CAA section 112(f)(2)(A), the EPA is required to perform a residual risk 

review within 8 years after initial promulgation of a MACT standard; unlike the technology 

review required under CAA 112(d)(6), this is not a recurring statutory requirement. The EPA’s 

subsequent risk based review of NESHAP is subject to the agency’s discretion and decisions to 

conduct any such reviews will be informed by the specific facts applicable to the source 

categories at issue. We do not agree that it is appropriate, at this time, to set a binding 

regulatory deadline for such a review for the source categories addressed in this rule. While we 

are not yet at the point where all HAP have dose-response values, we are generally capable of 

deriving reasonable risk estimates for those HAP which dominate the risks from any one source 

category. In the course of each residual risk assessment, should we encounter HAP without doseresponse values which carry the potential to create significant risks, we shall clearly point those 

out as uncertainties and target them for future IRIS assessments. Moreover, as additional doseresponse values become available, the EPA will incorporate these dose-response values into 

future risk assessments.

The EPA disagrees with the commenter that we did not state which HAP currently have 

no reference value. In the risk assessment document, there is a table for each source category 

that lists all the HAP emitted by the source category, and indicates whether there is an available 

cancer, chronic noncancer, and/or acute dose-response value.

Comment 2.1.5: Commenter 51 is concerned that the EPA is assessing noncancer 

hazards for lead solely through reliance on the 2008 National Ambient Air Quality Standards 

(NAAQS) for lead. The commenter states that this is relevant information but it is not protective 

enough to assess health risk from lead. The commenter goes on to describe that the NAAQS was 

created to protect the average exposed member of the population from an IQ point loss above 2 

points, not to protect the “most exposed” and most vulnerable member of that population. The 

commenter adds that the lead NAAQS was also designed to address only a single pollutant 

(elemental lead), while section 112(f)(2) requires the EPA to assess and address health risk from 

the combined effect of a source category on the most exposed person. According to the 

commenter, there is significant new information since the scientific review closed on the 

NAAQS suggesting that a stronger standard is needed. The commenter adds that lead can 

interact with other pollutants, such as arsenic, to cause greater harm than lead exposure alone. 

Finally, the commenter notes that section 112(f)(2) requires the EPA to create an “ample margin 

of safety to protect public health,” while the NAAQS only must satisfy the test to provide an 
6

“adequate margin of safety.” The commenter concludes that rather than only relying on the 

NAAQS to assess health risk from lead, the EPA should use all of the best available, most 

current information, including California’s lead health benchmark.

Response 2.1.5: We disagree with the comment that the lead NAAQS was designed to 

protect the average exposed member of the population from an IQ loss above 2 points. First, the 

primary lead NAAQS targets protection of the most susceptible group in the human population –

children – and is designed to protect against adverse effects to children’s most sensitive organ 

system – the developing neurological system. (See 73 FR at 66975, 66976.) Second, the primary 

NAAQS for lead is specifically targeted at those children living near major sources of lead, such 

as secondary smelters. (See 73 FR at 67002/3 “in applying the evidence-based framework, we 

are focused on a subpopulation of U.S. children, those living near air sources and more likely to 

be exposed at the level of the standard”; to the same effect see 73 FR 67000/3:“The framework 

in effect focuses on the sensitive subpopulation that is the group of children living near sources 

and more likely to be exposed at the level of the standard. The evidence-based framework 

estimates a mean air-related IQ loss for this subpopulation of children; it does not estimate a 

mean for all U.S. children”; 73 FR 67005/1:“the air-related IQ loss framework provides 

estimates for the mean air-related IQ loss of a subset of the population of U.S. children, and 

there are uncertainties associated with those estimates. It provides estimates for that subset of 

children likely to be exposed to the level of the standard, which is generally expected to be the 

subpopulation of children living near sources who are likely to be most highly exposed.”) In 

addition, in reviewing and sustaining the primary lead NAAQS, we note that the U.S. Court of 

Appeals for the D.C. Circuit specifically noted that the rule was targeted to protect children 

living near lead sources:

“EPA explained that the scientific evidence showing the impact of lead exposure in 

young children in the United States led it ‘to give greater prominence to children as the 

sensitive subpopulation in this review’ and to focus its revision of the lead NAAQS on the 

‘sensitive subpopulation that is the group of children living near [lead emission] sources 

and more likely to be exposed at the level of the standard.’ Given the scientific evidence 

on which it relied, the EPA’s decision to base the revised lead NAAQS on protecting the 

subset of children likely to be exposed to airborne lead at the level of the standard was 

not arbitrary or capricious.” Coalition of Battery Recyclers v. EPA, 604 F.3d 613, 618 

(D.C. Cir. 2010).

In response to the comment that the EPA is required to assess the combined effect of a 

source category on the most exposed person, we agree and consider our analysis to have done 

this. The approach used to calculate chronic non-cancer risks, developing the target-organ 

specific hazard index, specifically considers the combined effect of multiple pollutants on the 

same target organ. Any new scientific information concerning lead will be reviewed in 

accordance with the next NAAQS review process.

The commenter also makes the legal argument that the primary lead NAAQS provides an 

“adequate” margin of safety, but that section 112(f)(2) requires that a residual risk standard 

provide an “ample” margin of safety, reasoning from this that a NAAQS cannot just be 

substituted as the measure for evaluating acceptability of risk and that some greater level of 

protection is required. The EPA disagrees with the commenter that section 112(f)(2) requires 

that in all cases standards must be more protective than what is achieved by attainment of a 

primary NAAQS. Nothing in section 112(f)(2) requires a conclusion that a standard that results 

in attainment of a primary NAAQS might not also in fact provide an ample margin of safety to 
7

pretct public health. Further, to the extent the commenter’s argument rests on the difference 

between ‘adequate’ and ‘ample’ margin of safety, the argument is misplaced.2The EPA is 

considering the primary lead NAAQS --which incorporates an adequate margin of safety --

merely to determine whether lead risks from air-borne lead from P&R IV, PEPO or PAI 

facilities are acceptable or not. The acutal margin-of-safety determinations for this rule are 

conducted in accord with the two-step framework set forth in the Benzene NESHAP and the en 

banc opinion in the D.C. Circuit’s ruling in the Vinyl Chloride case. See not only Vinyl Chloride, 

824 F.2d 1146, 1165-66 (D.C. Cir. 1987), but also NRDC v. EPA, 902 F.2d 962, 973-74 (D.C. 

Cir. 1990) (distinguishing the NAAQS process, whereby the margin of safety analysis is 

incorporated as part of the standard without a two-step analysis, from residual risk 

determinations).

3

Using that framework, with its consideration of costs, cost-effectiveness, 

technological feasibility, and other factors set out in the Benzene NESHAP, at proposal we did 

not identify any additional controls beyond those that would need to be implemented to ensure 

an acceptable level of risk with an ample margin of safety to protect public health.

Comment 2.1.6: Commenter 51 states that the EPA must account for the increased 

susceptibility of children and pregnant women to HAP emissions from this source category in the 

risk assessment based on findings of the NAS review and CalEPA studies. The commenter is 

concerned that the EPA’s failure to include an adequate evaluation of increased early life 

susceptibility to HAP emissions systematically underestimates risk from the source categories 

for several HAP (polycyclic organic matter (POM), formaldehyde, arsenic, cadmium) and 

provides additional information supporting the need for these pollutant-specific analyses and 

information on the guidelines and other materials that the EPA should use to conduct such 

analyses. To satisfy its duty to protect children, the EPA must follow the best available science. 

At a minimum, the EPA must adopt the following: 

1. California Office of Environmental Health Hazard Assessment (Cal OEHHA) Cancer 

Guidelines (Age-Dependent Adjustment Factors) for all carcinogens and include prenatal susceptibility, and

2. Child-Specific Reference Doses (for Non-Cancer Impacts), and

3. Children‘s Default Safety Factor of At Least Ten (for Non-Cancer Chronic & Acute 

Impacts), where specific information on children‘s vulnerability is unavailable.

Response 2.1.6: We disagree with the general comment that the EPA should adopt the 

Cal OEHHA child-protective scientific approach on cancer. The EPA has a hierarchy of 

appropriate health benchmark values and in general, this hierarchy places greater weight on the 

EPA derived health benchmarks than those from other agencies (see 

http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf). Notably, this hierarchy 

favoring EPA benchmarks (when they exist) over all others has been endorsed by the SAB. 

Further, the EPA is currently evaluating whether it is appropriate to use the CalEPA childspecific reference doses, and we note that because there are currently no such values for HAP 

 

2

Indeed, the EPA’s utilization of a standard which also incorporates an adequate margin of safety to evaluate 

acceptability of risk, which is the first step in the section 112(f)(2) residual risk assessment, is an added conservative 

(i.e. protective) element in its approach here.

3

The court was referring to the predecessor provision to the current section 112(f), but its analysis is equally 

applicable to the revised provision. 
8

inhalation, their current utility would be limited to persistent and bioaccumulative (PB)-HAP, 

which may be associated with non-negligible ingestion exposures. That is, before using these 

child-specific reference doses (RfDs), the EPA would need to evaluate whether they have been 

appropriately derived.

We also disagree with the comment that the risk assessment for these source categories 

does not consider the groups that may be most at-risk in its risk assessments (e.g., pregnant 

women). When the EPA derives exposure reference concentrations and unit risk estimates for 

metal HAP, it also considers the most sensitive populations identified in the available literature, 

and importantly, these are the values used in our risk assessments (see US EPA. (2002). A 

review of the reference dose and reference concentration processes. EPA/630/P-02/002F. Risk 

Assessment Forum, Washington DC. Available online at 

http://www.epa.gov/raf/publications/pdfs/rfd-final.pdf). With respect to maternal exposure in 

utero specifically, we are unaware of literature that would allow for a robust characterization of 

risk during this stage of development.

We acknowledge that population subgroups, including children, may have a potential for 

risk that is greater than the general population due to greater relative exposure and/or greater 

susceptibility to the toxicant. As explained in previous actions, including the final synthetic 

organic chemical manufacturing industry (SOCMI) hazardous organic NESHAP (HON) RTR (71 

FR 76610-76611), the assessments we undertake to estimate risk account for this potential 

vulnerability. With respect to exposure, the risk assessments we perform implicitly account for 

this greater potential for exposure by assuming lifetime exposure, in which populations are 

conservatively presumed to be exposed to airborne concentrations at their residence 

continuously, 24 hours per day for a full lifetime, including childhood. With regard to children‘s 

potentially greater susceptibility to non-cancer toxicants, the assessments rely on EPA (or 

comparable) hazard identification and dose-response values which have been developed to be 

protective for all subgroups of the general population, including children. 

For example, a review of the chronic reference value process concluded that the EPA’s 

reference concentration (RfC) derivation processes adequately considered potential 

susceptibility of different subgroups with specific consideration of children, such that the 

resultant RfC values pertain to the full human population including sensitive subgroups, “a 

phrase which is inclusive of childhood.” With respect to cancer, the EPA uses the age-dependent 

adjustment factor approach referred to by the commenter, but limits the use of those factors only 

to carcinogenic pollutants that are known to act via mutagenic mode of action, in contrast to the 

OEHHA approach, which uses them across the board for all carcinogens regardless of mode of 

action. In lieu of chemical-specific data on which age or life-stage specific risk estimates or 

potencies can be determined, default age dependent adjustment factors can be applied when 

assessing cancer risk for early-life exposures to chemicals which cause cancer through a 

mutagenic mode. At the present time, there have been no peer-reviewed assessments that 

explicitly make a determination that any of the chemicals emitted by the source categories 

considered in this action cause cancer through a mutagenic mode of action. However, the 

estimated risks must also be considered in the context of the full set of assumptions used for this 

risk assessment. For example, we used a health-protective assumption of a 70-year exposure 

duration in our risk estimates; however, using the national average residency time of 12 years 

would reduce the estimate of risk by roughly a factor of 6. Our unit risk estimates for HAP are 

considered a plausible upper-bound estimate; actual potency is likely to be lower and some of 

which could be as low as zero. After considering these and other factors, we continue to consider 
9

the risks from emissions after application of the revisions to the Maximum Achievable Control 

Technology (MACT) standards for these source categories to provide an ample margin of safety 

(consistent with the Benzene NESHAP framework).

The EPA disagrees with the commenter’s statement that the EPA should use California 

EPA’s child specific-reference doses for school site risk assessments4in order to address the 

potential for early-life susceptibility. The EPA methods for assessing hazard and dose-response 

relationships for HAPs and developing RfCs and cancer risk estimates, as noted above, 

specifically address the potential for early-life susceptibility. Whenever data indicate increased 

susceptibility of a developmental lifestage or of a population group, those data are factored into 

the analysis. When data are inadequate to understand the effects of a specific pollutant on 

sensitive subpopulations, which for some pollutants may include children, the EPA’s risk 

assessment methods take that into account to ensure that resulting assessments address the 

possibility that such subpopulations might be more or less sensitive. Further, in the RTR risk 

assessments performed using the agency’s preferred dose-response values, exposure is 

characterized as occurring all day and every day over a lifetime, rather than only during specific 

periods of time during childhood.

Comment 2.1.7: Commenter 28 is concerned that the EPA has not taken steps to reduce 

the target organ-specific hazard index (TOSHI) to below 1 for the PAI source category.

Response 2.1.7: Pollutant-specific RfCs are not absolute thresholds, but estimates of 

chronic inhalation exposures at or below which health effects would not be expected to occur, 

including in sensitive subgroups. Further, RfCs are developed using a health-protective 

approach (see uncertainty discussion in section 10.2 of the Draft Residual Risk Assessment for 7 

Source Categories (Docket Item No. EPA-HQ-OAR-2011-0435-0018)), and TOSHI values of 1 

or less are (like RfC levels) generally considered to carry no appreciable risk of adverse health 

effects.

That said, the EPA generally does not draw bright lines of acceptability regarding cancer 

or noncancer risks from source category HAP emissions, for several reasons. There are 

uncertainties in the emissions and health effects information regarding the source category in 

question that should be considered when deciding exactly what level of cancer and noncancer 

risk should be considered acceptable. In addition, the source category-specific decision of what 

constitutes an acceptable level of risk should be a holistic one; that is, it should simultaneously 

consider all potential health impacts -- chronic and acute, cancer and noncancer, and 

multipathway, -- along with their uncertainties, when determining the acceptable level of source 

category risk. In other words, we look at the risk numbers within the context of the uncertainty 

associated with emissions, health benchmark values and, in the case of TOSHI values, target 

organ effect. The Benzene NESHAP decision framework of 1989 acknowledged this; in today’s 

world, such flexibility is even more imperative, because new information relevant to the question 

of risk acceptability is being developed all the time, and the accuracy and uncertainty of each 

 

4 We note that California EPA’s use of these numerical values, which do not exist for inhalation exposures, is 

limited to the context of risk assessment at proposed or existing California school sites and does not even extend to

their Air Hot Spots Risk Assessment program. Further the guidance for the California EPA school site assessment 

program specifies the use of California OEHHA or U.S. EPA IRIS values in the absence of the school site risk 

assessment child-specific values (Cal OEHHA, 2004 -

http://www.oehha.ca.gov/public_info/public/kids/pdf/SchoolscreenFinal.pdf). 
10

piece of information must be considered in a weight-of-evidence approach for each decision. 

This relevant body of information is growing fast (and it will continue to grow even faster), 

necessitating a flexible weight-of-evidence approach that acknowledges both complexity and 

uncertainty in the simplest and most transparent way possible. While this challenge is 

formidable, it is nonetheless the goal of the EPA’s RTR decision-making, and it is the goal of the 

risk assessment to provide the information to support the decision-making process.

For all of the P&R IV source categories and for the PEPO source category, the TOSHIs 

at both the actual and MACT-allowable emission levels are below 1.0. For the PAI source 

category, the TOSHI at the actual emission level is 0.7, and at the estimated MACT-allowable 

emission level, the TOSHI could be as high as 4. For this source category, weighing all the 

health risk factors, including the TOSHI at the actual emissions and the TOSHI at the potential 

MACT-allowable emission level, considering the uncertainty associated with the associated 

emissions estimate, the EPA determined that the risks were acceptable. As part of the second 

step ample margin of safety analysis, we did look for additional controls and process 

improvements that might further reduce risks in a cost-effective, technically feasible manner. In 

this case, we did not find any additional cost-effective controls and ultimately concluded that the 

current PAI MACT standards’ level of control brought risks to an acceptable level and is also 

the level of control that results in public health being protected with an ample margin of safety. 

See 77 FR at 1298-99. 

Comment 2.1.8: Commenter 28 opines that the EPA should consider risk based on 

potential or allowable emissions because emissions and associated impacts could increase over 

time, and analyses based on actual emissions may underestimate residual risk. The commenter 

notes that the thresholds for major source status were based on maximum potential-to-emit, and 

permits are issued based on potential emissions. Further, the commenter argues that limiting the 

scope of risk assessments to actual emissions would be inconsistent with the applicability 

sections of the MACT standards. While acknowledging that the EPA has relied less on actual 

emissions than it has in the past, the commenter would like to see more reliance on the use of 

allowable emissions.

In contrast, commenter 49 states that the EPA cannot lawfully use the MACT allowable 

emissions in risk assessments and residual risk determinations because the EPA has allegedly 

failed to provide any reasoned explanation why risk assessments based on actual emissions are 

inadequate. The commenter states that the language of section 112 requires that the EPA report 

on the actual health effects for people living in the vicinity of affected sources, which the 

commenter claims clearly signals that Congress expected the EPA to focus on actual risk and not 

hypothetical risk in implementing the requirements of section 112(f). In addition, because the 

risk methodology already reflects numerous conservative assumptions, the commenter asserts it 

makes no sense to add another layer of conservatism and the EPA has not provided any data to 

indicate analyses based on actual emissions result in negative bias.

Response 2.1.8: Consistent with previous risk assessments, the EPA considers both 

allowable and actual emissions in assessing chronic exposure and risk under section 112(f)(2). 

(See, e.g., National Emission Standards for Coke Oven Batteries (70 FR 19998-19999, April 15, 

2005); proposed and final National Emission Standards for Organic Hazardous Air Pollutants 

from the Synthetic Organic Chemical Manufacturing Industry (71 FR 34428, June 14, 2006, and 

71 FR 76603, December 21, 2006). This approach is both reasonable and consistent with the 

flexibility inherent in the Benzene NESHAP framework for assessing ample margin of safety. As 
11

a general matter, modeling allowable emission levels is inherently reasonable since this reflects 

the maximum level sources could emit and still comply with national emission standards. But it is 

also reasonable to consider actual emissions, where such data are available, in both steps of the 

risk analysis. See National Emission Standards for Coke Oven Batteries, 70 FR 19992, 19998 

(April 15, 2005). We disagree with commenter 28’s claim that the additional consideration of 

actual emissions conflicts with either the statutory major source definition that is based on 

potential to emit, or with applicability thresholds in MACT standards that are tied to major 

source status. Those thresholds still have the same full effect for determining the applicability of 

section 112 standards that they had before we conducted our residual risk assessments. 

Moreover, our risk assessments necessarily included information regarding sources with 

potential – not necessarily actual – emissions at major source levels. We also note that our use 

of allowable emission levels in the risk assessments in this rulemaking did not result in revising 

the previously established standards due to risk concerns. Therefore, our consideration of 

allowable emissions in the risk assessments did not result in regulatory decisions that affect 

commenter 49, and commenter 49’s objections to our use of allowable emissions are moot.

Comment 2.1.9: Commenters 28 and 51 state that the use of the census block centroid

dilutes the effect of sources’ emissions, as the maximum point of impact can be far from the 

centroid and may be at or near a facility’s property line, and suggested that the risks for a source 

category be based on concentrations at the fenceline and beyond and include risks to the 

maximally exposed individual. Commenter 51 states that using the census block centroids 

conflicts with the SAB recommendation that the EPA consider specific locations of residences, 

which may be closer to the fenceline than the census block centroids. The commenter adds that 

this is particularly inexcusable, given that an adjustment for the property line location was made 

for the assessment of acute risks.

Response 2.1.9: As we have explained in previous RTRs, such as the SOCMI HON RTR 

(71 FR 76603, December 21, 2006), the EPA believes that, in a national-scale assessment of 

lifetime inhalation exposures and health risks from facilities in a source category, it is 

appropriate to identify exposure locations where it may be reasonably expected that an 

individual will spend a majority of his or her lifetime. Further, in determining chronic risks, the 

EPA believes that it is appropriate to use census block information on where people actually 

reside, rather than points on a fence-line, to locate the estimation of exposures and risks to 

individuals living near such facilities. If a population did indeed live just outside of the fenceline 

of a facility, then it would result in a census block near the fenceline.

Census blocks are the finest resolution available as part of the nationwide population 

data (as developed by the US Census Bureau); each is typically comprised of approximately 40 

people or about 10 households. In EPA risk assessments, the geographic centroid of each census 

block containing at least one person is used to represent the location where all the people in that 

census block live. The census block centroid with the highest estimated exposure then becomes 

the location of maximum exposure, and the entire population of that census block experiences 

the maximum individual risk. In some cases, because actual residence locations may be closer to 

or farther from facility emission points, this may result in an overestimate or underestimate of 

the actual annual concentrations (although there is no systematic bias for average levels). Given 

the relatively small dimensions of census blocks in densely populated areas, there is little 

uncertainty introduced by using the census block centroids in lieu of actual residence locations. 

There is the potential for more uncertainty when census blocks are larger, although there is still 
12

no bias on average. 5The EPA concludes that the most appropriate locations at which to 

estimate chronic exposures and risks are the census block centroids because: 1) census blocks 

are the finest resolution available in the national census data, 2) facility fencelines do not 

typically represent locations where chronic exposures are likely because people do not typically 

live near the fenceline, and 3) there is no bias introduced into the estimate of the MIR by using 

census block centroid locations.

Comment 2.1.10: Commenter 51 states that the EPA has failed to collect and use the 

best available emissions data from these source categories by relying on the 2005 National 

Emission Inventory (NEI) to form its dataset. The commenter states that the EPA should have 

issued an Information Collection Request (ICR) to gather actual emission test data from the 

facilities in these source categories. The commenter further states that the EPA’s use of emission 

factors to develop its inventories underestimates actual emissions, as evidenced by studies in 

Texas. To improve its inventories, the commenter states that the EPA needs to require remote 

sensing and continuous monitoring to track and measure emissions, with technologies such as 

differential absorption light detection and ranging, solar occultation flux, CEREX UV Hound, 

and Accusense. The commenter also states that in addition or as an alternative, the EPA should 

require continuous emissions monitoring or performance tests every year, at a minimum, as it has 

done for other source categories. The commenter urges the EPA to collect the basic emissions 

information it needs before finalizing the rule, and barring that, the EPA should set stronger 

standards to protect public health under section 112(f)(2) to try to make up for the likely 

underestimated emissions, particularly from fugitive sources and flares. As an alternative, the 

commenter suggests the EPA commit to collect this data by a certain date within 3 years and 

commit to review the residual risk determination and 112(d)(6) decision within 1 year after 

gathering this data.

Response 2.1.10: The emissions data for the risk assessments in the proposed rules were 

derived from the NEI as well as data provided by industry. The sources of the data are 

documented in the docket. As stated in the EPA’s documentation on the 2005 NEI 

(http://www.epa.gov/ttn/chief/net/2005_nei_point.pdf), “[t]he 2005 NEI is a composite of 

emission estimates generated by state and local regulatory agencies, tribes, industry, and EPA. 

Because the estimates originated from a variety of sources and estimation methods, as well as 

for differing purposes, they will in turn vary in quality, pollutants included, level of detail, and 

geographic coverage. However, this compilation of emissions estimates represents the best 

available information to date.”

More generally, we note that the 2005 NEI for HAP is greatly improved since the first 

NEI compilation using 1996 data, and that it is sufficiently accurate and complete and 

constitutes the best information the EPA has to use in our analysis. We have worked diligently

with state and local agencies and tribes to improve emission inventories over the years, and we 

have instituted a number of quality assurance (QA) measures to improve data received from 

state and local agencies since 1996. Documentation for the 2005 NEI point source emissions 

inventory is available on the EPA's Clearinghouse for Inventories and Emissions Factors 

(CHIEF) website, http://www.epa.gov/ttn/chief/net/2005inventory.html. Quality assurance and 

augmentation procedures used for the 2005 NEI point sources are contained in the report, EI 

 

5 There is no bias because a residence has an equal likelihood of being farther from a source, compared to the block 

centroid’s distance, as it does being nearer to a source.
13

Quality Assurance and Data Augmentation for Point Sources, posted at: 

http://www.epa.gov/ttn/chief/net/2002inventory.html. The 2005 NEI data have been reviewed 

extensively internally and externally during a 9-month effort as part of the development of the 

2005 National Air Toxics Assessment (NATA). As part of the 2005 NATA review, more than one 

million records for HAP were revised. Updated test data and emission point information were 

received during the public comment period that addressed inaccuracies in the data. For these 

source categories, the EPA‘s review included an evaluation of facilities contained in the source 

category, the emissions units expected to be included for the processes in the source categories, 

coordinates and stack parameters, and the HAP compounds and emission levels typically seen. 

The NEI data were also reviewed by industry trade groups, including the American Chemistry 

Council (ACC) and the Society of Chemical Manufacturers and Affiliates (SOCMA), as well as 

several state air agencies, and the EPA revised the NEI data where we concluded comments 

from this review supported such adjustment. Section II.B of the January 9, 2012, proposal 

preamble (77 FR 1275) set forth a detailed explanation of the review that the EPA performed on 

the emissions data for the source categories subject to this final rule. In addition, as part of the 

January 9, 2012, proposal, we made the data sets available for review using a RTR data review 

tool in the docket and solicited comments on the data sets. The RTR review of the proposal data 

sets act as another external third party review mechanism in addition to the external 2005 NATA 

review of the RTR data sets. Several opportunities have been provided to review the data used in 

the current proposal. In addition, on February 4, 2013, the EPA asked NACAA to review the 

emissions data for PAI, PEPO, and P&R IV facilities in several states. The states of Texas and 

Louisiana were also asked to review emissions data for the PAI, PEPO, and P&R IV facilities in 

their state. Through enhanced NEI QA procedures, 2005 NATA review, industry, state, and 

NACAA review, public comment on proposal files, source category-specific engineering reviews, 

and modeling, improvements to the data files have been made. We believe the data sets used in 

this rulemaking are sufficiently accurate and complete and constitute the best information the 

EPA has concerning the emissions and risk from these source categories for conducting RTRs.

Comment 2.1.11: Commenter 51 states that it is unclear whether the EPA considered all 

HAP in the risk assessment, including those from currently uncontrolled emission points for 

which the EPA proposes to set standards. The commenter states that the EPA should confirm that 

it has assessed the health risks from all emitted HAP.

Response 2.1.11: We confirm with this response that we considered all HAP emitted from 

the source category in the risk assessments for the P&R IV, PAI, and PEPO source categories, 

including HAP emitted from currently uncontrolled emission points.

Comment 2.1.12: Commenter 51 states that the EPA should analyze risk based on what 

emissions may occur above the existing MACT standards, considering malfunctions and 

violations. The commenter states that the EPA must assess public health risk based on the 

likelihood of such events in addition to the use of the MACT-allowable emissions number. The 

commenter suggests that the EPA develop and apply a factor to the risk results based on 

available malfunction and violation data.

Response 2.1.12: We disagree with the commenter that emissions that exceed standards 

and are violations, whether or not caused by malfunction events, should be considered as part of 

the risk analysis for purposes of determining the sufficiency of pre-existing standards, 

particularly when we are revising the standards to eliminate any excused periods of non-
14

compliance during upset periods. The purpose of the risk review is to evaluate whether the 

emission limits -- the “standards promulgated pursuant to subsection (d)” not the noncompliance with those standards (section 112(f)(2)(A) -- should be made more stringent to 

reduce the risk posed after compliance with the underlying MACT standard. To the extent that a 

source is violating the underlying MACT standard, no tightening of the emission standard under 

the residual risk rule will avoid or militate against such violations.6In other words, a source that 

is violating the emission standard promulgated under section 112(d) would not be any more 

likely to be able to avoid such violations and comply with a different presumably more stringent 

standard promulgated under section 112(f). Such events are violations and subject to 

enforcement by the EPA, the states or citizens, and an action for injunctive relief is the most 

effective means to address violations whether or not they are caused by malfunctions if an 

emissions event poses a significant health or environmental risk.

Furthermore, the conservative estimates built into the acute risk assessment are sufficient 

to gauge worst-case potential acute health effects. The conservative estimates built in to the 

assessment include worst-case meteorology, emissions at ten (or two) times the maximum peak 

emission rate from all point sources simultaneously, and the sum of the maximum impact of each 

emission source, regardless of receptor location. Thus, even if we were to consider emissions 

that are in violation of the standard, we do not believe that they would result in any different 

level of control than we are promulgating here.

Comment 2.1.13: Commenter 51 states that the EPA has not used a high enough 

emissions factor to account for acute risks. The EPA used an emissions factor of 10 or 2 and has 

not demonstrated that this factor is high enough to assess true acute risks to the most-exposed 

individual, considering that the EPA has noted that peak emission events could reach 74 times 

the annual average for some industries and that with a control device failure, a facility could emit 

100 times more than its usual emissions if it usually controls 99% of emissions.

Response 2.1.13: The acute risk assessment methodology uses a tiered, iterative 

approach that begins with an assessment of an approximation of a worst-case exposure. To this 

end, the assumption that peak 1-hour emissions are equal to 10 (or 2) times the average 1-hour 

emissions rate is only one of the worst-case assumptions that we made in our acute health risk 

screening analysis. Other worst-case assumptions included: 

 For facilities with multiple emission points, peak 1-hour emissions were assumed to 

occur at all emission points at the same time.

 For facilities with multiple emission points, 1-hour concentrations at each receptor 

were assumed to be the sum of the maximum concentrations due to each emission 

point, regardless of whether those maximum concentrations occurred during the 

same hour. 

 Worst-case meteorology (from one year of local meteorology) was assumed to occur 

at the same time the peak emission rates occur. The recommended EPA local-scale 

dispersion model, AERMOD, is used for simulating atmospheric dispersion.

 A person was assumed to be located downwind at the point of maximum impact 

during this same 1-hour period, but no nearer to the source than 100 meters.

 

6

In this regard, note that the affirmative defense for malfunctions is a defense to civil penalties only, not to liability. 

The malfunction event remains a violation.
15

 The maximum impact was compared to multiple short-term health benchmarks for the 

chemical being assessed to determine if a possible acute health risk might exist.

Based on industry-specific information, we determined that a refined emissions multiplier 

of 2, rather than a multiplier of 10, better represents the peak hourly emission rates for several 

facilities in the PEPO and P&R IV source categories. Refer to a separate memorandum in the 

docket (Emissions Data and Acute Risk Factor Used in Residual Risk Modeling; Pesticide Active 

Ingredients, Polyether Polyols, and Group IV Polymers and Resins) for a detailed description of 

how the refined emissions multipliers were developed for the source categories. With regards to 

the failure of a control device, this would constitute a violation of the emission standard. The 

acute risk emissions factor is designed to account for fluctuations in emissions for facilities 

complying with the standards, not for facilities in non-compliance. Therefore, it would be 

inappropriate to use the emissions factor suggested by the commenter for purposes of 

determining whether the MACT standards’ current requirements are in need of revision under 

section 112(f)(2).

Comment 2.1.14: Commenter 51 stated concern that the EPA failed to perform an 

adequate multipathway risk assessment. One reason the commenter states the assessment is 

inadequate is that it does not account for all the PB pollutants. The commenter asserts that the 

EPA’s choice to restrict the multipathway screening assessment to only HAP that bioaccumulate 

is not supported by the 2003 Risk Assessment Guidance, because it ignores HAP that persist and 

accumulate in soils, including arsenic, nickel and other metals emitted by these source 

categories. Another reason the commenter believes the multipathway risk assessment is 

inadequate is that the EPA did not base the assessment on allowable emissions or consider 

emissions from malfunctions and violations. In addition, the commenter notes that the EPA did 

not assess all exposure routes, did not use the information from the multipathway analysis in the 

overall risk analysis, and did not add the multipathway risk found to the inhalation risk. The 

commenter asserts that the EPA may not assume that risks under the multipathway threshold are 

not significant enough to require a full analysis and that the EPA gives no justification for cutting 

off the significance threshold at the 1-in-1 million point. The commenter claims that, where the 

EPA found multipathway risks above the thresholds, the EPA must take action to better protect 

people’s health based on this information. The commenter opines that the EPA should update the 

incidental soil ingestion factors it uses in its multipathway risk assessments to fully account for 

the greater multipathway exposure and risk for children.

Response 2.1.14: We disagree that the multipathway assessment is inadequate due to 

restrictions in the pollutants included in the screening assessment. In the Air Toxics Risk 

Assessment Reference Library, we developed the current PB-HAP list considering all of the 

available information on persistence and bioaccumulation (see 

http://www.epa.gov/ttn/fera/risk_atra_main.html), specifically Volume 1 Appendix D). (The Air 

Toxics Risk Assessment Reference Library provides information on the fundamental principles of 

risk-based assessment for air toxics and how to apply those principles in different settings (e.g., 

facility-specific) as well as strategies for reducing risk at the local level.) This list considered 

HAP identified as PB-HAP by other EPA Program Offices (e.g., the Great Waters Program), as 

well as information from the PBT profiler (see http://www.pbtprofiler.net/). This list was peerreviewed by the SAB and found to be acceptable, and therefore we consider it to be reasonable 

for use in the RTR program. Based on these sources and the limited available information on the 
16

persistence and bioaccumulation of other HAP, we do not believe that the potential for 

multipathway risk from other HAP rises to the level of the PB-HAP currently on the list.

As noted in the docket memo MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV Production Source Categories

(Docket Item No. EPA-HQ-OAR-2011-0435-0007), allowable risks were equal to actual risks for 

all of these source categories, with one exception described below. Since (in most cases) actual 

risks equal allowable risks, the multipathway screening results presented based on actual 

emissions would be the same if based on allowable emissions. The one instance where actual 

risks did not equal allowable risks was for the PAI source category. The halogenated process 

vents could have a maximum ratio of MACT allowable to actual emissions of 6:1, or allowable 

emissions could be 6 times higher than actual emissions. This ratio was then applied to 

emissions of hydrogen chloride and chlorine and the allowable TOSHI from this source category 

was estimated to be 3, while the actual TOSHI was estimated to be 0.7. However, these two HAP 

are not included in the multipathway analysis so there would be no increase in multipathway 

results by including allowable emissions from this source category.

We did not combine the inhalation and multipathway risk assessment results for each 

pollutant because it is inappropriate to do so. The multipathway risk assessment conducted for 

proposal was a screening-level assessment (i.e., Tier 1). It used highly conservative assumptions 

designed to ensure that facilities with results below the screening threshold values did not have 

the potential for multipathway impacts of concern. The screening scenario is a hypothetical 

scenario. It is inappropriate to combine the results of a refined inhalation assessment, which 

produces a quantitative result, with a screening-level multipathway assessment, which produces 

a “yes/no” result. In situations where we have previously summed the inhalation and 

multipathway assessment results (e.g., secondary lead smelters), it was for two refined 

assessments, and still serves as an overestimate of potential risks given that it is highly unlikely 

that the same receptor has the maximum results in both assessments.

We disagree with the commenter that emissions that are violations of the standards should 

be considered as part of the risk analysis for purposes of determining whether the standards 

need to be revised under section 112(f)(2). The purpose of the risk review is to evaluate whether 

the emission limits should be made more stringent to reduce the risk posed after compliance with 

the underlying MACT standard. To the extent that a source is violating the underlying MACT 

standard, no tightening of the emission standard under the residual risk rule will avoid or 

militate against such violations. In other words, a source that is violating the emission standard 

promulgated under section 112(d) would not be any more likely to be able to avoid such 

violations and comply with a different presumably more stringent standard promulgated under 

section 112(f). Such events are violations and subject to enforcement by the EPA, the states, or 

citizens, and an action for injunctive relief is the most effective means to address violations 

whether or not they are caused by malfunctions if an emissions event poses a significant health 

or environmental risk.

We further note that we generally draw no bright lines of acceptability regarding cancer 

or noncancer risks from source category HAP emissions, and that it is always important to 

consider the specific uncertainties of the emissions and health effects information regarding the 

source category in question when deciding exactly what level of cancer and noncancer risk 

should be considered acceptable. In addition, the source category-specific decision of what 

constitutes an acceptable level of risk should be a holistic one; that is, it should simultaneously 

consider all potential health impacts -- chronic and acute, cancer and noncancer, and 
17

multipathway, -- along with their uncertainties, when determining the acceptable level of source 

category risk. In other words, we look at the risk numbers within the context of uncertainty 

associated with emissions, health benchmark values and, in the case of cancer and noncancer 

risks, the health effect associated with exposure. The Benzene NESHAP decision framework of 

1989 acknowledged this; in today’s world, such flexibility is even more imperative, because new 

information relevant to the question of risk acceptability is being developed all the time, and the 

accuracy and uncertainty of each piece of information must be considered in a weight-ofevidence approach for each decision. This relevant body of information is growing fast (and it 

will continue to grow faster and faster), necessitating a flexible weight-of-evidence approach 

that acknowledges both complexity and uncertainty in the simplest and most transparent way 

possible. While this challenge is formidable, it is nonetheless the goal of the EPA’s RTR 

decision-making, and it is the goal of the risk assessment to provide the information to support 

the decision-making process.

Regarding incidental soil contamination, the EPA has estimated risks from both direct 

and indirect pathways. Direct routes of exposure include direct ingestion of soil and exposure 

through dermal contact. However, because it has been demonstrated in past analyses that 

exposure levels associated with dermal contact are but a small fraction of exposure levels 

associated with ingestion and inhalation pathways, dermal exposures were not assessed for these 

source categories. 

2.2 Consideration of Risks from Entire Facilities, Industrial Clusters, and 

Other Sources in Risk Assessment

Comment 2.2.1: Commenter 51 states that the EPA should aggregate health risk. The 

commenter states that although the EPA does aggregate cancer and non-cancer risks across 

pollutants, it should also do so for acute risks in a similar way to the chronic TOSHI for the same 

organ system or systems, and should also do so for all pollutants in the multipathway assessment. 

The commenter states that the EPA should also create a metric to assess the total, combined 

health risks, which include the acute, cancer, chronic non-cancer, and multipathway risks for the 

source category.

Response 2.2.1: We have combined risk assessment results to the extent that it is 

appropriate to do so. We do consider the effect of mixtures of carcinogens. We do not use a 

TOSHI approach for acute noncancer like we do for chronic noncancer. We also do not combine 

the results of our inhalation and multipathway assessments.

As described in the risk assessment report (available in the docket for this action), we do

not sum results of the acute noncancer inhalation assessment to create a combined acute risk 

number that would represent the total acute risk for all pollutants that act in a similar way on the 

same organ system or systems (similar to the chronic TOSHI). As noted in previous responses, 

the worst-case acute screen is already a conservative scenario. That is, the acute screening 

scenario assumes worst-case meteorology, peak emissions for all emission points occurring 

currently and an individual being located at the site of maximum concentration for an hour. 

Thus, as noted in section 2.7.2 of the Draft Residual Risk Assessment for Seven Source 

Categories (Docket Item No. EPA-HQ-OAR-2011-0435-0018), “because of the conservative 

nature of the acute inhalation screening and the variable nature of emissions and potential 

exposures, acute impacts were screened on an individual pollutant basis, not using the TOSHI 

approach.” 
18

We did not combine the inhalation and multipathway risk assessment results for each 

pollutant because it is inappropriate to do so. The multipathway risk assessment conducted for 

proposal was a screening-level assessment (i.e., Tier 1). It used highly conservative assumptions 

designed to ensure that facilities with results below the screening threshold values did not have 

the potential for multipathway impacts of concern. The screening scenario is a hypothetical 

scenario, and due to the theoretical construct of the screening model, exceedances of the 

thresholds are not directly translatable into estimates of risk or hazard quotients for these 

facilities. In situations where we have previously summed the inhalation and multipathway 

assessment results (e.g., secondary lead smelters), it was for two refined assessments, and still 

serves as a conservative overestimate of potential risks given that it is highly unlikely that the 

same receptor has the maximum results in both assessments.

Comment 2.2.2: Commenter 51 states that the EPA has failed to satisfy section 112(f)(2) 

or to follow scientific recommendations or the best available science regarding the need to assess 

the full, cumulative impact of HAP exposure for affected local communities, citing the EPA’s 

most recent report on the subject, titled Concepts, Methods and Data Sources for Cumulative 

Health Risk Assessment of Multiple Chemicals, Exposures and Effects: A Resource Document, 

and recommendations by the SAB. The commenter states that for both its inhalation risk 

assessment and its multipathway risk assessment, the EPA fails to account for the impact of 

adding new air emissions to recent and past air emissions that the most-exposed people have 

already experienced from these source categories. As a result, according to the commenter, the 

EPA fails to adequately assess the cumulative impact of exposure to these source categories’ 

emissions. The commenter asserts that in many instances people living near these facilities 

already have background levels of past exposure and past pollution that increase their current 

health risk. The commenter adds that for areas like these, where there are multiple sources of air 

toxics and the individual sources in this category have emitted HAP for years, the EPA must 

address background as well as new health risk. 

In contrast, commenter 49 states that the EPA does not have authority to consider facilitywide risks because the CAA section 112(f)(2)(A) allegedly requires residual risk determinations 

to be conducted on a category-by-category basis and risk assessments to be focused exclusively 

on emissions from sources in the category or subcategory.

Response 2.2.2: The EPA conducted an assessment of the cumulative cancer risks from 

emitted carcinogens and the cumulative noncancer hazard indices from all emitted noncarcinogens affecting the same target organ system for both the source category emissions and 

the facility-wide emissions. This assessment excludes background contributions because 

technical limitations in the data sets would be insufficient to conduct a meaningful analysis. 

While the incorporation of additional background concentrations from the environment in our 

risk assessments (including those from mobile sources and other industrial and area sources) 

could be technically challenging, they are neither mandated nor barred from our analysis. In 

developing the decision framework in the Benzene NESHAP currently used for making residual 

risk decisions, the EPA rejected approaches that would have mandated consideration of 

background levels of pollution in assessing the acceptability of risk, concluding that comparison 

of acceptable risk should not be associated with levels in polluted urban air (54 FR 38044, 

38061, September 14, 1989). Background levels (including natural background) are not barred 

from the EPA‘s ample margin of safety (AMOS) analysis, and the EPA may consider them, as 
19

appropriate and as available, along with other factors, such as cost and technical feasibility, in 

the second step of its section 112(f) analysis.

We disagree with the comment that we failed to consider or account for cumulative risk. 

The EPA modeled whole-facility risks for both chronic cancer and non-cancer impacts to 

understand the risk contribution of the sources within these MACT categories. The individual 

cancer risks for each source category were aggregated for all carcinogens. In assessing 

noncancer hazard from chronic exposures for pollutants that have similar modes of action or 

(where this information is absent) that affect the same target organ, we aggregated the hazard 

quotients (HQ). This process creates, for each target organ, a TOSHI, defined as the sum of 

hazard quotients for individual HAP that affect the same organ or organ system. All TOSHI 

calculations presented here were based exclusively on effects occurring at the “critical dose” 

(i.e., the lowest dose that produces adverse health effects). Whole facility risks were estimated 

utilizing the 2005 NEI, with updated facility-wide and source category data files developed by 

the EPA through emission data updates from industry, states, and NACAA.

We also disagree with the commenter’s assertion that additional quantitative assessment of 

risks from sources outside the source category is required under the statute. The statute requires 

the EPA to provide the quantitative risk information necessary to inform RTR regulatory 

decisions, and to this end, the EPA conducts a comprehensive assessment of the risks associated 

with exposure to the HAP emitted by the source category and supplements that with additional 

information that is available about other possible concurrent and relevant risks.

2.3 Consideration of Demographics in Risk Assessment

Comment 2.3.1: Commenter 28 commends the EPA for considering environmental 

justice (EJ) issues in this proposal, with a focus on populations within a three-mile radius of 

facilities. However, the commenter suggests the EPA rule writers work with the EPA’s Office of 

Environmental Justice to develop specific criteria and guidance on how to interpret and apply the 

outcomes of EJ analyses in the rulemaking process and that the EPA update the poverty statistics 

used in the analyses to include 2010 census data.

Response 2.3.1: We note that we are working with the Office of Environmental Justice in 

an ongoing effort to develop new tools for considering environmental justice in rulemakings. 

While we intend to use the 2010 census data in future analyses, we do not believe that a rerun of 

our analysis using the 2010 census data would yield results that would change our overall 

conclusions regarding EJ impacts. Therefore, we have decided not to rerun the EJ analysis using 

the 2010 Census data.

Comment 2.3.2: Commenter 49 states that CAA section 112(f)(2)(A) expressly instructs 

the EPA to impose additional emissions controls if needed to provide an ample margin of safety 

to protect public health. The commenter says that the term “public health” cannot reasonably be 

interpreted to include consideration of environmental justice in the context of section 112(f), and 

therefore the EPA’s proposal to consider demographic analyses in conducting risk reviews is not 

a proper exercise of the EPA’s authority. Although “public health” is not defined in section 112 

or in the EPA’s 40 CFR Part 63 regulations, the Supreme Court observed in the context of the 

EPA’s NAAQS Program that the primary definition of the term should be applied, and that is 

public health means “the health of the public.” In the NAAQS program, the EPA interprets the 

term “public health” to include consideration of impacts on the population as a whole but also 
20

considers sensitive subpopulations identified by their health-based sensitivities, recognizing that 

the objective is to protect the group rather than any particular individual in the group. These 

sensitive subpopulations are identified independent of their demographic classifications. The 

commenter says that the EPA’s proposal to introduce demographic analyses to the determination 

of acceptable risk suggests that risk to some individuals is deemed more acceptable than risk to 

other individuals, and the commenter asserts that this type of political judgment has no place in a 

scientific evaluation of risk to public health.

Response 2.3.2: In this rulemaking, the EPA developed comparative analyses of the 

demographics of the populations within the vicinity of the facilities in these source categories as 

part of the risk assessment for each source category; the analyses did not change the results or 

conclusions in the assessments. As stated in the Benzene NESHAP, in determining the need for 

residual risk standards, we strive to limit to no higher than approximately 1-in-10 thousand 

(100-in-1 million) the estimated cancer risk that a person living near a plant would have if he or 

she were exposed to the maximum pollutant concentrations for 70 years and, in the ample of 

safety decision, to protect the greatest number of persons possible to an individual lifetime risk 

level of no higher than approximately 1-in-1 million. These considerations are made for all 

people regardless of racial or socioeconomic status. However, in determining whether to require 

additional standards under section 112(f), these levels are not considered rigid lines, and we 

weigh the cancer risk values with a series of other health measures and factors in both the 

decision regarding risk acceptability and in the ample margin of safety determination. We also 

consider cost of controls in the ample margin of safety determination. While we analyzed the 

demographic makeup of the populations surrounding the facilities within source categories 

addressed by this rule making, we ultimately concluded that the risks from each source category 

were acceptable and protected public health with an ample margin of safety. Thus, the results of 

our demographic analyses only served to provide information about the demographic makeup of 

the populations near facilities in each of these source categories, but did not drive regulatory 

outcomes. Therefore, commenter 49’s objections are moot.

Comment 2.3.3: Commenter 51 states that the EPA should assess the starting point or 

baseline health status of affected individuals or communities in addition to looking at the 

demographic census data as part of its socioeconomic analysis. The commenter also states that 

the EPA should follow the recommendations presented in the Environmental Justice Strategic 

Enforcement Assessment Tool (EJSEAT) by including other relevant EJ factors such as an 

assessment of the percent of population with limited English proficiency, infant mortality, and 

low birth weight births. The commenter further states that the EPA must actually use the data 

from this analysis in its decision-making process. The commenter urges the EPA to provide a 

plain-language statement of risks and benefits of the EPA’s final action to local communities for 

this and future actions in a way that lets them understand the levels of risk and what the EPA has 

determined is “acceptable” and “unacceptable” and what standard is required to provide an 

ample margin of safety.

Response 2.3.3: We are not able to determine the baseline health status of individuals or 

communities in a national rulemaking. Individual privacy issues as they relate to health records 

and the costs that would be associated with such an analysis make the analysis infeasible. 

Through the EPA’s interim guidance on EJ and the Action Development Process, the agency is 

encouraging rule writers and policy makers to look at the whole range of factors that impact 

communities and population groups when crafting rules. The EPA is continuing to discuss and 
21

pilot approaches that are consistent with the agency’s responsibilities regarding EJ as outlined 

in EO 12898. In determining the need for tighter residual risk standards, the EPA strives to limit 

to no higher than 100-in-1 million the estimated cancer risk for persons living near a plant if 

exposure to the maximum pollutant concentration for 70 years and to protect the greatest 

number of persons to a individual lifetime risk of no higher than 1-in-1 million. Considerations 

are made for all people regardless of racial or socioeconomic status.

With respect to the EJScreen tool (referred to as “EJSEAT” by the commenter), it is 

premature to determine whether it should be used in future demographic analyses after it 

becomes finalized. The EJScreen is currently a draft tool in development. Thus, it has not yet 

undergone a sufficient level of peer review to determine whether to incorporate it into our 

analyses, and it is quite possible that the finalized EJSEAT tool will be different than the draft 

tool that exists today.

It is the EPA’s goal to present all rule preambles and risk assessments in plain language, 

and we believe we have done so as much as possible. However, as future assessments are written 

we will consider the points raised in the comments provided above, and to the extent possible, 

incorporate those we believe will make our risk and rulemaking documents more informative.

2.4 Additional Standards to Address Risks

Comment 2.4.1: Commenter 51 states that the EPA failed to justify relying on the 

presumption of 100-in-1 million as the benchmark for cancer risk acceptability, rather than 

ensuring a greater reduction of cancer risk. The commenter believes that the EPA must update 

and reduce its presumption that 100-in-1 million lifetime cancer risk is acceptable based on new 

circumstances and evolving values since the 1980s. The commenter states that the EPA has both 

full authority and a responsibility to update its approach and reduce the presumptive level of 

what cancer risk is acceptable under section 112(f)(2). The commenter states that in setting this 

presumption of acceptable risk, the EPA recognized that it could not easily compare the risk 

from hazardous air pollution with the risk from other activities studied because of numerous 

differences. Specifically, the EPA stated that the consideration of the acceptability of a specific 

level of risk depends on factors including, but not limited to: the certainty and severity of the 

risk, the reversibility of the health effect, the knowledge or familiarity of the risk, and whether 

the risk is voluntarily accepted or involuntarily imposed. The commenter states that significant 

new information has been discovered and major circumstances have changed that should affect 

how the EPA applies these factors to a source category in a rulemaking today. The commenter 

states that during the more than two decades since the EPA established that presumption, 

dramatic scientific and societal advances have occurred that the EPA must take into account in 

its risk analysis.

Response 2.4.1: In 1990, Congress codified in section 112(f) of the CAA the approach we 

use for our residual risk analyses (i.e., the Benzene NESHAP, 54 FR 38044). Under that

approach, there is no single bright line (e.g., a 100-in-1 million cancer risk) that indicates that 

risk is “acceptable.” Rather, multiple health metrics, including the cancer risk, are considered 

to determine whether the risk is acceptable. Where we conclude that the risk is not acceptable, 

we cannot consider costs in requiring controls to bring risks down to an acceptable level. 

However, the analysis of whether risk is acceptable is not the endpoint. Once we determine that 

the existing MACT standards or identify what additional controls are sufficient to ensure risk is 

acceptable, we again review the health metrics in conjunction with considering the costs of 
22

controls to determine whether further additional controls should be required to provide an 

ample margin of safety to protect public health. The commenter does not provide support for its 

contention that “the risk that was acceptable in the world of the 1980s is no longer acceptable in 

today’s world.” Nor does the commenter explain how science has evolved in a way that would 

undermine the codified framework for determining acceptability.

Comment 2.4.2: Commenter 51 states that more stringent standards are required in order 

to satisfy section 112(f)(2) because the residual risk assessments are incomplete and 

underestimate risks, the determinations that risks are acceptable are incomplete and arbitrary, the 

EPA fails to provide an ample margin of safety to protect public health, and the EPA failed to 

provide adequate determinations of the environmental effects. 

Commenter 51 questions why, considering the statutory “aspirational goal” of achieving 

lifetime cancer risks below 1-in-1 million, the EPA is not requiring further emissions reduction 

to reduce risks to this level for these source categories. The commenter states that the acute risks 

should be found to be unacceptable because the risks were found to be above the EPA 

thresholds, did not consider combined effects of pollutants, were not based on MACT-allowable 

emissions, and did not include facility-wide information. The commenter also states that the 

chronic non-cancer risks should be found to be unacceptable because the assessment did not 

consider greater risks to children, cumulative impacts, and possible underestimates in the TOSHI 

levels, in which impacts above the critical dose may not have been included in the TOSHI 

calculations. The commenter also noted that staff recommendations in a 2002 internal EPA 

memo suggested the default HI limit be 0.2 rather than 1.0 to account for multiple sources of 

HAP emissions and stated that the EPA should reduce the TOSHI presumptive acceptability 

threshold to this level. The commenter states that the EPA also failed to explain why 

multipathway risks are acceptable when risks are above the presumptive thresholds for certain 

source categories and states that the EPA must require further reductions in multipathway risks 

to achieve acceptable levels. The commenter further states that the EPA has failed to 

demonstrate that risks from these source categories are acceptable because it did not perform a 

risk assessment to include past and background emissions or the cumulative impacts from the 

different types of health risks and HAP. The commenter states that the EPA should find risk 

unacceptable due to socioeconomic disparity in health risks.

Response 2.4.2: We note that in 1990 Congress codified in section 112(f) (2)(B) of the 

CAA the approach we use for our residual risk analyses. Under that approach, there is no single 

bright line (e.g., 100-in-1 million cancer risk) that indicates that risk is “acceptable.” Rather, 

multiple health metrics, including the cancer risk, are considered to determine whether the risk 

is acceptable. Where we conclude that the risk is not acceptable, we cannot and do not consider 

costs in requiring controls to bring risks down to an acceptable level. However, the analysis of 

whether risk is acceptable is not the endpoint. Once we determine that the existing MACT 

standards are sufficient to ensure that risk is acceptable, we again review the health metrics in 

conjunction with the costs of controls, technical feasibility, and other relevant factors, to 

determine whether additional controls should be required to provide an ample margin of safety.

The EPA disagrees with the commenter’s notion that any TOSHI value greater than 0.2 

should be considered unacceptable. We note that pollutant-specific RfCs are not absolute 

thresholds, but estimates of chronic inhalation exposures at or below which health effects would 

not be expected to occur after a lifetime of exposure, including in sensitive subgroups. We 

further note that these RfCs are developed using a health-protective approach (see uncertainty 
23

discussion in section 4.2 of the Draft Residual Risk Assessment for 7 Source Categories (Docket 

Item No. EPA-HQ-OAR-2011-0435-0018)), and that TOSHI values of 1 or less are generally 

considered to carry no appreciable risk of adverse health effects and that there is generally no 

need to compound this protection by suggesting that any source category maximum TOSHI value 

would need to be at or below 0.2 before we would consider it to be acceptable. Finally we note 

that the commenter’s source for its statement that default limits HI should or must be establish at 

0.2 rest on an internal EPA staff memo (from 2002) which was never adopted as agency policy 

(and never reviewed by the public or by any peer review body) and consequently carries no 

precedential weight.

Regarding the acute health risks, as described in the final Residual Risk Assessment for 7 

Source Categories (available in the docket for this action), we do not sum results of the acute 

noncancer inhalation screen because of its conservative nature and the variable nature of 

emissions and potential exposures. The use of allowable emissions is also not considered due to 

the conservative assumptions used to gauge worst-case potential acute health effects. The 

conservative estimates built in to the screen include: 1) worst-case meteorology (from one year 

of local meteorology); 2) that a person is located downwind at the point of maximum impact 

during this same 1-hour period; and 3) that all emission points have their peak emission rates 

occur simultaneously. Thus, we believe performing an acute screen based on allowable 

emissions would be overly conservative and at best, of questionable utility to decision makers. 

We do not perform a facility-wide assessment for acute risks. The emissions included in a 

facility-wide assessment have generally not been subjected to the same level of engineering 

review as the source category emission estimates and are likely to be less certain than our 

emissions estimates for the source category. That, combined with the already conservative 

nature of the acute assessment, would lead us to not conduct an acute risk assessment using 

facility-wide emissions.

We believe that further reductions based on multipathway risk are unnecessary for these 

source categories. Please see Response 2.1.14 for further discussion. See Response 2.1.6 

concerning the commenter’s assertion that the assessment did not consider greater risks to 

children.

The EPA disagrees with the comments that we did not consider aggregate or cumulative 

risks. As discussed in the risk document for this rule,7the assessments we conducted for the 

source categories consider the cumulative cancer risks from all carcinogens and the cumulative 

non-cancer hazard indices from all non-carcinogens (affecting the same target organ system) 

emitted from sources within the source category and also collocated sources at the same 

facilities. However, the commenter is correct that the assessments did not include background 

risks or contributions to risk from sources outside the facilities.

Section 112(f)(2) of the CAA expressly preserves our use of the two-step process for 

developing standards to address residual risk and interpret “acceptable risk” and “ample 

margin of safety” as developed in the Benzene NESHAP.8In the Benzene NESHAP, the EPA 

rejected approaches that would have mandated consideration of background levels of pollution 

 

7

See U.S. EPA’s Residual Risk Assessment for 7 Source Categories in the docket for the Group IV Polymers and 

Resins, Pesticide Active Ingredient Production, and Polyether Polyols Production rulemaking.

8 National Emission Standards for Hazardous Air Pollutants: Benzene Emissions from Maleic Anhydride Plants, 

Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By-Product Recovery 

Plants (54 FR 38044, September 14, 1989) (Benzene NESHAP).
24

in assessing the acceptability of risk, concluding that “...comparison of acceptable risk should 

not be associated with levels in polluted urban air. With respect to considering other sources of 

risk from benzene exposure and determining the acceptable risk level for all exposures to 

benzene, EPA considers this inappropriate because only the risk associated with the emissions 

under consideration are relevant to the regulation being established and, consequently, the 

decision being made.” (54 FR 38044, 38061, September 14, 1989). 

Although not appropriate for consideration in the determination of acceptable risk, we 

note that background risks or contributions to risk from sources outside the facilities under 

review could be one of the relevant factors considered in the ample margin of safety 

determination, along with cost and economic factors, technological feasibility, and other factors. 

Background risks and contributions to risk from sources outside the facilities under review were 

not considered in the ample margin of safety determination for this source category, mainly 

because of the significant uncertainties associated with emissions estimates for such sources. 

Our approach here is consistent with the approach we took regarding this issue in the HON 

RTR, which the court upheld in the face of claims that the EPA had not adequately considered 

background.

With regards to the comment concerning unacceptability due to socioeconomic disparity, 

under EO 12898, the EPA is directed to the greatest extent practicable and permitted by law, to 

make EJ part of its mission by identifying and addressing, as appropriate, disproportionately 

high and adverse human health or environmental effects of its programs, policies and activities 

on minority populations and low-income populations in the United States. Consistent with EO 

12898 and the Presidential Memorandum that accompanies it, the EPA’s EJ policies promote EJ 

by focusing attention and EPA efforts on addressing the types of environmental harms and risks 

that are prevalent among minority, low-income and indigenous populations. EO 12898 and the 

EPA’s EJ policies do not mandate particular outcomes from an action, but they demand that 

decisions involving the action be informed by a consideration of EJ issues. With respect to this 

rule, the EPA found the overall level of risk from the source categories to be acceptable and to 

provide an ample margin of safety for all populations in close proximity to these sources, 

including minority and low-income populations.

Comment 2.4.3: Commenter 51 states that the EPA’s AMOS analysis appears to be 

completely based on cost rather than on protecting public health. The commenter states that the 

EPA may not lawfully consider cost in deciding what the “ample margin of safety to protect 

public health” is but may only consider cost in determining whether additional standards are 

needed to prevent an adverse environmental effect. The commenter notes that the D.C. Circuit 

previously allowed the EPA to consider costs in the HON decision, but states that this case was 

wrongly decided, and the EPA should not rely on it to evade the CAA. The commenter also 

states that the EPA does not discuss how the health risk information shows an AMOS is provided 

by the proposed rule or explain what the ample margin is. The commenter states that the EPA’s 

determination that additional standards are not cost-effective is irrational and unsupported. The 

commenter states that the EPA appears to simply conclude with no explanation that the cost 

numbers are not reasonable, even though some are only $5/lb.

Response 2.4.3: The EPA disagrees with the commenter that the HON decision was 

wrongly decided and that the EPA relies on this decision to evade the CAA. As stated previously, 

ample margin of safety determinations for this rule are conducted separately after determining 

whether risks are acceptable after implementation of the MACT standards, in accord with the 
25

two-step framework set forth in the Benzene NESHAP. Using that framework, after determining 

that residual risks were already acceptable under the MACT standards, we considered costs, 

cost-effectiveness, technological feasibility, and other factors as set out in the Benzene NESHAP, 

at proposal we did not identify any additional controls beyond those that already ensure that 

risks are acceptable that would be needed to ensure an ample margin of safety. The EPA 

disagrees with the commenter that we cannot consider costs in the ample margin of safety 

determination step, as the D.C. Circuit squarely rejected the commenter’s position.

In accordance with the approach established in the Benzene NESHAP, we 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 the ample margin of safety determination for 

the source categories addressed by this rule making. The cancer and noncancer risk, number of 

persons at or above 1-in-1 million, and the annual cancer cases per year were presented in the 

proposal preamble for every source category addressed by this rule. With regards to the $5/lb 

cost identified by the commenter, the EPA found only one control option in the proposed rule 

that fell in this range ($11,000/ton), which was the beyond-the-floor option for equipment leaks 

from the P&R IV MACT equipment leak standards that apply to the polyethylene terephthalate

(PET) continuous thermal polyaspartic acid (TPA) high viscosity multiple end finisher 

subcategory. However, this option was part of the MACT floor determination for this emission 

point, not part of the ample margin of safety step. All of the options identified in the ample 

margin of safety step for these source categories had cost effectiveness values much greater than 

the value identified by the commenter ($244,000/ton), which the EPA stated as not being 

reasonable, given the level of emissions and risk reduction. 

Comment 2.4.4: Commenter 51 states that the EPA did not fulfill its duty to consider 

whether a more stringent limit is needed to protect the environment and may not base its 

environmental determination on the human health risk assessment alone. The commenter states 

that the EPA must perform an appropriate ecological assessment. The commenter also notes that 

the EPA does not appear to have engaged in an Endangered Species Act consultation.

Response 2.4.4: The EPA has developed a screening approach to examine the potential 

for adverse environmental effects as required under section 112(f)(2)(A) of the CAA. The 

environmental screen focuses on the following seven environmental HAP: 

 Five persistent bioaccumulative HAP (PB-HAP) – cadmium, dioxins/furans, 

polycyclic organic matter (POM), mercury (both inorganic mercury and methyl 

mercury), and lead.

 Two acid gases - hydrogen chloride (HCl) and hydrogen fluoride (HF). 

HAP that persist and bioaccumulate are of particular environmental concern because 

they accumulate in the soil, sediment, and water. The acid gases, HCl and HF, were included 

due to their well-documented potential to cause direct damage to terrestrial plants. For 

additional details on the environmental screening methodology, see the final residual risk 

document for this rulemaking.

We conducted an environmental risk screening assessment for all of the source 

categories addressed in this rulemaking. Of the 7 source categories addressed in this 

rulemaking, the PAI source category was the only one that had emissions of the environmental 

HAP listed above.
26

The PAI source category includes emissions of the environmental HAP HCl and HF. For 

HF and HCl, the average modeled concentration around each facility (i.e., the average 

concentration of all off-site data points in the modeling domain) did not exceed the ecological 

benchmarks. In addition, each individual modeled concentration of hydrogen chloride and 

hydrogen fluoride (i.e., each off-site data point in the modeling domain) was below the 

ecological benchmarks for all facilities. For additional information on the environmental 

screening results, see the final residual risk document for this rulemaking.

Based on our environmental screening analysis, we do not expect adverse environmental 

effects, as defined in CAA section 112 (a)(7), as a result of HAP emissions from any of the source 

categories addressed in this rulemaking. The EPA does not have information, nor did the 

commenter provide information to support the position that emissions from the source categories 

addressed in this rulemaking would result in environmental effects. Because our analyses do not 

indicate an environmental effect from these source categories, we disagree with the commenter’s 

statement that the EPA must engage in consultations (e.g., with the U.S. Fish & Wildlife Service 

and the National Marine Fisheries Service) under 16 U.S.C. 1536(a)(2).

3.0 Technology Review Assessment and Standards

Readers are referred to section VI of the final rule preamble for this action for additional 

comments, and the EPA’s responses to those comments, on the technology review assessment.

Comment 3.1: Commenter 51 asserts that to satisfy section 112(d)(6), the EPA must 

recalculate the MACT floors without consideration of costs and re-examine beyond the floor 

options today based on currently achievable emission levels. The commenter states that section 

112(d)(6) serves as an ongoing ratchet to continually require the EPA to update standards to keep 

pace with new technology in order to decrease emissions. The commenter asserts that the EPA 

cannot ignore improvements in technology based solely on costs and must require the maximum 

achievable level of control.

Response 3.1: The commenter is incorrect as a matter of law. Section 112(d)(6) requires 

the EPA to “review, and revise as necessary (taking into account developments in practices, 

processes, and control technologies), emission standards promulgated under this section no less 

often than every 8 years.” 

As the EPA has explained on several prior occasions, section 112(d)(6) does not require 

MACT standards to be recalculated. See 70 FR at 20008 (April 15, 2005); NRDC v. EPA, 529 F. 

3d at 1084. The EPA is not reopening that issue here, or otherwise reconsidering its 

interpretation of section 112(d)(6). Moreover, the argument that the EPA must recalculate floors 

in conducting a 112(d)(6) review was rejected by the D.C. Circuit in the HON opinion. See 529 

F. 3d at 1084 (“It is argued that the EPA was obliged to completely recalculate the maximum 

achievable control technology-in other words, to start from scratch. We do not think the words 

‘review, and revise as necessary’ can be construed reasonably as imposing any such 

obligation.”). Accordingly, we did not, as the commenter requests, re-calculate the MACT floors 

as part of our section 112(d)(6) review. 

Further, whether or not section 112(d)(6) is “technology forcing”, the EPA retains very 

significant discretion in balancing relevant factors in determining whether it is “necessary” to 

revise the existing technology-based MACT standards. See, e.g., Sierra Club v. EPA, 325 F. 3d 

374, 378 (D.C. Cir. 2003) (under CAA section 202(l)(2), EPA is to consider factors beyond pure 
27

technological capability, and the statute does not direct how EPA should weigh such factors). In 

reviewing section 112(d)(2) standards, and determining whether to revise them is “necessary” 

under section 112(d)(6), the EPA may take into consideration cost and feasibility when 

evaluating developments in practices, processes, and control technologies.

Comment 3.2: Commenter 29 suggests that the EPA revise subparts JJJ, MMM, and PPP 

to include the vapor balancing option in the proposed Uniform Standards for Storage Vessel and 

Transfer Operations (proposed 40 CFR part 65, subpart I). This option allows offsite facilities 

that clean and/or reload transport vehicles and barges to control emissions from a fixed roof 

atmospheric storage vessel by using vapor balancing. The commenter provided suggested rule 

language to incorporate this change for subparts MMM, PPP, and JJJ. The commenter also 

suggests the EPA revise subparts JJJ, MMM, and PPP to include the definition of “repair” as it is 

defined in the proposed Uniform Standards for Equipment Leaks (proposed 40 CFR part 65, 

subpart J), which is based on the detection method used to identify the leak or potential leak.

Response 3.2: While we appreciate these suggestions, these rule revisions were not 

included in the proposed rules, and we are not prepared to make these changes without 

providing an additional notice and opportunity for public comment, in part because we have not 

yet taken final action regarding the proposed Uniform Standards provisions the commenter 

supports to conclude that they are generally appropriate. Therefore, we are not adding these 

provisions to the final rules at this time. 

Comment 3.3: Commenter 57 submitted a supplemental late comment to other on-time 

comments and attachments (comments 51-56) that they provided on the proposed rule. The 

commenter urges the EPA to consider its recent consent decree with Marathon Petroleum 

Company, LP (Marathon) when setting standards for the PAI, PEPO, and P&R IV source 

categories. The commenter reports that the consent decree was filed in the U.S. District Court 

after the close of the comment period for the proposed rule and establishes requirements for 

emissions monitoring and reporting for Marathon’s covered flares. 

Commenter 57 states that in their on-time comments on the proposed rule, they requested 

that the EPA require facilities to develop flare minimization plans, conduct root cause analyses 

of flaring events, and improve flare monitoring by requiring technology such as gas 

chromatography and laser sensing and urges the EPA to consider consent decrees that the EPA 

has entered into in recent years. The commenter asserts that the requirements (which they list in 

their comment letter) that the EPA established under the consent decree with Marathon (included 

as an attachment with the comment letter) would reduce HAP emissions from Marathon’s flares 

by 140 tons per year (tpy) and reduce VOC emissions by 5,250 tpy. The commenter states that 

the consent decree highlighted Marathon’s investment in making changes to decrease emissions 

from its chemical flares and that the changes made will “save” the facility $5 million a year by 

reduction steam usage and increasing product recovery. 

Commenter 57 opines that the EPA must consider its April 2012 consent decree with 

Marathon as part of the PAI, PEPO, and P&R IV rulemaking. The commenter asserts that the 

decree demonstrates that there have been “developments” in the control of emissions from a 

similar source category that the EPA cannot ignore under CAA section 112(d)(6) and that, given 

the potential for large emissions reductions, the EPA must consider under CAA section 112(f)(2) 

whether such requirements would provide an “ample margin of safety to protect public health” 

for the subject source categories.
28

Response 3.3: First, we note that we are not required to consider or respond to the 

commenter’s suggestions in its late-submitted comments. However, to the extent allowed in the 

remaining time for promulgation of this final rule, we chose to review the commenter’s 

suggestions, and offer preliminary responses here in advance of any possible future regulatory 

undertaking that could be explored based on additional gathered data, which we do not 

currently have. The EPA is not at this time making changes to the flare provisions for the source 

categories addressed in this action. The commenter submitted their supplemental comment on 

June 21, 2012, which was well after the public comment period ended (March 30, 2012). It is 

likely that, rather than to take commenter 57’s suggestion to simply adopt new flare 

requirements in the final rule, we would need to undertake another round of proposed 

rulemaking and solicit comment on any amendments to the flare provisions for these NESHAP, 

in order to meet our procedural obligations under CAA section 307(d). 

In other contexts outside of this rulemaking, the EPA has recently begun studying the 

performance of flares to control HAP emissions, as governed by the EPA’s General Provisions 

at 40 CFR 63.11(b). In April 2012, the EPA conducted an external peer review of a draft 

technical report, Parameters for Properly Designed and Operated Flares

(http://www.epa.gov/ttn/atw/flare/2012flaretechreport.pdf). In this report, the EPA evaluated test 

data and identified a variety of parameters that may affect flare performance and that could be 

monitored to help assure good combustion efficiency. Based on feedback received from the 

external ad-hoc peer review panel, the EPA has since undertaken an initiative to go back and reevaluate parameters that may affect overall flare performance at source categories known to use 

flares for controlling HAP emissions (e.g., petroleum refining). 

Currently, PAI, PEPO, and P&R IV sources may choose to use a flare to reduce 

emissions from storage vessels and process vents to comply with the MACT standards, but are 

not required to do so. Our records indicate the use of flares in only the PAI and P&R IV source 

categories, though it may be possible that flares may also be in use in the PEPO source 

categories (e.g., as a back-up control device). However, we do not yet have sufficient flare 

performance data for the PAI, PEPO, and P&R IV source categories. Therefore, we are not at 

this time prepared to finalize any changes to the currently applicable regulations pertaining to 

the performance of flares in the PAI, PEPO, and P&R IV source categories, but we may explore 

whether to revise flare requirements in the future, if we conclude that new requirements are 

warranted and would be applicable to subject source categories. It is important to note that 

some of the requirements and parameters set forth in the Marathon consent decree (though 

appropriate for the Marathon facility) might not be able to be applied universally to other source 

categories based on the differing vent gases that are being flared.

Therefore, we are not prepared at this time to conclude either that the flare requirements 

imposed in the Marathon consent decree in fact represent developments in processes, practices 

and control technologies for the PAI, PEPO, and P&R IV source categories, such that it is 

necessary to determine whether to establish such requirements under CAA section 112(d)(6). 

Additionally, regarding the commenter’s claim that adding flare requirements would be 

necessary under section 112(f)(2) of the CAA in order to protect public health with an ample 

margin of safety, the EPA has already determined, based on risk assessments conducted for the 

subject source categories, that additional control to achieve an “ample margin of safety” for the 

PAI, PEPO, and P&R IV source categories is not needed, as the previously promulgated MACT 

standards already achieve the level of protection required by section 112(f)(2). See Docket ID 

No. EPA-HQ-OAR-2011-0435 for documentation of the risk assessments.
29

4.0 Startup, Shutdown, and Malfunction Exemption/Affirmative 

Defense Provisions

4.1 Startup, Shutdown, and Malfunction Exemption

Readers are referred to section VI of the final rule preamble for this action for additional 

comments, and the EPA’s responses to those comments, regarding comments received on 

removal of the startup, shutdown, and malfunction (SSM) exemption.

Comment 4.1.1: Commenters 38 and 41 note a control scenario currently used at one 

facility for periods of SSM would not be available with the removal of the SSM plan provisions. 

The commenters explain that one of commenter 38’s facilities has the capability to control 

emissions through a backup system. When using the backup system, the control devices for one 

unit controls emissions from two units. When this scenario is used, the process parameters can 

vary significantly from steady state conditions and some emissions may be routed to a secondary 

vent for pressure control. The emissions released during these events are estimated and reported, 

the potential to emit from these activities has been established through performance testing, the 

emissions are limited by a new source review permit, and HAP emissions impacts have been 

found acceptable by the state air permitting agency. This commenter and commenter 41 request 

this control scenario continue to be allowed.

Response 4.1.1: We disagree that this control scenario can be allowed under the MACT 

standards. With the removal of the SSM exemption, facilities are now required to meet the MACT 

emission limits during all periods, including SSM. Any excess emissions will be considered a 

violation of the standard. The rule language proposed by the commenter would essentially 

amount to allowing a facility to temporarily bypass their emissions control device in a way that 

renders the emissions exempt from emission limits, which the EPA believes would be inconsistent 

with the CAA’s requirement that emission limitations be continuously applicable. We 

acknowledge that process parameters may vary significantly from steady state conditions when 

transferring from one unit operation to another (as described by the commenter). The existing 

rule already includes flexible continuous process vent control compliance options. Current 

regulations not only allow owners or operators to comply by meeting a production based limit, 

but they are also allowed to comply by reducing emissions by 98 percent in a combustion device 

or to a concentration of 20 parts per million by volume (ppmv) on a dry basis (whichever is less 

stringent); combust the emissions in a boiler or process heater with a specified design heat input 

capacity or by introducing emissions into the flame zone; or combust emissions in a flare 

meeting specification requirements. If, however, none of these standards can be met, the 

affirmative defense to civil penalties provisions are available to sources experiencing a violation 

of the emission standards due to a malfunction.

Comment 4.1.2: Commenter 41 cites the EPA’s explanation of the difficulty of 

establishing emission standards for malfunctions due to the myriad of different types of 

malfunctions that can occur, and asserts that a pressure relief device (PRD) release is unique in 

that the “release” is an inherent function of the device, and therefore a work practice standard 

could be established.
30

Response 4.1.2: We disagree with the commenter. The releases are related to process 

upsets or other malfunctions that require the release of pressure to avoid damage to equipment 

and to prevent harm to personnel at the facility. Such releases are not routine, are unpredictable 

in nature, and are considered to be caused by malfunctions (e.g., poor design, improper 

maintenance, or operational error) that do not justify an exemption from standards that, under 

the CAA, apply continuously. The commenter failed to establish that the criteria for setting a 

work practice had been met, and as we explained in the preamble, it is impracticable to establish 

work practices or other alternative standards to manage these events and CAA section 112 does 

not require that we do so.

Comment 4.1.3: Commenter 44 states that the proposal to eliminate the SSM provisions 

in the proposed subparts is not based on an accurate reading of the decision of the D.C. Circuit in 

Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008). The commenter states that the EPA’s 

proposal for the standards to apply at all times is not consistent with Sierra Club v. EPA, as the 

court did not hold that the EPA is prohibited from setting separate standards for periods of SSM 

that are different than the emission limits during normal operations but held that the standards for 

those periods must be developed according to the section 112(d) MACT process and must be 

proven to be achievable under section 112(d). The commenter adds that there is ample precedent 

for the EPA applying a different standard during SSM events, and such a standard could include 

a design, equipment, work practice, or operational standard under section 112(h). The 

commenter notes that the definitions of “emission limitation” and “emission standard” have 

included provisions to limit “quantity, rate, or concentration of emissions of air pollutants on a 

continuous basis” since 1977, and since that time the EPA has not required sources to meet 

NSPS emission limits under CAA section 111 established for normal operations during SSM 

events. The commenter adds that Congress enacted the “continuous basis” language in section 

302(k) knowing the EPA’s emission standards under section 111 exempted SSM periods, and 

there is nothing in the legislative history of the 1977 or 1990 amendments to the CAA that 

suggests Congress intended to overturn that practice. The commenter noted that case law has 

affirmed the appropriateness of including special SSM provisions in standards issued under 

section 111. 

Response 4.1.3: The EPA does not claim that the Sierra Club case or the CAA constrains 

its authority to prescribe different standards for periods of startup or shutdown or for periods of 

malfunction. However, as explained in the preamble to the proposed and final rules, the EPA has 

determined that CAA section 112 does not require that emissions that occur during periods of 

malfunction be factored into development of section 112 standards. The EPA’s rationale for this 

view is explained in detail in the preamble as well. 

At proposal, we explained that the D.C. Court had recently vacated the SSM exemption 

contained in 40 CFR 63.6(f)(1) and 63.6(h)(1) that are part of the CAA section 112 General 

Provisions. Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008) cert. denied, 130 S. Ct 1735 

(2010). We further explained that, when incorporated into section 112(d) regulations for specific 

source categories, these two provisions exempt sources from the requirement to comply with 

otherwise applicable MACT standards during periods of SSM. We also explained that because 

these source categories rely on the General Provisions for SSM provisions, we were proposing 

to set standards that apply at all times, including during malfunctions. The EPA does not claim 

that the Sierra Club case constrains its authority to prescribe unique standards for SSM periods. 
31

Rather, the EPA’s view is that this decision calls into question the legality of source categoryspecific SSM exemptions in rules promulgated pursuant to section 112.

Further, in Medical Waste Institute v. EPA, 645 F. 3d 420, 425-27 (D.C. Cir. 2011), the 

D.C. Circuit Court held that the EPA may permissibly amend improper MACT determinations, 

including amendments to improperly promulgated floor determinations, using its authority under 

section 112(d)(2) and (3). The absence of standards for HAP emitted during SSM is not proper. 

National Lime, 233 F. 3d at 633-34; see also Medical Waste Institute, 645 F. 3d at 426 (resetting 

MACT floor, based on post-compliance data, permissible when the originally-established floor 

was improperly established, and permissibility of the EPA’s action does not turn on whether the 

prior standard was remanded or vacated). Similarly, the D.C. Circuit Court’s December 9, 

2011, decision in Portland Cement Ass’n v. EPA (D.C. Cir. No. 10-1358) confirms that the EPA 

is not constrained by CAA section 112(d)(6), and it may reassess its standards more often, 

including revising existing floors if need be. The commenters are, thus, incorrect that CAA 

section 112(d)(6) provides the exclusive authority to address standards that apply during SSM 

events. Here, the EPA adopted no MACT standard at all for HAP emitted during SSM, an 

approach soundly rejected by the D.C. Circuit Court in National Lime, 233 F. 3d at 633-34. 

Consequently, we have revised the standards so the emission limits of the rule apply at all times, 

including during periods of SSM. Where appropriate, we have adjusted the compliance 

demonstration provisions for certain standards to address startup and shutdown periods. We 

have also provided the ability to assert an affirmative defense to civil penalties for violations of 

standards that result from malfunctions. We believe this approach reasonably accommodates the 

requirements of the CAA and the Court’s reasoning in Sierra Club.

The EPA disagrees with commenters’ suggestion that the existence of an SSM exemption 

in rules implementing CAA section 111 in 1977 when Congress enacted the “continuous basis” 

language in the definition of “emission standard” is evidence that Congress approved of that 

regulatory SSM exemption. Commenters fail to cite legislative history or any other evidence 

supporting that Congress was aware or approved of that exemption and the Sierra Club decision 

makes clear that such exemptions are inconsistent with the Clean Air Act.

Comment 4.1.4: Commenter 44 states that the EPA offers little support for the assertion 

that it is reasonable to interpret section 112 as not requiring the EPA to account for malfunctions 

in setting emission standards. The commenter states that it does not make sense for the EPA to 

assert that malfunctions are part of normal operations but then exclude emissions from these 

parts of normal operations in the determination of the emission limits. The commenter states that 

due to the unplanned nature and variety of potential malfunctions, it would be difficult if not 

impossible for the EPA to gather data and set an emission standard for periods of malfunction. 

Due to these difficulties, the commenter suggests that under the authority of CAA section 112(h), 

the EPA prescribe alternative design, equipment, work practice, or operational standards where it 

is not feasible to set or enforce a numerical emission limit. The commenter adds that there are 

work practices that can be identified as being the best to minimize emissions during a 

malfunction, and the EPA must acknowledge the fact that even the best-performing sources 

experience malfunction events.

Response 4.1.4: The EPA’s rationale for its approach to malfunctions is discussed in the 

preambles to the proposed rule and this final action. 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. Accounting for malfunctions would be difficult, if not 
32

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. Setting work practice 

standards under CAA section 112 for malfunctions – as opposed to startup or shutdown periods 

– presents the same issues as setting numerical emission limits given the varied nature of 

malfunctions. Please see Response 4.1.6 for further discussion.

Comment 4.1.5: Commenter 44 states that the EPA has not justified adding new 

“general duty” language to the standards and should delete the new provisions. The commenter 

also states that the EPA lacks the authority to replace the previous reference to the General 

Provisions with somewhat different language in the individual subparts because these changes 

are not being proposed under 112(d)(6) or 112(f).

Response 4.1.5: The EPA disagrees that it lacks the authority to make the changes 

proposed. We have eliminated the SSM exemptions in these three NESHAP, consistent with 

Sierra Club v. EPA. As noted previously, the EPA relies on the CAA and Sierra Club for the 

elimination of the SSM exemption. The EPA is not limited to adopting such changes by CAA 

sections 112(d)(6) or (f)(2), but retains ongoing authority to revise its prior adopted section 

112(d)(2) and (3)-based standards whenever the agency identifies a flaw in such standards that 

renders them insufficient to meet the requirements of section 112(d)(2). See Medical Waste 

Institute v. EPA. The EPA explained in the proposal that we were adding language to this 

regulation to replace General Provision requirements that reference vacated SSM provisions (77 

FR 1288, 1299, 1302). The General Provisions “general duty” language that was previously 

referenced by these NESHAP includes language that is no longer necessary or appropriate in 

light of the elimination of the SSM exemption, so the EPA has modified the general duty 

requirements that were contained in 40 CFR 63.6(e) and placed them, modified, in 40 CFR 

63.1310(j)(4), 63.1360(e)(4), and 63.1420(h)(4). The revised general duty requirement language 

reflects the general duty to minimize emissions while eliminating the reference to periods 

covered by an SSM exemption. The current language in 40 CFR 63.6(e)(1)(i) characterizes what 

the general duty entails during periods of SSM. With the elimination of the SSM exemption, there 

is no need to differentiate between normal operations, startup and shutdown, and malfunction 

events in describing the general duty. Therefore the language the EPA is promulgating does not 

include that language from 40 CFR 63.6(e)(1).

Comment 4.1.6: Commenter 30 states that the EPA fails to provide adequate justification 

of why emission standards that apply during normal periods should also apply to malfunctions 

when emissions during malfunctions were not considered in developing the standards. The 

commenter states that CAA section 112 does not give the EPA the authority to replace MACT 

limits that consider the emission level achieved by the best performing sources, including periods 

where such sources experience malfunctions, with an affirmative defense to penalties. 

Commenter 44 states that the affirmative defense provisions do not cure the EPA’s failure to set 

emission standards that are achievable during SSM events and are not a substitute for setting 

achievable emission standards for these periods.

Commenters 29, 30, and 41 believe the EPA should promulgate separate standards under 

CAA section 112(h)(1) for periods of malfunction. Commenter 29 suggests that the EPA 

establish a work practice for malfunctions that result in only small levels of excess HAP 
33

emissions, such as 10 pounds of HAP, which requires the owner/operator to stop the emissions, 

stop the malfunction, and return to normal operations as soon as possible.

Response 4.1.6: The affirmative defense is not a replacement or alternative for a MACT 

limit and the EPA’s approach to malfunctions is not dependant on the affirmative defense. As we 

explained in the preamble to the proposed rule, 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 CAA section 112, emission standards for new 

sources must be no less stringent than the level “achieved” by the best controlled similar source, 

and for existing sources, generally, must be no less stringent than the average emission 

limitation “achieved” by the best performing 12 percent of sources in the category. There is 

nothing in CAA section 112 that directs the agency to consider malfunctions in determining the 

level “achieved” by the best performing or best controlled sources when setting emission 

standards. Moreover, while the EPA accounts for variability in setting emission standards 

consistent with the CAA section 112 case law, nothing in that case law requires the EPA to 

consider malfunctions as part of that analysis. 

CAA 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 malfunctions are sudden and unexpected events. 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 data-gathering necessary to solve a 

problem. We generally defer to an agency’s decision to proceed on the basis of imperfect 

scientific information, rather than to “invest the resources to conduct the perfect study.”). See 

also, Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) (“In the nature of things, no 

general limit, individual permit, or even any upset provision can anticipate all upset situations. 

After a certain point, the transgression of regulatory limits caused by ‘uncontrollable acts of 

third parties,’ such as strikes, sabotage, operator intoxication or insanity, and a variety of other 

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

discretion, not for specification in advance by regulation.”). In addition, the goal of a best 

controlled or best performing source is to operate in such a way as to avoid 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 CAA section 112, and is a reasonable 

interpretation of the statute.

4.2 Affirmative Defense Provisions

Comment 4.2.1: Commenter 51 urges the EPA not to adopt the affirmative defense 

provisions. The commenter states that the affirmative defense provisions are unlawful, and 

creates a new loophole that will reduce the deterrent impact of the proposed standards. The 
34

commenter argued that Congress plainly intended citizens to be able to enforce emission 

standards under the CAA using the full range of civil enforcement mechanisms available to the 

government, and, in the HAP context, subject only to the limitation that government not be 

“diligently prosecuting” its own civil enforcement action, according to CAA section 

304(b)(1)(B).

The commenter further states that the EPA exceeded its authority by attempting to 

impose additional Agency-created limits on civil penalties and that the proposed affirmative 

defense goes directly against Congressional intent that judges should determine the size of civil 

penalties whenever they are sought, and that the proposal will impermissibly chill citizen 

participation and the ability to win an effective, deterrent remedy in CAA enforcement actions.

The commenter observed that the CAA gives the EPA minimal discretion that only 

applies to administrative penalties which may be imposed under subsection 113(d), but no 

authority to compromise, modify or limit civil penalties that a court may impose under section 

113(e) or section 304. The commenter stated that it is improper for a court to fail to consider 

these factors, or to fail to make its own determination of what civil penalties are “appropriate” 

under CAA section 304(a), and EPA should not ask a court to ignore its legal duty . 

The commenter asserted that the burden the affirmative defense places on citizens makes 

it less likely that they will enforce the Act, that citizen participation in CAA enforcement will be 

hindered, in violation of citizens‘ rights to protect themselves from pollution and in direct 

conflict with congressional intent. The commenter stated that the affirmative defense imposes a 

technical burden on citizens, and the burden renders the defense impermissible. The commenter 

predicted that the affirmative defense would likely be used on a routine basis by polluters 

seeking to avoid penalties, just as the malfunction exemption was, and enforcement of the Act 

could suffer.

The commenter also states that if the EPA had the authority to promulgate any 

affirmative defense to penalties for malfunction, it should also promulgate strong reporting, 

monitoring, and other compliance measures, require a specific monetary penalty for each 

malfunction, and require that the affirmative defense cannot be used by a specific facility or 

company more than once within a set period of time, such as 10 years.

Response 4.2.1: For malfunctions, the EPA is finalizing the proposed affirmative defense 

language for violations of the standards that are caused by malfunctions with minor revisions 

discussed elsewhere in this section. As the EPA explained in the preambles to the proposed rule 

and final rule, the EPA recognizes that even equipment that is properly designed and maintained 

can fail and that such failure can cause a violation of the relevant emission standard. The EPA is 

including an affirmative defense in the final rule as we have in other recent section 111, 112 and 

section 129 rules so as to balance the tension, inherent in many types of air regulation, to ensure 

adequate compliance while simultaneously recognizing that despite the most diligent of 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) 

(emission limitations under CAA section 112 must both continuously apply and meet section 

112’s minimum stringency requirements, even during periods of SSM). Thus, the EPA is required 

to ensure that section 112 emission 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” 
35

limitations, on the one hand, are required, there is also case law indicating that in some 

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 D.C. 

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 case law such as Sierra Club v. EPA and the CAA 1977 amendments calls into 

question 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, the 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 also, Mont. Sulphur & Chem. Co. v. United States

EPA, 2012 U.S. App. LEXIS 1056 (Jan 19, 2012)(rejecting industry argument that reliance on 

the affirmative defense was not adequate). But 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. § 7602(k), and account for unplanned upsets and thus 

support the reasonableness of the standard as a whole. 

Further, the EPA’s view is that the affirmative defense is consistent with CAA sections 

113(e) and 304. Section 304 gives district court’s jurisdiction “to apply appropriate civil 

penalties.” Section 113(e)(1) identifies the factors that the Administrator or a court shall take 

into consideration in determining the amount of a penalty to be assessed only after it has been 

determined that a penalty is appropriate. The affirmative defense regulatory provision is not 

relevant to the amount of any penalty to be assessed under section 113(e) because if a court 

determines that the affirmative defense elements have been established, then a penalty is not 

appropriate and penalty assessment pursuant to the section 113(e)(1) factors does not occur.

The EPA’s view is that an affirmative defense to civil penalties for violations of 

applicable emission standards during periods of malfunction appropriately balances competing 

concerns. On the one hand, citizen enforcers are concerned about additional complications in 

their enforcement actions. On the other hand, industrial sources are concerned about being 

penalized for violations caused by malfunctions that could not have been prevented and were 

otherwise appropriately handled (as reflected in the affirmative defense criteria). The EPA is 

promulgating the affirmative defense applicable to malfunctions under the delegation of general 

regulatory authority set out in section 301(a)(1) of the Act, 42 U.S.C. § 7601(a)(1), in order to 

balance this tension between provisions of the Act and the practical reality, as case law 

recognizes, that technology sometimes fails. See generally Citizens to Save Spencer County v. U. 

S. Environmental Protection Agency, 600 F.2d 844, 873 (D.C. Cir. 1979) (using section 301(a) 

authority to harmonize inconsistent guidelines related to the implementation of federal 

preconstruction review requirements).

The EPA disagrees that the affirmative defense provision will hamper citizen 

enforcement. First, injunctive relief is still available and the threat of penalties would not deter 

violations in cases where all of the conditions of the affirmative defense have been satisfied 
36

because the affirmative defense criteria ensure that all reasonable steps were taken to prevent a 

malfunction that causes excess emissions.

Further, litigating whether a source has met the affirmative defense will not burden 

citizen groups any more or less than would litigating the appropriate penalty amount in the 

penalty assessment stage of a citizen suit enforcement action, because the section 113(e) penalty 

assessment criteria and the affirmative defense criteria are similar and in fact overlap. For 

example, the requirement that the Administrator or the court consider “good faith efforts to 

comply” is bound to generate the type of fact-intensive disputes that the commenter complains 

of. In addition, several of the affirmative defense criteria are exactly the type of criteria the 

Administrator or Court might consider in determining whether a source made “good faith efforts 

to comply.” For example, to take advantage of the affirmative defense, the source must prove by 

a preponderance of the evidence that, among other things, the excess emissions “were caused by 

an unavoidable failure of air pollution control and monitoring equipment, process equipment, or 

a process to operate in a normal or usual manner” and “could not have been prevented through 

careful planning, proper design or better operation and maintenance practices” and “did not 

stem from any activity or event that could have been foreseen and avoided, or planned for.”

Thus, the EPA does not expect the affirmative defense provision to significantly alter the 

burden of bringing a citizen enforcement action. For those cases that do proceed to trial, even in 

the absence of this affirmative defense, sources generally raise equitable arguments to argue for 

a low penalty and citizens often rebut such arguments. Therefore, as a practical matter, the EPA 

does not expect the affirmative defense provision to materially affect the practice of CAA 

enforcement.

The EPA is not adopting the commenter’s suggestion with respect to compensatory 

damages or limits on the frequency of use of the affirmative defense. It is not clear that the EPA 

has authority to require the automatic imposition of compensatory damages, and even if such 

authority exists, the EPA does not think automatic imposition of damages is appropriate, as it

would unduly complicate the enforcement process. Ensuring that malfunctions do not recur can 

be handled through imposition of appropriate injunctive relief. In addition, the EPA’s view is 

that it would not be appropriate to limit a source’s ability to take advantage of the affirmative 

defense to one time over a specified period of time such as 10 years, given that the affirmative 

defense is only available when the source could not have prevented the excess emissions. With 

respect to the commenter’s suggested reporting requirements, the reporting requirements in the 

rule being promulgated already require malfunction reporting, and the affirmative defense 

provisions require that parties choosing to assert the affirmative defense meet additional 

malfunction reporting requirements. Any such reports submitted to the EPA are publicly 

available pursuant to CAA section 114.

Comment 4.2.2: Several commenters (29, 30, 31, 38, and 44) state that the affirmative 

defense provisions are overly burdensome and are not realistically attainable due to the specific 

language of the required criteria. The commenters request that the EPA clarify and redefine the 

criteria considering attainability. Commenter 31 suggests several modifications to the affirmative 

defense provisions. One suggestion is to rely on the phrase “preponderance of evidence,” as is 

used in paragraph (a) of these provisions but is later contradicted by the use of “any” and “all.” 

Another suggestion is to make the definition of malfunction match that of the General 

Provisions, where the phrase “not reasonably preventable” is used rather than the phrase 

“sudden, infrequent, and unavoidable failure.” Commenter 29 suggests revising the affirmative 
37

defense provisions to remove the reference to off-shift and overtime labor because responding to 

malfunctions is many times a case-by-case situation and the use of overtime or off-shift labor is 

only one consideration in how to address a malfunction. This commenter also suggests removing 

the requirement for contemporaneous operating logs because its facilities use electronic media to 

document actions, and a printed and signed log is an outdated mode of documentation. 

Commenter 44 requested that the term “infrequent,” and subjective phrases, such as “if at all 

possible,” be removed from the regulatory text, as these terms could be subject to different 

interpretations by regulatory agencies.

Response 4.2.2: The EPA believes the affirmative defense criteria are well-defined and 

will assist the EPA and the courts in making reasoned determinations as to the establishment of 

affirmative defenses. The EPA does not believe the terms and conditions of the affirmative 

defense are overly subjective, extreme or need further qualification. The EPA and the courts 

have expertise and experience in evaluating and applying criteria such as those for the 

affirmative defense. Many of the conditions in the affirmative defense are modeled after the 

affirmative defense in the EPA‘s state implementation plan (SIP) SSM policy, See, e.g., State 

Implementation Plans: Policy Regarding Excessive Emissions During Malfunctions, Startup, and 

Shutdown (Sept. 20, 1999). Other conditions are modeled after a Federal Implementation Plan 

promulgated by the EPA (40 CFR 50.1312) and recently affirmed by the U.S. Court of Appeals 

for the 9th Circuit (Montana Sulphur & Chemical Co. v EPA, _666 F.3d 1174 (9th Cir. 2012). 

The EPA‘s view is that use of consistent terms in establishing affirmative defense regulations and 

policies across various CAA programs will promote consistent implementation of those rules and 

policies. Several states have adopted the EPA‘s SIP SSM policy into their SIPs. We do not have 

any indication that parties to enforcement proceedings have had any significant difficulties 

applying the terms of these SIP affirmative defenses. The EPA notes, however, that the 

references to off-shift and overtime labor have been removed from the final affirmative defense 

criteria.

With respect to the comment concerning operating logs, the EPA believes that log entries 

should be made contemporaneously, which does not mean, at the exact time that the engineers 

are taking actions to address the malfunction, but rather immediately thereafter. That way, more 

accurate records of the malfunction can be expected, as opposed to records reconstructed long 

after the malfunction. “Properly signed” means that the records should be signed by an engineer 

or other employee with knowledge of the situation, in a legible manner so that enforcement 

officials can tell who made the record and what their responsibilities were. The EPA generally 

accepts documents in electronic format, as long as the format is compatible with the 

requirements of the standards. For the affirmative defense provisions, the owner or operator of a 

facility experiencing an exceedance of its emission limit(s) during a malfunction must notify the 

Administrator by telephone or fax transmission of the exceedance. However, the written reports 

are required to demonstrate that the affirmative defense provisions have been met. In the case of 

signed logs, the EPA accepts electronically signed operating logs, where the format and method 

of submission meets the regulatory criteria and are compatible with the EPA’s and the delegated 

authorities’ electronic submission systems. Any source submitting records electronically should 

exercise due diligence to assure receipt by the EPA and the delegated authority.

Comment 4.2.3: Commenter 31 is concerned that an affirmative defense implies that the 

facility is guilty until proven innocent and that the proposed language improperly puts the burden 

of proof on the facility rather than on the EPA. Commenter 30 also states that the affirmative 
38

defense criteria force an affected source to admit to a violation of the emission limit before the 

EPA initiates an enforcement action without any assurance that it can successfully avail itself of 

the affirmative defense. Commenter 31 suggests that the EPA establish a rebuttable presumption 

rather than affirmative defense where it is presumed that the facility did everything in their 

power to minimize emissions during these events, unless the EPA proves certain facts that are 

enumerated in the rules. According to the commenter, this would allow the EPA to challenge the 

alleged deviation without compromising the legal rights of either party. Commenter 44 also is 

concerned that the affirmative defense provisions imply the facility is guilty until proven 

innocent and put the burden of proof on the facility rather than the EPA. This commenter states 

that the EPA must modify the provisions substantially so that they do not require sources to 

prove their innocence.

Response 4.2.3: The affirmative defense does not change the burden of proof with respect 

to establishing a violation. The burden of proof that a violation occurred remains with the 

plaintiff in an enforcement action. See, e.g., 40 CFR 22.24. If a violation has been established 

and a source wishes to assert the affirmative defense with respect to penalties, the source does 

bear the burden of establishing that the elements of the affirmative defense have been met. This 

burden-shifting is appropriate because the source is in a better position to determine the facts 

required to establish the defense. See, e.g., Arizona Pub. Serv. Co. v. EPA, 562 F.3d 1116, 1120, 

1129-30 (10th Cir. 2009) (rejecting industry challenge to the EPA’s use of an affirmative defense 

to address excess emissions during malfunction events.). The EPA does not agree that the 

affirmative defense should operate as the commenter suggests. The commenter improperly seeks 

to shift the burden of proof regarding eligibility for the affirmative defense from the source to the 

party bringing the enforcement action. It is the source, not the EPA (or other party taking 

enforcement action) that has the information relevant to assess whether a particular event 

qualifies as a malfunction and meets the affirmative defense.

Comment 4.2.4: Commenters 29 and 31 suggest revisions or removal of the formal root 

cause analyses required by the affirmative defense provisions. Commenters 31 and 38 suggest a 

formal root cause analysis should only be required when other reasonable methods fail to show 

the cause of a malfunction or when the serious nature of an event might make such an analysis 

necessary. Commenter 29 states that formal root cause analyses are not needed because 

malfunction events are already routinely investigated and formal root cause analyses will detract 

from candid inquiries into the events. Commenter 44 states that the root cause analysis 

requirement may make the affirmative defense unavailable if the source is not able to determine 

the primary cause of the malfunction. The commenters state that it should be expected that in 

many causes the primary cause will not be ascertainable or that it will not be possible to identify 

a way to ensure the malfunction will not recur. 

Response 4.2.4: The root cause analysis requirements specify that the purpose of the root 

cause analysis is “to determine, correct, and eliminate the primary cause of the malfunction.” 

While the root cause analysis itself does not necessarily assure that these purposes will be 

satisfied, in most cases, the EPA believes that a properly conducted root cause analysis will have 

such results. The EPA does not assume that all malfunctions require an identical degree of 

investigation. The EPA expects that the effort required to do a root cause analysis will vary 

depending on the nature of the malfunction.

The commenter does not explain the view that preparation of a root cause analysis would 

detract from candid inquires into the events, and the EPA sees no reason that requiring such an 
39

analysis to be prepared would do so. Indeed, the EPA has specified in consent decrees that root 

cause analyses be conducted and we have never had complaints from the defendants saying that 

this detracts from candid inquires into the events. 

Comment 4.2.5: Commenters 38, 41 and 44 state that the EPA estimate of $1,459 to 

assert an affirmative defense for a malfunction is not credible, appears entirely arbitrary, and is 

remarkably low given the number of different demonstrations and root cause analysis that are 

required of a source. Commenters 38 and 41 estimate that the cost of a full root cause failure 

analysis is roughly $15,000 to $19,000, based on institutional knowledge, interviews of principle 

investigators, travel costs and other expected costs. The commenters note that the resources that 

will be needed to perform the root cause analyses will dilute the facilities’ ability to focus on the 

issues that pose the greatest risk. Commenters 38 and 41 opine that the burden imposed by the 

affirmative defense standards has been greatly underestimated by the EPA, and estimates that the 

cost is at least an order of magnitude greater than the EPA estimates.

Response 4.2.5: As part of an affirmative defense, we are requiring that an owner or 

operator conduct a root cause analysis and submit it with their semiannual compliance report to 

the Administrator, as documentation of having met the conditions and requirements for asserting 

an affirmative defense. The EPA believes it has provided clear criteria within the affirmative 

defense provisions to support the development of an affirmative defense report. The EPA believes 

that these provisions will result in a minor administrative burden, but will result in sources 

analyzing their violation emissions to reduce or avoid those emissions in the future, which is an 

environmental benefit. The purpose of the analysis is to identify, correct, and eliminate or reduce 

the probability of the primary cause of the malfunction in order to prevent another from 

occurring. A root cause analysis is not mandatory and is only required if a source seeks to assert 

an affirmative defense. However, such an analysis is beneficial in resolving or preventing 

violations and excess emissions whether the source seeks to assert the affirmative defense or not. 

A root cause analysis is one example of what constitutes good air pollution control practices to 

minimize emissions.

Owner operators will often employ such analyses as part of their normal operations, 

because any regulatory noncompliance event may impact the safety of workers, the environment, 

and/or the continued operation of the plant. Therefore, these events typically are, or should be, 

investigated and resolved by industry, whether or not their ultimate intention is to assert 

affirmative defense. While there may be a cost associated with conducting a root cause analysis, 

an owner or operator may eventually recoup the cost of the analysis by eliminating or reducing 

the likelihood of another similar failure. Avoiding such failures may increase the reliability of 

production, and avoid the cost of lost production time, material and equipment losses, and 

further compliance and safety violations.

While we (and the commenters) acknowledge that the complexity of a malfunction event 

can vary, the EPA must disagree that the costs cited by the commenters represent the typical cost 

of an analysis. Our technical and managerial hour estimates may not be representative of all 

potential expenditures that are not already incurred during normal operations, but our estimates 

were similar to a portion of the cost analyses submitted by commenters 38 and 41. Commenters 

38 and 41’s analyses differed from ours by including expenses that, for any given event, may or 

may not be necessary. Our estimate is based on the assumption that the data gathering, 

recordkeeping and reporting that is already required by the applicable subparts will supply a 

portion of the information required for the analysis to support an assertion of affirmative 
40

defense. In addition, we anticipate that not all analyses will require contracted or off-site 

technical support, an assumption supported by the same commenters. As such we consider our 

estimate to be a reasonable estimate for the purpose of estimating the regulatory burden on 

affected sources for these rules.

Comment 4.2.6: Commenter 38 believes the EPA underestimates the number of events 

that would require a root cause analysis in the proposed rule. For instance, according to the 

commenter, a single PET production unit may have 150 PRDs, and at an estimated release rate of 

0.5%, there would be roughly 2 events to evaluate every three years for a single facility just for 

PRD releases. The commenter adds that a leaking PRD above the equipment leak threshold 

would add another leaking PRD per year to the total for a facility with 150 PRDs. Commenter 41 

states that it collected data on PRD releases from 40 chemical production sites that collectively 

had 14,139 PRDs in service. The commenter reported that 181 releases from these PRDs were 

identified, for a release rate of a little over 1 percent.

Response 4.2.6 The EPA recognizes that the number of events that would violate the 

prohibition of pressure releases to the atmosphere that could lead to an owner or operator to 

conduct a root cause analysis can vary. By definition, malfunctions are unplanned/unpredictable 

events. The commenter implies that 2 events per facility for three years is a reasonable number 

to anticipate. Affected sources can and do operate for three years without malfunctions serious 

enough to trigger an emergency release of HAP to the atmosphere. The EPA notes that the data 

collected by the commenter regarding the number of PRDs and PRD releases from chemical 

production sites was comprised of facilities throughout the entire chemical sector, and not just 

the source categories addressed in this rulemaking, which would overestimate the number of 

PRDs/PRD releases for the source categories subject to this action.

A pressure release is a release triggered by pressure that is greater than the maximum 

allowable working pressure of the PRD. The final rules prohibit pressure releases to the 

atmosphere from PRDs in organic HAP service, unless the PRD is routed to a control device, 

process, or drain system. However, different PRD provisions/standards are applicable to leaks 

which may occur after a PRD has a pressure release because the seal does not reseat properly. 

The leaks referenced by the commenter are covered under the standard for leak detection and 

repair (LDAR). Under the LDAR standards, to ensure that the PRD is properly reseated, these 

rules require LDAR monitoring within 5 days of a PRD release. For all three source categories, 

the existing requirements for PRDs already specify that the PRD must always be operated with 

no detectable emissions (i.e., 500 ppm above background).

Comment 4.2.7: Commenters 29, 31, and 44 suggest that the immediate notification 

requirements in the affirmative defense provisions be removed. The commenters added that if the 

notification requirement is kept, the EPA should allow electronic communication and 

recordkeeping. Commenters 29 and 30 state the immediate notification requirements are 

duplicative of requirements of SARA/CERCLA/EPCRA and many state regulations and will be 

burdensome for both facilities and agencies to review. Commenter 30 adds these requirements 

may report emissions not in exceedance of emission limits, it is not clear to whom the reports 

would be submitted, and they should be replaced with a semi-annual reporting requirement. In 

addition, Title V Operating Permit requirements include reporting of events in which emission 

limits have been exceeded in semi-annual deviation reports, and these reports can be used to 

supply information on the affirmative defense criteria. Commenter 44 requests that malfunction 
41

reporting be required on a semi-annual basis to avoid problems with being able to submit a report 

within 45 days and potential issues with requesting and receiving an extension of the reporting 

deadline in a timely manner. 

In contrast, commenter 51 states that the EPA must promulgate specific public reporting 

and notification requirements for malfunctions and any exceedance that occurs. While the EPA 

proposes to require malfunction reporting within 2 days by telephone and a written report within 

30 days if the facility intends to use an affirmative defense, the commenter states this reporting 

should be required regardless of whether a facility intends to use an affirmative defense, and the 

timing of the telephone call and report should actually be shorter. The commenter declares that 

the EPA must require the call within 24 hours and make a notice available publicly through the 

EPA’s website and through ECHO within 24 hours. The commenter also asserts that within 24 

hours of receiving this notification, the EPA should provide this information to the appropriate 

EPA Regional Office and direct the Regional Office to notify the local community of the event 

on the Internet, direct communication, and through all available means. The commenter states 

that the EPA should further require the facility to provide notification to the community through 

an appropriate public forum, such as the company website, press release to the local newspaper, 

radio and TV news station, within 24 hours. The commenter further declares the written report 

should be required within 7 days and distributed to the public using the same distribution method 

as the earlier notification and that this report should include the nature of the event, the duration 

of the event, and estimate of emissions released during the event, and a description and time of 

correction actions taken and planned to be taken.

Response 4.2.7 We agree with the first set of commenters regarding the timing of some of 

the reporting requirements and have revised the reporting requirement for asserting an 

affirmative defense in 40 CFR 63.1310(k) of subpart JJJ, 63.1360(k) of subpart MMM, and 

63.1420(i) of subpart PPP to remove the 2-day notification requirement. We have revised these 

sections in the final rules to allow an owner or operator of the affected source seeking to assert 

an affirmative defense after experiencing a violation of its emission limit(s) or a violation of an 

emission standard during a malfunction to submit a written report to the Administrator in the 

first periodic compliance, deviation report or excess emission report otherwise required after the 

initial occurrence of the violation of the relevant standard, unless such report is due less than 45 

days after the violation, in which case the affirmative defense report could be included in the 

next such required report. We do not agree with the latter commenter that the suggested 

notification and reporting requirements are necessary, as they would be duplicative of the 

immediate notification requirements of SARA/CERCLA/EPCRA, would be burdensome for both 

facilities and agencies to review, and would not enhance compliance beyond that of the existing 

requirements for reporting violations of emission limits.

An affirmative defense to civil penalties for violations of emission limits that are caused 

by malfunctions is available to a source owner or operator if he can demonstrate that certain 

criteria and requirements are satisfied. The criteria ensure that the affirmative defense is 

available only where the event that causes a violation of the emission limit meets the definition of 

malfunction in 40 CFR 63.2 (sudden, infrequent, not reasonably preventable and not caused by 

poor maintenance and or careless operation) and where the source owner or operator took all 

appropriate actions to minimize emissions. 

If a source is in compliance and does not encounter malfunctions that cause a violation 

of the standard, we do not expect this activity to be routinely performed by a source owner or 

operator. The decision to meet the reporting and recordkeeping requirements rests with the 
42

source owner or operator, who must weigh the cost of meeting the requirements against his 

perceived need to prepare an affirmative defense. 

Comment 4.2.8: Commenter 31 asserts that not allowing an affirmative defense in an 

action for injunctive relief is arbitrary and capricious. The commenter opines that the EPA 

should allow facilities to assert an affirmative defense for the exceedance of an emission limit 

during malfunctions if the EPA seeks to enforce that emission limit through injunctive relief and 

suggested eliminating that exclusion from the affirmative defense provisions. The commenter 

states that the type of legal action sought should have no bearing on the availability of this 

defense, as the definition of malfunction does not change with the type of legal action the EPA 

uses.

Commenter 44 states that it is not clear what civil penalties the affirmative defense 

covers. The commenter believes the affirmative defense should apply to civil penalties, civil 

administrative penalties, noncompliance penalties, enforcement actions by the EPA, states, or 

citizen-suit plaintiffs, and injunctive relief. 

Response 4.2.8: In response to the commenter that states that it is not clear what civil 

penalties the affirmative defense covers, the affirmative defense applies to civil penalties, 

including civil administrative penalties and penalties under section 120, but does not apply to 

injunctive relief or criminal penalties. The affirmative defense is available in any civil action to 

enforce the standards set forth in these rules, whether such action is brought by the EPA, a state 

or local authority or a citizen. The EPA does not intend to provide an affirmative defense to 

criminal charges as the very nature of criminal charges is that there is alleged to be a knowing 

violation (CAA Section 113(c)(1-3), or a knowing or negligence release that threatens imminent 

danger to persons (CAA Section 113(c)(4)and (5)). In these circumstances, it is likely that the 

source did not do all that could be done to prevent the excess emissions. However, if there are 

circumstances that justify a knowing release, such circumstances can be raised in any 

enforcement action and may be the basis for a defense.

In response to the comment that affirmative defense should be made available in an 

action for injunctive relief, in some cases injunctive relief may still be appropriate and necessary 

to remedy an existing violation and to bring a violating source into compliance. Therefore, we 

believe that it is not appropriate for our regulations to generally allow for an affirmative defense 

in cases of injunctive relief.

Comment 4.2.9: Commenter 44 believes the affirmative defense provisions should apply 

to the potential violation of emission limits during a startup or shutdown event as well as during 

malfunctions, if the EPA is to use such affirmative defense.

Response 4.2.9: The EPA is promulgating the affirmative defense for malfunctions only, 

not for periods of startup and shutdown. The EPA believes that malfunction events should be 

treated differently than periods of startup and shutdown, which are predictable and routine 

aspects of a source’s operations. Because startup and shutdown periods are part of a source’s 

normal operations, the same approach to compliance with, and enforcement of, applicable 

emission standards during those periods should apply as otherwise applies during a source’s 

operations. Further, periods of startup and shutdown -- but not malfunctions -- are taken into 

account when establishing section 112 emission standards. For these reasons, the EPA does not 

believe it is appropriate to apply the affirmative defense provisions to startup and shutdown 

periods.
43

Comment 4.2.10: Commenter 44 states that the EPA has not justified changing 

conditions that apply to performance testing. The commenter contends that where the proposed 

rule removed previously applicable references to the NESHAP General Provisions that required 

performance tests to be conducted based on normal operating conditions of the affected source 

and specified that “operations during periods of startup, shutdown, and malfunction shall not 

constitute representative conditions for the purpose of a performance test,” the proposal would 

allow the EPA to direct a source to conduct performance testing during abnormal operations, 

such as startups, shutdown, or malfunctions. The commenter states that the EPA cannot “amend” 

existing MACT standards in a way that can make the standards more stringent without first 

providing an adequate justification for departing from the EPA’s previous judgment about the 

appropriate conditions for performance testing.

Response 4.2.10: As noted by the commenter, we eliminated the SSM exemption as it 

applies to performance testing under 40 CFR 63.7(e)(1) and we specify that “[p]erformance 

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” 

(at 40 CFR 63.1333(a), 63.1365(b), and 63.1437(a)). One of the reasons for this is because the 

General Provisions selectively apply to part 63 standards and some part 63 standards establish 

alternative standards or compliance demonstration methods during startup and shutdown 

periods that may require performance testing during startup and shutdown periods. Sections 

63.1333(a), 63.1365(b), and 63.1437(a) specify the conditions that performance testing must be 

conducted for the PAI, PEPO and P&R IV MACT standards. The final requirements do not 

allow for performance tests to be conducted during periods of malfunction, and the conditions 

for conducting performance testing for the existing MACT standards have not changed, with one 

exception. The final 40 CFR part 63, subpart JJJ amendments allow facilities to comply with an 

alternative compliance determination option to meet mass emissions per mass product limits 

during startup and shutdown periods. In order to use this alternative compliance determination 

option, owners or operators would meet a mass emissions per mass product limit by either: (1) 

keeping records that establish the raw material feed rate and production rate were both zero; (2) 

meeting the limit by dividing the emission rate during startup or shutdown by the rate of polymer 

produced from the most recent performance test associated with a production rate greater than 

zero; or (3) keeping records that establish the operating parameters of the control device used to 

comply with the rule were maintained at the level established to meet the emission limit at 

maximum representative operating conditions. This alternative compliance determination option 

is not mandated.

Comment 4.2.11: Commenter 51 states that the past history of the SSM exemption and 

compliance problems for these source categories demonstrates a need for strong and more 

frequent monitoring, testing, and reporting requirements and enforcement provisions. The 

commenter declares that the EPA must implement enforcement provisions that prevent and 

remedy emission spikes, malfunctions, and other violations in a way that will be enforceable by 

citizens in the Title V permits for these source categories. The commenter further states that the 

EPA should review the proposed monitoring requirements and ensure they are stringent enough 

to enable easy assessment of whether a facility is in full compliance with the standards within a 

short period of time of any violation. 
44

Response 4.2.11: We believe that the removal of the SSM exemption will reduce 

compliance problems that may have been associated with the exemption and excess emission 

spikes, as facilities have an incentive to avoid the related violations and penalties, without the 

need to institute more frequent monitoring, testing, and reporting requirements. We further 

believe that the monitoring requirements included in these rules are sufficient to ensure 

compliance with the standards regardless of whether or when a violation occurs. Under the 

provisions of 40 CFR 63.15, the public can request access to reports submitted to the regulatory 

agency whenever they choose, with the exception of information protected through 40 CFR part 

2 (e.g., confidential business information). In addition, as discussed in section 5.0 below, we are 

promulgating requirements for electronic reporting of emissions test data that will improve 

public access to emissions information.

Comment 4.2.12: Commenter 51 states that additional requirements are needed for times 

of malfunctions, including requirements for automatic shut-off of malfunctioning equipment, 

requirements to assign responsibility to the plant manager or high-up staff member which allows 

only that person to restart the equipment, and requirements that corrective actions be taken 

immediately. The commenter also states that for a facility that has had one or more malfunction, 

exceedance or other violation in the prior month, the facility must obtain written authorization 

from the EPA to restart the equipment, and the EPA should only authorize the restart after 

making a public determination that the facility has instituted the corrective measures the EPA 

requires. The commenter further asserts that for a facility with 4 or more exceedances or 

malfunctions in the same quarter, the EPA must require automatic shutdown of the operation for 

a period of time to conduct and publish a full investigation and ensure correction of the 

problem(s). 

Response 4.2.12: We disagree with the commenter that the suggested additional 

requirements regarding malfunctions are necessary. The EPA believes that the monitoring 

requirements of the final rule are sufficient to ensure compliance with the emission standards, 

and that it is not necessary to prescribe when or who may restart equipment that has 

malfunctioned. With respect to the commenter’s suggested reporting requirements, the reporting 

requirements in the final rules already require malfunction reporting and the affirmative defense 

provisions require that parties choosing to assert the affirmative defense meet additional 

malfunction reporting requirements. Any such reports submitted to the EPA are publicly 

available subject to the requirements of CAA section 114(c).

5.0 Electronic Reporting Requirements

Comment 5.1: Commenter 41 comments that the proposal to require the use of the 

Electronic Reporting Tool (ERT) is not appropriate as the costs and burdens imposed cannot yet 

be determined. Also, the regulated community cannot fully comment on the cost of duplicating 

reports using the ERT for Method 18 and other methods not currently supported by the ERT. 

Response 5.1: The rule only requires that test methods supported by the ERT be reported 

using the ERT. The EPA believes that the costs and burdens of using the ERT are not significant 

for several reasons. The electronic reporting requirement does not add any additional testing 

and it does not change the timing of when test reports are due: the requirement only states that 

reports be submitted electronically. The ERT is fully functional and has been used successfully 

by industry for several years. It was designed to capture all of the information which is submitted 
45

in a typical test report and was also designed with input from States and the stack testing 

industry.

Comment 5.2: For test methods not supported by the ERT currently, such as Method 18, 

commenters 29 and 30 request that the EPA propose the addition of specific tests to the ERT and 

provide up to a 60 day comment period on the proposed addition and associated reporting forms 

and requirements. Commenters 38 and 41 note that without a formal notice that changes are 

being made to the ERT, facilities are at risk of noncompliance with the ERT requirements 

because they have no way to know which test methods must be submitted to ERT unless they 

actively monitor the EPA’s web site. This commenter also states that the EPA should wait to 

propose the use of the ERT tool for these NESHAP until the tool is capable of managing the 

reports typically generated by these industries. Commenter 41 recommends that the EPA remove 

the ERT requirement, or if the EPA insists on its inclusion, the ERT requirements should be 

limited to the methods which are incorporated in the ERT at the time of rule proposal. 

Response 5.2: The rule language is clear that only test methods supported by the ERT 

must be reported using the ERT. There is a list of ERT-supported methods on the EPA’s ERT 

website. In addition, the methods are listed in the ERT itself. There should be no confusion as to 

which methods are ERT-supported. If the facilities wish, the EPA recommends joining the 

CHIEF listserv, which one can do by emailing join-chief@lists.epa.gov, to be notified of 

enhancements made to the ERT.

Comment 5.3: Commenters 29, 38, and 41 note that requiring electronic reporting to the 

EPA does not increase the ease and efficiency of data submittal for the regulated community 

because state agencies also want the reports submitted to them in their own standard format. The 

commenters request that the EPA work with state and local agencies to provide a one-stop 

location for submittal of air emissions testing results. Commenter 38 states the EPA should wait 

to propose the use of the ERT tool for these NESHAP until coordination with state and local 

governments is achieved to avoid duplicative reporting. 

Response 5.3: The EPA worked with State and local agencies as well as stack testing 

companies (who typically prepare test reports) to develop the ERT. The ERT was designed to 

accept data and information that is typically collected during a performance test. Some State and 

local agencies have begun accepting the ERT as their reporting mechanism, and with 

experience, we believe acceptance by other States will increase. In some instances State and 

local agencies may still want a hard copy of a test report. The ERT can generate a printed test 

report or export the report to a word processor for reformatting. This report can be submitted to 

the State or local agency. The EPA believes that electronic reporting is a more efficient way to 

collect test data and has set up a retrieval system such that State agencies can access files that 

have been submitted using the ERT. As more State agencies adopt electronic reporting, we 

believe that the need for paper reports will be diminished.

Comment 5.4: Commenter 30 is concerned that confidential business information (CBI) 

would be made publicly available through electronic reporting of performance tests and suggests

electronic submission of this information be voluntary only.

Response 5.4: The commenter is incorrect that CBI would be made available through 

electronic reporting. Facilities can and should submit CBI according to the EPA’s CBI 

procedures (see 40 CFR 2.301), as they have always been able to do. As noted in the preamble to 
46

this final rule, owners or operators who claim that some of the information being submitted for 

performance tests is CBI must submit a complete ERT file including information claimed to be 

CBI on a compact disk, flash drive, or other commonly used electronic storage media to the 

EPA. The electronic media must be clearly marked as CBI and mailed to U.S. 

EPA/OAQPS/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 the 

EPA via Central Data Exchange (CDX).

Comment 5.5: Commenter 41 comments that under the proposed rule 40 CFR 

63.1439(e)(10), all performance test reports must be submitted to the ERT within 60 days, but 

because the rule does not reference the general provisions 40 CFR 63.10(d)(2), there is no 

allowance for obtaining additional time to complete this due to unforeseen circumstances or for 

the difficulties involved with completing particularly complex reports.

Response 5.5: The EPA does not expect that facilities will need additional time to report 

emissions testing information because of the electronic reporting requirement. The electronic 

reporting requirement does not add additional testing: rather it only requires that reports be 

submitted electronically using the ERT for ERT-supported test methods. The EPA realizes there 

will be a learning curve for first-time users of the ERT. The EPA has placed webinars and other 

training tools on the EPA’s ERT website to help ERT users. The ERT has been in use for over 5 

years now and the EPA has taken many steps to improve the tool and user-friendliness, and as a 

result, the number of inquiries we receive has decreased significantly. The rules either reference 

the General Provisions for reporting performance tests or contain their own requirements. As 

allowed in 40 CFR 63.10(d)(2), the reporting requirements in this rule are modifying the basic 

requirements specified in 40 CFR 63.10(d)(2) by specifying that the performance test data be 

submitted electronically.

Comment 5.6: Commenter 51 supports the EPA’s proposal to require electronic 

reporting. The commenter also states that the EPA should immediately disclose reports received 

through the ERT to the public on the internet within 7 days of receipt without requiring a 

Freedom of Information Act (FOIA) request.

Response 5.6: The EPA has established an electronic submittal and retrieval system such 

that non-CBI portions of test reports submitted via the CDX can be viewed by the public in the 

EPA’s Webfire database; a FOIA request is not necessary.

6.0 Pressure Relief Device Provisions

Readers are referred to section VI of the final rule preamble for this action for additional 

comments, and the EPA’s responses to those comments, on the proposed PRD provisions.

Comment 6.1: Commenters 29, 33, and 41 request three years to add alarms to their 

PRD mechanical release indicator system, which would allow for time to properly research, 

specify, budget, purchase, install and test the equipment. Commenters 29 and 41 request that 

while the proposal preamble indicates a three-year compliance period, this timeframe should be 

written into the proposed regulatory language. This commenter suggests specific compliance 

date information be inserted into 40 CFR 63.1311, 63.1364, and 63.1422.
47

In contrast, commenter 51 states that the EPA must require more expeditious compliance 

with the PRD monitoring requirements to assure facilities meet the requirements “as 

expeditiously as practicable,” as required by the CAA. The commenter states that it is unclear 

why sources need 3 years and could not meet the requirements within 6 months or less.

Response 6.1: We do not agree with the commenter who asserted that these activities 

could be completed for all subject sources within 6 months or less. The first step that facility 

owners and operators have to accomplish is to read and understand the final rule requirements 

as they apply to them and their facilities. Then, although there may be some facilities that may be 

able to comply with the PRD monitoring requirements within 6 months or less because they 

already have the necessary equipment in place to comply with the PRD monitoring requirements 

set out in the final rule, it is presumed that there will be numerous facilities that will need to 

research, purchase and test equipment to meet the PRD monitoring requirements. Once the 

necessary equipment is in place and tested, procedures will then need to be developed and 

personnel trained to ensure that procedures are properly implemented, for both safety and 

compliance purposes. To accomplish any of these necessary steps within six months would be 

optimistic. 

Additionally, as provided for in CAA section 112(i)(3)(A), it was our intent to allow 3 

years for facilities to comply with the new PRD compliance assurance requirements, and we 

have added provisions in 40 CFR 63.1311, 63.1364, and 63.1422 to explicitly state the dates for 

which compliance with these provisions will be required. We believe that this time is needed 

regardless of whether an owner or operator of a facility chooses to comply with the PRD 

compliance assurance provisions by installing PRD mechanical release indicator systems and 

alarms or by employing parameter monitoring. This time period will allow facilities to research 

equipment and vendors, install, test, and properly operate the equipment by the compliance date.

Comment 6.2: Commenter 29 states that the EPA should clarify that the term “any 

release to the atmosphere” from PRDs in 40 CFR 63.1331, 63.1363, and 63.1434 is referring to a

“pressure release” as defined in40 CFR 63.161 and 63.1361, rather than fugitive leaks that are 

covered under provisions for equipment leaks. Commenters 30, 38, 41, and 47 would also like 

the EPA to clarify that small “fugitive” releases will continue to be regulated under existing 

equipment leak detection and repair requirements. Commenter 38 notes it is also technically 

infeasible to comply with a ban on fugitive emissions from all PRDs. 

Response 6.2: The provisions of 40 CFR 63.1331, 63.1363, and 63.1434 have been 

amended to address specific technological concerns expressed by industry regarding the 

provisions proposed. However, as with the proposed provisions, the final provisions are intended 

to prohibit releases to the atmosphere from PRDs in organic HAP service, unless routed to a 

control device, process, or drain system. We have clarified in these sections that the releases 

discussed are “pressure releases” as defined in 40 CFR 63.1361 of subpart MMM, 40 CFR 

63.161 as referred to in 40 CFR 63.1312 of subpart JJJ, and we have added the definition for 

“pressure release” to subpart PPP in 40 CFR 63.1423. We have also consolidated all of the 

fugitive leak monitoring requirements for PRDs under 40 CFR 63.1331 of subpart JJJ, 63.1363 

of subpart MMM, and 63.1434 of subpart PPP. 

Comment 6.3: Commenter 29 states that the EPA should clarify that a pressure release 

from a PRD could be considered a malfunction rather than an automatic violation, and 

commenter 30 states that pressure release devices are designed to prevent equipment from 
48

exceeding maximum allowable working pressures during upset situations and releases from them 

should be considered malfunctions rather than violations. Commenter 41 states that PRDs 

prevent catastrophic breaches of process equipment, which would result in far higher emissions 

than those resulting from a release from a PRD. The commenter asserts that the EPA is 

essentially asking plant operators to choose to allow the release to occur resulting in a violation, 

or prevent the release thus creating the potential for a catastrophic breach. The commenter states 

that any standard prohibiting releases to the atmosphere from PRDs must include appropriate 

routes to demonstrate the legal status of the vent without a presumption of non-compliance. 

Commenter 29 points out that the proposal preamble states the affirmative defense would 

be available for pressure releases related to a process or control device malfunction, however, the 

rule language of 40 CFR 63.1331(a)(9), 63, 1363(b)(4) and 63.1434(c) states that such a release 

is a violation without further language regarding malfunctions.

Response 6.3: In this CAA section 112(d) NESHAP rulemaking, we have developed 

emission standards that are continuous and consistent with Sierra Club v. EPA. The final rules 

remove the SSM exemption and expressly prohibit pressure releases to the atmosphere from 

PRDs in organic HAP service, unless the PRD is routed to a control device, process, or drain 

system. We believe that PRD releases are caused by malfunctions, and in such occurrences the 

affirmative defense would be potentially available. While this is not explicitly stated in the text of 

40 CFR 63.1331(a)(9), 63.1363(b)(4) or 63.1434(c), the affirmative defense is potentially 

available for all violations caused by malfunctions, including PRD releases.

Comment 6.4: Commenter 29 states that the EPA should take into account existing 

programs that require reporting of PRD discharges and corrective action before establishing new 

PRD requirements. For instance, materials subject to CERCLA or SARA must have releases 

reported if over certain thresholds, some state agencies require reporting of upset emissions over 

a reportable quantity, and some states require excess emissions from PRDs to be reported as 

deviations from the Title V permit conditions. 

Response 6.4: While reporting PRD releases may be required under certain 

circumstances for certain facilities or in certain areas of the country, it is not uniformly required 

for all of the facilities subject to the P&R IV, PEPO, or PAI MACT standards. To ensure this 

information is reported by all of these facilities, we are amending the rules to require that this 

information be reported in the semi-annual periodic report.

Comment 6.5: Commenters 29, 30, 38, and 41 suggest certain types of PRDs should be 

excluded from PRD monitoring requirements because they have a low potential to emit large 

quantities of HAP. Commenter 29 notes that such PRDs include those that discharge materials 

into another process vessel, are in place for thermal expansion on liquid lines, are associated with 

tubing or tubing sized lines and sampling systems, and those associated with portable equipment, 

which would also be more difficult to provide an alarm back to the control room due to their 

movable nature. Commenter 41 adds to this list PRDs that are not in gas/vapor service, PRDs in 

systems with little potential for loss to the atmosphere (low vapor pressures), PRDs that are 

routed to a closed vent system and control device, and PRDs that are routed to a process. For 

PRDs with little potential for loss to the atmosphere, the commenter suggests that the EPA set a 

de minimis reporting value equal to the reportable quantity (RQ) values in EPCRA and/or 

CERCLA. 
49

Response 6.5: We do not agree with the commenters that PRDs that emit smaller 

amounts of HAP should be excluded from PRD monitoring and reporting requirements. 

However, we have amended the final rules to exempt PRDs from monitoring requirements if a 

PRD in organic HAP service is designed and operated to route all pressure releases through a 

closed vent system to a control device or process. Both the closed vent system and control device 

(if applicable) must meet specified requirements.

Comment 6.6: Commenters 29 and 47 state that the EPA should clarify in 40 CFR 

63.1331(a)(9)(iii), 63.1363(b)(4)(iii), and 63.1434(c)(3) that the trigger for reporting pressure 

releases are excess emissions and not malfunctions of pressure release indicators.

Response 6.6: We agree with the commenters and have added language to these sections 

to clarify that owners or operators are only required to report releases when a pressure release 

to the atmosphere from a PRD in organic HAP service occurs during the reporting period.

Comment 6.7: Commenter 46 is concerned that the EPA may propose similar PRD 

requirements for other MACT standards that would affect its member companies, many of whom 

are small businesses that typically produce high-value products in discrete batches. The 

commenter states that pressure relief events at these facilities are less likely and would not result 

in large quantities of HAP emissions. At such facilities, the PRD requirements fail from a costbenefit perspective, and would present a significant financial burden if the same cost estimates 

are used for other source categories as they were for the three source categories addressed in this 

proposal.

Response 6.7: The EPA notes that this action has revised the provisions proposed for 

PRDs for the PAI, PEPO, and P&R IV source categories in response to comments received from 

the affected industry. Nonetheless, we cannot speculate as to whether or not the proposed 

requirements or final requirements in this action are appropriate for the source categories cited 

by the commenter whose member companies would not be subject to this rule. The EPA will 

consider those issues if and when they arise in future rulemakings for other source categories.

Comment 6.8: Commenter 41 states that there is no indication that the EPA intended the 

PRD monitoring devices to measure other parameters that are required in the deviation report, 

such as quantity of HAP emitted and duration of discharge, and therefore must clarify that the 

information required to be submitted in the report can be estimated using available information.

Response 6.8: We did not intend to indicate that the same equipment used to monitor 

PRDs would be required to measure HAP emitted and/or the duration of the discharge. 

Facilities may use available information, engineering judgement, and/or calculations to estimate 

emissions but must report how the emissions estimate was derived.

Comment 6.9: Commenter 41 states it has collected PRD data from 40 chemical sector 

sites, and disputes the EPA’s claims that PRD releases may not be identified and controlled in a 

timely manner, and asserts that several monitoring methods are commonly used by companies to 

identify PRD releases. The commenter further claims that PRD releases to the atmosphere are 

extremely infrequent, which is inconsistent with the EPA’s claim that such releases are common, 

citing data from the South Coast Air Quality Management District (SCAQMD) in support of 

Proposed Amended Rule 1173. The commenter states that PRD releases are typically of short 

duration and it is in the best interest of a plant operator to detect PRD releases even without any 
50

requirement. The commenter states that emissions to the atmosphere from PRD releases are 

usually small, and the proposed requirements would not provide additional information related to 

the occurrence of higher emission releases and would not result in faster resolution of the 

situation.

In contrast, commenter 51 states that the EPA must finalize the prohibition on emissions 

from PRDs and states there is no valid justification for retaining any exemption from the 

standards.

Response 6.9: We agree with commenter 51 that pressure release emissions from PRDs 

should not be permitted to occur. Regardless of whether commenter 41 is correct that releases 

are infrequent, of short duration, and emission releases are of small quantities, PRD releases of 

HAP emissions do occur, are considered to be the result of malfunctions, and are prohibited. If 

any pressure release events that occur are related to a process or control device malfunction, the 

owner or operator could potentially claim the affirmative defense to civil penalties.

7.0 Source Category Specific Comments

7.1 Source Category Specific Comments – Group IV Polymers and Resins

Readers are referred to section VI of the final rule preamble for this action for additional 

comments, and the EPA’s responses to those comments, on the proposed regulation of 

previously-unregulated sources in the P&R IV MACT standards.

Comment 7.1.1: Commenter 33 notes that the EPA did not include the styrene 

acrylonitrile resin (SAN) resins manufacturing facility it operates in Louisville, Kentucky in the 

risk assessment for the P&R IV source category. However, in detailed modeling that has been 

conducted for the facility, the SAN resins manufacturing cancer risks are less than 1-in-1 million 

to the maximally exposed nearby resident and the non-carcinogenic risks are less than 0.01. The 

commenter believes this information confirms the low risks the EPA found for this source 

category.

Commenter 50 suggests that another facility, INEOS, which produces acrylonitrile 

butadiene styrene (ABS) in Addyston, Ohio, should potentially be included in the risk 

assessment for one or both of the ABS and SAN source categories.

Response 7.1.1: We have added these facilities to the risk assessments for the SAN source 

category (Zeon) and the ABS source category (INEOS ABS). The INEOS ABS facility does not 

appear to produce SAN resins and was not added to the risk assessment for that source category. 

The results of the revised risk assessment for the source categories can be found in the final 

Residual Risk Assessment for 7 Source Categories, available in the docket for this action (EPAHQ-OAR-2011-0435). We note that the risk estimates for these facilities did not change the 

maximum risk levels to the most exposed individual for the source categories and did not affect 

our determinations regarding risk acceptability and ample margin of safety.9

Comment 7.1.2: For Subparts JJJ and PPP, commenter 29 suggests adding the definition 

of PRD from the HON directly to these subparts to improve clarity. For Subpart PPP, the 

 

9

See U.S. EPA’s Residual Risk Assessment for 7 Source Categories in the docket for this rulemaking.
51

commenter also suggests that, for consistency, the term “relief valve” as used in Subpart PPP be 

changed to “pressure relief device.” Commenter 30 states that it is unclear what the EPA 

considers a “pressure relief device.” For example, it is unclear whether the safety devices on 

process vessels intended to release under high pressures or those intended to open and close due 

to working losses would be considered “pressure relief devices.” This commenter also suggests 

the EPA use the definition of pressure release device from the HON.

Response 7.1.2: We agree with the commenters that using the definition of PRD from the 

HON and adding that definition to these rules would enhance clarity, and we have revised the 

definitions in each subpart accordingly. We have also revised subpart PPP to refer to “pressure 

relief device” rather than “relief valve”.

Comment 7.1.3: For Subpart JJJ, commenter 29 pointed out that the proposed rule had 

incorrect citations in 40 CFR 63.1335 for records and reporting of malfunctions.

Response 7.1. 3: We agree with the commenter that there was a referencing error and 

have revised 40 CFR 63.1335 to correct these references.

Comment 7.1.4: Commenters 29 and 41 point out that a malfunction of emissions 

monitoring equipment could lead to an excursion because there would be an absence of 

monitoring data to demonstrate what the emissions were during that time. These commenters and 

commenter 48 suggest the EPA reinstate the proposed removal of provisions in subparts JJJ and 

PPP that allow one excused excursion per reporting period so one such loss of monitoring data 

will not itself result in a violation of the emission standard. 

Response 7.1.4: The EPA recognizes that monitoring system malfunctions do not 

necessarily result in emissions greater than allowed by the standard. The provisions of 40 CFR 

63.1326(e) of subpart JJJ and 63.1430(d) of subpart PPP allow that monitoring system 

breakdowns, repairs, calibration checks, and zero (low-level) and high level adjustments are not 

required to be included in the calculations to determine whether there has been sufficient 

monitoring data collected.

Comment 7.1.5: Commenter 50 supports the EPA’s conclusion that the residual risks 

associated with the ABS and SAN source categories are acceptable and that additional 

technological requirements are not necessary to reduce risks. The commenter notes that since the 

P&R IV NESHAP was implemented in 1996, the emissions of acrylonitrile have dropped by 

82% according to the TRI, which supports the conclusion that the emissions from these source 

categories are being managed well by the current NESHAP.

Response 7.1.5: We thank the commenter for this feedback.

Comment 7.1.6: One commenter (61) identified several incorrect or missing references 

in subpart JJJ that should be corrected or added, including: removing the reference to 40 CFR 

63.7(e)(1) in 40 CFR 63.1333(a)(1); removing the proposed reference to “monitoring system 

malfunction” in 40 CFR 63.1335(d)(7); removing the reference to 40 CFR 63.1335(b)(1)(i)(B) 

and 40 CFR 63.181(g)(2)(iii) in entry §63.8(c)(1)(ii) in Table 1; and revising the proposed 

references in 40 CFR 63.1335(b)(1)(i)(B) and (b)(1)(ii).

Response 7.1.6: The EPA has corrected the identified errors in the final rule.
52

7.2 Source Category Specific Comments – Pesticide Active Ingredient 

Production

Comment 7.2.1: Commenter 29 suggests the language of 40 CFR 63.1365(c)(2)(i)(D)(3) 

and the definition of “process condenser” be revised to clarify that the initial process condenser 

demonstration requirements apply only where a HAP is heated above its boiling point, only 

apply to HAP associated with batch process vents, and do not apply to HAP as an impurity. The 

commenter also requests that an option be provided to measure the liquid temperature in the 

receiver as an alternative to measuring the exhaust gas temperature. The commenter notes that 

similar amendments were made in 2008 to the condenser provisions in the MON.

Response 7.2.1: The EPA disagrees with the commenter that it is necessary to clarify 

when the initial demonstration requirement for process condensers applies, as we believe that 

the existing language is clear as to when it is necessary to conduct an initial demonstration. In 

addition, the proposed revisions to the MON cited the commenter have not been finalized, nor 

were they proposed in this action, and as such, we do not believe it to be appropriate to adopt 

them at this time. We also disagree that it is necessary to revise the definition of “process 

condenser” such that it only applies to condensers that recover material from batch process 

vents, as we believe that the existing definition is sufficient.

The EPA disagrees that an option should be provided for measuring the liquid 

temperature in the receiver as an alternative to measuring the exhaust gas temperature. The 

EPA’s concern about the alternative parameter proposed to monitor is that we are unsure 

whether the receiver liquid temperature would be as sensitive an indicator of the condenser 

performance as the exhaust gas temperature. For example, if the receiver liquid has a relatively 

high flow rate, its temperature may not fluctuate nearly as much as the exhaust gas temperature. 

If this were the case, it would be more difficult to use the receiver liquid temperature to identify 

periods when the condenser is not achieving a high enough removal efficiency to ensure 

compliance with the applicable HAP emission standard.

Comment 7.2.2: Commenter 29 requests a change to the Precompliance Plan 

requirements so that sources that had not previously submitted a Precompliance Plan could 

submit one when they plan to change their compliance approach due to process changes or new 

information after the compliance date.

Response 7.2.2: We agree with the commenter and in response to the comment we have 

revised the Precompliance Plan/Report requirements in each of the three MACT standards 

accordingly. Since a Precompliance Plan/Report is only required where certain compliance 

options are chosen or alternative compliance options are being requested, not all existing 

sources would have submitted a Precompliance Plan/Report prior to the compliance date and 

not all new sources would have submitted one with the application for construction or 

reconstruction. The revisions added in this action clarify that sources may submit a 

Precompliance Plan/Report to request alternative compliance options after the compliance date 

has passed or construction or preconstruction applications have already been submitted.

Comment 7.2.3: Commenter 29 requests an alternative monitoring option for packed 

scrubbers to allow measurement of the liquid-to-gas ratio in lieu of the scrubber liquid flow rate 

or pressure drop. The commenter states this is another good indicator of performance and allows 

for better control in operations. The commenter notes that the HON and 40 CFR part 63, subpart 

SS contain requirements that allow for the recording and reporting the scrubber liquid to gas 
53

ratio and the pH of the scrubber effluent to demonstrate compliance for scrubbers used with 

other control devices for halogenated streams.

Response 7.2.3: We agree with the commenter and in response to the comment we have 

revised the requirements for packed scrubbers accordingly. By allowing the measurement of the 

liquid-to-gas ratio in lieu of the liquid flow rate or pressure drop in the scrubber, facilities will 

be able to drop their liquid flow rate during periods of low vent flow, but still maintain adequate 

liquid flow to scrub the gas stream. As the commenter correctly points out, this will also make 

the requirements consistent with the HON and 40 CFR part 63, subpart SS.

Comment 7.2.4: Commenters 41 and 45 request that the EPA revise the definition of 

“Pesticide Active Ingredient” to reflect changes in references used in the definition since 

promulgation of the rule. The current definition refers to the EPA form 3540-16, the Pesticides 

Report for Pesticide-Producing establishments, which has changed since the 1999 version. The 

commenters suggest the rule be amended to reference the 1999 version of the EPA form 3540-

16, which would eliminate the need to modify the rule when the form is modified in the future.

Response 7.2.4: We agree with the commenter and in response to the comment we have 

revised the definition of “Pesticide Active Ingredient” to reference the 1999 version of EPA form 

3540-16. The revised definition clarifies that PAI materials are identified by product 

classification codes used to represent PAIs, and are the same codes used in block 19 of the 1999 

version of EPA Form 3540-16, the Pesticides Report for Pesticide-Producing Establishment.

Comment 7.2.5: Commenter 41 comments that when considering the total amount of 

operating hours and the 75% monitoring data requirement for a day, the owner/operator should 

be allowed to subtract the time during periods of monitoring system breakdowns, repairs, 

calibration checks, and zero (low-level) and high-level adjustments. These provisions should be 

added to 40 CFR 63.1366(b)(7) regarding excursions to make Subpart MMM consistent with 

Subpart JJJ.

Response 7.2.5: We disagree that facilities should be allowed to subtract the time periods 

referenced by the commenter for the 75% monitoring data requirement. The 25% missing data 

allowance is intended to already include such time periods

Comment 7.2.6: One commenter (61) identified several incorrect or missing references 

in subpart MMM that should be corrected or added, including: removing references to 40 CFR 

63.1366(b)(8)(iv) in 40 CFR 63.1366(b)(8), (b)(8)(i), (b)(8)(ii), and (b)(8)(iii); and revising 40 

CFR 63.1367(e) to reference subpart F instead of subpart G.

Response 7.2.6: The EPA has corrected the identified errors in the final rule.

7.3 Source Category Specific Comments – Polyether Polyols Production

Comment 7.3.1: Commenter 51 states that the EPA must set limits for vents at facilities 

where the total vent output of nonepoxide organic HAP is less than 11,800 kg/yr for the PEPO 

source category. The commenter states that the EPA lacks the authority to exempt any sources 

that emit HAP.

Response 7.3.1: We disagree that additional limits are required for nonepoxide organic 

HAP vents that emit less than 11,800 kg/yr. The 11,800 kg/yr applicability criteria level was 

included in the existing PEPO standard based on 40 CFR part 63, subpart U (Group I Polymers 
54

and Resins), which adopted the Batch Achievable Control Technology (ACT) control 

applicability criteria10 that apply to VOC emissions from batch process vents and represents a 

90 percent VOC control level. The methodology used to develop control options and levels in the 

Batch ACT utilizes the parameters of annual emissions and average flow rate to identify which 

streams are reasonable to control from a cost and technical feasibility standpoint. As with the 

HON and other MACT standards, the control applicability criteria set out in the Batch ACT were 

based on general vent stream characteristics, and not on process-specific parameters.11 Due to 

the similarities between the processes studied in the ACT (i.e., Synthetic Resins Manufacturing, 

Synthetic Organic Chemicals Manufacturing Industry), and the general nature of the 

applicability criteria, the EPA concluded that these criteria were appropriate to use in defining 

the MACT floor for nonepoxide organic HAP batch process vents. The 90 percent Batch ACT 

control level applicability criteria was selected because the estimated cost-effectiveness for this 

level was comparable to the cost-effectiveness for the HON continuous vent provisions 

(approximately $3,000 per Megagram) and was determined to represent the MACT floor for 

batch process vents. Under the final PEPO MACT standards, if the emissions are greater than 

11,800 kilograms per year (26,000 pounds per year), they are used to calculate a threshold flow 

rate. This threshold flow rate is then compared to the actual combined annual average flow rate 

for all the vents. If the actual combined annual average flow rate is less than the threshold flow 

rate, the group of vents is Group 1 and subject to Group 1 control requirements. If the annual 

emissions of TOC or nonepoxide organic HAP from the combination of process vents from batch 

unit operations that are associated with the use of nonepoxide organic HAP to make or modify a 

polyether polyol for a PMPU are less than 11,800 kg/yr, the owner or operator of that PMPU is 

not required to comply with the control requirement provisions but are subject to recordkeeping 

and reporting requirements. (64 FR 29420, June 1, 1999). Thus, in the PEPO MACT standards 

we did not “exempt” sources that emit HAP from standards, but instead structured the way our 

standards applied to the HAP sources depending upon the results of the floor analysis showing 

what kinds of control requirements should apply to which sources. 

Comment 7.3.2: One commenter (61) identified several incorrect or missing references 

in subpart PPP that should be corrected or added, including: removing the reference to 40 CFR 

63.6(i)(6)(i)(D) in 40 CFR 63.1422(d)(2) and (e)(1) and 63.1439(e)(4)(ii); revising the reference 

to paragraph (j)(2)(iv) to be paragraph (j)(2)(v) in 40 CFR 63.1427(k)(3)(ii); revising the 

reference to 40 CFR 63.1430(j) or (k) to be 40 CFR 63.1430(i) or (j) in 40 CFR 

63.1428(h)(2)(ii); revising the reference to Table 5 to be Table 7 in 40 CFR 63.1429(d)(1); 

revising the reference to 40 CFR 63.1430(d) to be 63.1438(a)-(d) in 40 CFR 63.1429(d)(1); 

removing the reference to 40 CFR 63.1439(e)(3)(ii)(A) in 40 CFR 63.1434(d); removing the 

reference to paragraph (g) in 40 CFR 63.1438(f)(4); removing the reference to 40 CFR 

63.9(b)(6) in 40 CFR 63.1439(e)(3); adding a reference to 40 CFR 63.113(i) in 40 CFR 

63.1439(e)(5)(vii) and (e)(6)(iii)(D)(3); revising the entries for §63.1(a)(7) and (8) and 

 

10 U.S. Environmental Protection Agency. “Control of Volatile Organic Compound Emissions From Batch 

Processes.” February 1994. (EPA-453/R-93-017)

11 U.S. Environmental Protection Agency. Hazardous Air Pollutant Emissions from Process Units in the Elastomer 

Manufacturing Industry – Supplementary Information Document for Proposed Standards. Memorandum from Phil

Norwood, EC/R to Leslie Evans, EPA. “MACT Floors and Regulatory Alternatives for the Elastomer Production 

Industry (Polymers and Resins I).” pgs. 7 and 10.
55

§63.1(c)(4) in Table 1 to be reserved; adding entries for §63.107 and §63.153 in Table 2; and 

revising the entry for §63.160-63.182 in Table 2 to reference 40 CFR 63.1434(b) through (h) 

instead of 40 CFR 63.1434(b) through (g).

Response 7.3.2: The EPA has corrected the identified errors in the final rule.

Comment 7.3.3: One commenter (61) identified several incorrect or missing references 

in subpart PPP that they believed should be corrected or added, including: adding several 

references to definitions in subparts A, F, G, and H in 40 CFR 63.1423; and adding entries for 

Tables 1, 2, and 3 of subpart F in Table 2.

Response 7.3.3: The EPA disagrees that the revisions suggested by the commenter are 

necessary.

8.0 Other Comments

Comment 8.1: Commenter 26 suggests that businesses choose to use good plastic resin, 

such as the polyolefin and waste rice plastics her business uses, which do not generate poisonous 

pollution. The commenter states that government support for biomass energy companies will 

help our environment. The commenter and commenter 28 also support the establishment of 

standards for previously unregulated P&R IV emission points.

Response 8.1: We acknowledge the commenter’s support for the additional standards for 

unregulated P&R IV emission points. The commenter’s other remarks are beyond the scope of 

this rule.

Comment 8.2: Commenter 34 asks that the EPA raise the national emission standards to 

be stricter and provide for cleaner air.

Response 8.2: We believe we have taken the appropriate actions to address the mandates 

of CAA section 112(d)(6) and (f)(2) for these source categories. 

Comment 8.3: Commenter 38 agrees with and incorporates the comments by ACC and 

CRWI by reference. Commenters 45 and 48 note that they fully support the comments provided 

by ACC. Commenter 49 also supports ACC’s comments, including those of ACC’s 

Formaldehyde Panel. Commenter 41 states that it adopts and incorporates the comments of the 

SSM Coalition by reference.

Response 8.3: We have addressed all of the comments from ACC, CRWI, and the SSM 

Coalition.

Comment 8.4: Commenter 46 is concerned about cumulative cost impacts of all the 

recent rules the EPA has been promulgating, particularly for small businesses. The commenter 

notes that the compliance costs are daunting when considering the PRD requirements, the 

reconsidered Chemical Manufacturing Area Source (CMAS) rule, the Boiler MACT and area 

source rules, the proposed heat exchangers standards, and the proposed uniform standards.

Response 8.4: We do not believe there will be a large cumulative cost impact for the 

facilities regulated by 40 CFR 63 subparts JJJ, MMM, or PPP. The revisions to the CMAS rule, 

the boiler MACT, the proposed heat exchanger standards and the proposed Uniform Standards 

do not apply to or impact the affected facilities subject to subparts JJJ, MMM, or PPP. In 

regards to the PRDs, we do not believe the revised requirements included in the final rules for 
56

PRD monitoring impose significant compliance costs. As explained in the preamble to the final 

rule, many facilities will only be required to perform additional recordkeeping and reporting 

with their semi-annual reports, while others will be adding work practices that incur minimal 

capital or annual costs. Additionally, in our economic impacts analysis for the proposed rule, we 

found that only two of the 42 parent companies with facilities in these three source categories 

would be classified as small businesses, and we found that the cost imposed on these companies 

is a small fraction of the companies’ revenues and should yield small economic impacts on these 

chemical producers. We have certified officially that there were no significant impacts to a 

substantial number of small businesses (or SISNOSE) for this rule. 

Comment 8.5: Commenter 51 states that the EPA is required to set standards that satisfy 

section 112(d) to control each pollutant at the maximum achievable level rather than re-applying 

the existing standards that are not pollutant specific. The commenter further states that if the 

EPA intends to use total organic HAP as a surrogate for each emitted pollutant, it must satisfy 

the 112(d) test to use a surrogate to do so. For the PEPO source category, it appears epoxide may 

also be a surrogate, which the EPA must rationally justify using or set pollutant-specific limits.

Response 8.5: Consistent with CAA section 112(d)(2) and (3),the EPA has set standards 

for all HAP emitted from the PEPO source category. Contrary to the commenters’ assertion, the 

EPA is not obligated to set a separate MACT standard naming each and every individual HAP 

emitted by PEPO sources. Rather, as the Court recognized in Mossville Envt’l Action Now v. 

Whitman, 370 F.3d 1232, 1242 (D.C. Cir. 2004) (quoting Nat’l Lime Ass’n v. EPA, 233 F.3d at 

637), the EPA has authority to use surrogates to regulate HAP “if it is reasonable to do so[.]” 

Nor are we required, in implementing sections 112(f)(2) and (d)(6), to revisit prior MACT 

determinations, including surrogacy determinations in those MACT determinations. We note, 

however, that epoxide is not used as a surrogate in the PEPO source category. The rule contains 

emission limits specific to epoxide HAP and non-epoxide HAP based on the HAP emitted and 

specific to each emission point.

Comment 8.6: Commenter 51 notes that it seems like an unusual coincidence for source 

categories to have “allowable” emissions approximately equal to “actual” emissions, as the EPA 

found, and this indicates the need for better monitoring and reporting to determine what the true 

levels of emissions are. 

Response 8.6: Where facilities are following the requirements of the standards, the 

actual emissions will be equal to the emissions allowable under the standards if they are not 

pursuing emission reductions that go beyond the level of the standards. This is common where 

work practices and equipment standards are required by the MACT standards. See the 

memorandum available in the docket, MACT Allowable Emissions and Risks for the Pesticide 

Active Ingredient, Polyether Polyols, and Polymers and Resins IV Production Source Categories

(Docket Item No. EPA-HQ-OAR-2011-0435-0007), for more information on the actual to 

MACT-allowable emissions analysis performed for these source categories.

Comment 8.7: Commenters 29 and 48 state that the EPA should clarify that the reporting 

requirements for excursions only apply to excursions that result in HAP emissions in excess of 

an applicable emission limit. The commenter also states that the EPA should only require 

quarterly reporting in subparts JJJ and PPP when an affected source has excursions during 

consecutive reporting periods. Quarterly reporting would place an unnecessary burden on an 
57

affected source when a single emission point has a single excursion and is redundant of the Title

V requirements to immediately report excess emissions that pose a significant hazard to the 

surrounding community and to report deviations semi-annually. The commenter suggests the 

following language:

§63.1335(e)(6)(xii)(A)(1):

The owner or operator of an affected source shall submit quarterly reports for a period of 

1 year for an emission point or process section if the emission point or process section 

meets the conditions of (e)(6)(xii)(A)(1) and (D) of this section for two consecutive 

reporting periods.

Response 8.7: We disagree with the commenter that only excursions resulting in HAP 

emissions above the applicable emission limits should be reported. Excursions can result from 

monitoring parameter levels being outside established ranges or from a lack of sufficient data to 

determine compliance with the emission limits. These excursions are considered violations of the 

standards and must be reported in the semi-annual report. However, we do agree that with the 

removal of the allowance for one excursion per semi-annual reporting period, this would result 

in facilities being required to perform quarterly reporting for the affected source if any point at 

that affected source experienced an excursion. This would be overly burdensome for both the 

facility and the reviewing agency and was not the intention of the original MACT standards. 

Accordingly, we have revised the language of subparts JJJ and PPP to require quarterly 

reporting only when there have been repeat excursions for the same equipment in consecutive 

semi-annual reporting periods. This requirement will ensure that enhanced reporting is carried 

out for only for equipment with potential compliance issues.

Comment 8.8: Commenter 51 states that the EPA should create a community complaint 

mechanism that ensures citizen complaints concerning air pollution receive an immediate 

response, in which the EPA commits to initiate an investigation and provide a publicly available 

report of the investigation results, including whether it leads to an enforcement action, within 7 

days.

Response 8.8: The EPA takes citizen pollution complaints seriously and is committed to 

responding to complaints. We invite you to help us protect our nation's environment by 

identifying and reporting environmental violations. The EPA's Report an Environmental 

Violation website provides a way for you to report suspected environmental violations.

(http://www.epa.gov/compliance/complaints/moreinfor.html) 

Assuring compliance with our nation's environmental laws is one of EPA's primary 

commitments. In carrying out this responsibility, we use many different approaches. One 

approach is to seek help from you by asking you to provide EPA with information about 

potentially harmful environmental activities in your communities and workplaces. Reports from 

the public have led to state and federal enforcement cases and ultimately served environmental 

protection well.