Page 1 of 225

The comments reflect interagency review of the draft rule under

EOs 12866 and 13563. They are subject to further policy review.

6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2010-1041, EPA-HQ-OAR-2010-1042; FRL-9303-4]

RIN 2060-AQ90

National Emissions Standards for Hazardous Air Pollutants: 

Mineral Wool Production and Wool Fiberglass Manufacturing

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: The EPA is proposing amendments to the national 

emissions standards for hazardous air pollutants for Mineral 

Wool Production and Wool Fiberglass Manufacturing to address the 

results of the residual risk and technology review that the EPA 

is required to conduct by the Clean Air Act. The proposed 

Mineral Wool Production amendments include emissions limits for

carbonyl sulfide, hydrogen fluoride and hydrochloric acid for

cupolas; add combined collection and curing processes as new 

regulated sources; and include emissions limits for 

formaldehyde, phenol and methanol for combined collection and 

curing operations. Modifications to the testing and monitoring 

and related notification, recordkeeping and reporting 

requirements are also proposed. 
Page 2 of 242

The proposed amendments for the Wool Fiberglass 

Manufacturing source category include emissions limits for

chromium compounds, hydrogen fluoride, hydrochloric acid and 

particulate matter for glass-melting furnaces at major sources; 

revised emissions limits for formaldehyde, and the addition of 

emissions limits for phenol and methanol for bonded product

lines at major sources; and modifications to testing and 

monitoring and related notification, recordkeeping and reporting 

requirements.

These proposed rules only apply to major sources, but we

plan to regulate wool fiberglass area sources in a future 

action.

We are also proposing to revise provisions addressing 

periods of startup, shutdown and malfunction to ensure that the 

rules are consistent with a recent court decision.

DATES: Comments must be received on or before [INSERT THE DATE 

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

Under the Paperwork Reduction Act, comments on the information 

collection provisions are best assured of having full effect if 

the Office of Management and Budget receives a copy of your 

comments on or before [INSERT THE DATE 30 DAYS AFTER THE DATE OF 

PUBLICATION IN THE FEDERAL REGISTER].

Public Hearing. If anyone contacts the EPA requesting to speak 

at a public hearing by [INSERT THE DATE 10 DAYS AFTER THE DATE 
Page 3 of 242

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

be held on [INSERT THE DATE 15 DAYS AFTER THE DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

ADDRESSES: Submit your comments, identified by Docket ID Numbers

EPA-HQ-OAR-2010-1041 and EPA-HQ-OAR-2010-1042, by one of the 

following methods:

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

for submitting comments.

 Email: a-and-r-docket@epa.gov, Attention Docket ID Number 

EPA-HQ-OAR-2010-1041 and EPA-HQ-OAR-2010-1042.

 Fax: (202) 566-9744, Attention Docket ID Number EPA-HQ-OAR2010-1041 or EPA-HQ-OAR-2010-1042.

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

Center, EPA West (Air Docket), Attention Docket ID Number 

EPA-HQ-OAR-2010-1041 or EPA-HQ-OAR-2010-1042, U.S. 

Environmental Protection Agency, Mailcode: 2822T, 1200 

Pennsylvania Ave., NW, Washington, DC 20460. Please include 

a total of two copies. In addition, please mail a copy of 

your comments on the information collection provisions to 

the Office of Information and Regulatory Affairs, Office of 

Management and Budget, Attn: Desk Officer for EPA, 725 17th

Street, NW, Washington, DC 20503. 
Page 4 of 242

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

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

Washington, DC 20004, Attention Docket ID Number EPA-HQOAR-2010-1041 or EPA-HQ-OAR-2010-1042. Such deliveries are 

only accepted during the Docket’s normal hours of 

operation, and special arrangements should be made for 

deliveries of boxed information.

Instructions. Direct your comments on the Mineral Wool RTR to 

Docket ID Number EPA-HQ-OAR-2010-1041 and direct your comments 

on the Wool Fiberglass RTR to Docket ID Number EPA-HQ-OAR-2010-

1042. The EPA’s policy is that all comments received will be 

included in the public docket without change and may be made 

available on-line at http://www.regulations.gov, including any 

personal information provided, unless the comment includes 

information claimed to be CBI or other information whose 

disclosure is restricted by statute. Do not submit information 

that you consider to be CBI or otherwise protected through 

http://www.regulations.gov or email. The 

http://www.regulations.gov website is an “anonymous access” 

system, which means the EPA will not know your identity or 

contact information unless you provide it in the body of your 

comment. If you send an email comment directly to the EPA 

without going through http://www.regulations.gov, your email

address will be automatically captured and included as part of 
Page 5 of 242

the comment that is placed in the public docket and made 

available on the Internet. If you submit an electronic comment, 

the EPA recommends that you include your name and other contact 

information in the body of your comment and with any disk or CDROM you submit. If the EPA cannot read your comment due to 

technical difficulties and cannot contact you for clarification, 

the EPA may not be able to consider your comment. Electronic 

files should avoid the use of special characters, any form of 

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

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

EPA Docket Center homepage at 

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

Docket. The EPA has established dockets for this rulemaking 

under Docket ID Number EPA-HQ-OAR-2010-1041 (Mineral Wool 

Production) and EPA-HQ-OAR-2010-1042 (Wool Fiberglass 

Manufacturing). All documents in the docket are listed in the 

http://www.regulations.gov index. Although listed in the index, 

some information is not publicly available, e.g., CBI or other 

information whose disclosure is restricted by statute. Certain 

other material, such as copyrighted material, is not placed on 

the Internet and will be publicly available only in hard copy.

Publicly available docket materials are available either 

electronically in http://www.regulations.gov or in hard copy at 

the EPA Docket Center, EPA West, Room 3334, 1301 Constitution 
Page 6 of 242

Ave., NW, Washington, DC. The Public Reading Room is open from 

8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 

holidays. The telephone number for the Public Reading Room is 

(202) 566-1744, and the telephone number for the EPA Docket 

Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: For questions about this 

proposed action, contact Ms. Susan Fairchild, Sector Policies 

and Programs Division (D243-04), Office of Air Quality Planning 

and Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, North Carolina 27711, telephone (919) 541-5167; 

fax number: (919) 541-3207; and email address: 

fairchild.susan@epa.gov. For specific information regarding the 

risk modeling methodology, contact Mr. Chris Sarsony, Health and 

Environmental Impacts Division (C539-02), Office of Air Quality 

Planning and Standards, U.S. Environmental Protection Agency, 

Research Triangle Park, North Carolina 27711; telephone number: 

(919) 541–4843; fax number: (919) 541–0840; and email address: 

sarsony.chris@epa.gov. For information about the applicability 

of the NESHAP to a particular entity, contact Scott Throwe, 

Office of Enforcement and Compliance Assurance; US EPA

Headquarters Ariel Rios Building; 1200 Pennsylvania Avenue, N. 

W.; Mail Code: 2227A; Washington, DC 20460; telephone number: 

(202) 564–7013; fax number: (202) 564–0050; email address:

throwe.scott@epa.gov.
Page 7 of 242

SUPPLEMENTARY INFORMATION:

Organization of this Document. The information in this 

preamble is organized as follows:

I. Preamble Acronyms and Abbreviations

II. General Information

A. Does this action apply to me?

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

information?

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

D. When will a public hearing occur?

III. Background Information

A. What are NESHAP?

B. What litigation is related to this proposed action?

IV. Mineral Wool and Wool Fiberglass Source Categories

A. Overview of the Mineral Wool Production Source Category and 

MACT Standards.

B. Overview of the Wool Fiberglass Manufacturing source category

and 1999 MACT rule.

C. What data collection activities were conducted to support 

this action?

V. Analyses Performed

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

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

this proposal?

C. How did we perform the technology review?

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

E. What analyses were performed for the Mineral Wool Production 

Source Category under the Regulatory Flexibility Act?

VI. Summary of Proposed Decisions and Actions

A. What are the proposed decisions and actions related to the 

Mineral Wool Production NESHAP?

B. What are the proposed decisions and actions related to the 

Wool Fiberglass Manufacturing NESHAP?

C. What are the proposed decisions and actions related to 

startup, shutdown and malfunction?

D. What are the proposed decisions and actions related to 

electronic reporting?

VII. Rationale for the Proposed Actions for the Mineral Wool 

Production Source Category

A. What data were used for the NESHAP analyses?
Page 8 of 242

B. What are the proposed decisions regarding surrogacy 

relationships?

C. What are the proposed decisions regarding certain unregulated 

emissions sources?

D. What are the proposed decisions regarding subcategorization?

E. What are the results from the risk assessments performed and 

the proposed decisions for the Mineral Wool Production Source 

Category?

F. What are our proposed decisions for the Mineral Wool 

Production source category based on risk acceptability and ample 

margin of safety?

G. What are the results from the technology review and proposed 

decisions?

VIII. Rationale for the Proposed Actions for the Wool Fiberglass 

Manufacturing Source Category

A. What data were used for the NESHAP analyses?

B. What are the proposed decisions regarding surrogacy 

relationships?

C. What are the proposed decisions regarding certain unregulated 

emissions sources?

D. What are the results from the risk assessments and analyses 

and the proposed decisions for the Wool Fiberglass Manufacturing 

Source Category?

E. What are our proposed decisions for the Wool Fiberglass 

Manufacturing source category based on risk acceptability and 

ample margin of safety?

F. What are the results from the technology review and proposed 

decisions?

IX. Summary of Cost, Environmental, and Economic Impacts for the 

Mineral Wool Source Category

A. What are the affected sources in the Mineral Wool Production 

source category?

B. How are the impacts for this proposal evaluated?

C. What are the air quality impacts for the Mineral Wool 

Production source category?

D. What are the water quality and solid waste impacts?

E. What are the secondary impacts?

F. What are the energy impacts?

G. What are the cost impacts for the Mineral Wool Production 

source category?

H. What are the economic impacts for the Mineral Wool Production 

source category?

I. What are the benefits for the Mineral Wool Production source 

category?

J. What demographic groups might benefit the most from this 

regulation?
Page 9 of 242

X. Summary of Cost, Environmental, and Economic Impacts for the 

Wool Fiberglass Manufacturing Source Category

A. What are the affected sources in the Wool Fiberglass 

Manufacturing source category?

B. How are the impacts for this proposal evaluated?

C. What are the air quality impacts?

D. What are the water quality and solid waste impacts?

E. What are the secondary impacts?

F. What are the energy impacts?

G. What are the cost impacts?

H. What are the economic impacts?

I. What are the benefits?

J. What demographic groups might benefit the most from this 

regulation?

XI. Request for Comments

XII. Submitting Data Corrections

XIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and 

Executive Order 13563: Improving Regulation and Regulatory 

Review

B. Paperwork Reduction Act.

C. Regulatory Flexibility Act.

D. Unfunded Mandates Reform Act.

E. Executive Order 13132: Federalism.

F. Executive Order 13175: Consultation and Coordination with 

Indian Tribal Governments.

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks.

H. Executive Order 13211: Actions Concerning Regulations That 

Significantly Affect Energy Supply, Distribution, or Use.

I. National Technology Transfer and Advancement Act.

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations.

I. Preamble Acronyms and Abbreviations

Several acronyms and terms used to describe industrial 

processes, data inventories, and risk modeling are included in 

this preamble. While this may not be an exhaustive list, to ease 
Page 10 of 242

the reading of this preamble and for reference purposes, the 

following terms and acronyms are defined here:

ACGIH American Conference of Governmental Industrial 

Hygienists

AEGL acute exposure guideline levels 

AERMOD air dispersion model used by the HEM-3 model

ATSDR Agency for Toxic Substances and Disease Registry

BACT best available control technology 

BLDS bag leak detection systems

BTF beyond the floor

CAA Clean Air Act

CalEPA California EPA

CA-REL California reference exposure level

CBI Confidential Business Information

CFR Code of Federal Regulations

CIIT Chemical Industry Institute of Toxicology

CO carbon monoxide

COS Carbonyl sulfide

EJ environmental justice

EPA Environmental Protection Agency

ERPG Emergency Response Planning Guidelines 

ERT Electronic Reporting Tool

ESP electrostatic precipitators

FA flame attenuation

GP General Provisions

GHG Greenhouse Gases

HAP hazardous air pollutants

HCl Hydrogen chloride

HEM Human Exposure Model

HEM-3 Human Exposure Model, Version 3

HF Hydrogen fluoride

HI Hazard Index

HQ Hazard Quotient

IRFA Initial Regulatory Flexibility Analysis

IRIS Integrated Risk Information System

kg/MG kilogram/megawatt

km kilometer
Page 11 of 242

LAER lowest achievable emissions rate

lb/ton pounds per ton

lb/yr pounds per year

MACT maximum achievable control technology

mg/L milligrams per liter

mg/m3 milligrams per cubic meter

MIR maximum individual risk

NAAQS National Ambient Air Quality Standard 

NAICS North American Industry Classification System

NaOH sodium hydroxide

NAS National Academy of Sciences

NATA National Air Toxics Assessment

NESHAP National Emissions Standards for Hazardous Air 

Pollutants

NIOSH National Institutes for Occupational Safety and 

Health

NRC National Research Council

NTTAA National Technology Transfer and Advancement Act

OAQPS Office of Air Quality Planning and Standards

OMB Office of Management and Budget

PB-HAP hazardous air pollutants known to be persistent and 

bio-accumulative in the environment 

PM particulate matter

RACT reasonably available control technology

RBLC RACT/BACT/LAER Clearinghouse 

RCRA Resource Conservation and Recovery Conservation

REL reference exposure level

RFA Regulatory Flexibility Act

RfC reference concentrations

RfD reference dose

RS rotary spin

RTO regenerative thermal oxidizers

RTR residual risk and technology review

SAB Science Advisory Board

SBA Small Business Administration

SBAR Small Business Advocacy Review

SCC Source Classification Codes

SER Small Entity Representatives

SO2 sulfur dioxide
Page 12 of 242

SSM startup, shutdown, and malfunction

TC Toxicity Characteristics

TCLP Toxicity Characteristic Leaching Procedure

TLV threshold limit value

TOSHI target organ-specific hazard index

tpy tons per year

TRIM Total Risk Integrated Modeling System

TTN Technology Transfer Network

UF uncertainty factors

μg/m3 microgram per cubic meter

UMRA Unfunded Mandates Reform Act

UPL upper predictive limit

URE unit risk estimate

WHO World Health Organization

WWW worldwide web

II. General Information

A. Does this action apply to me?

The regulated industrial source categories that are the 

subject of this proposed rule are listed in Table 1 of this 

preamble. Table 1 of this preamble is not intended to be 

exhaustive, but rather provides a guide for readers regarding 

the entities likely to be affected by this proposed action.

These standards, once finalized, will be directly applicable to 

affected sources. Federal, state, local, and tribal government 

entities are not affected by this proposed action.

In 1992 the EPA defined the Mineral Wool Production source 

category as any facility engaged in producing mineral wool fiber 

from slag or rock. Mineral wool is a material used mainly for 

thermal and acoustical insulation. This category includes, but 
Page 13 of 242

is not limited to, the following process units: a cupola furnace 

for melting the mineral charge; a blow chamber in which air and, 

in some cases, a binder is drawn over the fibers, forming them 

to a screen; a curing oven to bond the fibers; and a cooling 

compartment. 

In 1992 the EPA defined the Wool Fiberglass Manufacturing 

source category as any facility engaged in producing wool 

fiberglass from sand, feldspar, sodium sulfate, anhydrous borax, 

boric acid or any other materials. In the wool fiberglass 

manufacturing process, molten glass is formed into fibers that 

are bonded with an organic resin to create a wool-like material 

that is used as thermal or acoustical insulation. The category 

includes, but is not limited to the following processes: glassmelting furnace, marble forming, refining, fiber forming, binder

application, curing and cooling. 

Table 1. NESHAP and Industrial Source Categories Affected By 

This Proposed Action

Source Category NESHAP NAICS code1

Mineral Wool 

Production 

Mineral Wool 

Production

327993

Wool Fiberglass 

Manufacturing

Wool Fiberglass 

Manufacturing

327993

1 North American Industry Classification System

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

information?
Page 14 of 242

In addition to being available in the docket, an electronic 

copy of this proposal will also be available on the WWW through 

the EPA’s TTN. Following signature by the EPA Administrator, a 

copy of this proposed action will be posted on the TTN’s policy 

and guidance page for newly proposed or promulgated rules at the 

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

In addition, a copy of each rule showing specific changes 

proposed under this action is available in their respective 

dockets. The TTN provides information and technology exchange in 

various areas of air pollution control.

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

Submitting CBI. Do not submit information containing CBI to 

the EPA through http://www.regulations.gov or email. Clearly 

mark the part or all of the information that you claim to be 

CBI. For CBI information on a disk or CD ROM that you mail to 

the EPA, mark the outside of the disk or CD ROM as CBI and then 

identify electronically within the disk or CD ROM the specific 

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

version of the comment that includes information claimed as CBI, 

a copy of the comment that does not contain the information 

claimed as CBI must be submitted for inclusion in the public 

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

CBI, mark the outside of the disk or CD ROM clearly indicating 

that it does not contain CBI. Information not marked as CBI will 
Page 15 of 242

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

docket without prior notice. Information marked as CBI will not 

be disclosed except in accordance with procedures set forth in 

40 CFR part 2. Send or deliver information identified as CBI 

only to the following address: Roberto Morales, OAQPS Document 

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

Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, North Carolina 27711, Attention Docket ID Number 

EPA-HQ-OAR-2010-1041 (Mineral Wool RTR) or Attention Docket ID 

Number EPA-HQ-OAR-2010-1042 (Wool Fiberglass RTR).

D. When will a public hearing occur?

If a public hearing is held, it will begin at 10:00 a.m. on 

[INSERT DATE 15 DAYS AFTER THE DATE OF PUBLICATION IN THE 

FEDERAL REGISTER] and will be held at a location to be 

determined. Persons interested in presenting oral testimony or 

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

contact Ms. Pamela Garrett, Office of Air Quality Planning and 

Standards, Sector Policies and Programs Division, (D243-01), 

U.S. Environmental Protection Agency, Research Triangle Park, 

North Carolina 27711; telephone number: (919) 541–7996; email 

address: garrett.pamela@epa.gov.

III. Background Information

A. What are NESHAP?

1. What is the statutory authority for NESHAP? 
Page 16 of 242

Section 112 of the CAA establishes a two-stage regulatory 

process to address emissions of HAP from stationary sources. In 

the first stage, after the EPA has identified categories of 

sources emitting one or more of the HAP listed in CAA section 

112(b), CAA section 112(d) calls for us to promulgate NESHAP for 

those sources. “Major sources” are those that emit or have the 

potential to emit 10 tpy or more of a single HAP or 25 tpy or 

more of any combination of HAP. For major sources, these 

technology-based standards must reflect the maximum degree of 

emissions reductions of HAP achievable (after considering cost, 

energy requirements, and non-air quality health and 

environmental impacts) and are commonly referred to as MACT 

standards. Area sources are those that emit less than major 

amounts of HAP.

MACT standards must require the maximum degree of emissions 

reduction through the application of measures, processes, 

methods, systems, or techniques, including, but not limited to, 

measures that (A) reduce the volume of or eliminate pollutants 

through process changes, substitution of materials or other 

modifications; (B) enclose systems or processes to eliminate 

emissions; (C) capture or treat pollutants when released from a 

process, stack, storage or fugitive emissions point; (D) are 

design, equipment, work practice or operational standards 

(including requirements for operator training or certification); 
Page 17 of 242

or (E) are a combination of the above (CAA section 112(d)(2)(A)-

(E)). The MACT standards may take the form of design, equipment, 

work practice or operational standards where the EPA first 

determines either that, (A) a pollutant cannot be emitted 

through a conveyance designed and constructed to emit or capture 

the pollutants, or that any requirement for, or use of, such a 

conveyance would be inconsistent with law; or (B) the 

application of measurement methodology to a particular class of 

sources is not practicable due to technological and economic 

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

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

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

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

floor cannot be less stringent than the emissions control that 

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

The MACT floors for existing sources can be less stringent than 

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

the average emissions limitation achieved by the best-performing 

12 percent of existing sources in the category or subcategory 

(or the best-performing 5 sources for categories or 

subcategories with fewer than 30 sources). In developing MACT 

standards, we must also consider control options that are more 

stringent than the floor. We may establish standards more 

stringent than the floor based on considerations of the cost of 
Page 18 of 242

achieving the emissions reductions, any non-air quality health 

and environmental impacts, and energy requirements.

The EPA is then required to review these technology-based 

standards and revise them “as necessary (taking into account 

developments in practices, processes, and control technologies)” 

no less frequently than every 8 years, under CAA section 

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

completely recalculate the prior MACT determination, and, in 

particular, is not obligated to recalculate the MACT floors.

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

The second stage in standard-setting focuses on reducing 

any remaining “residual” risk according to CAA section 112(f).

This provision requires, first, that the EPA prepare a Report to 

Congress discussing (among other things) methods of calculating 

the risks posed (or potentially posed) by sources after 

implementation of the MACT standards, the public health 

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

legislation regarding such remaining risk. The EPA prepared and 

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

453/R–99–001) in March 1999. Congress did not act in response to 

the report, thereby triggering the EPA’s obligation under CAA 

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

Section 112(f)(2) of the CAA requires us to determine, for 

source categories subject to certain MACT standards, whether 
Page 19 of 242

those emissions standards provide an ample margin of safety to 

protect public health. If the MACT standards that apply to a 

source category emitting a HAP that is “classified as a known,

probable, or possible human carcinogen do not reduce lifetime 

excess cancer risks to the individual most exposed to emissions 

from a source in the category or subcategory to less than onein-one million,” the EPA must promulgate residual risk standards 

for the source category (or subcategory) as necessary to provide 

an ample margin of safety to protect public health (CAA section 

112(f)(2)(A)). This requirement is procedural. It mandates that 

the EPA establish CAA section 112(f) residual risk standards if 

certain risk thresholds are not satisfied, but does not 

determine the level of those standards (NRDC v. EPA, 529 F. 3d 

at 1083). The second sentence of CAA section 112(f)(2) sets out 

the substantive requirements for residual risk standards: 

protection of public health with an ample margin of safety based 

on the EPA’s interpretation of this standard in effect at the 

time of the CAA amendments. Id. This refers to the National 

Emissions Standards for Hazardous Air Pollutants: Benzene 

Emissions from Maleic Anhydride Plants, Ethylbenzene/Styrene 

Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and 

Coke By-Product Recovery Plants (Benzene NESHAP),(54 FR 38044, 

September 14, 1989), described in the next paragraph.
Page 20 of 242

The EPA may adopt residual risk standards equal to existing 

MACT standards if the EPA determines that the existing standards 

are sufficiently protective, even if (for example) excess cancer 

risks to a most exposed individual are not reduced to less than 

one-in-one million. Id. at 1083, (“If the EPA determines that 

the existing technology-based standards provide an ‘ample margin 

of safety,’ then the agency is free to readopt those standards 

during the residual risk rulemaking”). Section 112(f)(2) of the 

CAA further authorizes the EPA to adopt more stringent 

standards, if necessary “to prevent, taking into consideration 

costs, energy, safety, and other relevant factors, an adverse 

environmental effect.”1

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

two-step process for developing standards to address any 

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

developed in the Benzene NESHAP. The first step in this process 

is the determination of acceptable risk. This determination 

“considers all health information, including risk estimation 

uncertainty, and includes a presumptive limit on MRI [cancer]2 of 

 

1 “Adverse environmental effect” is defined in CAA section 

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

which may be reasonably anticipated to wildlife, aquatic life, 

or natural resources, including adverse impacts on populations 

of endangered or threatened species or significant degradation 

of environmental qualities over broad areas.

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

to cancer risk. MIR, one metric for assessing cancer risk, is 
Page 21 of 242

approximately 1-in-10 thousand [i.e., 100-in-1 million]” (54 FR 

38045). In the second step of the process, the EPA sets the 

standard at a level that provides an ample margin of safety “in 

consideration of all health information, including the number of 

persons at risk levels higher than approximately 1-in-1 million, 

as well as other relevant factors, including costs and economic 

impacts, technological feasibility, and other factors relevant 

to each particular decision” (Id.)

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

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

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

interpretation set out in the Benzene NESHAP, and the Court in 

NRDC v. EPA concluded that the EPA’s interpretation of CAA 

section 112(f)(2) is a reasonable one. See NRDC v. EPA, 529 F.3d 

at 1083 (D.C. Cir. 2008), which says “[S]ubsection 112(f)(2)(B) 

expressly incorporates the EPA’s interpretation of the CAA from 

the Benzene standard, complete with a citation to the Federal 

Register.” See also, A Legislative History of the Clean Air Act 

Amendments of 1990, volume 1, p. 877 (Senate debate on 

Conference Report). We also notified Congress in the Residual 

Risk Report to Congress that we intended to use the Benzene 

 

the estimated risk were an individual exposed to the maximum 

level of a pollutant for a lifetime.
Page 22 of 242

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

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

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

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

we strive to provide maximum feasible protection against risks 

to health from hazardous air pollutants by (1) protecting the 

greatest number of persons possible to an individual lifetime 

risk level no higher than approximately 1-in-1 million; and (2) 

limiting to no higher than approximately 1-in-10 thousand [i.e., 

100-in-1 million] the estimated risk that a person living near a 

facility would have if he or she were exposed to the maximum 

pollutant concentrations for 70 years. 

The agency also stated that, “The EPA also considers 

incidence (the number of persons estimated to suffer cancer or 

other serious health effects as a result of exposure to a 

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

exposed population. Incidence measures the extent of health 

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

estimate of the occurrence of cancer or other serious health 

effects in the exposed population.” The agency went on to 

conclude that “estimated incidence would be weighed along with 

other health risk information in judging acceptability.” As 

explained more fully in our Residual Risk Report to Congress, 

the EPA does not define “rigid line[s] of acceptability,” but 
Page 23 of 242

rather considers broad objectives to be weighed with a series of 

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

The determination of what represents an “acceptable” risk is 

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

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

quoting the D.C. Circuit’s en banc Vinyl Chloride decision at 

824 F.2d 1165) recognizing that our world is not risk-free.

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

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

individual is no higher than approximately 1-in-10 thousand, 

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

discussed the maximum individual lifetime cancer risk as being 

“the estimated risk that a person living near a plant would have 

if he or she were exposed to the maximum pollutant 

concentrations for 70 years.” Id. We explained that this measure 

of risk “is an estimate of the upper bound of risk based on 

conservative assumptions, such as continuous exposure for 24 

hours per day for 70 years.” Id. We acknowledge that maximum 

individual lifetime cancer risk “does not necessarily reflect 

the true risk, but displays a conservative risk level which is 

an upper-bound that is unlikely to be exceeded.” Id.

Understanding that there are both benefits and limitations 

to using maximum individual lifetime cancer risk as a metric for 

determining acceptability, we acknowledged in the 1989 Benzene 
Page 24 of 242

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

take into account the strengths and weaknesses of this measure 

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

in-1 million (1-in-10 thousand) provides a benchmark for judging

the acceptability of maximum individual lifetime cancer risk, 

but does not constitute a rigid line for making that 

determination.

The agency also explained in the 1989 Benzene NESHAP the 

following: “In establishing a presumption for MIR [maximum 

individual cancer risk], rather than a rigid line for 

acceptability, the agency intends to weigh it with a series of 

other health measures and factors. These include the overall 

incidence of cancer or other serious health effects within the 

exposed population, the numbers of persons exposed within each 

individual lifetime risk range and associated incidence within, 

typically, a 50- km exposure radius around facilities, the 

science policy assumptions and estimation uncertainties 

associated with the risk measures, weight of the scientific 

evidence for human health effects, other quantified or 

unquantified health effects, effects due to co-location of 

facilities, and co-emissions of pollutants.” Id.

In some cases, these health measures and factors taken 

together may provide a more realistic description of the 

magnitude of risk in the exposed population than that provided 
Page 25 of 242

by maximum individual lifetime cancer risk alone. As explained 

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

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

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

determining an ‘ample margin of safety,’ again includes 

consideration of all of the health factors, and whether to 

reduce the risks even further.” In the ample margin of safety 

decision process, the agency again considers all of the health 

risks and other health information considered in the first step.

Beyond that information, additional factors relating to the 

appropriate level of control will also be considered, including 

costs and economic impacts of controls, technological 

feasibility, uncertainties and any other relevant factors.

Considering all of these factors, the agency will establish the 

standard at a level that provides an ample margin of safety to 

protect the public health and prevent adverse environmental 

effects, taking into consideration costs, energy, safety, and 

other relevant factors, as required by CAA section 112(f) (54 FR 

38046).

2. How do we consider the risk results in making decisions?

In past residual risk determinations, the EPA presented a 

number of human health risk metrics associated with emissions 

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

of persons in various risk ranges; cancer incidence; the maximum 
Page 26 of 242

noncancer HI; and the maximum acute noncancer hazard. In 

estimating risks, the EPA considered source categories under 

review that are located near each other and that affect the same 

population. The EPA provided estimates of the expected 

difference in actual emissions from the source category under 

review and emissions allowed pursuant to the source category 

MACT standard. The EPA also discussed and considered risk 

estimation uncertainties. The EPA is providing this same type of 

information in support of these actions.

The agency acknowledges that the Benzene NESHAP provides 

flexibility regarding what factors the EPA might consider in 

making our determinations and how they might be weighed for each 

source category. In responding to comment on our policy under 

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

by the Administrator permits consideration of multiple measures 

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

also incidence, the presence of noncancer health effects, and 

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

on the most exposed individuals can be reviewed as well as the 

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

in each individual case. This approach complies with the Vinyl

Chloride mandate that the Administrator ascertain an acceptable 

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

assess available data. It also complies with the Congressional 
Page 27 of 242

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

particular measure of public health risk from the EPA's 

consideration with respect to CAA section 112 regulations, and, 

thereby, implicitly permits consideration of all measures of 

health risk which the Administrator, in [her] judgment, believes 

are appropriate to determining what will ‘protect the public 

health.’”

For example, the level of the MIR is only one factor to be 

weighed in determining acceptability of risks. The Benzene 

NESHAP explains “an MIR of approximately 1-in-10 thousand should 

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

risks increase above this benchmark, they become presumptively 

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

the other health risk measures and information in making an 

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

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

presumptively acceptable level is unacceptable in the light of 

other health risk factors.” Similarly, with regard to the ample 

margin of safety analysis, the Benzene NESHAP states that: “the 

EPA believes the relative weight of the many factors that can be 

considered in selecting an ample margin of safety can only be 

determined for each specific source category. This occurs mainly 

because technological and economic factors (along with the 
Page 28 of 242

health-related factors) vary from source category to source 

category.” 

B. What litigation is related to this proposed action?

In 2007, the D.C. Circuit (Court) found that the EPA had 

erred in establishing emissions standards for sources of HAP in 

the NESHAP for Brick and Structural Clay Products Manufacturing 

and Clay Ceramics Manufacturing, 67 FR 26,690 (May 16, 2003), 

and consequently vacated the rule.3 These errors included 

incorrectly calculated MACT emission limits, instances where EPA 

failed to set emission limits, and instances where EPA failed to 

regulate processes that emitted HAP. We are taking action to 

correct errors in both the Mineral Wool and Wool Fiberglass 

NESHAP for HAP that are not regulated. Some pollutants were 

represented in the 1999 MACT rules by surrogates; other 

pollutants were not regulated at all in the rule. In both these 

cases, we are establishing pollutant-specific emission limits. 

With the exception of PM as a surrogate for all HAP metals,

where surrogacy relationships exist, we are proposing to remove

that surrogacy. We are also correcting one unregulated HAPemitting process in the Mineral Wool NESHAP.

 

3 Sierra Club v. EPA, 479 F. 3d 875 (D.C. Cir. March 13, 2007).
Page 29 of 242

In two earlier court decisions4,5 the court found EPA had 

erred in not setting MACT standards for every HAP emitted from a 

source. Therefore, with the exception of PM as a surrogate for 

HAP metals,in this action we are proposing emission limits for 

all HAP emitted from Mineral Wool and Wool Fiberglass. We note 

that we have established through previous analyses upheld by the 

court6 that PM is an appropriate surrogate for HAP metals, 

therefore, we retain that surrogacy relationship in these 

proposed rules.

In separate litigation, the Court vacated portions of two 

provisions in EPA’s CAA section 112 regulations that govern 

emissions of HAP during periods of SSM.7 Specifically, the Court 

vacated the SSM exemption contained in 40 CFR §§ 63.6(f)(1) and 

63.6(h)(1) that are part of regulations commonly referred to as 

the GP rule. 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. Because both of the 

Mineral Wool and Wool Fiberglass NESHAP relied on the GP rule 

for startup and shutdown provisions (40 CFR §§ 63.1194 and 

 

4 Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855 (D.C. Cir. 

2001) (per curiam).

5 National Lime Ass’n v. EPA, 233 F.3d 625 (D.C. Cir. 2000).

6 Sierra Club v. EPA, 353 F. 3d 976 (D.C. Cir. 2004).

7 Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008), cert. 

denied, 130 S. Ct 1735 (2010).
Page 30 of 242

63.1386(c)), we are also proposing to revise these provisions 

for both of the Mineral Wool and Wool Fiberglass source 

categories.

Recent litigation8 led to a consent decree under which we 

must propose these amendments no later than October 31, 2011; 

and promulgate no later than June 29, 2012.

IV. Mineral Wool and Wool Fiberglass Source Categories

A. Overview of the Mineral Wool Production Source Category and 

MACT Standards.

The NESHAP (or MACT rule) for the Mineral Wool Production 

source category was promulgated on June 1, 1999 (64 FR 29490),

and codified at 40 CFR part 63, subpart DDD. As promulgated in 

1999, the NESHAP applies to affected sources of HAP emissions at 

mineral wool production facilities. As defined in the 1992 EPA 

report, “Documentation for Developing the Initial Source 

Category List” (EPA-450/3/91/030, July 1992), a “mineral wool 

facility” is “any facility engaged in producing mineral wool 

fiber from slag, rock or other materials, excluding sand or 

glass.”

The MACT rule for the Mineral Wool Production source 

category does not apply to facilities that manufacture wool 

fiberglass from sand, feldspar, sodium sulfate, anhydrous borax, 

 

8 Consent Decree, Sierra Club v. Jackson (No. 09-cv-00152SBA, 

N.D. Cal., Sept. 27, 2010).
Page 31 of 242

boric acid or other similar materials.

9 Although there are some 

similarities among rock that may be used for both mineral wool 

and wool fiberglass production, the two industries are distinct. 

Mineral wool is used in cases in which fireproofing, structural 

strength and sound attenuation are needed, such as in high 

occupancy commercial and industrial buildings. Wool fiberglass 

is used primarily for insulation, in residential and small 

commercial buildings. Some wool fiberglass facilities also 

operate a ceiling tile or pipe product manufacturing line. The 

manufacturing of ceiling tile is not regulated under the Wool 

Fiberglass Manufacturing MACT Standard.

Today, there are seven mineral wool facilities that are 

subject to the MACT rule. No new mineral wool facilities have 

been built in the last 21 years and the agency does not 

anticipate new mineral wool facilities will be built in the 

foreseeable future. According to the size definition applied to 

this industry by the U.S. SBA(750 company employees or less), 5 

of the 7 firms, employing 540 employees altogether, are

classified as a small business.

Mineral wool is a fibrous, glassy substance consisting of 

silicate fibers typically 4 to 7 micrometers in diameter, made 

 

9 Wool fiberglass produced from sand, feldspar, sodium sulfate, 

anhydrous borax, boric acid, etc. are a part of the wool 

fiberglass source category, which is also addressed in this 

action.
Page 32 of 242

from natural rock (such as basalt, granite and other rock), 

blast furnace slag, glass cullet, coke and other similar 

materials. Products made from mineral wool are widely used in 

thermal and acoustical insulation and other products where 

mineral wool fiber is added to impart structural strength or 

fire resistance. In the mineral wool manufacturing process, raw 

materials (e.g., rock and slag) are melted in a cupola using 

coke as fuel; the molten material is then formed into fiber. In 

the production of mineral wool products that do not require high 

rigidity, oil is typically applied to suppress dust and add some 

strength to the fiber; the fiber is then sized and bagged or 

baled. This is known as a “nonbonded” product which is 

manufactured on a “nonbonded” production line.

For mineral wool products requiring a higher structural 

rigidity, typically a phenol/formaldehyde binder may be applied 

to the fiber. The binder-laden fiber mat is then thermoset in a 

curing oven and cooled. This is known as a “bonded” product 

which is made on a “bonded product” line. The major differences 

between the “nonbonded” and “bonded” production lines are the 

application of binder during fiber collection and the use of a

curing oven. Four facilities only manufacture nonbonded 

products, while the other three facilities operate both bonded 

and nonbonded production lines. A total of 11 cupolas and 3
Page 33 of 242

curing ovens are operated by the facilities in this source 

category.

HAP emission sources at mineral wool production facilities 

include the cupola where the mineral charge is melted; a 

collection chamber, in which air and a binder are drawn over the 

fibers, forming them into a mat against a screen; and a curing

oven that bonds the fibers (for bonded products). HAP are 

emitted from the cupolas, curing ovens and collection operations 

when collection occurs with curing. Collection at nonbonded 

product lines does not emit HAP. COS accounts for the majority 

of the HAP emissions from these facilities (approximately 224

tpy and 51 percent of the total HAP emissions by mass). The 

majority of HAP emissions (approximately 58 percent of the total

HAP by mass, including HF and HCl are from the cupolas. The 

remainder of the HAP are from bonded lines, including phenol, 

formaldehyde, and methanol. Although the majority of HAP are 

emitted from the cupola, the emissions (primarily formaldehyde

and phenol) that were significant in evaluating risk are from 

the collection chambers on the bonded lines. Formaldehyde and 

phenol are emitted only from bonded mineral wool production 

lines; these lines include emissions from the application of the 

binder during collection and curing.

The current NESHAP requires control of PM emissions, as a 

surrogate for HAP metals, from the cupolas and formaldehyde 
Page 34 of 242

emissions from the curing ovens. Fabric filters are the control 

devices used by this industry to reduce both PM and HAP metal 

emissions from cupolas. Emissions from collection operations are 

not regulated under the current NESHAP, but collection and 

curing ovens are generally controlled using RTOs and fabric 

filters.

The existing MACT rule applies to each existing, new and 

reconstructed cupola or curing oven in a mineral wool production 

facility. All mineral wool production facilities that are major 

sources are subject to the standards. For all cupolas, the 1999 

MACT rule specifies a numerical emission limit for PM, as a 

surrogate for metal HAP. For new and reconstructed cupolas, 

emissions limits are specified for CO, as a surrogate for COS.

Emissions limits for formaldehyde are also specified (as a 

surrogate for phenol emissions) for each existing, new, and 

reconstructed curing oven. Under the 1999 MACT rule, a mineral 

wool production facility may elect to comply with a numerical 

formaldehyde or CO emission limit expressed in mass of emissions 

per unit of production (kg/MG of melt or lb/ton of melt) or a 

percent reduction standard. PM emissions from existing, new, and 

reconstructed cupolas are limited to an outlet concentration of 

0.05 kg/Mg (0.10 lb/ton) of melt, 40 CFR 63.1178(a). CO 

emissions limits from new and reconstructed cupolas are limited 

to an outlet concentration of 0.05 kg/Mg (0.10 lb/ton) of melt 
Page 35 of 242

or 99 percent CO removal, 40 CFR 63.1178(a). Formaldehyde 

emissions limits from existing, new, and reconstructed curing 

ovens are limited to an outlet concentration of 0.03 kg/Mg (0.06 

lb/ton) of melt or 80 percent formaldehyde removal, 40 CFR 

63.1179(a).

B. Overview of the Wool Fiberglass Manufacturing source category 

and 1999 MACT rule.

The NESHAP (or MACT rule) for the Wool Fiberglass 

Manufacturing source category was promulgated on June 14, 1999 

(62 FR 31695), and codified at 40 CFR part 63, subpart NNN. As 

promulgated in 1999, the MACT rule applies to affected sources 

of HAP emissions at wool fiberglass manufacturing facilities.

Although the source category definition includes all 

manufacturers of wool fiberglass, the 1999 MACT rule (40 CFR 

63.1381) defines a “wool fiberglass manufacturing facility” as 

“any facility manufacturing wool fiberglass on a RS

manufacturing line producing bonded building insulation or on a 

FA manufacturing line producing bonded pipe insulation and 

bonded heavy-density products.” The MACT rule for the Wool 

Fiberglass Manufacturing source category does not apply to

facilities that manufacture mineral wool from rock, slag, and 

other similar materials. In addition, RS and FA manufacturing 

lines that produce nonbonded products (in which no phenol-
Page 36 of 242

formaldehyde binder is applied) are not subject to the current 

standards.

Wool fiberglass products are primarily used as thermal and 

acoustical insulation for buildings, automobiles, aircraft, 

appliances, ductwork and pipes. Other uses include liquid and 

air filtration. Approximately 90 percent of the wool fiberglass 

currently produced is used for residential and commercial 

building insulation products. Today, wool fiberglass is 

currently manufactured in the United States by 5 companies 

operating 29 facilities across 16 states. According to the size 

definition applied to this industry by the U.S. SBA (750 company 

employees or less), none of these companies are classified as a 

small business. One new wool fiberglass facility was recently 

built in 2007 and one wool fiberglass facility closed in 2010.

Because several furnaces have been idled across the industry, 

current production of wool fiberglass is below production levels 

from previous years, and several months of stockpiled products 

exist at wool fiberglass companies, we do not expect new wool 

fiberglass facilities to be built in the near future.

Wool fiberglass is manufactured in a process that forms 

thin fibers from molten glass. Over 90 percent of the wool 

fiberglass industry produces insulation; two plants also operate 

a pipe product line and one plant operates a ceiling tile line

(although the production of ceiling tile is not part of this 
Page 37 of 242

MACT standard). A typical wool fiberglass manufacturing line 

consists of the following processes: (1) heating of raw 

materials and/or cullet in a furnace to a molten state, (2)

preparation of molten glass for fiberization, (3) formation of 

fibers into a wool fiberglass mat or pipe insulation product, 

(4) curing the binder-coated fiberglass mat, (5) cooling the mat 

(this process is not always present) and (6) backing, cutting, 

and packaging.

The primary component of most types of wool fiberglass is 

silica sand, but wool fiberglass also includes varying 

quantities of feldspar, sodium sulfate, anhydrous borax, boric

acid, and may be made entirely of glass cullet, crushed recycled 

glass. Wool fiberglass manufacturing plants typically operate

one or more manufacturing lines. Refined raw materials for the 

glass batch are weighed, mixed, and conveyed to the glassmelting furnace, which may be gas-fired, electric, oxygenenriched or a combination of gas and electric. 

Two methods of forming fibers are used by the industry, RS 

and FA. In the RS process, centrifugal force causes molten glass 

to flow through small holes in the wall of a rapidly rotating 

cylinder. In the FA process, molten glass flows by gravity from 

a small furnace, or pot, to form threads that are then

attenuated (stretched to the point of breaking) with air and/or 

flame.
Page 38 of 242

After the fibers are formed, they are sprayed with a binder 

to hold the fibers together. These bonded fibers are then 

collected as a mat on a conveyor. Binder compositions vary with 

product type. At the time of development of the MACT standard, 

wool fiberglass mat was typically made using a phenolformaldehyde resin based binder. According to the trade 

organization, only a few insulation products are currently made 

using a formaldehyde-based binder because new formaldehyde- and

HAP-free binder formulations have been developed in recent 

years.

10 Most new binder formulations are now HAP-free. According 

to the information collected through a survey by the industry, a

few pipe insulation products made from wool fiberglass are still 

made at two facilities using a phenol-formaldehyde based binder.

After application of the binder and formation of the mat, 

the conveyor carries the newly formed mat through an oven to

cure the thermosetting resin and then through a cooling section. 

Some products, such as those made on FA manufacturing lines, do 

not require curing and/or cooling.

Process emissions sources include the furnace where the 

charge is melted; the collection process, in which air carrying 

a binder is drawn over the fibers, forming them into a mat; and 

 

10 Letter from the North American Insulation Manufacturers 

Association (NAIMA). June 8, 2011 Letter.
Page 39 of 242

the curing oven that bonds the fibers (for bonded products

only).

HAP, including chromium compounds, are emitted from glassmelting furnaces. Glass-melting furnaces are constructed using 

refractory bricks or blocks (commonly called refractories), that 

provide thermal insulation and corrosion protection. The 

refractory bricks re-direct the heat of the furnace back into 

the melt. Refractories are produced to withstand the extreme 

corrosive thermal conditions of a furnace and may contain a 

variety of mineral materials, including chromium, and more 

specifically chromic oxide.

13

In a wool fiberglass glass-melting furnace, sufficient 

temperatures are reached to drive the transformation of chromium 

from the trivalent to the hexavalent valence state. Because of 

the corrosive properties of the molten glass and the fining 

agents (salts added to the top of the molten glass layer which 

act to draw the gas bubbles out of the molten glass), the 

refractory of the inner furnace walls are eroded and fresh 

refractory is continually exposed along the metal/glass line 

within the furnace. As a result, when the glass-melting furnace 

is constructed using refractories containing high percentages of 

chromium, the emission levels of chromium compounds continuously 

 

13 Chromium in Refractories. Sept. 2000. Dr. Mariano Velez, 

Ceramic Engineering Dept., Univ. Missouri-Rolla.
Page 40 of 242

increase over the life of the furnace according to the 

increasingly exposed refractory surface area.

16,17,18

In addition, organic HAP (formaldehyde, phenol, and 

methanol) may be released from RS forming and curing processes

and FA forming and curing processes.

The 1999 MACT rule applies to process emissions from each 

of the following existing, newly constructed, and reconstructed 

sources: glass-melting furnaces located at a wool fiberglass 

manufacturing plant, RS manufacturing lines that produce 

building insulation, and FA manufacturing lines producing pipe 

insulation. The MACT rule also applies to FA manufacturing lines 

producing heavy-density products. 

The 1999 MACT rule requires control of PM emissions from 

the glass-melting furnaces and formaldehyde emissions from the 

RS and FA lines. Typical control devices to reduce PM and HAP 

emissions from furnaces include both wet and dry ESP and fabric 

filters. Low and high-temperature thermal oxidizers are used to 

control phenol, formaldehyde, and methanol from curing 

operations on bonded lines.

 

16 Notes of April 14, 2011 telephone discussion between Carlos 

Davis, Environmental Manager, Certainteed, Kansas City, KS; 

and Susan Fairchild, project lead, USEPA/OAQPS/SPPD.

17 Region 7 Certainteed, Kansas City, KS; meeting and site visit 

notes.

18 Emissions Test Results from Certainteed, Kansas City, KS. 2005 

and 2008.
Page 41 of 242

The 1999 MACT rule limits PM emissions to an outlet 

concentration of 0.50 lb of PM per ton of glass pulled for both 

existing and new furnaces, 40 CFR 63.1382. Emissions of 

formaldehyde from RS manufacturing lines are limited to an 

outlet concentration of 1.2 lb/ton of glass pulled for existing 

sources and 0.80 lb/ton of glass pulled for new sources. 

Emissions of formaldehyde from FA manufacturing lines producing 

pipe insulation are limited to an outlet concentration of 6.8 

lb/ton of glass pulled from both existing and new sources, 40 

CFR 63.1382. Emissions of formaldehyde from FA manufacturing 

lines producing heavy-density products are limited to an outlet 

concentration of 7.8 lb/ton of glass pulled for new sources; no 

emission limit is specified for existing FA manufacturing lines 

producing heavy-density products, 40 CFR 63.1382. A surrogate 

approach, where PM serves as a surrogate for HAP metals and

formaldehyde serves as a surrogate for organic HAP, was used in 

the 1999 MACT rule to allow for easier and less expensive 

testing and monitoring requirements.

The industry trade association has advised us that because 

the wool fiberglass industry has voluntarily phased out most 

uses of phenol-formaldehyde based binders, there may now be only 

two wool fiberglass facilities that are subject to the current 

MACT rule. If this is accurate, 27 of the 29 facilities 

manufacturing wool fiberglass may not be considered major 
Page 42 of 242

sources due to the phaseout of phenol-formaldehyde based 

binders. We are soliciting comment on our understanding that 

there will be no major sources in the wool fiberglass insulation 

source category (other than pipe insulation products)by the end 

of the 2012 calendar year.

C. What data collection activities were conducted to support 

this action?

In June 2010, the industry conducted a voluntary survey

among all companies that own and operate mineral wool production

and wool fiberglass manufacturing facilities. The survey sought

test data for PM, CO and HAP emissions and information on the

process equipment, control devices, point and fugitive 

emissions, practices used to control point and fugitive 

emissions, and other aspects of facility operations. Facilities 

were asked to seek and obtain prior EPA approval where new test 

data for a subset of processes, control devices and operations 

would be submitted as representative of an untested subset of 

processes, control devices and operations. In addition,

facilities were allowed, in lieu of conducting new testing and 

with prior EPA approval, to submit existing and well-documented 

test data that were representative of current operations using 

the recommended test methods in the industry survey.

Furthermore, the EPA requested, and industry agreed, that a 

subset of the facilities that were thought to be representative 
Page 43 of 242

of emission sources from both the mineral wool and wool 

fiberglass industries would conduct additional emissions testing

for certain HAP from specific processes. The bases for 

representativeness included design type and size of process 

units or equipment; fuel type; operating temperatures; control 

devices; and raw material content. Facilities completed and 

submitted responses to the industry survey in the spring of 

2011. 

In summary, the EPA received existing emissions test data 

from all 7 mineral wool facilities and 26 of the 29 wool 

fiberglass facilities, with some facilities submitting data for 

multiple years. Mineral wool facilities provided existing test 

data on cupolas, curing ovens, and collection operations. Wool 

fiberglass facilities provided existing test data on one or more 

of the following emission sources: glass-melting furnaces, 

curing ovens, forming, and collection operations. Emissions test 

data provided by facilities in both source categories, including 

the emission unit and pollutant tested, varied widely by 

facility. 

The mineral wool industry included testing for most HAP 

metals, CO, PM and certain organic HAP (formaldehyde, phenol, 

methanol and COS). Pollutants tested for by the wool fiberglass 

manufacturing source category included most HAP metals, 

including chromium and hexavalent chromium, PM, formaldehyde, 
Page 44 of 242

phenol and methanol. The EPA completed the dataset by assigning 

emission estimates from tested processes and their known 

production rates to the similar represented processes based on 

production rates at the untested processes. A copy of the 

dataset can be found in the docket to this proposed rule.

The results of these emission tests were compiled into a 

database for each source category, which is available in the 

docket for this action.

V. Analyses Performed

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

The EPA conducted a risk assessment that provided estimates 

of (1) the MIR posed by the HAP emissions from the 7 mineral 

wool facilities and 29 wool fiberglass manufacturing facilities 

in the source categories, (2) the distribution of cancer risks 

within the exposed populations, (3) the total cancer incidence, 

(4) estimates of the maximum TOSHI for chronic exposures to HAP 

with the potential to cause chronic non-cancer health effects, 

(5) worst-case screening estimates of HQ for acute exposures to 

HAP with the potential to cause non-cancer health effects, and 

(6) an evaluation of the potential for adverse environmental 

effects. In June of 2009, the EPA’s SAB conducted a formal peer 

review of the risk assessment methodologies used in its review 

of the document entitled, “Risk and Technology Review Assessment 
Page 45 of 242

Methodologies.”

19 We received the final SAB report on this review 

in May of 2010.

20 Where appropriate, we have responded to the key 

messages from this review in developing the current risk 

assessment; we will be continuing our efforts to improve our 

assessments by incorporating updates based on the SAB 

recommendations as they are developed and become available. The 

risk assessment consisted of seven primary steps, as discussed 

below. The docket for this rulemaking contains the following 

document, which provides more information on the risk assessment 

inputs and models: Draft Residual Risk Assessment for the 

Mineral Wool Production and Wool Fiberglass Manufacturing Source 

Categories.

1. Establishing the Nature and Magnitude of Actual 

Emissions and Identifying the Emissions Release Characteristics.

For each facility in the Mineral Wool Production and Wool 

Fiberglass Manufacturing source categories, we developed and 

compiled an emissions profile (including emissions estimates, 

stack parameters, and location data) based on the information 

provided by the industry survey, the emissions test data, and 

 

19 US EPA, 2009. Risk and Technology Review (RTR) Risk Assessment 

Methodologies: For Review by the EPA’s Science Advisory Board 

with Case Studies – MACT I Petroleum Refining Sources and 

Portland Cement Manufacturing. EPA-452/R-09-006. Available at: 

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

20 US EPA, 2010. SAB’s Response to EPA’s RTR Risk Assessment 

Methodologies. Available at:

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A852

5771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
Page 46 of 242

various calculations. We used the production rates of tested 

processes to assign emissions to untested but similar processes 

based on known production rates at the untested processes. The 

site-specific emissions profiles include annual estimates of 

process emissions for the 2010 timeframe, as well as emissions 

release characteristics such as emissions release height, 

temperature, velocity, and location coordinates. We are 

requesting comment on the assumptions used to complete the 

dataset, including assumptions we made to assign emission rates. 

The primary risk assessment is based on estimates of the 

actual emissions (though we also analyzed allowable emissions 

and the potential risks due to allowable emissions). We received 

a substantial amount of emissions test data and other 

information from the industry survey that enabled us to derive 

estimates of stack emissions of certain HAP for all of the 

facilities in both source categories. The wool fiberglass 

industry provided emission testing on all known pollutants, 

including total chromium and hexavalent chromium, PM, and other 

metals at furnaces they considered to be representative of other 

furnaces operated by the company. Where different furnace types 

were used to melt fiberglass, industry usually tested 

representative furnaces for each furnace type. The 

representative furnaces were chosen by industry according to 

production rates and furnace type. For untested furnaces, 
Page 47 of 242

industry provided the normal operating rate in terms of tons of 

glass produced per hour. We estimated emissions at untested 

furnaces by using data from the representative tested furnaces.

To do this, we used test data from representative furnaces that 

provided emissions rates of all tested pollutants on a pound per 

hour basis. We applied this pound per hour basis to the untested 

furnaces with the known production rates of those furnaces to 

estimate pounds per hour of pollutants. We considered furnace 

type and company when making these assignments.

We consider these estimates to be very good because they 

are based upon known emission test methods, have test reports 

that verify the results, were signed as being true and accurate 

by authorized company representatives, and also signed as being 

accurate by the testing company. In addition, one testing 

company was used by the industry to conduct all the emissions 

testing using approved EPA methods. We are requesting comment on 

our use of the available test data to assign emission estimates 

to untested emission points.

2. Establishing the Relationship between Actual Emissions 

and MACT-Allowable Emissions Levels.

The emissions data in our data set consists of actual stack 

emissions and, where we did not have actual emissions data, 

estimates of emissions based on a subset of operations that were 

representative of such emission points. In the EPA’s experience, 
Page 48 of 242

with most source categories, we generally have found that 

“actual” emissions levels are lower than the emissions levels 

that a facility is allowed to emit under the MACT standards. The 

emissions levels allowed to be emitted by the MACT standards are

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

represents the highest emissions level that could be emitted by 

facilities without violating the MACT standards.

As we discussed in prior residual risk and technology 

review rules, assessing the risks at the MACT-allowable level is 

reasonable since these risks reflect the maximum level at which 

sources could emit while still complying with the MACT 

standards. However, we also explained that it is reasonable to 

consider actual emissions, where such data are available, in 

both steps of the risk analysis, in accordance with the Benzene 

NESHAP (54 FR 38044, September 14, 1989). Considering actual 

emissions is reasonable because source categories typically seek 

to perform better than required by emissions standards to 

provide an operational cushion and to accommodate the 

variability in manufacturing processes and control device 

performance. Facilities’ actual emissions may also be 

significantly lower than MACT-allowable emissions for other 

reasons such as State requirements, improvements in performance 

of control devices since by the MACT standards, or reduced 

production. In this case, we are reducing the allowable 
Page 49 of 242

emissions limits to the levels of actual emissions. For this 

reason, for the pollutants emitted, we are using only actual 

emissions in our risk analysis.

For both the Mineral Wool Production and Wool Fiberglass 

Manufacturing source categories, we evaluated actual and

allowable stack emissions. Appendices 1a and 1b of the Draft 

Residual Risk Assessment for the Mineral Wool Production and 

Wool Fiberglass Manufacturing Source Categories, available in 

the docket, further describe the estimates of MACT-allowable 

emissions and the estimates of risks due to allowable emissions.

a. Actual and allowable emissions for the Mineral Wool 

Production source category.

The analysis of allowable emissions for the Mineral Wool 

Production source category was largely focused on formaldehyde

emissions, which we considered the most important HAP emitted 

from this source category based on our screening level risk 

assessment and the HAP for which we had the most data. However, 

we also considered allowable emissions for other HAP, including 

HAP metals and COS. To estimate the difference between the 

actual and allowable emissions, we averaged the actual 

formaldehyde emission rates of manufacturing lines provided by 

facilities and compared those values to the maximum level 

allowed by the existing MACT standard (i.e., 0.06 pounds of 

formaldehyde per ton of melt) from all curing ovens. 
Page 50 of 242

We realize that these estimates of allowable emissions are 

theoretical high-end estimates as facilities must maintain 

average emissions levels at some level below the MACT limit to 

ensure compliance with the standard at all times because of the 

day-to-day variability in emissions. Nevertheless, these highend estimates of allowable emissions were adequate for us to 

estimate the magnitude of allowable emissions and the 

differences between the estimates of actual emissions and the 

MACT allowable emissions.

Based on this analysis, we conclude that all facilities in 

the mineral wool source category are emitting formaldehyde at 

levels lower than allowable and that the differences between 

actual and allowable emissions are significant. For the 

facilities producing bonded product, the estimated actual 

emissions were up to three times lower than allowable emissions.

That is, MACT-allowable emissions were determined to be three

times the actual emissions for all pollutants in the Mineral 

Wool Production category. Therefore, we multiplied the actual 

stack emissions from each facility by a factor of 3 to derive 

estimates of allowable emissions for modeling (whether these 

emissions were measured by testing or calculated based on 

representative emission tests).

b. Analysis of allowable and actual emissions for the Wool 

Fiberglass Manufacturing source category.
Page 51 of 242

The analysis of allowable emissions for the Wool Fiberglass 

Manufacturing source category was largely focused on emissions 

of chromium compounds and formaldehyde because these are the 

only pollutants emitted with significant health risks. To 

estimate the difference between the actual and allowable 

emissions, we averaged the actual formaldehyde emission rates of 

manufacturing lines provided by facilities and compared those 

values to the maximum level allowed by the existing MACT 

standard (i.e., 1.2 or 0.8 lb/ton of glass pulled for 

formaldehyde).

We realize that these estimates of allowable emissions are 

theoretical high-end estimates as facilities must maintain 

average emissions levels at some level below the MACT limit to 

ensure compliance with the standard at all times because of the 

day-to-day variability in emissions. Nevertheless, these highend estimates of allowable emissions were adequate for us to 

estimate the magnitude of allowable emissions and the 

differences between the estimates of actual emissions and the 

MACT allowable emissions. Based on this analysis, we conclude 

that allowable emissions are estimated to be three times higher

than actual emissions. Therefore, to develop the MACT-allowable 

emissions, the actual stack emissions for formaldehyde, phenol 

and methanol were multiplied by a factor of 3. The range of 

differences between actual and allowable formaldehyde emission 
Page 52 of 242

levels is significant, that is, for some sources there was 

little difference between actual and allowable emission levels, 

other times, allowable emissions were up to 5 times greater than

actual emissions. MACT-allowable emissions for chromium 

compounds were determined to be equal to actual emissions since 

there is currently no emissions limit for chromium compounds.

3. Conducting Dispersion Modeling, Determining Inhalation

Exposures, and Estimating Individual and Population Inhalation 

Risks.

Both long-term and short-term inhalation exposure 

concentrations and health risks from each source in both the 

source categories addressed in this proposal were estimated 

using the HEM (Community and Sector HEM–3 version 2.1 Beta). The 

HEM–3 performs three primary risk assessment activities: (1) 

Conducting dispersion modeling to estimate the concentrations of 

HAP in ambient air, (2) estimating long-term and short-term 

inhalation exposures to individuals residing within 50 km of the 

modeled sources, and (3) estimating individual and populationlevel inhalation risks using the exposure estimates and 

quantitative dose-response information.

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

of the EPA’s preferred models for assessing pollutant 
Page 53 of 242

concentrations from industrial facilities.

21

HEM–3 draws on three 

data libraries to perform the dispersion modeling and to develop 

the preliminary risk estimates. The first is a library of 

meteorological data, which is used for dispersion calculations. 

This library includes 1 year of hourly surface and upper air 

observations for more than 200 meteorological stations, selected 

to provide coverage of the United States and Puerto Rico. A 

second library of United States Census Bureau census block

22

internal point locations and populations provides the basis of 

human exposure calculations (Census, 2000). In addition, for 

each census block, the Census library includes the elevation and 

controlling hill height, which are used in dispersion 

calculations. A third library of pollutant unit risk factors and 

other health benchmarks is used to estimate health risks. These 

risk factors and health benchmarks are the latest values 

recommended by the EPA for HAP and other toxic air pollutants. 

These values are available at 

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

discussed in more detail later in this section.

 

21

U.S. EPA. Revision to the Guideline on Air Quality Models: 

Adoption of a Preferred General Purpose (Flat and Complex 

Terrain) Dispersion Model and Other Revisions (70 FR 68218, 

November 9, 2005).

22

A census block is generally the smallest geographic area for 

which census statistics are tabulated. 
Page 54 of 242

In developing the risk assessment for chronic exposures, we 

used the estimated annual average ambient air concentration of 

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

emissions data in the source category. The air concentrations at 

each nearby census block centroid were used as a surrogate for 

the chronic inhalation exposure concentration for all the people 

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

facility as the cancer risk associated with a continuous 

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

weeks per year for a 70-year period) to the maximum 

concentration at the centroid of an inhabited census block. 

Individual cancer risks were calculated by multiplying the 

estimated lifetime exposure to the ambient concentration of each 

of the HAP (in micrograms per cubic meter) by its URE, which is 

an upper bound estimate of an individual’s probability of 

contracting cancer over a lifetime of exposure to a 

concentration of 1 microgram of the pollutant per cubic meter of 

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

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

carcinogenic pollutants without an EPA IRIS value, we look to 

other reputable sources of cancer dose-response values, often 

using CalEPA URE values, where available. We may use doseresponse values in place of or in addition to other values, if 

appropriate, in cases where new, scientifically credible dose-
Page 55 of 242

response values have been developed in a manner consistent with 

the EPA guidelines and have undergone a peer review process 

similar to that used by the EPA.

With regard to formaldehyde, the EPA determined in 2004 

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 

dose-response 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. Based on subsequent published 

research, however, EPA changed its determination regarding the 

CIIT model 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 in May of 2011. The EPA is reviewing the public comments

and the NAS independent scientific peer review. The EPA will 

follow the NAS Report recommendations and will present results 

obtained by implementing the biologically based dose-response 

(BBDR) model for formaldehyde. The EPA will compare these 

estimates with those currently presented in the External Review 

draft of the assessment and will discuss their strengths and 

weaknesses. As recommended by the NAS committee, appropriate 

sensitivity and uncertainty analyses will be an integral 

component of implementing the BBDR model. The draft IRIS 

assessment will be revised in response to the NAS peer review 
Page 56 of 242

and public comments and the final assessment will be posted on 

the IRIS database. In the interim, we will present findings 

using the 1991 IRIS value as a primary estimate, and may also 

consider other information as the science evolves. As described 

in the risk assessment, the IRIS URE for formaldehyde is 1.3 x 

10-5 ug/m3, whereas, the CIIT URE for formaldehyde is 5.5 x 10-9

ug/m3. 

Incremental individual lifetime cancer risks associated 

with emissions from the source category were estimated as the 

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

those classified as carcinogenic to humans, likely to be 

carcinogenic to humans and suggestive evidence of carcinogenic 

potential

24

) emitted by the modeled source. Cancer incidence and 

the distribution of individual cancer risks for the population 

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

category as part of these assessments by summing individual 

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

 

24

These classifications also coincide with the terms "known 

carcinogen, probable carcinogen and possible carcinogen," 

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

previous Guidelines for Carcinogen Risk Assessment, published 

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

of these individual compounds to obtain the cumulative cancer 

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

their 2002 peer review of EPA's NATA entitled, NATA -

Evaluating the National-scale Air Toxics Assessment 1996 Data 

-- an SAB Advisory, available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/214C6E915BB04E14852

570CA007A682C/$File/ecadv02001.pdf.
Page 57 of 242

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

limitations of Gaussian dispersion models, including AERMOD. 

To assess risk of noncancer health effects from chronic 

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

common target organ system to obtain the HI for that target 

organ system (or TOSHI). The HQ for chronic exposures is the 

estimated chronic exposure divided by the chronic reference 

level, which is either the EPA RfC, defined as “an estimate 

(with uncertainty spanning perhaps an order of magnitude) of a 

continuous inhalation exposure to the human population 

(including sensitive subgroups) that is likely to be without an 

appreciable risk of deleterious effects during a lifetime,” or, 

in cases where an RfC from the EPA’s IRIS database is not 

available, the EPA will utilize the following prioritized 

sources for our chronic dose-response values: (1) The Agency for 

Toxic Substances and Disease Registry Minimum Risk Level, which 

is defined as “an estimate of daily human exposure to a 

substance that is likely to be without an appreciable risk of 

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

exposure”; (2) the CalEPA Chronic REL, which is defined as “the 

concentration level at or below which no adverse health effects 

are anticipated for a specified exposure duration”; and (3), as 

noted above, in cases where scientifically credible doseresponse values have been developed in a manner consistent with 
Page 58 of 242

the EPA guidelines and have undergone a peer review process 

similar to that used by the EPA, we may use those dose-response 

values in place of or in concert with other values.

Screening estimates of acute exposures and risks were also 

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

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

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

time when both the peak (hourly) emission rate and worst-case 

dispersion conditions (1991 calendar year data) occur. The acute 

HQ is the estimated acute exposure divided by the acute doseresponse value. In each case, acute HQ values were calculated 

using best available, short-term dose-response values. These 

acute dose-response values, which are described below, include 

the acute REL, AEGL and ERPG for 1-hour exposure durations. As 

discussed below, we used conservative assumptions for emission 

rates, meteorology and exposure location for our acute analysis. 

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

Risk Assessment Guidelines, Part I, The Determination of Acute 

Reference Exposure Levels for Airborne Toxicants, an acute REL 

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

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

effects are anticipated for a specified exposure duration.” 

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

adverse health effect reported in the medical and toxicological 
Page 59 of 242

literature. Acute REL values are designed to protect the most 

sensitive individuals in the population by the inclusion of 

margins of safety. Since margins of safety are incorporated to 

address data gaps and uncertainties, exceeding the acute REL 

does not automatically indicate an adverse health impact.

AEGL values were derived in response to recommendations 

from the NRC. As described in Standing Operating Procedures of 

the National Advisory Committee on Acute Exposure Guideline 

Levels for Hazardous Substances

(http://www.epa.gov/opptintr/aegl/pubs/sop.pdf),

25

“the NRC’s 

previous name for acute exposure levels—community emergency 

exposure levels—was replaced by the term AEGL to reflect the 

broad application of these values to planning, response, and 

prevention in the community, the workplace, transportation, the 

military, and the remediation of Superfund sites.” This document 

also states that AEGL values “represent threshold exposure 

limits for the general public and are applicable to emergency 

exposures ranging from 10 minutes to 8 hours.” The document lays 

out the purpose and objectives of AEGL by stating (page 21) that 

“the primary purpose of the AEGL program and the National

Advisory Committee for Acute Exposure Guideline Levels for 

Hazardous Substances is to develop guideline levels for once-in-

 

25

NAS, 2001. Standing Operating Procedures for Developing Acute 

Exposure Levels for Hazardous Chemicals, page 2.
Page 60 of 242

a-lifetime, short-term exposures to airborne concentrations of 

acutely toxic, high-priority chemicals.” In detailing the 

intended application of AEGL values, the document states (page 

31) that “[i]t is anticipated that the AEGL values will be used 

for regulatory and nonregulatory purposes by U.S. Federal and 

state agencies and possibly the international community in 

conjunction with chemical emergency response, planning and 

prevention programs. More specifically, the AEGL values will be 

used for conducting various risk assessments to aid in the 

development of emergency preparedness and prevention plans, as 

well as real-time emergency response actions, for accidental 

chemical releases at fixed facilities and from transport 

carriers.”

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

airborne concentration of a substance above which it is 

predicted that the general population, including susceptible 

individuals, could experience notable discomfort, irritation or 

certain asymptomatic nonsensory effects. However, the effects 

are not disabling and are transient and reversible upon 

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

“Airborne concentrations below AEGL–1 represent exposure levels 

that can produce mild and progressively increasing but transient 

and nondisabling odor, taste, and sensory irritation or certain 

asymptomatic, nonsensory effects.” Similarly, the document 
Page 61 of 242

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

as ppm or mg/m3) of a substance above which it is predicted that 

the general population, including susceptible individuals, could 

experience irreversible or other serious, long-lasting adverse 

health effects or an impaired ability to escape.”

ERPG values are derived for use in emergency response, as 

described in the American Industrial Hygiene Association’s 

document entitled, Emergency Response Planning Guidelines (ERPG) 

Procedures and Responsibilities

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

which states that, “Emergency Response Planning Guidelines were 

developed for emergency planning and are intended as health 

based guideline concentrations for single exposures to 

chemicals.”

26

The ERPG–1 value is defined as “the maximum 

airborne concentration below which it is believed that nearly 

all individuals could be exposed for up to 1 hour without 

experiencing other than mild transient adverse health effects or 

without perceiving a clearly defined, objectionable odor.” 

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

concentration below which it is believed that nearly all 

individuals could be exposed for up to 1 hour without 

experiencing or developing irreversible or other serious health 

 

26

ERP Committee Procedures and Responsibilities. November 1, 

2006. American Industrial Hygiene Association.
Page 62 of 242

effects or symptoms which could impair an individual’s ability 

to take protective action.”

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

ERPG values include the similarly-defined severity levels 1 and 

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

not been developed; in these instances, higher severity level 

AEGL–2 or ERPG–2 values are compared to our modeled exposure 

levels to screen for potential acute concerns.

Acute REL values for 1-hour exposure durations are 

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

values. Even though their definitions are slightly different, 

AEGL–1 values are often the same as the corresponding ERPG–1 

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

Maximum HQ values from our acute screening risk assessments 

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

particular pollutant. In cases where our maximum acute HQ value 

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

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

value).

To develop screening estimates of acute exposures, we 

developed estimates of maximum hourly emission rates by 

multiplying the average actual annual hourly emission rates by a 

factor to cover routinely variable emissions. We chose the 

factor based on process knowledge and engineering judgment and 
Page 63 of 242

with awareness of a Texas study of short-term emissions 

variability, which showed that most peak emission events, in a 

heavily-industrialized four county area (Harris, Galveston, 

Chambers and Brazoria Counties, Texas) were less than twice the 

annual average hourly emission rate. The highest peak emission 

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

the 99th percentile ratio of peak hourly emission rate to the 

annual average hourly emission rate was 9.

27

This analysis is 

provided in Appendix 4 of the Draft Residual Risk Assessment for 

the Mineral Wool Production and Wool Fiberglass Manufacturing

Source Categories, which is available in the docket for this 

action. Considering this analysis, unless specific process 

knowledge or data are available to provide an alternate value, 

to account for more than 99 percent of the peak hourly 

emissions, we apply a conservative screening multiplication 

factor of 10 to the average annual hourly emission rate in these 

acute exposure screening assessments. The factor of 10 was used 

for the Wool Fiberglass Manufacturing source category, but we 

determined that a factor of 3 is more appropriate for the 

Mineral Wool Production source category (for more details see 

the Acute Effects Factor for Mineral Wool Manufacturing 

Operations document in the docket for this rulemaking).

 

27

See 

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

l or docket to access the source of these data.
Page 64 of 242

For the mineral wool source category, we used data from the 

highest formaldehyde emitting source among the mineral wool 

producers. That company also presented the highest risk due to 

formaldehyde emissions. This company provided the agency with 10 

years of measurements of binder formulation, formaldehyde 

content in binders, binder application rates, and binder 

retention rates. Because the industry must manufacture their 

product for use in fireproofing, they must keep meticulous 

records of production specifics. These data are used to show 

compliance with Underwriters Laboratories and other building 

construction safety standards. From this specific 10-year data 

set, the EPA determined that, on a worst-case possible basis, 

formaldehyde could be emitted at levels no more than three times 

the actual rate. The worst-case scenario is possible if the 

binder contained the maximum amount of resin possible, the resin 

contained the maximum amount of formaldehyde possible, was 

sprayed at the maximum rate possible, and retained in the 

product at the minimum level possible. These data were used to 

in the risk assessment to determine the acute health effects 

hazard index. For Mineral Wool Production, the plant-specific 

acute factors were calculated and ranged from 1.0 to 1.6. Based 

on these results, and to allow for additional uncertainty in 

emissions, we used an acute factor of 3.0. The calculation we 
Page 65 of 242

used to determine this acute factor is available in the docket 

to this rule.

28

In cases where acute HQ values from the screening step were 

less than or equal to 1, acute impacts were deemed negligible

and no further analysis was performed. In cases where an acute 

HQ from the screening step was greater than 1, additional sitespecific data were considered to develop a more refined estimate 

of the potential for acute impacts of concern. The data 

refinements employed for these source categories consisted of 

using the site-specific facility layout to distinguish facility 

property from an area where the public could be exposed. These 

refinements are discussed in the draft risk assessment document, 

which is available in the docket for each of these source 

categories. Ideally, we would prefer to have continuous 

measurements over time to see how the emissions vary each hour 

over an entire year. Having a frequency distribution of hourly 

emission rates over a year would allow us to perform a 

probabilistic analysis to estimate potential threshold 

exceedances and their frequency of occurrence. Such an 

evaluation could include a more complete statistical treatment 

of the key parameters and elements adopted in this screening 

 

28 Acute Factor Memo. Cindy Hancy and David Reeves, RTI; to Susan 

Fairchild, USEPA/OAQPS/SPPD; EPA Project Lead. August 30, 

2011.
Page 66 of 242

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

is rare, hence our use of the multiplier approach.

To better characterize the potential health risks 

associated with estimated worst-case acute exposures to HAP, and 

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

of EPA’s RTR risk assessment methodologies30, we examine a wider 

range of available acute health metrics than we do for our 

chronic risk assessments. This is in response to the 

acknowledgement that there are generally more data gaps and 

inconsistencies in acute reference values than there are in 

chronic reference values. By definition, the acute CA-REL 

represents a health-protective level of exposure, with no risk 

anticipated below those levels, even for repeated exposures; 

however, the health risk from higher-level exposures is unknown.

Therefore, when a CA-REL is exceeded and an AEGL-1 or ERPG-1 

level is available (i.e., levels at which mild effects are 

anticipated in the general public for a single exposure), we 

have used them as a second comparative measure. Historically, 

comparisons of the estimated maximum off-site one-hour exposure 

levels have not been typically made to occupational levels for 

the purpose of characterizing public health risks in RTR 

 

30 The SAB peer review of RTR Risk Assessment Methodologies is 

available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525

771F00668381/$File/EPA-SAB-10-007-unsigned.pdf
Page 67 of 242

assessments. This is because occupational ceiling values are not 

generally considered protective for the general public since 

they are designed to protect the worker population (presumed 

healthy adults) for short duration (<15 minute) increases in 

exposure31. As a result, for most chemicals, the 15-minute

occupational ceiling values are set at levels higher than a onehour AEGL-1, making comparisons to them irrelevant unless the 

AEGL-1 or ERPG-1 levels are exceeded (US EPA 2009). Such is not 

the case when comparing the available acute inhalation health 

effect reference values for formaldehyde (US EPA 2009).

The worst-case maximum estimated 1-hour exposure to 

formaldehyde outside the facility fence line for the mineral 

wool source category is 0.47 mg/m3. This estimated worst-case 

exposure exceeds the 1-hour REL by a factor of 8 (HQREL = 8) and 

is below the 1-hour AEGL-1 (HQAEGL-1 = 0.4). This exposure 

estimate does not exceed the AEGL-1, or exceed the workplace 

ceiling level guideline for the formaldehyde value developed by 

the NIOSH32 “for any 15 minute period in a work day” (NIOSH REL-

 

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

Values for Formaldehyde in Graphical Arrays of Chemical-Specific 

Health Effect Reference Values for Inhalation Exposures (Final 

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

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

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003

32 National Institutes for Occupational Safety and Health 

(NIOSH). Occupational Safety and Health Guideline for 

Formaldehyde; http://www.cdc.gov/niosh/docs/81-

123/pdfs/0293.pdf
Page 68 of 242

ceiling value of 0.12 mg/m3; HQNIOSH = 4). The estimate is at the 

value developed by the ACGIH as “not to be exceeded at any time” 

(ACGIH TLV-ceiling value of 0.37 mg/m3; HQACGIH = 1).

Additionally, the estimated maximum acute exposure exceeds the 

Air Quality Guideline value that was developed by the World 

Health Organization33 for 30-minute exposures (0.1 mg/m3; HQWHO = 

5).

For the wool fiberglass manufacturing source category, the 

worst-case maximum estimated 1-hour exposure to formaldehyde 

outside the facility fence line is 1.92 mg/m3. This estimated 

worst-case exposure exceeds the 1-hour REL by a factor of 30 

(HQREL = 30) and the 1-hour AEGL-1 (HQAEGL-1 = 2). This exposure 

estimate also exceeds multiple workplace ceiling level 

guidelines for formaldehyde, including the value developed by 

the American Conference of Governmental Industrial Hygienists 

(ACGIH) as “not to be exceeded at any time” (ACGIH TLV-ceiling 

value of 0.37 mg/m3; HQACGIH = 5), and the value developed by the 

National Institutes for Occupational Safety and Health (NIOSH)

“for any 15 minute period in a work day” (NIOSH REL-ceiling 

value of 0.12 mg/m3; HQNIOSH = 16). Additionally, the estimated 

 

33 WHO (2000). Chapter 5.8 Formaldehyde, in Air Quality 

Guidelines for Europe, second edition. World Health 

Organization Regional Publications, European Series, No. 91. 

Copenhagen, Denmark. Available on-line at 

http://www.euro.who.int/__data/assets/pdf_file/0005/74732/E7192

2.pdf. 
Page 69 of 242

maximum acute exposure exceeds the Air Quality Guideline value 

that was developed by the World Health Organization34 for 30-

minute exposures (0.1 mg/m3; HQWHO = 19). Id.

We solicit comment on the use of the occupational values 

described above in the interpretation of these worst-case acute 

screening exposure estimates for both the Mineral Wool 

Production and Wool Fiberglass Manufacturing source categories.

4. Conducting Multipathway Exposure and Risk Modeling.

The potential for significant human health risks due to 

exposures via routes other than inhalation (i.e., multi-pathway 

exposures) and the potential for adverse environmental impacts 

were evaluated in a three-step process. In the first step, we 

determined whether any facilities emitted any PB-HAP in the 

environment. There are 14 PB-HAP compounds or compound classes 

identified for this screening in the EPA’s Air Toxics Risk 

Assessment Library (available at 

http://www.epa.gov/ttn/fera/risk_atra_vol1.html). They are 

cadmium compounds, chlordane, chlorinated dibenzodioxins and 

furans, dichlorodiphenyldichloroethylene, heptachlor, 

hexachlorobenzene, hexachlorocyclohexane, lead compounds, 

 

34 WHO (2000). Chapter 5.8 Formaldehyde, in Air Quality 

Guidelines for Europe, second edition. World Health 

Organization Regional Publications, European Series, No. 91. 

Copenhagen, Denmark. Available on-line at 

http://www.euro.who.int/__data/assets/pdf_file/0005/74732/E7192

2.pdf. 
Page 70 of 242

mercury compounds, methoxychlor, polychlorinated biphenyls,

polycyclic organic matter, toxaphene and trifluralin. 

Since three of these PB-HAP (lead, cadmium, and mercury

compounds) are emitted by at least one facility in both source 

categories, we proceeded to the second step of the evaluation. 

In this step, we determined whether the facility-specific 

emission rates of each of the emitted PB–HAP were large enough 

to create the potential for significant non-inhalation human or 

environmental risks under reasonable worst-case conditions. To 

facilitate this step, we developed emission rate thresholds for 

each PB–HAP using a hypothetical worst-case screening exposure 

scenario developed for use in conjunction with the EPA’s 

TRIM.FaTE model. The hypothetical screening scenario was 

subjected to a sensitivity analysis to ensure that its key 

design parameters were established such that environmental media 

concentrations were not underestimated (i.e., to minimize the 

occurrence of false negatives or results that suggest that risks 

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

also minimize the occurrence of false positives for human health 

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

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

emission threshold values for each of the PB–HAP identified in 

the source category datasets to assess the potential for 
Page 71 of 242

significant human health risks or environmental risks via noninhalation pathways. 

None of the facilities in the Mineral Wool Production and 

Wool Fiberglass Manufacturing source categories reported 

emissions of PB-HAP that were greater than the de minimis

threshold levels, indicating no potential for significant multipathway risks from these facilities. Therefore, multi-pathway 

exposures and environmental risks were deemed negligible and no 

further analysis was performed. This analysis is provided in the

Draft Residual Risk Assessment for the Mineral Wool Production 

and Wool Fiberglass Manufacturing Source Categories, which is 

available in the docket for this action.

5. Assessing Risks After Control Options.

In addition to assessing baseline inhalation risks and 

screening for potential multi-pathway risks, where appropriate, 

we also estimated risks considering the potential emission 

reductions that would be achieved by the particular control 

options under consideration. In these cases, the expected 

emissions reductions were applied to the specific HAP and 

emissions sources in the source category dataset to develop 

corresponding estimates of risk reductions. More information on 

the risks remaining after controls are in place to meet the 

emissions limits is available in the Draft Residual Risk 

Assessment for the Mineral Wool Production and Wool fiberglass 
Page 72 of 242

Manufacturing Source Categories, which is available in the 

docket for this action.

6. Conducting Facility Wide Risk Assessments

To put the source category risks in context, we also 

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

includes all HAP-emitting operations within a contiguous area 

and under common control. In other words, for each facility that 

includes one or more sources from one of the source categories 

under review, we examine the HAP emissions not only from the 

source category of interest, but also from all other emission 

sources at the facility. For both source categories, all 

significant HAP sources have been included in the source 

category risk analysis and there are no other significant HAP 

emissions sources present. Therefore, we conclude that the 

facility wide risk is essentially the same as the source 

category risk for both the mineral wool and wool fiberglass 

source categories and that no separate facility wide analysis is 

necessary.

7. Considering Uncertainties in Risk Assessment.

Uncertainty and the potential for bias are inherent in all 

risk assessments, including those performed for the source 

categories addressed in this proposal. Although uncertainty 

exists, we believe that our approach, which uses conservative 

tools and assumptions, ensures that our decisions are health-
Page 73 of 242

protective. A brief discussion of the uncertainties in the 

emissions datasets, dispersion modeling, inhalation exposure 

estimates and dose-response relationships follows below. A more 

thorough discussion of these uncertainties is included in the 

draft risk assessment documentation (referenced earlier) 

available in the docket for this action.

a. Uncertainties in the Emissions Datasets.

Although the development of the MACT datasets involved 

quality assurance/quality control processes, the accuracy of 

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

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

to which assumptions made to complete the datasets are 

inaccurate, errors in estimating emissions values and other 

factors. The emission estimates considered in this analysis 

generally are annual totals for certain years that do not 

reflect short-term fluctuations during the course of a year or 

variations from year to year.

The estimates of peak hourly emission rates for the acute 

effects screening assessment were based on a multiplication 

factor of 10 applied to the average annual hourly emission rate, 

which is intended to account for emission fluctuations due to 

normal facility operations. 

b. Uncertainties in Dispersion Modeling.
Page 74 of 242

While the analysis employed the EPA’s recommended regulatory 

dispersion model, AERMOD, we recognize that there is uncertainty 

in ambient concentration estimates associated with any model, 

including AERMOD. In circumstances where we had to choose 

between various model options, where possible, model options 

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

provide an overestimate of ambient air concentrations of the HAP 

rather than underestimates. However, because of practicality and 

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

building downwash) have the potential in some situations to 

overestimate or underestimate ambient impacts. For example, 

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

facility locations can be a significant distance from the site 

where these data were taken. Despite these uncertainties, we 

believe that the approach considered in the dispersion modeling 

analysis for off-site locations and census block centroids 

should generally yield overestimates of ambient HAP 

concentrations.

c. Uncertainties in Inhalation Exposure.

The effects of human mobility on exposures were not 

included in the assessment. Specifically, short-term mobility 

and long-term mobility between census blocks in the modeling 
Page 75 of 242

domain were not considered.

35

The assumption of not considering 

short- or long-term population mobility does not bias the 

estimate of the theoretical MIR, nor does it affect the estimate 

of cancer incidence since the total population number remains 

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

of individual risks across the affected population, shifting it 

toward higher estimated individual risks at the upper end and 

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

thereby increasing the estimated number of people at specific 

risk levels.

In addition, the assessment predicted the chronic exposures 

at the centroid of each populated census block as surrogates for 

the exposure concentrations for all people living in that block. 

Using the census block centroid to predict chronic exposures 

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

who live further from the facility, and under-predict exposures 

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

Thus, using the census block centroid to predict chronic 

exposures may lead to a potential understatement or 

overstatement of the true maximum impact, but is an unbiased 

estimate of average risk and incidence. 

 

35

Short-term mobility is movement from one micro-environment to 

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

is movement from one residence to another over the course of a 

lifetime.
Page 76 of 242

The assessments evaluate the cancer inhalation risks 

associated with continuous pollutant exposures over a 70-year 

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

reality, both the length of time that modeled emissions sources 

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

years), and the domestic growth or decline of the modeled 

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

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

a given source category. Depending on the characteristics of the 

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

overestimate both in individual risk levels and in the total 

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

a facility maintains or increases its emission levels beyond 70 

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

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

the risks could potentially be underestimated. Annual cancer 

incidence estimates from exposures to emissions from these 

sources would not be affected by uncertainty in the length of 

time emissions sources operate. 

The exposure estimates used in these analyses assume 

chronic exposures to ambient levels of pollutants. Because most 

people spend the majority of their time indoors, actual 

exposures may not be as high, depending on the characteristics 

of the pollutants modeled. For many of the HAP, indoor levels 
Page 77 of 242

are roughly equivalent to ambient levels, but for very reactive 

pollutants or larger particles, these levels are typically 

lower. This factor has the potential to result in an 

overstatement of 25 to 30 percent of exposures.

36

In addition to the uncertainties highlighted above, there 

are several factors specific to the acute exposure assessment 

that should be highlighted. The accuracy of an acute inhalation 

exposure assessment depends on the simultaneous occurrence of 

independent factors that may vary greatly, such as hourly 

emissions rates, meteorology, and human activity patterns. In 

this assessment, we assume that individuals remain for 1 hour at 

the point of maximum ambient concentration as determined by the 

co-occurrence of peak emissions and worst-case meteorological 

conditions. These assumptions would tend to overestimate actual 

exposures since it is unlikely that a person would be located at 

the point of maximum exposure during the time of worst-case 

impact.

d. Uncertainties in Dose-Response Relationships.

There are uncertainties inherent in the development of the 

dose-response values used in our risk assessments for cancer 

effects from chronic exposures and noncancer effects from both 

chronic and acute exposures. Some uncertainties may be 

 

36

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

453/R–01–003; January 2001; page 85.)
Page 78 of 242

considered quantitatively, and others generally are expressed in 

qualitative terms. We note as a preface to this discussion a 

point on dose-response uncertainty that is brought out in the 

EPA 2005 Cancer Guidelines; namely, that “the primary goal of 

the EPA actions is protection of human health; accordingly, as 

an agency policy, risk assessment procedures, including default 

options that are used in the absence of scientific data to the 

contrary, should be health protective.” (EPA 2005 Cancer 

Guidelines, pages 1–7). This is the approach followed here as 

summarized in the next several paragraphs. A complete detailed 

discussion of uncertainties and variability in dose-response 

relationships is given in the residual risk documentation, which 

is available in the docket for this action. 

Cancer URE values used in our risk assessments are those 

that have been developed to generally provide an upper bound 

estimate of risk. That is, they represent a “plausible upper 

limit to the true value of a quantity” (although this is usually 

not a true statistical confidence limit).

37

In some 

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

in other circumstances, the risk could also be greater.

38

When 

 

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

38

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

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

considered to be equally plausible and which is based on 

maximum likelihood estimates.
Page 79 of 242

developing an upper bound estimate of risk and to provide risk 

values that do not underestimate risk, health-protective default 

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

adequate health-protection, the EPA typically uses the upper 

bound estimates rather than lower bound or central tendency 

estimates in our risk assessments, an approach that may have 

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

benefits analysis). 

Chronic noncancer reference (RfC and RfD) values represent 

chronic exposure levels that are intended to be healthprotective levels. Specifically, these values provide an 

estimate (with uncertainty spanning perhaps an order of 

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

inhalation exposure (RfC) to the human population (including 

sensitive subgroups) that is likely to be without an appreciable 

risk of deleterious effects during a lifetime. To derive values 

that are intended to be “without appreciable risk,” the 

methodology relies upon an UF approach (U.S. EPA, 1993, 1994) 

which includes consideration of both uncertainty and 

variability. When there are gaps in the available information, 

UF are applied to derive reference values that are intended to 

protect against appreciable risk of deleterious effects. The UF
Page 80 of 242

are commonly default values,

39

e.g., factors of 10 or 3, used in 

the absence of compound-specific data; where data are available, 

UF may also be developed using compound-specific information. 

When data are limited, more assumptions are needed and more UF 

are used. Thus, there may be a greater tendency to overestimate 

risk in the sense that further study might support development 

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

fewer default assumptions are needed. However, for some 

pollutants, it is possible that risks may be underestimated. 

While collectively termed “uncertainty factor,” these factors 

account for a number of different quantitative considerations 

when using observed animal (usually rodent) or human toxicity 

data in the development of the RfC. The UF are intended to 

 

39

According to the NRC report, Science and Judgment in Risk 

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

approaches, based on general scientific knowledge and policy 

judgment, that are applied to various elements of the risk 

assessment process when the correct scientific model is 

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

the Federal Government: Managing the Process, defined default 

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

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

data to the contrary” (NRC, 1983a, p. 63). Therefore, default 

options are not rules that bind the agency; rather, the agency 

may depart from them in evaluating the risks posed by a 

specific substance when it believes this to be appropriate. In 

keeping with EPA’s goal of protecting public health and the 

environment, default assumptions are used to ensure that risk 

to chemicals is not underestimated (although defaults are not 

intended to overtly overestimate risk). See EPA, 2004, An 

Examination of EPA Risk Assessment Principles and Practices, 

EPA/100/B–04/001 available at:

http://www.epa.gov/osa/pdfs/ratf-final.pdf.
Page 81 of 242

account for: (1) variation in susceptibility among the members 

of the human population (i.e., inter-individual variability); 

(2) uncertainty in extrapolating from experimental animal data 

to humans (i.e., interspecies differences); (3) uncertainty in 

extrapolating from data obtained in a study with less-thanlifetime exposure (i.e., extrapolating from sub-chronic to 

chronic exposure); (4) uncertainty in extrapolating the observed 

data to obtain an estimate of the exposure associated with no 

adverse effects; and (5) uncertainty when the database is 

incomplete or there are problems with the applicability of 

available studies. Many of the UF used to account for 

variability and uncertainty in the development of acute 

reference values are quite similar to those developed for 

chronic durations, but they more often use individual UF values 

that may be less than 10. UF are applied based on chemicalspecific or health effect-specific information (e.g., simple 

irritation effects do not vary appreciably between human 

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

the purpose for the reference value (see the following 

paragraph). The UF applied in acute reference value derivation 

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

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

observed adverse effect (exposure) level to no observed adverse 

effect (exposure) level adjustments; and (4) uncertainty in 
Page 82 of 242

accounting for an incomplete database on toxic effects of 

potential concern. Additional adjustments are often applied to 

account for uncertainty in extrapolation from observations at 

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

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

Not all acute reference values are developed for the same 

purpose and care must be taken when interpreting the results of 

an acute assessment of human health effects relative to the 

reference value or values being exceeded. Where relevant to the 

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

at different levels of severity should be factored into the risk 

characterization as potential uncertainties.

Although every effort is made to identify peer-reviewed 

reference values for cancer and noncancer effects for all 

pollutants emitted by the sources included in this assessment, 

some HAP continue to have no reference values for cancer or 

chronic noncancer or acute effects. Since exposures to these 

pollutants cannot be included in a quantitative risk estimate, 

an understatement of risk for these pollutants at environmental 

exposure levels is possible. For a group of compounds that are 

either unspeciated, or do not have reference values for every 

individual compound (e.g., glycol ethers), we conservatively use 

the most protective reference value to estimate risk from 

individual compounds in the group of compounds. 
Page 83 of 242

Additionally, chronic reference values for several of the 

compounds included in this assessment are currently under the 

EPA IRIS review and revised assessments may determine that these 

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

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

reviews are completed prior to our taking final action for these 

source categories and if dose-response metric changes enough to 

indicate that the risk assessment supporting this notice may 

significantly understate human health risk.

When we identify acute impacts which exceed their relevant 

benchmarks, we pursue refining our acute screening estimates. 

For the Mineral Wool Production source category, we used a 

refined emissions multiplier of 3 to estimate the peak hourly 

emission rates from the average rates. For a detailed 

description of how the refined emissions multiplier was 

developed for the Mineral Wool Production source category see 

the memo on the Acute Effects Factor for Mineral Wool 

Manufacturing Operations, which is in the docket for this 

action. For the Wool Fiberglass Manufacturing source category, 

data were not available to develop a refined emissions 

multiplier; therefore, the default emissions multiplier of 10 

was used.

e. Uncertainties in the Multi-Pathway and Environmental 

Effects Assessment.
Page 84 of 242

We generally assume that when exposure levels are not 

anticipated to adversely affect human health, they also are not

anticipated to adversely affect the environment. For each source 

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

multi-pathway and environmental effects is necessary. As 

discussed above, we conclude that the potential for these types 

of impacts is low for these source categories.

f. Uncertainties in the Facility Wide Risk Assessment.

Given that the same general analytical approach and the 

same models were used to generate facility wide risk results as 

were used to generate the source category risk results, the same 

types of uncertainties discussed above for our source category 

risk assessments apply to the facility wide risk assessments. 

Because the source category processes are the only processes at 

each facility, there is no greater uncertainty for facility wide

emissions.

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

this proposal?

Based on our risk assessment we are proposing that risks 

due to hexavalent chromium and formaldehyde are acceptable, with 

a maximum individual cancer risk for the source category at 40-

in-one million. Emissions testing at the facility presenting 

this risk indicated that 92 percent of the total chromium 
Page 85 of 242

compounds were hexavalent chromium. In the second step of the 

process, the EPA sets the standard at a level that provides an 

ample margin of safety.

We found from our risk assessment that risks due to 

hexavalent chromium were acceptable at 40-in-one million. In the 

second step of our risk assessment, we considered whether any 

cost-effective measures, technologies or practices are available 

to reduce risks further to an “ample margin of safety”. We found 

two methods whereby hexavalent chromium emissions can be reduced 

at wool fiberglass facilities and we are proposing in this

action emission limits for hexavalent chromium from wool 

fiberglass facilities that will provide an ample margin of 

safety to protect the public health and prevent adverse 

environmental effects. We discuss these methods further in 

Sections V.A., VIII. D and VIII. E of this preamble.

In past residual risk actions, the EPA has presented and 

considered a number of human health risk metrics associated with 

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

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

the maximum non-cancer HI; and the maximum acute non-cancer 

hazard (72 FR 25138, May 3, 2007; 71 FR 42724, July 27, 2006).

In our most recent proposals (75 FR 65068, October 21, 2010 and 

75 FR 80220, December 21, 2010), the EPA also presented and 

considered additional measures of health information, such as 
Page 86 of 242

estimates of the risks associated with the maximum level of 

emissions which might be allowed by the current MACT standards 

(see, e.g., 75 FR 65068, October 21, 2010 and 75 FR 80220, 

December 21, 2010). The EPA also discussed and considered risk 

estimation uncertainties. The EPA is providing this same type of 

information in support of the proposed actions described in this 

Federal Register notice.

The agency is considering all available health information 

to inform our determinations of risk acceptability and ample 

margin of safety under CAA section 112(f). The agency

acknowledges that the Benzene NESHAP provides flexibility 

regarding what factors the EPA might consider in making 

determinations and how these factors might be weighed for each 

source category. Thus, the level of the MIR is only one factor 

to be weighed in determining acceptability of risks.

The EPA wishes to point out that certain health information 

has not been considered to date in making residual risk 

determinations. In assessing risks to populations in the 

vicinity of the facilities in each category, we present risk 

estimates associated with HAP emissions from the source category 

alone (source category risk estimates) and the risks due to HAP 

emissions from the entire facility at which the covered source 

category is located (facility wide risk estimates). We have not 

attempted to characterize the risks associated with all HAP 
Page 87 of 242

emissions impacting the populations living near the sources in 

these categories. That is, at this time, we do not attempt to 

quantify those HAP risks that may be associated with emissions 

from other facilities that are not included in the source 

categories in question, including mobile source emissions, 

natural source emissions, persistent environmental pollution, 

and atmospheric transformation in the vicinity of the sources in 

these categories.

The agency understands the potential importance of 

considering an individual’s total exposure to HAP in addition to 

considering exposure to HAP emissions from the source category 

and facility. This is particularly important when assessing noncancer risks, where pollutant-specific exposure health reference 

levels (e.g., RfC) are based on the assumption that thresholds 

exist for adverse health effects. For example, the agency

recognizes that, although exposures attributable to emissions 

from a source category or facility alone may not indicate the 

potential for increased risk of adverse non-cancer health 

effects in a population, the exposures resulting from emissions 

from the facility in combination with emissions from all of the 

other sources (e.g., other facilities) to which an individual is 

exposed may be sufficient to result in increased risk of adverse 

non-cancer health effects. In May 2010, the EPA SAB advised us 

“... that RTR assessments will be most useful to decision makers 
Page 88 of 242

and communities if results are presented in the broader context 

of aggregate and cumulative risks, including background 

concentrations and contributions from other sources in the 

area.”40

Although we are interested in placing source category and 

facility wide HAP risks in the context of total HAP risks from 

all sources combined in the vicinity of each source, we are 

concerned about the uncertainties of doing so. At this point, we 

believe that such estimates of total HAP risks will have 

significantly greater associated uncertainties than for the 

source category or facility wide estimates, and hence would 

compound the uncertainty in any such comparison. This is because 

we have not conducted a detailed technical review of HAP 

emissions data for source categories and facilities that have 

not previously undergone an RTR review or are not currently 

undergoing such review.

C. How did we perform the technology review?

For our technology review, we identified and evaluated the 

developments in practices, processes and control technologies

 

40 The EPA’s responses to this and all other key recommendations 

of the SAB’s advisory on RTR risk assessment methodologies 

(which is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A852

5771F00668381/$File/EPA-SAB-10-007-unsigned.pdf) are outlined 

in a memo to this rulemaking docket from David Guinnup 

entitled, EPA’s Actions in Response to the Key Recommendations 

of the SAB Review of RTR Risk Assessment Methodologies.
Page 89 of 242

that have occurred since the 1999 MACT rules were promulgated.

In cases where we identified such developments, we analyzed the 

technical feasibility of and the estimated impacts (costs, 

emissions reductions, risk reductions, etc.) of applying these 

developments. We then decided, based on impacts and feasibility, 

whether it was necessary to propose amendments to the regulation 

to require any of the identified developments.

Based on our analyses of the data, information collected 

under the voluntary industry survey, our general understanding 

of both of the industries and other available information on 

potential controls for these industries, we identified potential 

developments in practices, processes, and control technologies.

For the purpose of this exercise, we considered any of the 

following to be a “development”:

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

not identified and considered during development of the 

1999 MACT rules.

 Any improvements in add-on control technology or other 

equipment (that were identified and considered during 

development of the 1999 MACT rules) that could result in 

significant additional emissions reduction.
Page 90 of 242

 Any work practice or operational procedure that was not 

identified or considered during development of the 1999 

MACT rules.

 Any process change or pollution prevention alternative that 

could be broadly applied to the industry and that was not 

identified or considered during development of the 1999 

MACT rules.

 Any development in equipment or technology that could 

result in increased HAP emissions.

In addition to reviewing the practices, processes, and

technologies that were not considered at the time we developed 

the 1999 MACT rules, we reviewed a variety of data sources for 

the mineral wool and wool fiberglass industries. Among the data 

sources we reviewed were the NESHAP for various industries that 

were promulgated after the 1999 MACT rules. We reviewed the 

regulatory requirements and/or technical analyses associated 

with these regulatory actions to identify any practices, 

processes and control technologies considered in these efforts 

that could possibly be applied to emissions sources in the 

Mineral Wool Production and Wool Fiberglass source categories, 

as well as the costs, non-air impacts, and energy implications 

associated with the use of these technologies. We reviewed 

scientific and technical literature regarding refractory 
Page 91 of 242

products including high chrome refractories and consulted 

experts in the refractory manufacturing field. 

Control technologies, classified as RACT, BACT, or LAER

apply to stationary sources depending on whether the sources are 

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

facility. We consulted the EPA’s RBLC to identify potential 

technology advances. BACT and LAER (and sometimes RACT) are 

determined on a case-by-case basis, usually by state or local 

permitting agencies. The EPA established the RBLC to provide a 

central database of air pollution technology information 

(including technologies required in source-specific permits) to 

promote the sharing of information among permitting agencies and 

to aid in identifying future possible control technology options 

that might apply broadly to numerous sources within a category 

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

over 5,000 air pollution control permit determinations that can 

help identify appropriate technologies to mitigate many air 

pollutant emissions streams. We searched this database to 

determine whether it contained any practices, processes, or 

control technologies for the types of processes covered by the 

Mineral Wool Production and Wool Fiberglass Manufacturing MACT

rules.

Additionally, we requested information from facilities

regarding developments in practices, processes, or control 
Page 92 of 242

technology. Finally, we reviewed other information sources, such 

as State and local permitting agency databases and industrysupported databases.

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

In addition to the analyses described above, we also 

reviewed other aspects of the MACT standards for possible 

revision. Based on this review we have identified several 

aspects of the MACT standards that we believe need revision.

This includes proposing revisions to the startup, shutdown, and 

malfunction provisions of the MACT rule in order to ensure that 

they are consistent with a recent court decision in Sierra Club 

v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008).

We are proposing HAP-specific emission limits for COS, 

phenol, and methanol in place of surrogacy in the MACT 

standards. The proposed rule also would regulate the collection 

process as a source of HAP emissions of phenol, methanol and 

formaldehyde that were not included in the 1999 Mineral Wool 

MACT standard. 

In addition, we are proposing other various minor changes 

with regards to editorial errors and other revisions to promote 

the use of plain language. The analyses and proposed decisions 

for these actions are presented in Section VI of this preamble.

E. What analyses were performed for the Mineral Wool Production 

Source Category under the Regulatory Flexibility Act?
Page 93 of 242

Section 609(b) of the RFA requires a Panel to be convened 

prior to publication of the IRFA that an agency may be required 

to prepare under the RFA. The RFA directs the Panel to report on 

the comments of small entity representatives and make findings 

on the following elements:

 a description and estimate of the number of small 

entities to which the proposed rule will apply; 

 a description of projected reporting, recordkeeping and 

other compliance requirements of the proposed rule, 

including an estimate of the classes of small entities 

that will be subject to the requirements and the type of 

professional skills necessary for preparation of the 

report or record;

 an identification, to the extent practicable, of all 

relevant federal rules which may duplicate, overlap, or 

conflict with the proposed rule; and 

 descriptions of any significant alternatives to the 

proposed rule which accomplish the stated objectives of 

applicable statutes and which minimize any significant 

economic impact of the proposed rule on small entities. 

This analysis must discuss any significant alternatives 

such as:
Page 94 of 242

 the establishment of differing compliance or reporting 

requirements or timetables that take into account the 

resources available to small entities;

 the clarification, consolidation, or simplification of 

compliance and reporting requirements under the rule 

for such small entities;

 the use of performance rather than design standards; 

and

 an exemption from coverage of the rule, or any part 

thereof, for such small entities.

Once completed, the Panel Report presents the results of 

the analyses identified in the above list, and is provided to 

the agency issuing the proposed rule and is included in the 

rulemaking record. The agency is to consider the Panel’s 

findings when completing the draft of the proposed rule. In 

light of the Panel Report, and where appropriate, the agency is 

also to consider whether changes are needed to the IRFA for the 

proposed rule or the decision on whether an IRFA is required.

The Panel’s findings and discussion are based on the 

information available at the time the final Panel Report is 

published. The EPA will continue to conduct analyses relevant to 

the proposed rule, and additional information may be developed 

or obtained during the remainder of the rule development 

process.
Page 95 of 242

Any options identified by the Panel for reducing the rule’s 

regulatory impact on small entities may require further analysis 

and/or data collection to ensure that the options are 

practicable, enforceable, environmentally sound and consistent 

with the CAA and its amendments. The Mineral Wool SBAR Panel 

convened on June 2, 2011, to address regulatory flexibility 

alternatives and opportunities for the mineral wool industry.

VI. Summary of Proposed Decisions and Actions

Pursuant to CAA sections 112(d)(2), 112(d)(6) and 112(f), 

we are proposing to revise the 1999 MACT rules relative to 

mineral wool production and wool fiberglass manufacturing to 

include the standards and requirements summarized in this 

section. More details of the rationale for these proposed 

standards and requirements are provided in Sections VII and VIII

of this preamble. In addition, as part of these rationale 

discussions, we solicit public comment and data relevant to 

several issues. The comments we receive during the public 

comment period will help inform the rule development process as 

we work toward promulgating a final action.

A. What are the proposed decisions and actions related to the 

Mineral Wool Production NESHAP?

The following sections discuss the proposed decisions and 

actions regarding unregulated pollutants and emissions sources 

(i.e., the MACT floors), recordkeeping and notification, 
Page 96 of 242

compliance and other proposed decisions and actions related to 

subcategorization of emissions sources and the findings of the 

SBAR Panel.

1. Addressing Unregulated Pollutants and Emissions Sources

from Mineral Wool Production.

In the course of evaluating the 1999 MACT rule, we 

identified certain HAP for which we failed to establish emission 

standards in the original MACT (i.e., COS, HF, HCl, phenol, and 

methanol) and certain unregulated processes (i.e., collection).

Some of these HAP (COS, phenol, and methanol) were not regulated 

under the 1999 MACT rule because they were represented by 

surrogates (i.e., CO and formaldehyde). The EPA did not regulate 

HF and HCl in the 1999 rule although these HAP are emitted from 

cupolas. The 1999 MACT rule also did not regulate any HAP 

emitted from collection processes that occur on a bonded line 

even though these processes emit the HAP phenol, formaldehyde, 

and methanol. According to National Lime v. EPA, 233 F. 3d 625, 

634 (D.C. Cir. 2000), the EPA has a “clear statutory obligation 

to set emissions standards for each listed HAP”. As a part of 

the information collected in 2010 to support this proposal, we

specifically evaluated COS, HF, and HCl from cupolas and 

formaldehyde, phenol and methanol from collection and curing 

operations.
Page 97 of 242

For the Mineral Wool Production source category, we are 

proposing MACT limits for: (1) COS, HF and HCl for existing, new

and reconstructed cupolas; and (2) formaldehyde, phenol and 

methanol for existing, new and reconstructed combined collection 

and curing operations. The collection process emits HAP when a 

phenol-formaldehyde based binder is sprayed during collection. 

Such collection processes immediately precede curing ovens. Both 

processes emit HAP when they occur on bonded production lines, 

but of the two processes, only the curing oven was regulated 

under the 1999 MACT standard. This proposed rule regulates 

collection and curing as a combined process on bonded production 

lines under three subcategories (one subcategory for each 

combined process design). The proposed emissions limits were

calculated using the 99 percent UPL method.

We considered beyond-the-floor options for COS, HF, and HCl 

standards for all cupolas, and for formaldehyde, phenol and 

methanol for all combined collection and curing operation

designs, as required by section 112(d)(2) of the Act. However, 

we decided not to propose any limits based on the beyond-thefloor analyses for COS, HF, HCl, formaldehyde, phenol, and 

methanol for these sources because of the costs, potential 

disadvantages of additional controls (including the cost of RTO

and unintended SO2 emissions), non-air environmental impacts, and 

adverse energy implications associated with use of these 
Page 98 of 242

additional controls. The beyond-the-floor analyses are presented 

in the technical documentation for this action (see MACT Floor 

Analysis for the Mineral Wool Production Manufacturing Source 

Category and the MACT Floor Analysis for the Wool Fiberglass 

Manufacturing Source Category), and are available in the docket 

for this action.

In summary, we are proposing the following emissions limits

for existing, new, and reconstructed cupolas in the Mineral Wool 

Production Source Category as presented in Table 2. We are not 

proposing changes to the PM emissions limits in the 1999 MACT 

rule for Mineral Wool Production, and for this reason they are 

not included in the proposed limits in Table 2 below.

Table 2. Mineral Wool Production Proposed Emissions limits for 

Existing, New, and Reconstructed Cupolas, pound of pollutant per 

ton of melt

Pollutant

Emission Limit (lb/ton of melt)

Existing Cupolas

New and 

Reconstructed 

Cupolas

COS 3.3 0.017

HF 0.014 0.014

HCl 0.0096 0.0096

2. Subcategorization.

Under CAA section 112(d)(1), the EPA has the discretion to 

“...distinguish among classes, types, and sizes of sources 

within a category or subcategory in establishing...” standards.

When separate subcategories are established, a MACT floor is 

determined separately for each subcategory. To determine whether 
Page 99 of 242

the mineral wool production facilities warrant subcategorization 

for the MACT floor analysis, the EPA reviewed unit and process 

designs, operating information, and air emissions data compiled 

in the industry survey data set and other information collected 

by the agency for development of the NESHAP for this source 

category. Based on this review, the EPA concluded that there are 

significant design and operational differences in the collection 

operations at each of the three facilities that operate a bonded 

line in this source category. 

For the unregulated process that emits HAP (i.e., 

collection and curing for facilities that operate a bonded 

line), we are proposing to subcategorize combined collection 

operations and curing ovens designs into three subcategories 

based on what the industry is currently using: vertical, 

horizontal and drum. When separate subcategories are 

established, a MACT standard is determined separately for each 

subcategory. To determine whether the mineral wool production 

facilities warrant subcategorization for the MACT floor 

analysis, the EPA reviewed unit and process designs, operating 

information and air emissions data compiled in the industry 

survey data set and other information collected by the agency

for development of the NESHAP for this source category. Based on 

this review, the EPA concluded that there are significant design 

and operational differences in the collection operations at each 
Page 100 of 242

of the three facilities that operate a bonded line in this 

source category. The combined collection and curing designs 

consist of three design types: vertical, horizontal and drum.

For each existing, new, and reconstructed combined collection 

and curing operation, we are proposing the following emissions 

limits as presented in Table 3.

Table 3. Mineral Wool Production Proposed Emissions limits for 

Existing, New, and Reconstructed Combined Collection and Curing 

Operations, pound of pollutant per ton of melt

Design Pollutant Emission Limit

(lb/ton of melt) 

Vertical Formaldehyde 0.46

Phenol 0.52

Methanol 0.63

Horizontal Formaldehyde 0.054

Phenol 0.15

Methanol 0.022

Drum Formaldehyde 0.067

Phenol 0.0023

Methanol 0.00077

3. Reporting and Recordkeeping Notifications.

We are proposing to revise certain reporting and 

recordkeeping requirements of 40 CFR part 63, subpart DDD. 

Specifically, we are proposing that facilities maintain records 

and prepare and submit performance test reports on the frequency 

described below in Compliance Dates and Approaches to comply 

with the proposed emissions limits for COS, HF, HCl, 

formaldehyde, phenol, methanol and the existing PM limit.

Although the PM limits in the existing MACT do not change as a 

result of this proposed rule we are proposing the same 
Page 101 of 242

reporting, recordkeeping requirements for PM as for the other 

pollutants addressed under this proposed rule. We are also 

proposing language that would require the use of electronic 

reporting for all test methods that are supported by the ERT.

Methods supported by ERT may be found at 

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

4. Compliance Dates and Approaches.

We are proposing that facilities that commenced 

construction or reconstruction on or before [INSERT DATE OF 

PUBLICATION OF THIS PROPOSED RULE IN THE FEDERAL REGISTER] must 

demonstrate compliance with the requirements of this subpart no 

later than 3 years after the effective date of this rule. 

Affected sources that commenced construction or reconstruction 

after the effective date of this rule must demonstrate 

compliance with the requirements of this subpart no later than 

the effective date of the rule or upon start-up, whichever is 

later. 

We are proposing that compliance testing for PM, COS, 

formaldehyde, phenol and methanol be conducted using the same 

test methods as required by the 1999 MACT rule (i.e., Method 5 

for PM and Method 318 for the organic HAP). We are proposing 

that sources can use either Test Method 26A or Test Method 320 

to determine compliance for HF and HCl.
Page 102 of 242

We are proposing both an initial performance test and

repeat testing every 5 years or more often if the raw materials 

charged to the cupola change by more than 10 percent of that 

used for the initial performance test. Finally, we propose that 

continuous monitoring of appropriate operating parameters for

control devices (e.g., RTO), cupolas, curing ovens and/or 

collection operations will be required as parametric monitoring. 

This is to ensure continuous compliance with the PM, COS, HF, 

HCl, formaldehyde, phenol and methanol emissions limits.

5. Other Decisions and Actions.

In addition to the proposed decisions and actions 

discussed above, we are also proposing changes to the use of 

surrogates in the existing rule and to subcategorize the 

combined collection operations and curing oven designs from 

those facilities operating bonded lines. We also discuss here 

the findings of the SBAR panel.

a. Surrogacy.

As described in Sections III.B and VII.B of this preamble, 

the court, in the Brick MACT decision (Sierra Club v. EPA, 479 

F. 3d 875 (D.C. Cir. March 13, 2007))

3, found that the EPA has a 

“clear statutory obligation to set emission standards for each 

listed HAP,” which does not allow it to “avoid setting standards 

for HAP not controlled with technology.” Because we did not 

conduct analyses that would support the use of CO as a surrogate 
Page 103 of 242

for COS, or formaldehyde for methanol and phenol, we cannot 

demonstrate that we established emission limits for COS, 

methanol and phenol in the 1999 MACT standard. Therefore, the

agency is proposing to add emission limits for both phenol and 

methanol. Similarly, the agency is proposing to discontinue the 

use of CO as a surrogate for COS, and to set emission limits for 

COS. The proposed emissions limits for formaldehyde, phenol, 

methanol and COS are presented in Tables 2 and 3, above. We are 

soliciting comment on our decisions to discontinue use of 

formaldehyde and CO as surrogates; any person wishing to 

establish or reestablish surrogacy relationships of one 

pollutant for others should provide emissions testing to support 

their conclusions.

b. Small Business Advocacy Review Panel.

For purposes of assessing the impacts of the proposed rule

on small entities, the RFA defines small entities as including 

“small businesses,” “small governments,” and “small 

organizations” (5 USC 601). The regulatory revisions being 

considered by the EPA for this rulemaking are expected to affect 

a variety of small businesses, but would not affect any small 

governments or small organizations. The RFA references the 

definition of “small business” found in the Small Business Act, 

which authorizes the SBA to further define “small business” by 

regulation. The SBA definitions of small business by size 
Page 104 of 242

standards using the NAICS can be found at 13 CFR 121.201. For 

the Mineral Wool Production source category (NAICS code 327993), 

the SBA size standard for a small business is 500 employees.

Based on this size designation, there are currently 5 small 

businesses operating with a total number of 540 employees.

Under section 609(b) of the RFA, the Panel is to report its 

findings related to these four items:

 A description of and, where feasible, an estimate of 

the number of small entities to which the proposed 

rule will apply;

 A description of the projected reporting, 

recordkeeping and other compliance requirements of the 

proposed rule, including an estimate of the classes of 

small entities which will be subject to the 

requirement and the type of professional skills 

necessary for preparation of the report or record;

 Identification, to the extent practicable, of all 

relevant federal rules which may duplicate, overlap or 

conflict with the proposed rule; and

 A description of any significant alternatives to the 

planned proposed rule which would minimize any 

significant economic impact of the proposed rule on 

small entities consistent with the stated objectives 

of the authorizing statute.
Page 105 of 242

The Panel’s most significant findings and discussion with 

respect to each of these items are summarized below. To read the 

full discussion of the Panel findings and recommendations, see 

Section 9 of the Panel Report.

1. Number and Types of Entities Affected

Six companies exist in this industry; five of the six 

companies are small businesses. All small businesses in the 

mineral wool production industry operate under NAICS code 

327993.

2. Recordkeeping, Reporting and Other Compliance Requirements

The proposed rule under consideration potentially impacts 

small businesses by requiring new emission limits on processes 

that were not regulated under the MACT standard promulgated in 

1999, by requiring emission limits for pollutants that were not 

regulated under the MACT, or both processes and pollutants not 

regulated under the MACT. All companies are subject to Title V 

operating permits requirements, and as such will be required to 

add the newly regulated processes to their operating permits 

along with compliance demonstrations that the processes meet 

each pollutant emission limit in the rule. Compliance testing 

will be required to be conducted using EPA methods for each 

pollutant. Reporting and recordkeeping requirements are not 

expected to change from the MACT, with the exception of 

additional pollutants and processes included in such reports.
Page 106 of 242

3. Related Federal Rules

NAAQS: the most prevalent technology for reducing COS 

emissions will increase emissions of SO2. Under the current 

NAAQS, none of the small entities are in nonattainment areas, so 

installation of emissions control equipment should not subject 

them to additional permitting requirements under the SO2 NAAQS.

However, the EPA cannot make such assurances about future NAAQS 

or future nonattainment zones, so there is a risk that future 

compliance with this rule could trigger additional emissions 

control requirements through the Title V/prevention of 

significant deterioration permit program.

GHG: Most emissions control strategies identified by the 

EPA during the Panel would increase the energy intensity of 

mineral wool production. Although the Panel does not have 

specific information about the GHG emissions of individual 

facilities in this industry, these facilities could be subject 

to GHG permitting as that program is phased in under the 

Tailoring Rule.

4. Regulatory Flexibility Alternatives

The Panel agrees that the EPA does not have discretion in a 

number of areas that SER commented upon. Specifically, the EPA 

does not have the discretion to set the MACT floor emission 

limits at levels suggested by the SER. The Panel recognizes that 

EPA has the authority to review the MACT standard for 
Page 107 of 242

completeness, risk, and technology improvements, and that the 

agency is currently under court order to conduct the risk and 

technology review for the mineral wool source category and 

propose amendments to the standard by October 31, 2011, and 

promulgate the amendments by October 31, 2012. However, whenever 

opportunities for regulatory flexibility arise, and when that 

regulatory flexibility can work to lessen impacts to small 

businesses, the Panel recommends that the EPA propose amendments 

to the mineral wool MACT that offer such regulatory flexibility 

to the maximum extent possible. Specifically, these 

opportunities arise in the following situations:

 Selection of the averaging method in calculating the 

MACT floor for COS from cupolas and phenol, 

formaldehyde and methanol emissions from collection 

and curing processes; and

 Subcategorization of regulated processes, when 

appropriate.

The Panel recommends that the EPA not require BTF emission 

limits for the mineral wool industry. Such limits are likely to 

have additional cost impacts to industry. In addition, the EPA 

did not identify BTF measures for consideration and has found 

that the results of the risk assessment show acceptable risks 

from this source category.
Page 108 of 242

The Panel recommends subcategorization of collection along 

the lines described in Section 3 of the Panel Report, 

specifically, subcategorization for vertical collection and 

curing, horizontal collection and curing, and drum collection 

and curing. Based on available information, the Panel believes 

that emission standards based on the average emission limits 

across both collection and curing processes at each of the three 

subcategories would minimize the burden on small entities while 

fully complying with the EPA’s obligations under section 112. 

The Panel also recommends setting MACT limits for new sources 

equal to MACT limits for existing sources.

The Panel recommends that the EPA allow the maximum amount 

of time within its discretion (3 years) and work with state 

permitting authorities to provide for the additional year 

permitted by the statute.

The Panel recommends that the EPA provide a detailed 

discussion in the preamble to the proposed rule that outlines 

the manner in which small entities may demonstrate compliance 

with the rule, when finalized, during start-up and shutdown. The 

Panel also recommends that the EPA propose allowing an 

affirmative defense against compliance actions for malfunction 

events, consistent with other section 112 rules recently 

promulgated. For more information on the SBAR Panel review 

process and findings, see Section IV.E of this preamble and the 
Page 109 of 242

Final Report of the Small Business Advocacy Review Panel on the 

EPA’s Planned Proposed Rule Risk and Technology Review (RTR) 

Amendments to the National Emission Standard for Hazardous Air 

Pollutants (NESHAP) for Mineral Wool Production October 2011 in 

the docket.

c. Technical corrections to the rule.

We are also proposing revisions to certain terms in the 

existing NESHAP. Specifically, we are proposing to replace the 

term “incinerator” with “regenerative thermal oxidizer” to avoid 

confusion with rules promulgated under CAA section 129 and any 

new requirement that may be imposed on something called an 

“incinerator”. We are also proposing to specify performance 

testing frequency for RTOs. 

B. What are the proposed decisions and actions related to the 

Wool Fiberglass Manufacturing NESHAP?

The following sections discuss the decisions proposed by 

this action with regard to the following topics: unregulated 

pollutants and emissions sources; the risk review; the 

technology review; our plans regarding area sources; 

recordkeeping, reporting and notification requirements;

compliance requirements; and other proposed decisions and 

actions (i.e., changes in surrogacy and terminology cleanup).

1. Addressing Unregulated Pollutants and Emissions Sources.
Page 110 of 242

In the course of evaluating the 1999 MACT rule, we 

identified certain HAP for which we failed to establish emission 

standards in the original MACT (i.e., HF, HCl, phenol and 

methanol). As stated earlier, the EPA has “clear statutory 

obligation to set emissions standards for each listed HAP”. 

National Lime v. EPA, 233 F. 3d 625, 634 (D.C. Cir. 2000). The 

EPA specifically evaluated HF and HCl, from glass-melting 

furnaces and formaldehyde, phenol and methanol from RS 

manufacturing lines and FA manufacturing lines.

a. Surrogacy.

As described in Sections III. B and VII.B of this preamble, 

the Court, in the Brick MACT decision, also found that the EPA 

erred when we did not establish emission limits for each 

HAPemitted from industrial processes regulated by the MACT 

standard. We are proposing to replace CO as a surrogate for COS 

with COS emissions limits. We are also proposing to discontinue

use of formaldehyde as a surrogate for phenol and methanol. We 

are, therefore, proposing to add emission limits for COS, phenol 

and methanol. The proposed emissions limits can be found in 

Tables 4-6, below.

Table 4. Proposed Emissions limits for Rotary Spin (RS) 

Manufacturing Lines (pound of pollutant/ton of melt)

Pollutant Existing RS 

Lines

New and Reconstructed 

RS Lines

Formaldehyde 0.17 0.020

Phenol 0.19 0.0011

Methanol 0.48 0.00067
Page 111 of 242

Table 5. Proposed Emissions limits for Flame Attenuation (FA) 

Manufacturing Lines (pound of pollutant/ton of melt)

Pollutant Existing FA 

Lines

New and Reconstructed 

FA Lines

Formaldehyde 5.6 3.3

Phenol 1.4 0.46

Methanol 0.50 0.50

Table 6. Proposed Emissions limits for Glass-Melting Furnaces 

(pound of pollutant/ton of melt)

Pollutant Existing 

Furnaces

New and Reconstructed 

Furnaces

HF 0.002 0.00078

HCl 0.0015 0.00078

b. Emission Limits for Unregulated HAPs.

For the Wool Fiberglass Manufacturing source category, we 

are proposing MACT limits for HF and HCl for glass-melting 

furnaces; formaldehyde, phenol and methanol from existing, new,

and reconstructed RS manufacturing lines; and formaldehyde, 

phenol and methanol from existing, new, and reconstructed FA

manufacturing lines. The proposed emissions limits can be found 

in Tables 4-6 above.

Section 112(d)(3)(B) of the CAA requires that the MACT 

standards for existing sources be at least as stringent as the 

average emissions limitation achieved by the best performing 12 

percent of sources (for which the Administrator has or could 

reasonably obtain emissions information) in a category with more 

than 30 sources. The Wool Fiberglass Manufacturing source 
Page 112 of 242

category consists of 29 facilities with approximately 80 glassmelting furnaces. Since there are more than 30 furnaces, we 

based the MACT floor limit on the average emissions limitation 

achieved by the best performing 12 percent of furnaces.

The EPA must exercise its judgment, based on an evaluation 

of the relevant factors and available data, to determine the 

level of emissions control that has been achieved by the best 

performing sources under variable conditions. It is recognized 

in the case law that the EPA may consider variability in 

estimating the degree of emissions reduction achieved by bestperforming sources and in setting MACT floors. See Mossville 

Envt’l Action Now v. EPA, 370 F.3d 1232, 1241–42 (D.C. Cir 2004) 

(holding that the EPA may consider emissions variability in 

estimating performance achieved by best-performing sources and 

may set the floor at a level that a best-performing source can 

expect to meet “every day and under all operating conditions”).

More details on how we calculate MACT floors and how we account 

for variability are described in the MACT Floor Analysis for the 

Wool Fiberglass Manufacturing Source Category which is available 

in the docket for this proposed action.

We considered beyond-the-floor options for the HF and HCl 

standards for all of the glass-melting furnaces and the 

formaldehyde, phenol and methanol standards for all RS

manufacturing lines and FA manufacturing lines, as required by 
Page 113 of 242

section 112(d)(2) of the Act. We decided not to propose any 

limits based on the beyond-the-floor analyses for any of these 

pollutants because of the costs, non-air environmental impacts,

and adverse energy implications associated with use of these 

additional controls. The beyond-the-floor analysis is presented 

in the technical documentation for this action (MACT Floor 

Analysis for the Mineral Wool Production Source Category and the

MACT Floor Analysis for the Wool Fiberglass Manufacturing Source 

Category).

2. Proposed decisions based on the Risk Review.

Based on the results of our risk assessment and risk review

(which are described in more detail in Section VIII of this 

preamble), we are proposing emission limits for chromium 

compounds under the authority of section 112(f)(2) of the CAA of 

0.006 pounds of total chromium per thousand tons of glass 

pulled. As explained in Section VIII of this preamble, we are 

proposing these limits as an outcome of our ample margin of 

safety analysis.

3. Proposed decisions based on the Technology Review for 

the Wool Fiberglass Industry.

As explained in Sections VI.B and VIII.E of this preamble, 

we are proposing emissions limits for PM, under section 

112(d)(6)(see Table 12 of Section VIII in this preamble).

Furthermore, as explained in Section VIII.F of this preamble, we 
Page 114 of 242

are proposing emissions limits for chromium compounds under 

section 112(d)(6) of the CAA as part of our technology review 

(see those sections for details) of 0.006 pounds of total 

chromium per thousand tons of glass pulled, which is the same 

limit we are proposing under Section 112(f)(2) of the CAA.

In our technology review for this industry, we discovered 

and evaluated two new technology developments that affect 

emissions from wool fiberglass manufacturing furnaces: furnace 

control technologies and high chrome refractories. These are 

discussed below.

Wool fiberglass furnaces are now equipped with air 

pollution control devices that achieve emissions of about 0.014 

pounds PM per ton of glass produced. This is about 50 times 

lower than required under the MACT rule (0.5 lb PM per ton glass 

produced). In light of the record and additional data we 

received on PM emissions, we are proposing revised PM limits 

under the technology review of the wool fiberglass source 

category (as described in Section VIII of this preamble).

Glass-melting furnaces are constructed using refractories, 

which direct the heat of the furnace back into the melt. We are 

aware of a new technology that is used to significantly extend 

the life of the wool fiberglass furnace: refractories that are 

made of almost 100 percent chromium compounds and that are used 

to construct entire furnaces or very large parts of furnaces.
Page 115 of 242

Based on emission testing of one furnace, it appears that the

levels of chromium compounds that can be emitted when glassmelting furnaces are constructed from high chrome refractories 

can be significant. This facility operates two furnaces. The 

total chromium compound emissions at this facility are estimated 

as 913 lb/yr assuming that both furnaces emit at a similar rate.

This includes 840 pounds of hexavalent chromium. Industry 

information indicates that the furnaces emitting the highest 

levels of chromium compounds are constructed in whole or in part 

from these types of refractories. (Notes of April 14, 2011; 

Region 7 Certainteed Notes).

12,13

It is our understandng that because of the corrosive 

properties of the molten glass, fresh refractory is continuously

exposed to the molten glass along the metal/glass contact line 

in the glass-melting furnace process. This increases the surface 

area of the refractory that is exposed to the molten glass. As a 

result, when the glass furnace is constructed using high chrome 

refractories, the emission levels of chromium compounds 

continuously increase over the life of the furnace (Please refer 

to notes of April 14, 2011, telephone discussion between Susan 

Fairchild and Certainteed). One industry spokesperson estimated 

that 20,000 lb/yr of refractory are worn away from the inside 
Page 116 of 242

walls of one wool fiberglass furnace and ducted to the control 

device before venting to the atmosphere.41

On August 31, 2011, industry representatives met with the 

agency to provide data, in an attempt to improve our 

understanding of the levels of chromium content in refractory 

products used at wool fiberglass furnaces and their impacts on 

chromium complund emissions. In the meeting industry 

representatives stated the following:

 the use of chromium in refractories is important to wool 

fiberglass operations because it extends the useful life of 

the furnace;

 chromium content of furnaces vary from 0 to 95 percent; there 

is no distinction between the types of refractories used at 

the highest chrome emitting furnace and the refractories used 

to construct other glass furnaces that emit low levels of 

hexavalent chromium.

 the type of furnace used at the high chromium emitting 

facility may may be responsible for increased hexavalent 

chromium emissions

However, the information from the meeting appears to 

contradict other information on the reason for certain furnaces 

to have elevated chromium emissions. As previously discussed, 

 

41 Meeting between U.S. EPA, wool fiberglass industry 

representatives and NAIMA (trade association). August 31, 

2011. At USEPA offices in Research Triangle Park, NC.
Page 117 of 242

emission test results from the 2010 testing and previous 

statements made to the EPA from owners/operators (Notes of April 

14, 2011,Certainteed; Region 7 Certainteed notes) seem to inmly 

that the high chromium emissions are due to the chromium content

of the refractory. Because of this contradictory information we 

are requesting additional emissions testing of wool fiberglass 

furnaces (discussed below). We are also soliciting comment on 

whether and how to subcategorize industry according to furnace 

type, or type of refractory. Commenters should also provide 

emissions test data to support their assertions regarding the 

correct manner in which to subcategorize the industry.

As shown in Table 12 of Section VIII of this preamble, we 

are proposing chromium compound emissions limits of 0.00006 

lb/ton of glass produced. These limits would apply to wool 

fiberglass furnaces at major sources. However, there are no 

differences in furnaces at major sources and those at area 

sources. We are concerned about the levels of hexavalent 

chromium that can be emitted by area sources where furnaces may 

be constructed or reconstructed using high chrome refractories. 

We are announcing today our plans to regulate wool fiberglass 

area sources in a future action. We have issued a section 114 

information collection request to the wool fiberglass industry 

to collect comprehensive information specific to the chrome

content of the refractories used to construct their glass-
Page 118 of 242

melting furnaces and obtain complete chromium emissions test 

data. This information will enable us determine the scope of the 

source category (in terms of the universe of wool fiberglass 

producers that are area sources and that emit hexavalent 

chromium) to be regulated in the future action.

We are requesting information specific to wool fiberglass 

furnaces, including information on the chromium content of the 

refractories used in furnace construction, process rates and 

emissions testing. Nevertheless, we are soliciting comment from 

the public on our approach to limit emissions of chromium 

compounds as well as other alternatives to reducing emissions of 

chromium compounds, especially hexavalent chromium.

4. Reporting, Recordkeeping and Notification Requirements

We are proposing to revise certain recordkeeping 

requirements of 40 CFR part 63, subpart NNN. Specifically, we 

are proposing that facilities maintain records and prepare and 

submit performance test reports to comply with the proposed 

emissions limits for PM, chromium compounds, HF, HCl, 

formaldehyde, phenol and methanol. Because refractory products 

can contain chromium compounds that can then be emitted to the 

ambient air during wool fiberglass manufacturing, we are 

proposing that owners/operators of glass manufacturing furnaces 

maintain records of the refractory brick composition from which 

the furnaces are constructed, including any rebricking or 
Page 119 of 242

additional layers of refractory that are added to the outside 

furnace walls. In addition, owners and operators are required to 

keep records of the occurrence and duration of each malfunction 

or operation of the air pollution control equipment and 

monitoring equipment. We are also proposing requirements for the 

use of electronic reporting for all test methods that are 

supported by the ERT. Methods supported by ERT may be found at 

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

5. Compliance Dates and Approaches.

With regard to formaldehyde, HCL, HF, phenol and methanol, 

we are proposing that facilities that commenced construction or 

reconstruction on or before [INSERT DATE OF PUBLICATION OF THIS 

PROPOSED RULE IN THE FEDERAL REGISTER] must demonstrate 

compliance with the requirements of this subpart no later than 3

years after the effective date of this rule. Affected sources 

that commenced construction or reconstruction after the proposal 

date of this rule must demonstrate compliance with the 

requirements of this subpart no later than the effective date of 

the rule or upon start-up, whichever is later. We are proposing 

an initial performance test within 90 days of promulgation of 

the final rule.

With regard to total chromium compounds, we are proposing 

that the requirements under CAA section 112(f)(2), if finalized, 

must be implemented no later than 90 days after the effective 
Page 120 of 242

date of this rule, but the EPA may extend that timeframe for 

circumstances under which we believe the additional time is 

necessary for installation of air pollution control equipment or 

other measures to reduce HAP emissions. We are, therefore,

allowing affected sources up to one year from the effective date 

of this rule to demonstrate compliance with the chromium 

emission limits. Consistent with CAA section 112(f)(4)(B), we 

are proposing that a one-year compliance period is necessary so 

that affected facilities have adequate time to install 

additional controls and demonstrate compliance, including the 

time necessary to purchase, install and test control equipment.

Because these limits reflect the reductions from glass making 

furnaces required under both sections 112(d)(6) and 112(f)(2), 

we believe a one-year compliance timeframe is needed for the 

same reasons provided above. In addition, we are proposing that 

the PM emissions limit that would reflect reductions required 

for the glass making furnaces pursuant to CAA section 112(d)(6) 

must be met no later than one year after the effective date of 

this rule. We believe this time is needed to either enable 

installation of replacement bags, or if a facility decides to 

add a new baghouse in series with an existing baghouse, seek 

bids, select a vendor, install and test the new equipment; 

prepare and submit the reports in this proposed rule, if 

finalized.
Page 121 of 242

Therefore, we are proposing that wool fiberglass facilities 

would be required to show compliance with both PM and the 

chromium limits within 1 year of promulgation of this standard.

We are soliciting comments on this aspect of this proposed 

action.

Additionally, we propose that compliance with the proposed 

chromium compounds emissions limits be demonstrated by annual 

performance tests for all glass-melting furnaces subject to this 

rule as described in Section VI.B.2 of this preamble. We are 

proposing additional annual performance testing no later than 12 

calendar months following the initial or previous performance or 

compliance test to demonstrate compliance with the chromium 

compounds emissions limit for furnaces.

We are proposing both an initial performance test and

repeat testing every 5 years on the RS and FA lines and each 

time the binder formulation changes by more than 10 percent as 

compared to the binder formulation used in the initial 

performance test. We are seeking comment on whether the binder 

formulation variability of 10 percent as used here is 

appropriate. 

We are proposing that compliance testing for PM, 

formaldehyde, phenol and methanol be conducted using the same 

test methods as required by the 1999 MACT rule (i.e., Method 5 

for PM and Method 318 for formaldehyde, phenol and methanol). We 
Page 122 of 242

are proposing Test Method 26A be used to determine compliance 

for HF and HCl and Test Method 0061 be used to ensure compliance 

with the chromium compounds emission limit.

We propose that continuous monitoring of temperatures of 

control devices (e.g., fabric filters, wet and dry ESP, 

scrubbers) for glass-melting furnaces, RS manufacturing lines, 

and FA manufacturing lines will be required as parametric 

monitoring to ensure continuous compliance with the PM, chromium 

compounds, HF, HCl, formaldehyde, phenol and methanol emissions

limits.

Because the recent test data for glass-melting furnaces 

show a significant portion of the chromium compounds are 

hexavalent chromium, we are requiring Test Method 0061 be used 

to ensure compliance with the chromium compounds emission limit 

and as the most cost effective method to determine both total 

chromium and hexavalent chromium from wool fiberglass furnace 

stacks. Sources must report both total chromium and hexavalent 

chromium using this method or all chromium emissions are assumed 

to be hexavalent chromium.

6. Other Decisions and Actions.

In addition to the proposed decisions and actions discussed 

above, we are also proposing surrogacy changes and some general 

cleanup in terminology to the existing rule.

a. Surrogacy.
Page 123 of 242

As described in Sections III.B and VIII.B in this preamble, 

the Court found that the EPA has a “clear statutory obligation 

to set emission standards for each listed HAP.” Because we did 

not conduct analyses that would support the use of formaldehyde 

as a surrogate for methanol and phenol, we cannot currently

demonstrate that we established emission limits for the HAP 

methanol and phenol in the 1999 MACT standard. Therefore, we are 

proposing the emissions limits for phenol and methanol, which 

are presented in Tables 4-6, above.

b. Technical corrections to the rule.

We are also proposing revisions to certain terms in the 

existing NESHAP. Specifically, we are proposing to replace the 

term “incinerator” with “RTO” and specify performance test 

frequency. 

C. What are the proposed decisions and actions related to 

startup, shutdown and malfunction?

The United States Court of Appeals for the District of 

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

CAA section 112 regulations governing the emissions of HAP 

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

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

Specifically, the Court vacated the SSM exemption contained in 

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

regulation, commonly referred to as the “General Provisions 
Page 124 of 242

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

incorporated into CAA section 112(d) regulations for specific 

source categories, these two provisions exempt sources from the 

requirement to comply with the otherwise applicable CAA section 

112(d) emissions standard during periods of SSM.

We are proposing the elimination of the SSM exemption in 

this rule. Consistent with Sierra Club v. EPA, the EPA is 

proposing standards in this rule that apply at all times. We are 

also proposing several revisions to Table 1 to subparts DDD and 

NNN of part 63 (the General Provisions Applicability table). For 

example, we are proposing to eliminate the incorporation of the 

General Provisions’ requirement that the source develop an SSM 

plan. We also are proposing to eliminate or revise certain 

recordkeeping and reporting that related to the SSM exemption.

The EPA has attempted to ensure that we have not included in the 

proposed regulatory language any provisions that are 

inappropriate, unnecessary, or redundant in the absence of the 

SSM exemption. We are specifically seeking comment on whether 

there are any such provisions that we have inadvertently 

incorporated or overlooked.

In proposing the standards in this rule, the EPA has taken 

into account startup and shutdown periods and, for the reasons 

explained below, is proposing emissions limits for those 

periods. Information on periods of startup and shutdown received 
Page 125 of 242

from the industry survey indicate that emissions during these 

periods are less than emissions during production. Control 

devices such as baghouses for PM and metal HAP particulate 

control and RTO for COS control are started up before the 

process units, and are operational during the shutdown phase of 

a process. Therefore, no increase in emissions is expected 

during these periods. Because the processes are ducted to the 

control device before startup and after shutdown, and because 

emissions during startup and shutdown are not more than 

emissions during production, startup and shutdown emissions 

limits should be equivalent to the emissions limits for 

production. Production based emissions limits are expressed in 

this rule on a pound of pollutant per ton melt basis. However, 

during startup and shutdown, there is no melt being produced. 

Therefore, separate standards for periods of startup and 

shutdown were developed by translating the production-based 

emissions limits from a pound per ton basis to a pound of 

pollutant per hour basis and are being proposed in this rule.

Periods of startup, normal operations and shutdown are all 

predictable and routine aspects of a source’s operations.

However, by contrast, malfunction is defined as a “sudden, 

infrequent, and not reasonably preventable failure of air 

pollution control and monitoring equipment, process equipment or 

a process to operate in a normal or usual manner * * *” (40 CFR 
Page 126 of 242

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

require that emissions that occur during periods of malfunction

be factored into development of CAA section 112 standards. Under 

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

less stringent than the level “achieved” by the best controlled 

similar source and for existing sources generally must be no 

less stringent than the average emissions 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 

emissions standards. Moreover, while the EPA accounts for 

variability in setting emissions standards consistent with the 

CAA section 112 case law, nothing in that case law requires the 

agency to consider malfunctions as part of that analysis.

Section 112 of the CAA 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.

Further, accounting for malfunctions would be difficult, if 

not impossible, given the myriad different types of malfunctions 

that can occur across all sources in the category and given the 
Page 127 of 242

difficulties associated with predicting or accounting for the 

frequency, degree and duration of various malfunctions that 

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

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

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

typically has wide latitude in determining the extent of datagathering necessary to solve a problem. The court generally 

defers to the 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 
Page 128 of 242

malfunctions is consistent with CAA section 112 and is a 

reasonable interpretation of the statute. 

In the event that a source fails to comply with the 

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

malfunction event, the EPA would determine an appropriate 

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

the source to minimize emissions during malfunction periods, 

including preventative and corrective actions, as well as root 

cause analyses to ascertain and rectify excess emissions. The 

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

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

infrequent, not reasonably preventable” and was not instead 

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

CFR 63.2 (definition of malfunction).

Finally, the EPA recognizes that even equipment that is 

properly designed and maintained can sometimes fail and that 

such failure can sometimes cause an exceedance of the relevant 

emissions standard (see, e.g., State Implementation Plans: 

Policy Regarding Excessive Emissions During Malfunctions, 

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

Emissions During Startup, Shutdown, Maintenance and Malfunctions 

(Feb. 15, 1983)). The EPA is, therefore, proposing to add to the 

final rule an affirmative defense to civil penalties for 

exceedances of emissions limits that are caused by malfunctions.
Page 129 of 242

See 40 CFR 63.542 (defining “affirmative defense” to mean, in 

the context of an enforcement proceeding, a response or defense 

put forward by a defendant, regarding which the defendant has 

the burden of proof, and the merits of which are independently 

and objectively evaluated in a judicial or administrative 

proceeding). We also are proposing other regulatory provisions 

to specify the elements that are necessary to establish this 

affirmative defense; the source must prove by a preponderance of 

the evidence that it has met all of the elements set forth in 40 

CFR 63.552 (40 CFR 22.24). The criteria ensure that the 

affirmative defense is available only where the event that 

causes an exceedance of the emissions limit meets the narrow 

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

not reasonable preventable and not caused by poor maintenance 

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

the affirmative defense, the source must prove by a 

preponderance of the evidence that excess emissions “[w]ere 

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

pollution control and monitoring equipment, process equipment, 

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

criteria also are designed to ensure that steps are taken to 

correct the malfunction, to minimize emissions in accordance 

with 40 CFR 63.543(j) and to prevent future malfunctions. For 

example, the source must prove by a preponderance of the 
Page 130 of 242

evidence that “[r]epairs were made as expeditiously as possible 

when the applicable emissions limitations were being exceeded...”

and that “[a]ll possible steps were taken to minimize the impact 

of the excess emissions on ambient air quality, the environment 

and human health....” In any judicial or administrative 

proceeding, the Administrator may challenge the assertion of the 

affirmative defense and, if the respondent has not met its 

burden of proving all of the requirements in the affirmative 

defense, appropriate penalties may be assessed in accordance 

with CAA section 113 (see also 40 CFR 22.27).

The EPA included an affirmative defense in the proposed 

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

of air regulation, to ensure adequate compliance while 

simultaneously recognizing that despite the most diligent of 

efforts, emission limits may be exceeded under circumstances 

beyond the control of the source. The EPA must establish 

emission standards that “limit the quantity, rate, or 

concentration of emissions of air pollutants on a continuous 

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

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

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

that section 112 emissions limitations are continuous. The 

affirmative defense for malfunction events meets this

requirement by ensuring that even where there is a malfunction, 
Page 131 of 242

the emission limitation is still enforceable through injunctive 

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

required, there is also case law indicating that in many 

situations it is appropriate for the EPA to account for the 

practical realities of technology. For example, in Essex 

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

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 undermine the relevance of these 

cases today, they support the EPA’s view that a system that 

incorporates some level of flexibility is reasonable. The 

affirmative defense simply provides for a defense to civil 

penalties for excess emissions that are proven to be beyond the 

control of the source. By incorporating an affirmative defense, 

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, 
Page 132 of 242

1272-73 (9th Cir. 1977). 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.

D. What are the proposed decisions and actions related to 

electronic reporting?

Records must be maintained in a form suitable and readily 

available for expeditious review, according to 63.10(b)(1). 

Electronic recordkeeping and reporting is available for many 

records, and is the form considered most suitable for 

expeditious review if available. Electronic recordkeeping and 

reporting is encouraged in this proposal and some records and 

reports are required to be kept in electronic format. Records 

required to be maintained electronically include the output of 

continuous monitors and the output of the BLDS. Additionally, 

standard operating procedures for the BLDS and fugitive 

emissions control are required to be submitted to the 

Administrator for approval in electronic format. 

VII. Rationale for the Proposed Actions for the Mineral Wool 

Production Source Category
Page 133 of 242

As discussed in Section VI.A of this preamble, we evaluated 

emissions limits for PM, COS, HF, HCl, formaldehyde, phenol and 

methanol at mineral wool production facilities. This section of 

the preamble provides the results of the RTR, our rationale for 

the proposed actions and decisions concerning changes to the 

1999 MACT rule for the Mineral Wool Production source category.

A. What data were used for the NESHAP analyses?

To perform the technology review and residual risk analysis 

for the Mineral Wool NESHAP, we created a comprehensive dataset 

based on existing and new test data provided by the 7 mineral 

wool facilities. As described in Section IV.C of this preamble,

the voluntary industry survey requested available information 

regarding process equipment, control devices, point and fugitive 

emissions, practices used to control fugitive emissions, and 

other aspects of facility operations. In addition to the 

industry survey, each owner/operator was asked to submit reports 

for any recent emissions tests conducted at their facility and 

to conduct additional emissions tests in 2010 for certain HAP 

from specific processes. Pollutants tested for the mineral wool 

source category in 2010 included most HAP metals, CO, PM and 

certain organic HAP (formaldehyde, phenol, methanol and carbonyl 

sulfide).

B. What are the proposed decisions regarding surrogacy 

relationships?
Page 134 of 242

In the 1999 MACT rule, PM serves as the surrogate for metal

HAP42 at existing and new cupolas, CO serves as the surrogate for 

COS at new cupolas and formaldehyde serves as the surrogate for 

phenol and methanol from curing ovens. The 1999 MACT standard 

does not have emissions limits for COS, HCl or HF from existing 

cupolas; limits for phenol or methanol from curing; or emissions 

limits for any pollutants from collection operations. We are 

proposing HAP-specific emission limits for these pollutants 

under CAA section 112(d)(3)in this action. The agency is 

retaining use of PM as a surrogate for HAP metals. As discussed 

in Sections III.B and VII.B. of this preamble, the Court found 

that the EPA must set emission limits for each listed HAP

(Sierra Club v. EPA, 479 F. 3d 875 (D.C. Cir. March 13, 2007))

3,

and agreed with the EPA that nothing in the CAA suggests that it 

is prohibited from resetting the MACT floors in order to correct 

our own errors. They also agreed that the approach our 

petitioners labeled “MACT-on-MACT” would be more accurately 

described as “MACT-on-Unsupportable-Standards-ErroneouslyLabeled-as-MACT”

44. With regard to the evaluation of potential 

MACT limits for HAP metals from this source category, consistent 

with the explanation presented in the proposal of the 1999 MACT 

 

42 The HAP metals emitted from mineral wool cupolas include 

antimony, arsenic, beryllium, cadmium, chromium, cobalt, 

mercury, manganese, nickel, lead and selenium.

44 Sierra Club v. EPA, 167 F. 3d 658 (D.C. Cir. March 2, 1999)
Page 135 of 242

rule (NESHAP for Mineral Wool Production, Proposed Rule, June 1, 

1997, 64 FR 29490) for this source category describing the 

appropriateness of PM as a surrogate for HAP metals, we continue 

to consider PM as an appropriate surrogate for HAP metals in the 

proposed amendments to the NESHAP in this action.

The agency is proposing emissions limits for phenol and 

methanol because the concentration of formaldehyde in a specific 

binder formulation is independent of phenol and/or methanol. The 

mineral wool industry commented during the small business 

advocacy review that the binder ingredients and formulation can 

vary from one mineral wool company to the next, and that the 

test data from one company is not necessarily relevant for or 

representative of another company.

In summary, under 112(d)(3) we are proposing emission 

limits for COS, HF and HCl from cupolas; and for formaldehyde, 

methanol and phenol from bonded lines. 

C. What are the proposed decisions regarding certain unregulated 

emissions sources?

In the course of evaluating the Mineral Wool Production 

source category, we identified certain HAP for which we failed 

to establish emission standards in the original MACT. See 

National Lime v. EPA, 233 F. 3d 625, 634 (D.C. Cir. 2000) (the 

EPA has “clear statutory obligation to set emissions standards 

for each listed HAP”). Specifically, we evaluated emissions 
Page 136 of 242

standards for COS, HF and HCl for cupolas and formaldehyde, 

phenol and methanol for curing ovens and collection operations

at mineral wool production facilities, that are not specifically 

regulated in the existing 1999 MACT standard. We are proposing 

emissions limits for these pollutants and processes pursuant to 

112(d)(2) and 112(d)(3) as discussed in Section V.A of this 

preamble.

D. What are the proposed decisions regarding subcategorization?

The EPA collected information from the mineral wool 

companies that operate bonded lines to better understand the 

different equipment designs and whether all collection processes 

are the same, or whether design and manufacturing process 

differences warranted consideration of subcategories for the 

collection process. This process led to the identification of 

three distinct process design subcategories: vertical, 

horizontal and drum. Because collection processes only emit HAP 

if they occur on a bonded line, we are proposing to bundle 

collection operations and curing ovens together for each of 

three subcategories and propose new emissions limits for 

formaldehyde, phenol, and methanol at combined collection/curing 

on bonded lines. The following discussion involves the rationale 

for subcategorization of collection operations into three 

subcategories:

1. The Vertical Collection Design.
Page 137 of 242

During the production of wool fiberglass on a bonded 

production line using a vertical collection design, the molten 

rock/slag mixture is poured from the cupola spout onto a group 

of stainless steel drums spinning in opposite directions. The 

spinning drums form fine fibers of the mineral mixture. High air 

volume directs the fibers off the fiberization spinners toward a 

fast-moving porous vertical conveyor belt. A strong vacuum is 

drawn on the opposite side of the belt causing the fibers to lie

against the vertical belt as it moves upward. At the top of the 

conveyance, the belt travels around a curve, the vacuum is 

released, and the fibers are moved onto a second belt that 

conveys the layer of binder-sprayed mineral wool fibers into the 

curing oven. Because the conveyor belt is vertical, the air 

volume drawn through the belt and fiber layer must be very high 

and the resulting fiber layer that is collected on the belt is 

thin. In this design, ‘shot’ (BB-sized black granules that are 

high in iron as a result of using slag from the iron and steel 

industry) falls out of the fiber layer. The vertical design is 

used to produce a specific type of mineral wool that is low in 

‘shot’ and may be used in the hydroponic gardening market as 

well as in a specialized market of insulation products in which 

shot is undesirable. 

Currently, only one facility operates this type of 

collection design. Formaldehyde, phenol and methanol MACT floors 
Page 138 of 242

for existing, new and reconstructed sources in this subcategory 

were based on emissions test runs for combined curing and 

collection operations from this facility.

2. The Horizontal Collection Design.

Horizontal collection is similar to vertical collection, 

but because the conveyor belt is horizontal it works with 

gravitational forces. The layer of mineral wool collected on a 

horizontal belt is thinner than that collected on a vertical 

belt, and the ‘shot’ is not selectively removed. The air volume 

that is drawn through the fiber layer is much lower than in the 

vertical design, and therefore the air stream is conducive to 

thermal oxidation at the hottest part of the cupola exhaust 

stack or the existing thermal oxidizer on the curing oven. 

Currently, only one facility operates this type of 

collection design. Formaldehyde, phenol and methanol MACT floors 

for existing, new and reconstructed sources in this subcategory 

were based on emissions test runs for combined curing and 

collection operations from this facility.

3. The Drum Collection Design.

In the drum collection design, fibers are drawn using a 

very high volume air flow into the center of a rotating drum.

The sides of the rotating drum have small holes that allow the 

air flow to exit, but which trap the fibers. The angle of the 

drum and the use of a vacuum and centrifugal force pull the 
Page 139 of 242

fibers against the inside wall of the drum and out the end. The 

entire drum is enclosed and the air flow may be vented to the 

hottest part of the cupola exhaust stack or to the existing 

thermal oxidizer on the curing oven.

Currently, only one facility operates this type of 

collection. Formaldehyde, phenol, and methanol MACT floors for 

existing, new, and reconstructed sources in this subcategory 

were based on emissions test runs for combined curing and 

collection operations from this facility.

E. What are the results from the risk assessments performed and 

the proposed decisions for the Mineral Wool Production Source 

Category?

As described in Section V.A of this preamble, we conducted 

an inhalation risk assessment for all HAP emitted from the 

Mineral Wool Production source category. We also conducted 

multipathway screenings for cadmium, mercury, and lead. Details 

of the risk assessments and additional analyses can be found in 

the draft residual risk documentation referenced in Section V.A

of this preamble, which is available in the docket for this 

action. The agency considered the available health information -

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

incidence; the maximum non-cancer HI; the maximum acute noncancer hazard; the extent of non-cancer risks; the potential for 

adverse environmental effects; and the distribution of risks in 
Page 140 of 242

the exposed population (54 FR 38044, September 14, 1989) – in 

developing the proposed CAA section 112(f)(2) standards for the 

Mineral Wool Production source category.

1. Inhalation Risk Assessment Results for the Mineral Wool 

Production Source Category.

Table 7 of this preamble provides an overall summary of the 

results of the inhalation risk assessment. 

Table 7. Mineral Wool Production Inhalation Risk Assessment 

Results

Maximum

Individual

Cancer Risk

(in 1 million)1

Estimated 

Population

at 

increased 

Risk of 

cancer ≥ 

1-in-1 

Million

Estimated 

Annual

Cancer

Incidence 

(cases 

per year)

Maximum

Chronic Non-cancer

TOSHI2

Maximum 

Screening

Acute 

Noncancer 

HQ3

Based on 

Actual 

Emissions 

Level

Based on 

Allowable 

Emissions 

Level

Based on 

Actual 

Emissions 

Level

Based on 

Allowable 

Emissions 

Level

4 10 1,650 0.0004 0.04 0.1

8 (REL)

0.4 

(AEGL-1, 

ERGP-1)

1 Estimated maximum individual excess lifetime cancer risk due to HAP 

emissions from the source category.

2 Maximum TOSHI. The highest TOSHI for the Mineral Wool Production source 

category is for the respiratory system. 

3 The maximum HQ acute value of 8 is driven by emissions of formaldehyde. It 

is also based on a refined emissions multiplier of 3 which was used to 

estimate the peak hourly emission rates from the average rates. See section 

V.A. of this preamble for explanation of acute dose-response values.

The results of the chronic inhalation cancer risk 

assessment indicate that, based on estimates of current actual 

emissions, the MIR could be up to 4-in-1 million, with 

formaldehyde primarily driving these risks. The total estimated 

cancer incidence from this source category based on actual 

emission levels is 0.0004 excess cancer cases per year or one 
Page 141 of 242

case in every 2,500 years, with emissions of formaldehyde and 

arsenic compounds contributing 64 percent and 33 percent,

respectively, to this cancer incidence45. In addition, we note 

that no persons are estimated to have cancer risks greater than 

10-in-1 million, and approximately 1,650 people are estimated to 

have risks greater than 1-in-1 million as a result of emissions 

from 1 facility. When considering the risks associated with 

MACT-allowable emissions, the MIR could be up to 10-in-1 

million. The maximum modeled chronic non-cancer TOSHI value for 

the Mineral Wool Production source category could be up to 0.04 

with emissions of formaldehyde dominating those impacts, 

indicating no significant potential for chronic non-cancer 

impacts.

Our screening analysis for worst-case acute impacts 

indicates the potential for only one pollutant, formaldehyde, to 

exceed an HQ value of 1 at only one facility in this source 

category, with a potential maximum HQ up to8. A refined 

emissions multiplier of 3 was used to estimate the peak hourly 

emission rates from the average rates. Refer to Appendix 7 of 

 

45 We note that the MIR for this source category would not change 

if the CIIT URE for formaldehyde had been used in the 

assessment, although the total cancer incidence would decrease 

by 52 percent. The MIR for the source category would remain at 

40 due to Cr(VI). There is an ongoing IRIS reassessment for 

formaldehyde, and future RTR risk assessments will use the 

cancer potency for formaldehyde that results from that 

reassessment. As a result, the current results may not match

those of future assessments.
Page 142 of 242

the draft residual risk document in the docket for a detailed 

description of how the refined emissions multiplier was 

developed for the Mineral Wool Production source category. The 

worst-case acute impact estimate occurs at a facility that is 

located in a rural area with a small population. Since the acute 

modeling scenario is worst-case because of its confluence of 

peak emission rates and worst-case dispersion conditions, and 

since the HQ estimates for formaldehyde based on the AEGL-1 and 

ERPG-1 values for this facility are well below 1, we are 

proposing to find that acute noncancer health impacts of concern 

are unlikely. 

With respect to the potential for adverse environmental 

effects from non PB-HAP, we note that that there is a lack of 

information about specific adverse environmental effects 

occurring at given concentrations of the HAP emitted by this 

source category. However, given that all chronic non-cancer HQ

values considering actual emissions are less than 1 using human 

health reference values, we believe that it is unlikely that 

adverse environmental effects would occur at the actual HAP 

concentrations estimated in our human health risk assessment.

2. Multipathway Risk Assessments and Results.

There were no exceedances of screening emissions rates for 

the PB HAP emitted by the facilities in the Mineral Wool 
Page 143 of 242

Production source category, thus we have no concerns about 

potential multi-pathway risks from this source category.

3. Facility Wide Risk Assessment Results.

For all facilities in this source category, there are no 

other significant HAP emissions sources present beyond those 

included in the source category. All significant HAP sources 

have been included in the source category risk analysis.

Therefore, we conclude that the facility wide risks are 

essentially the same as the source category risks.

F. What are our proposed decisions for the Mineral Wool 

Production source category based on risk acceptability and ample 

margin of safety?

1. Risk Acceptability 

As noted in Section V.A of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the numbers of persons in various risk 

ranges; cancer incidence; the maximum noncancer HI; the maximum 

acute noncancer hazard; the extent of noncancer risks; the 

potential for adverse environmental effects; and distribution of 

risks in the exposed population; and risk estimation uncertainty 

(54 FR 38044, September 14, 1989) in developing the proposed CAA 

section 112(f)(2) standards for this source category.

Based on the inhalation risk assessment, we estimate that 

the cancer risks to the individual most exposed could be up to
Page 144 of 242

4-in-1 million due to actual emissions and up to 10-in-1 million 

due to MACT-allowable emissions, mainly due to formaldehyde 

stack emissions. We estimate that the incidence of cancer based 

on actual emissions is 0.0004 excess cancer cases per year or 

one case every 2,500 years, and that about 1,650 people face a 

cancer risk greater than 1-in-1 million due to HAP emissions 

from this source category. Our assessments also indicated a low 

potential for HAP emissions from these sources to pose any 

significant adverse environmental effects or human health multipathway risks or chronic noncancer human health risks due to 

inhalation. While our acute risk screening ruled out the 

possibility of acute impacts of concern for all pollutants 

except for formaldehyde at one facility, we ultimately concluded 

that the potential for acute impacts of concern at this facility 

is low. The risk assessment for this source category was largely 

based on facility-specific stack test data and emissions 

estimates, indicating a high degree of confidence in the 

results. Considering all of the above information, we are 

proposing that the current risks due to actual HAP emissions 

from this source category are acceptable. 

While the estimated chronic risks associated with MACTallowable emissions from this source category are slightly 

higher than risk estimates based on actual emission levels, they 

are still well below 100 in one million and there are no other 
Page 145 of 242

significant risks. Therefore, we propose the risks due to 

allowable emissions are also acceptable.

2. Ample Margin of Safety.

As explained earlier in Section V of this preamble, the 

agency again considers all of the health risks and other health 

information considered in the first step. Beyond that

information, we evaluate the cost and feasibility of available 

control technologies and other measures (including the controls, 

measures and costs reviewed under the technology review) that 

could be applied in this source category to further reduce the 

risks due to emissions of HAP identified in our risk assessment. 

Based on our research and analyses as discussed in Section 

V.C of this preamble, we have not identified any feasible 

control options beyond what we are requiring in our proposed 

standards for emissions sources described above, and are 

therefore not proposing additional controls, under section 

112(f)(2). Therefore, we are proposing that the MACT standards 

for the mineral wool production source category, as revised per 

above, provide an ample margin of safety to protect public 

health and prevent adverse environmental effects.

Nevertheless, we are soliciting comments and information 

regarding additional control measures and work practices that 

may be available and their feasibility in further reducing stack

emissions of COS, HF, HCl, formaldehyde, phenol, and methanol,
Page 146 of 242

or additional monitoring that may be warranted to ensure 

adequate control of these emissions.

G. What are the results from the technology review and proposed 

decisions?

Based on our technology review, we believe that the 

reductions in HAP emissions since promulgation of the 1999 

Mineral Wool Production MACT rule are directly related to 

improvements in two areas: (1) improvements in fabric filter 

control technology (e.g., improved bag materials, replacement of 

older baghouses) and (2) addition of regenerative thermal 

oxidizers (RTOs) and oxygen injection to control emissions from 

cupolas. Additional reductions have been achieved due to the use 

of low-sulfur raw materials at one facility. The RTOs and lower 

sulfur raw materials are discussed above (in Section VII.C of 

this preamble) since these controls and measures are relevant to 

development of the MACT standards for COS and other organic HAPs 

under Section 112(d)(2) of the CAA, and in the beyond the floor 

analyses (described in Section VII.C of this preamble) that we 

also do as part of the MACT standard evaluations under Section 

112(d)(2) and 112(d)(3).

In this section, as part of our technology review, we 

describe developments in development in fabric filter

technologies and the relationship to PM emissions.
Page 147 of 242

Slight improvements in fabric filter control technology are 

reflected in the emissions test data collected under the 

industry survey. The emissions limit for PM under the 1999 MACT 

rule is a production-based limit of 0.1 pounds of PM per ton of 

melt for new and existing cupolas. Based on our analysis of 

survey responses and test data collected under the industry 

survey, this industry primarily uses fabric filters to control 

emissions of metal HAP, and sources affected by the current PM 

limit are achieving PM concentrations at control device outlets 

that are only slightly below the current limit (see Technology 

Review for the Mineral Wool Production Manufacturing Source 

Category). Given fluctuations in control device performance and 

mineral wool production fluctuations, we do not believe that 

developments in practices, processes, and control technologies 

warrant revisions to the PM limit in the 1999 MACT rule to 

reflect HAP metal emissions levels achieved in practice.

Moreover, the RBLC did not identify any practices, 

processes, or control technologies applicable to the emission 

sources in this source category that were not identified and 

evaluated during the original MACT development. 

In summary, we have not identified any additional relevant 

cost-effective developments in technologies, practices or 

processes since promulgation of the MACT rule to further reduce 

HAP emissions. Therefore, we are not proposing any changes to 
Page 148 of 242

the MACT standards in this action as a result of our technology 

review under Section 112(d)(6) for Mineral Wool Production.

Additional details regarding these analyses can be found in 

the following technical document for this action which is 

available in the docket: Technology Review for the Mineral Wool 

Production Manufacturing Source Category.

VIII. Rationale for the Proposed Actions for the Wool Fiberglass 

Manufacturing Source Category

As discussed in Section VI.B of this preamble, we evaluated 

emissions limits for PM, chromium compounds, HF, HCl, 

formaldehyde, phenol, and methanol at wool fiberglass 

manufacturing facilities. This section of the preamble provides 

the results of the RTR, our rationale for the proposed actions 

for the Wool Fiberglass Manufacturing source category, and our 

proposed decisions concerning changes to the 1999 MACT rule.

A. What data were used for the NESHAP analyses?

To perform the technology review and residual risk analysis 

for the Wool Fiberglass Manufacturing NESHAP, we created a 

comprehensive dataset based on existing and new test data 

provided by 26 of the 29 wool fiberglass facilities. As 

described in Section IV.C of this preamble, the voluntary 

industry survey requested available information regarding 

process equipment, control devices, point and fugitive 

emissions, practices used to control fugitive emissions, and 
Page 149 of 242

other aspects of facility operations. In addition to the ICR 

survey, each facility was asked to submit reports for any recent 

emissions tests conducted and to conduct additional emissions 

tests in 2010 for certain HAP from specific processes.

Pollutants tested for the wool fiberglass source category in 

2010 included most HAP metals, PM, and certain organic HAP (HF, 

HCl, formaldehyde, phenol, and methanol).

As discussed in Section IV.C above, in the emissions 

testing for the survey, industry requested to conduct emission 

testing on furnaces they believed were representative of the 

other furnaces in operation. The EPA and industry agreed that 

the bases for representativeness would include a variety of 

factors such as processing the same materials, producing the 

same products and being the same type of furnace. Furnace 

construction and refractory composition were not factors that 

were presented by industry as having an effect on HAP emissions, 

and those factors were not used as a basis of representativeness 

for the resulting data set. During analysis of the test data, 

the EPA discovered high emissions of chromium compounds, 

including hexavalent chromium, and that these emissions were 

mostly from certain furnaces constructed of high chrome 

refractories.

The Wool Fiberglass Manufacturing source category consists 

of 29 facilities with 80 furnaces, 54 RS manufacturing lines and 
Page 150 of 242

less than 30 FA manufacturing lines. Since there are more than 

30 furnaces and RS lines, we based the MACT floor limits on the 

average emissions limitation achieved by the best performing 12 

percent of sources. Therefore, the MACT floor for HF and HCl 

from glass-melting furnaces was based on the 10 best performing 

furnaces; the 7 best performing RS lines; and the 5 best 

performing FA lines.

The stack test data were used to calculate the MACT floors 

using the 99 percent UPL for glass-melting furnaces, RS

manufacturing lines, and FA manufacturing lines from wool 

fiberglass manufacturing plants. The UPL analysis is explained 

in more detail in MACT Floor Analysis for the Wool Fiberglass 

Manufacturing Source Category, which is available in the docket 

for this proposed action. The results from the MACT floor 

analysis are presented in Section VI.B of this preamble.

B. What are the proposed decisions regarding surrogacy 

relationships?

A surrogate approach is used to allow for easier and less 

expensive measurement and monitoring requirements. In the 1999 

MACT rule for this source category, PM serves as the surrogate 

for metal HAPs46 at existing and new glass-melting furnaces and 

 

46 The HAP metals emitted from wool fiberglass glass-melting 

furnaces include antimony, arsenic, beryllium, cadmium, 

chromium, cobalt, mercury, manganese, nickel, lead, and 

selenium.
Page 151 of 242

formaldehyde serves as the surrogate for phenol and methanol 

from forming and curing at RS manufacturing lines and forming 

and curing at FA manufacturing lines. As described in Sections

III.B and VIII.B in this preamble, the court found that the EPA 

erred when we did not set emission limits for each HAP emitted 

by industry processes in the MACT standards.

48 Therefore, the

agency is proposing HAP-specific emissions limits for phenol and 

methanol.

C. What are the proposed decisions regarding certain unregulated 

emissions sources?

As discussed earlier in Section VI.B of this preamble, we 

identified certain HAP for which we failed to establish emission 

standards in the original 1999 MACT. In the 1999 MACT rule, we 

used formaldehyde as a surrogate for phenol and methanol, and we 

did not establish HAP-specific emission limits for phenol, 

methanol, HF and HCl. For this action we evaluated emissions 

standards for HF, HCl, phenol, and methanol at wool fiberglass 

manufacturing facilities, described below, that are not 

specifically regulated in the existing 1999 MACT standard. The 

EPA is therefore proposing to set emissions limits for these HAP 

emissions, under CAA section 112(d)(3) in this action.

 

48 Sierra Club v. EPA, 479 F. 3d 875 (D.C. Cir. March 13, 2007).
Page 152 of 242

D. What are the results from the risk assessments and analyses 

and the proposed decisions for the Wool Fiberglass Manufacturing 

Source Category?

An inhalation risk assessment was completed for all HAP 

emitted for the Wool Fiberglass Manufacturing source category.

Details of the risk assessments and additional analyses can be 

found in the residual risk documentation referenced in Section 

V.A of this preamble. The agency considered the available health 

information -- the MIR; the numbers of persons in various risk 

ranges; cancer incidence; the maximum non-cancer HI; the maximum 

acute non-cancer hazard; the extent of non-cancer risks; the 

potential for adverse environmental effects; and distribution of 

risks in the exposed population (54 FR 38044, September 14, 

1989) – in developing the proposed CAA section 112(f)(2) 

standards for the Wool Fiberglass Manufacturing source category.

1. Inhalation Risk Assessment Results for the Wool 

Fiberglass Manufacturing Source Category.

Table 8 of this preamble provides an overall summary of the 

results of the inhalation risk assessment. 

Table 8. Wool Fiberglass Manufacturing Inhalation Risk 

Assessment Results

Maximum

Individual

Cancer Risk

(in 1 million)1

Estimated 

Population

at 

increased 

Risk of 

cancer ≥ 

1-in-1 

Million

Estimated 

Annual

Cancer

Incidence 

(cases 

per year)

Maximum

Chronic Non-cancer

TOSHI2

Maximum 

Screening

Acute 

Noncancer 

HQ3

Based on 

Actual 

Emissions 

Level

Based on 

Allowable 

Emissions 

Level

Based on 

Actual 

Emissions 

Level

Based on 

Allowable 

Emissions 

Level
Page 153 of 242

40 60 849,000 0.05 0.2 0.5

30 (REL)

2 (AEGL1, ERPG1)

1 Estimated maximum individual excess lifetime cancer risk due to HAP 

emissions from the source category. Hexavalent chromium is the primary 

driver for cancer risk.

2 Maximum TOSHI. The highest TOSHI for the Wool Fiberglass Manufacturing 

source category is for the respiratory system.

3 The maximum HQ acute value of 30 is driven by emissions of formaldehyde. See 

section V.A. of this preamble for explanation of acute dose-response 

values.

The results of the chronic inhalation cancer risk 

assessment indicate that, based on estimates of current actual 

emissions, the maximum individual lifetime cancer risk (MIR) 

could be up to 40-in-1 million. The major contributor to this 

cancer risk is hexavalent chromium that is emitted from the 

furnace refractory brick. The greatest amount of hexavalent 

chromium emitted from a single source is from a facility that 

currently uses a type of refractory brick that is made almost 

entirely of chromium compounds. In addition, we note that 

approximately 12,000 people are estimated to have cancer risks 

greater than 10-in-1 million as a result of formaldehyde and 

hexavalent chromium emissions at 2 facilities, and approximately 

849,000 people are estimated to have risks greater than 1-in-1 

million as a result of formaldehyde and hexavalent chromium

emissions from 15 facilities. The maximum estimated chronic noncancer TOSHI value for the Wool Fiberglass Manufacturing source 

category is 0.2 with emissions of formaldehyde dominating those 
Page 154 of 242

impacts, indicating no significant potential for chronic noncancer impacts.

Based on the acute REL to assess possible acute non-cancer 

effects due to emissions of formaldehyde, our analysis indicates

that the maximum acute HQ value could exceed a value of 1 at a 

total of 7 facilities due to formaldehyde emissions49, with one

facility in this source category indicating the potential to 

create a maximum worst-case HQ value up to 30. This maximum 

worst-case acute impact corresponds to a maximum HQ of 2 based 

on the AEGL-1 and ERPG-1 levels for formaldehyde. Altogether, 

these results indicate that we cannot rule out the potential for 

formaldehyde emissions from this source category to cause acute 

impacts of mild concern, such as eye and nose irritation. 

Repeated exposures to these levels (i.e., at or above the AEGL-1 

and ERPG-1) could cause further health concerns.

With respect to the potential for adverse environmental 

effects from non PB-HAP, we note that that there is a lack of 

information about specific adverse environmental effects 

occurring at given concentrations for the HAP emitted by this 

source category. However, given that all chronic non-cancer HQ 

values considering actual emissions are less than 1 using human 

health reference values, we believe that it is unlikely that 

 

49 Individual facility acute HQ values for all facilities can be 

found in Appendix 6 of the risk assessment document that is 

included in the docket for this proposed rulemaking. 
Page 155 of 242

adverse environmental effects would occur at the actual HAP 

concentrations estimated in our human health risk assessment.

2. Auxiliary Risk Characterization.

As indicated in Section VIII.D.1 above, the MIR for the 

Wool Fiberglass Manufacturing source category could be up to 40-

in-1-million based on actual emissions. The major contributor to 

this cancer risk is hexavalent chromium. The greatest amount of 

risk is from one facility that uses a type of refractory brick 

that is described by the company as “high chrome”12,13.( (Notes of 

April 14, 2011, Certainteed); (Region 7 Certainteed Notes).

Because the use of high chrome refractories extends the 

life of the furnace from a maximum of 10 years to at least 15 

years, and the cost of furnace construction is increased by 

about 15 percent when it is reconstructed using high chrome 

refractories12 (Notes of April 14, 2011, Certainteed) we believe 

that there is a financial incentive for other facilities to 

switch to this high chromium refractory at the time they rebuild

their furnaces. For this reason, we performed an auxiliary risk 

characterization analysis to assess the potential maximum 

individual lifetime cancer risks in the event that the other 28 

Wool Fiberglass facilities switch to the high chromium brick.

For the auxiliary risk characterization analysis it was assumed 

that the hexavalent chromium emissions for each facility would 

be the same as that for the facility with annual emissions of 
Page 156 of 242

420 lbs of hexavalent chromium per furnace. Table 9 of this 

preamble provides a summary of the results of this auxiliary 

inhalation risk assessment.

Table 9. Wool Fiberglass Manufacturing Auxiliary Inhalation Risk 

Assessment Results

Potential 

Maximum

Individual

Cancer Risk

(in 1 million)1

Estimated 

Population

at increased 

Risk of 

cancer ≥ 1-

in-1 Million

Estimated 

Population

at increased 

Risk of 

cancer ≥ 10-

in-1 Million

Estimated 

Population

at increased 

Risk of 

cancer ≥ 100-

in-1 Million

Estimated 

Annual

Cancer

Incidence 

(cases per 

year)

Based on Actual 

Emissions Level

900 7,300,000 460,000 8,100 0.46

1 Estimated maximum individual excess lifetime cancer risk due to HAP 

emissions from the source category.

The results of the auxiliary analysis indicate that, under 

this scenario, the estimated emissions from 14 facilities could 

lead to maximum individual lifetime cancer risks greater than 

100-in-1-million, with the highest emitting facility posing a 

potential maximum individual risk of 900-in-1-million. Under 

this scenario, 8,100 people would be exposed to risks greater 

than 100-in-1-million, 460,000 people would be exposed to risks 

of greater than 10-in-1-million, and over 7 million people would 

be exposed to cancer risks of greater than 1-in-1-million.

In summary, the auxiliary risk analysis indicates that if 

other facilities switch to high chromium refractory, emissions 

of hexavalent chromium could potentially pose unacceptable risks 

to public health due to inhalation exposures resulting from 

stack emissions of hexavalent chromium.
Page 157 of 242

3. Multipathway Risk Assessments and Results.

None of the facilities in the Wool Fiberglass Manufacturing 

source category reported emissions of PB HAP that were greater 

than the screening emission rates. Therefore, multi-pathway 

exposures and environmental risks were deemed negligible.

4. Facility Wide Risk Assessment Results.

For this source category, there are no other significant 

HAP emissions sources present beyond those included in the 

source category. All significant HAP sources have been included 

in the source category risk analysis. Therefore, we conclude 

that the facility wide risk is essentially the same as the 

source category risk and that no separate facility wide analysis 

is necessary.

E. What are our proposed decisions for the Wool Fiberglass 

Manufacturing source category based on risk acceptability and 

ample margin of safety?

1. Risk Acceptability.

As noted in Section VIII.D of this preamble, we weigh all 

health risk factors in our risk acceptability determination, 

including the MIR; the numbers of persons in various risk 

ranges; cancer incidence; the maximum noncancer HI; the maximum 

acute noncancer hazard; the extent of noncancer risks; the 

potential for adverse environmental effects; and distribution of 

risks in the exposed population; and risk estimation uncertainty 
Page 158 of 242

(54 FR 38044, September 14, 1989) in developing the proposed CAA 

section 112(f)(2) standards for this source category.

Based on the inhalation risk assessment, we estimate that 

the cancer risks to the individual most exposed could be up to

as 40-in-1 million due to actual emissions and up to as 60-in-1 

million due to MACT-allowable emissions, mainly due to 

formaldehyde and chromium stack emissions. We estimate that the 

incidence of cancer based on actual emissions is 0.05 excess 

cancer cases per year or one case every 20 years, and that about 

850,000 people face a cancer risk greater than 1-in-1 million 

due to the HAP emissions from this source category. 

Our assessments also indicate a low potential for HAP 

emissions from these sources to pose any significant adverse 

environmental effects, human health multi-pathway effects, or

chronic noncancer human health risks. Our acute risk screening 

ruled out the possibility of acute impacts of concern for all 

pollutants but one, formaldehyde, at seven facilities, with a 

maximum worst-case HQ estimated to be 30 based on the REL and 2 

based on the AEGL-1 (or ERPG-1, which is equivalent). While this 

means we cannot rule out the potential for acute concerns due to 

formaldehyde emissions from these facilities, we note that the 

use of formaldehyde is being phased out in this industry, and 

will be eliminated from all but 2 facilities in the source 

category. Since the cancer risks due to actual and allowable 
Page 159 of 242

emissions (based on the current composition of refractory bricks 

used by this source category) are well within the acceptable 

range (i.e., less than 100-in-1 million) and since we have no 

additional significant concerns regarding other potential human 

health or environmental impacts, we are proposing that the 

current risk levels due to actual and MACT-allowable emissions 

are acceptable.

2. Ample Margin of Safety Analysis and Proposed Decisions.

As described above, we are proposing that the risks 

associated with the actual and MACT-allowable stack emissions 

from this source category are acceptable based on the current 

composition of refractory bricks used by this source category. 

However, as discussed in Section VIII.D(2) of this preamble, if 

other wool fiberglass facilities reconstructed their furnaces 

with high chromium refractory bricks, the maximum individual 

cancer risks would be higher and likely result in a finding of 

unacceptable risks.

According to our 2-step process for assessing risks, after 

we evaluate whether risks are ‘acceptable’ we evaluate whether 

cost effective measures are available to reduce risks further, 

to provide an ‘ample margin of safety’. As stated in Section 

VIII.F of this preamble, both NaOH scrubbers and a furnace 

rebuild are considered cost effective when hexavalent chromium 

levels are high. NaOH scrubbers achieve at least 95 percent 
Page 160 of 242

reduction in hexavalent chromium emissions at other industries. 

Transferring this technology to the wool fiberglass industry is 

reasonable and would reduce hexavalent chromium to levels that 

would achieve an ample margin of safety. Therefore, we are 

proposing emission limits of 0.06 lb of total chromium compounds 

per thousand tons (or 60 lb of total chromium compounds per 

million tons) of glass pulled in this action (as presented in 

Table 10) under Section 112(f)(2) of the CAA in this action. We 

believe this limit would achieve an ample margin of safety to 

protect public health and prevent adverse environmental effects. 

Table 10. Proposed Emissions limits for Glass-Melting Furnaces 

based on Risk Review

Pollutant Pounds of pollutant per thousand tons of 

melt

Chromium 

Compounds

0.06

These emission limits apply to furnaces at major sources in 

the wool fiberglass manufacturing source category. However, 

there are no differences in furnaces at major sources and area 

sources. We are concerned about the levels of hexavalent 

chromium that can be emitted by area sources where furnaces may 

be constructed using high chrome refractories. Therefore we plan 

to collect additional information from industry to inform 

regulation of area sources in a future action.

The emission limits we are proposing for chromium compounds 

under 112(f)(2) are identical to the chromium compounds limits 
Page 161 of 242

we are proposing under 112(d)(6), as described in Section VIII. 

F of this preamble.

Our assessments also indicate a low potential for HAP 

emissions from these sources to pose any significant adverse 

environmental effects, human health multi-pathway effects, or 

chronic noncancer human health risks. Our acute risk screening 

ruled out the possibility of acute impacts of concern for all 

pollutants but one, formaldehyde, at seven facilities, with a 

maximum worst-case HQ estimated to be 30 based on the REL and 2 

based on the AEGL-1 or ERPG-1, which is equivalent

(formaldehyde). While this means we cannot rule out the 

potential for acute concerns due to formaldehyde emissions from 

these facilities, we note that the worst-case acute HQs are 

based on conservative assumptions (e.g., worst-case meteorology 

coinciding with peak short-term one-hour emissions from each 

emission point, with a person located at the point of maximum

concentration during that hour). Moreover, the use of 

formaldehyde is being phased out in this industry, and will be 

eliminated from all but 2 facilities in the source category. 

Since the cancer risks due to actual emissions are well within 

the acceptable range (i.e., less than 100-in-1 million) and 

since we have no additional significant concerns regarding other 

potential human health or environmental impacts, and since we 

have not identified any additional cost-effective controls to 
Page 162 of 242

further reduce formaldehyde emissions, we are proposing that the 

MACT rule along with all the proposed amendments described above 

(including the emissions limits for chromium and formaldehyde) 

will provide an ample margin of safety to protect public health 

and prevent adverse environmental effects.

We are soliciting comments and information regarding 

additional control measures, work practices that may be 

available, and their feasibility in further reducing emissions 

of formaldehyde, chromium compounds, HCl, and HF, or additional 

monitoring that may be warranted to ensure adequate control of 

stack emissions. We specifically request information on other 

criteria on which a chromium compounds emission limit should be 

based that would reduce risks from hexavalent chromium.

3. Analysis of the resulting risk after the proposed

requirements are in place.

We conducted an assessment to estimate the risks based on a 

post-control scenario reflecting all the proposed requirements 

for the emissions described above (including the proposed 

emissions limit for chromium compounds). Details are provided in 

the Draft Residual Risk Assessment for the Mineral Wool 

Production and Wool Fiberglass Manufacturing Source Categories, 

EPA’s Office of Air Quality Planning and Standards Office of Air 

and Radiation, September 2011, which is available in the docket 

to this rule. 
Page 163 of 242

Table 11 of this preamble provides an overall summary of 

the results of the post-control inhalation risk assessment. As 

compared to Table 8, the MIR decreased from 40-in-1 million to 

20-in-1 million, primarily as a result of one facility replacing 

the high chrome refractory bricks at the facilities that 

currently exceed the proposed chromium standard. These estimates 

are based on the dataset compiled using the industry’s emissions 

test data from their 2010 industry survey responses, which show 

three furnaces would have to reduce chromium emissions to meet 

the limit in the proposed rule. 

Table 11. Post Control Inhalation Risk Estimates for Wool 

Fiberglass (result of Chromium control)

Maximum

Individual

Cancer Risk

(in 1 

million)

Based on 

Actual 

Emissions 

Level1

Estimated 

Population

at increased 

Risk of 

cancer ≥ 1-

in-1 Million

Estimated 

Annual

Cancer

Incidence 

(cases per 

year)

Maximum 

Chronic Noncancer TOSHI 

Based on 

Actual 

Emissions 

Level2

Maximum 

Screening

Acute Noncancer HQ3

20 282,000 0.02 0.2 30

In addition, we estimated that the formaldehyde emissions 

would be at or below the MACT standard for all facilities once 

this rule is fully implemented and we are not proposing that 

additional control options be implemented.

In a letter dated June 8, 2011, the industry trade 

association (NAIMA) stated that “NAIMA can provide documentation 

that all major sources have already converted or have announced 

plans to convert to non-phenol formaldehyde binders. Essentially 
Page 164 of 242

non-formaldehyde binders are or will be used industry-wide.” A 

copy of this letter has been placed in the docket for this 

action (see NAIMA’s Response for the Fiberglass Industry to 

EPA’s Formaldehyde and Collection Questions). Based on this 

information and the information provided by the industry in 

their 2010 survey, we estimate that 27 of the 29 wool fiberglass 

manufacturing facilities will have HAP emissions below the 10 

and 25 tpy thresholds and will not be subject to the major 

source MACT requirements. We further estimate that there may be 

two facilities manufacturing pipe insulation or heavy density 

insulation products that will be major sources of HAP emissions 

on the compliance date of these proposed amendments to subpart 

NNN. If NAIMA is correct in that formaldehyde will be phased out 

by the compliance date of these proposed amendments, we 

anticipate that the estimated inhalation risks due to 

formaldehyde would further decrease. 

In summary, we are proposing that the MACT standard, with 

the changes we are proposing in this action, will provide an 

ample margin of safety and prevent adverse environmental 

effects.

F. What are the results from the technology review and proposed 

decisions?

Based on our technology review, we determined that there 

have been advances in emissions control measures since the Wool 
Page 165 of 242

Fiberglass Manufacturing NESHAP was originally promulgated in 

1999. Since promulgation, we estimate that industry-wide metal 

HAP emissions from process sources have been reduced by 

approximately 76 percent. Due to industry’s efforts to replace 

phenol-formaldehyde binders, more than 95 percent of 

formaldehyde, phenol, and methanol emissions have been reduced 

(or will be by 2012). As a result actual PM (metal HAP),

formaldehyde, phenol, and methanol emissions from process 

sources at all wool fiberglass manufacturing facilities are 

significantly lower than are allowed under the 1999 MACT rule. 

We believe that the reductions in metal HAP emissions since 

promulgation of the 1999 MACT rule are mainly directly related 

to improvements in two areas: (1) improvements in fabric filter 

control technology (e.g., improved bag materials, replacement of 

older baghouses) and (2) the use of electrostatic precipitators 

(ESPs). Our review also indicates that high chrome refractories 

are a new technology used in wool fiberglass furnaces that the 

available data indicate result in an increase in emissions of 

chromium compounds. The results of our analyses and our proposed 

decisions for these areas under CAA section 112(d)(6) are 

presented in the following sections. Based on these data, we 

believe that developments in practices, processes, and control 

technologies warrant revisions to the 1999 NESHAP. Additional 
Page 166 of 242

details regarding these analyses can be found in Technology 

Review for the Wool Fiberglass Manufacturing Source Category.

The improvements in fabric filter control technology are 

reflected in the emissions test data collected under the 

industry survey. Two types of PM control are used in the wool 

fiberglass manufacturing industry: fabric filters (baghouses) 

and electrostatic precipitators. Electrostatic precipitators 

(ESP) may be configured as either wet ESPs or dry ESPs. The 

emissions limit for PM under the 1999 MACT rule is a productionbased limit of 0.5 pounds of PM per ton of glass pulled 

applicable to all glass melting furnaces. Based on our analysis 

of survey responses and test data collected under the industry 

survey, this industry primarily uses fabric filters to control 

emissions of metal HAP, and the vast majority of sources 

affected by the current PM limit are achieving PM emissions at 

control device outlets that are far below the current limit. Id.

Most, if not all, sources reported PM emissions (coming out 

of the stacks after the control devices) that are less than 10 

percent of the current limit, with several sources achieving PM 

emissions that are two to three orders of magnitude lower than 

the current limit. Based on these data, we believe that 

developments in practices, processes, and control technologies 

warrant revisions to the 1999 MACT rule, under section 

112(d)(6). Our analysis of emissions data provided in the survey 
Page 167 of 242

conducted by industry indicates that stacks equipped with a 

well-performing fabric filter or ESP can achieve exhaust PM 

concentrations of less than 0.014 lb/ton of glass pulled. We 

estimate that all of the wool fiberglass facilities would be 

able to comply with this revised limit without additional 

controls. We estimate that this would result in small reductions 

of metal HAP emissions since there will only be a couple of 

facilities subject to the PM limits and the available data on 

some of the furnaces at those facilities indicates they are 

currently meeting the proposed PM emission limit. We do not 

anticipate additional energy use associated with this revised 

limit. Furthermore, we do not anticipate any adverse non-air 

environmental impacts associated with the implementation of this 

revised limit. Therefore, we are proposing that reducing the PM 

limit in the NESHAP from 0.50 lb of PM per ton of glass pulled 

to 0.014 lb of PM per ton of glass pulled (see Table 12) is both 

feasible and cost effective. Therefore, we are proposing a 

revised PM limit in the NESHAP of 0.014 lb of PM per ton of 

glass pulled in this action. We have based these statements on 

information we received from the industry in their survey

responses; nevertheless, we are seeking comment on our 

estimation that all wool fiberglass manufacturers can meet the 

PM emission limits without additional controls.
Page 168 of 242

We conducted a review of the available test data for 

chromium compounds including hexavalent chromium emissions from 

glass furnaces. We found that for most furnaces, measured 

emissions were near or below detection limits of the methods 

used for testing (EPA Method 29 followed by EPA Method 0061). In 

contrast, the chromium emissions for a few furnaces were several 

orders of magnitude higher than the rest of the industry. The 

facility emitting the highest level of hexavalent chromium, at 

840 lb/yr, advised us that the reason chromium tested very high 

was due to the refractory products, high chrome refractories, 

from which the furnaces are constructed (Notes of April 14, 

2011, Certainteed)

12. Based on the emissions testing and 

information on high chrome refractories, we believe changes to 

the 1999 MACT rule are warranted under CAA section 112(d)(6). 

The data indicate that well performing wool fiberglass 

furnaces emit small amounts of chromium compounds, that is, they 

emit less than 0.06 pounds of chromium compounds (Cr) per 

thousand tons of glass pulled. However, three facilities 

currently operate furnaces that emit chromium in excess of this 

rate. Chromium emissions from these high emitters range from 9 

to 840 lb/yr. Furnaces operating below this rate generally emit 

less than 1 pound per year; many of these tested below the 

detection level of the test method. The data indicate that there 

is a ‘break’ between the furnaces emitting less than the 
Page 169 of 242

proposed limit and those emitting greater amounts of chromium. 

Data further indicate there are no wool fiberglass manufacturers 

with low glass production rates but high levels of chrome 

emissions. We are therefore proposing to set a chromium 

compounds emission limit of 0.06 lb of chromium per thousand 

tons of glass pulled as shown in Table 12. 

Under section 112(d)(6), we are proposing this emission 

limit for chromium compounds taking into account the 

developments in practices, processes and technology by the wool 

fiberglass industry since promulgation of the 1999 MACT 

standard. The emission limits we are proposing for chromium 

compounds under 112(d)(6) are identical to the chromium 

compounds limits we are proposing under 112(f)(2), as described 

in Section VIII.E of this preamble.

We estimate that the 2 remaining major source wool 

fiberglass facilities would be able to comply with this chromium 

compounds emission limit. We estimate that if the high chromium 

emitting facilities remain major sources, these new emission 

limits would result in annual reductions of 1,155 pounds of 

chromium compounds, specifically hexavalent chromium and there 

will be no reductions at the remaining facilities because data 

indicate they are currently meeting the proposed chromium 

emission limit.
Page 170 of 242

Wet scrubbers are not generally in use in this industry. 

However, we evaluated their use to achieve reductions in

hexavalent chromium for furnaces emitting chrome above the 

levels being proposed. Sodium hydroxide (NaOH) scrubbers are in 

use for furnace operations at other industries for chromium 

compounds reduction. We have evaluated the use of NaOH scrubbers 

for the wool fiberglass manufacturing industry and find that the 

control technology can be adapted for use in the wool fiberglass 

industry from the chromium electroplating industry and from 

certain high temperature metallurgical industries.

50

We do anticipate an additional energy use associated with 

this revised limit if sources choose to install NaOH scrubbers 

to remove hexavalent chromium from the furnace gases. We 

anticipate the affected sources may incur disposal costs of 

hexavalent chromium contaminated materials associated with the 

implementation of this emission limit. We anticipate that two 

sources which currently emit chromium at levels slightly higher 

than the proposed limit will be able to meet it by installing 

NaOH scrubbers (which selectively remove the hexavalent form of 

chromium from the exhaust air). This cost is about $300 per 

pound hexavalent chromium removed if these companies install a

NaOH scrubber in series with the existing furnace control. A 

 

50 NaOH Scrubber Information. Telephone discussion and emails 

between vendors, companies, and EPA. Steffan Johnson, 

Measurement Policy Group, USEPA/OAQPS/SPPD.
Page 171 of 242

wool fiberglass facility could also choose to rebuild the glass 

furnace using refractories with low chromium contents. The cost 

of that option would be prorated to consider the remaining 

useful life of the existing high chromium furnace and would cost 

about $12,000 per pound chromium compounds removed. We expect 

that for the highest chromium emitting wool fiberglass furnace 

emitting 500 lb chromium per year, this option would be used to 

meet the proposed limit. We base this estimate on two factors: 

1) the furnace is at the end of its useful life and is expected 

to be reconstructed in 2013 (Notes of April 14, 2011; Region 7 

Certainteed Notes)12,13 and 2) the NaOH scrubber achieves about 95

percent reduction (NaOH Scrubber Information)42, which is not 

quite enough to meet the proposed chromium emission limit.

The cost of the control equipment to wool fiberglass plants is 

about $225,000 for installation and annual operation and 

maintenance costs of about $5000 per year. We compared the cost 

of the controls to the sales or revenues of the companies that 

would incur costs to comply with the chromium emission limits. 

The economic impact on these firms, measured in annual 

compliance costs as a percent of sales or revenues, is less than 

0.001 percent for each of the affected firms.51

 

51 Economic Impact and Initial Regulatory Flexibility Analysis. 

September 2011
Page 172 of 242

We therefore, we propose that requiring the 0.06 lb 

chromium per thousand tons of melt limit in the NESHAP is both 

feasible and cost effective. We solicit comment on this 

comparison and the use of this value as a reasonable cost to 

reduce chromium.

Table 12. Proposed Emissions limits for Glass-Melting Furnaces 

based on Technology Review

Pollutant Pounds pollutant per ton of melt

PM 0.14 

Chromium 

Compounds

0.00006

This proposed limit for chromium compounds (of 0.06 lb per 

thousand tons chromium limit) under CAA Section 112(d)(6) is the 

same limit being proposed under Section 112(f)(2) that was 

described earlier in this notice. We believe that these proposed 

revisions for chromium and PM are cost effective revisions and 

reflect the current developments in processes and technology by 

this industry. (i.e., well performing air pollution control).

IX. Summary of Cost, Environmental, and Economic Impacts for the 

Mineral Wool Source Category

Here we discuss the anticipated air, water, solid waste and 

energy impacts in addition to the cost and economic impacts to 

the industry as a result of the proposed amendments to the 1999 

MACT rule.
Page 173 of 242

A. What are the affected sources in the Mineral Wool Production 

source category?

We anticipate that the 7 mineral wool production facilities 

currently operating in the United States will be affected by 

these proposed amendments.

B. How are the impacts for this proposal evaluated?

For the proposed amendments to the Mineral Wool Production 

source category, the air quality, water quality, solid waste, 

and energy impacts were determined based on the need for 

additional control technologies and actions required to meet the 

proposed emissions limits. The Economic Impact Analysis

considered annual sales and revenue data from the facilities 

within this source category and their ability to meet the 

proposed amendments. The following sections discuss the cost, 

environmental, and economic impacts to the Mineral Wool 

Production source category. (Economic Impact Analysis for the 

Mineral Wool and Wool Fiberglass RTRs. US EPA. October 2011.)

C. What are the air quality impacts for the Mineral Wool 

Production source category?

The EPA estimated the emissions reductions that are 

expected to result from the proposed amendments to the 1999 MACT 

rule compared to the 2010 baseline emissions estimates. A 

detailed documentation of the analysis can be found in: Cost 
Page 174 of 242

Impacts of the Revised NESHAP for the Mineral Wool Production 

Manufacturing Source Category.

Emissions of formaldehyde from mineral wool production 

facilities have declined over the last 12 years as a result of 

federal rules, state rules and on the industry’s own initiative. 

The current proposal would not reduce formaldehyde, phenol, or 

methanol emissions from their current levels. Under the proposed 

emissions limits for cupolas, COS, HF, and HCl emissions would 

be reduced by a combined 23 percent compared to 2010 levels 

reported in the industry survey responses. We estimated that the 

COS emissions reductions would be 41 tpy from cupolas.

Based on the emissions data available to the EPA, we 

believe that all facilities will be able to comply with the 

proposed emissions limits for COS, HF, HCl, formaldehyde, 

phenol, and methanol without additional controls because they 

can reduce emissions using raw material substitution or oxygen 

injection as discussed previously in Section VII.F of this 

preamble.

D. What are the water quality and solid waste impacts?

We do not anticipate any adverse water quality or solid 

waste impacts from the proposed amendments to the 1999 MACT rule

because the requirements proposed would not change the existing 

requirements that impact water quality or solid waste.

E. What are the secondary impacts?
Page 175 of 242

Indirect or secondary air quality impacts include impacts 

that will result from the increased electricity usage associated 

with the operation of control devices, as well as water quality 

and solid waste impacts (which were just discussed) that might 

occur as a result of these proposed actions. We anticipate that 

the mineral wool production facilities will be able to comply 

with the proposed amendments without having to install 

additional control technologies such as RTOs. In addition, those 

facilities that switch to low-sulfur raw materials will most 

likely reduce air emissions of SO2.

F. What are the energy impacts?

Energy impacts in this section are those energy 

requirements associated with the operation of emission control 

devices. Potential impacts on the national energy economy from 

the rule are discussed in the economic impacts section. There 

would be little national energy demand increase from the 

operation of any of the control options analyzed under the 

proposed NESHAP amendments.

G. What are the cost impacts for the Mineral Wool Production 

source category?

Each facility was evaluated for its ability to meet the 

proposed emissions limits for PM, COS, HF, and HCl emissions 

from cupolas and formaldehyde, phenol, and methanol emissions 

from combined collection operations and curing designs. The 
Page 176 of 242

memorandum, Cost Impacts of the Revised NESHAP for the Mineral 

Wool Production Manufacturing Source Category, includes a 

complete description of the cost estimate methods used for this 

analysis and is available in the docket.

We identified several ways in which mineral wool producers 

reduce the COS emissions from cupolas, enabling them to comply 

with the proposed emission limit of 3.3 lb COS per ton of melt. 

These methods include raw material substitution, oxygen 

injection, and installation of an RTO. We found two approaches 

to raw material substitution: slag and rock. One mineral wool 

manufacturer purchases low-sulfur slag, a waste product from a 

local steel plant. Another plant owns and operates a local 

quarry from which they obtain rock that does not contain sulfur. 

The low-sulfur slag or rock is used in the cupola in place of 

high-sulfur slag. Because sulfur is not added into the cupola 

with the raw materials, it is not emitted as sulfur compounds 

from the stack in the form of COS or SO2 during production. As 

shown in their title V permit, another plant uses oxygen 

injection to accelerate the reaction of COS to CO2 and SO2, 

thereby reducing that company's COS emissions.

However, most mineral wool plants have installed 

regenerative thermal oxidizers to convert the high 

concentrations of COS in the cupola exhaust gas to energy that 

is returned to the cupola. This technology reduces the 
Page 177 of 242

consumption of coke up to 30 percent and, because of the cost of 

coke, this technology pays for itself over a period of several 

years. Emissions of COS are below 0.04 lb COS per ton melt when 

an RTO is installed for energy reclamation and new source MACT 

is based upon the use of this technology.

One facility is expected to incur an incremental annualized 

cost of $360,000 for low-sulfur raw materials (rock) if they use 

that option to comply with the COS requirement for cupolas. That 

cost would be lessened to no more than $20,000 for installation 

of oxygen injection, which is another alternative. We do not 

anticipate this plant would install an RTO to comply with the 

rule. The total industry-wide costs for monitoring for COS, HF, 

and HCl from the cupolas is $146,000, while the total costs for 

monitoring for formaldehyde, phenol, and methanol from the 

combined collection and curing operations is $42,000.

The total annualized costs for the proposed rule are 

estimated at $548,000 (2010 dollars). Table 13 provides a 

summary of the estimated costs and emissions reductions 

associated with the proposed amendments to the Mineral Wool 

Production NESHAP presented in this action.

Table 13. Estimated Costs and Reductions for the Mineral Wool 

Production Proposed Standards in this Action

Proposed 

Amendment

Estimated 

Capital 

Cost 

($MM)

Estimated 

Annual 

Cost 

($MM)

Total HAP 

Emissions 

Reductions 

(tons per 

year)

Cost 

Effectiveness 

in $ per ton 

total HAP 

reduction

COS limit; 0 0.360 41 8,780
Page 178 of 242

Low-Sulfur 

Materials

Additional 

testing and 

monitoring

0 0.243 N/A N/A

H. What are the economic impacts for the Mineral Wool Production 

source category?

We performed an economic impact analysis for mineral wool 

producers nationally using the annual compliance costs estimated 

for this proposed rule.(Economic Impact and Initial Regulatory 

Flexibility Analysis. October 2011)

43. The impacts to most 

producers affected by this proposed rule are annualized costs of 

less than one percent of their revenues using the most current 

year available for revenue data. One producer will experience an 

annualized cost of 6.7 percent of its revenue, however. Both 

demand and supply in this sector are inelastic to price changes.

Thus, if producers could pass through the entire cost of the 

rule to consumers, we would expect prices to increase by less 

than one percent, with no change in output. Conversely, if 

producers could not pass through any of the cost by increasing 

the price, we would expect output to decline by less than one 

percent.

Hence, the overall economic impact of this proposed rule 

should be low on most of the affected industry and its 

consumers. For more information, please refer to the Economic 
Page 179 of 242

Impact Analysis for this proposed rulemaking that is available 

in the public docket. Id.

I. What are the benefits for the Mineral Wool Production source 

category?

The proposed Mineral Wool Production NESHAP amendments are 

expected to result in approximately 23 percent reduction in COS;

HF, and HCl are not reduced. We have not quantified the monetary 

benefits associated with these reductions.

J. What demographic groups might benefit the most from this 

regulation?

The worst-case nature of our acute screening assessment 

suggests that the potential for adverse effects carries a 

relatively low probability of occurrence. The EPA concludes

that, based on our analyses, the risks associated with MACTallowable and actual emissions (primarily due to formaldehyde

emissions from stacks) from this source category are acceptable.

Thus, a demographic analysis was not conducted. 

X. Summary of Cost, Environmental, and Economic Impacts for the 

Wool Fiberglass Manufacturing Source Category

A. What are the affected sources in the Wool Fiberglass 

Manufacturing source category?

We evaluated the impacts to the affected sources based on 

all available information, including two significant sources: 

the 2010 emissions testing and subsequent conversations with 
Page 180 of 242

NAIMA and individuals operating industry facilities. According 

to the 2010 emissions test data, there are 3 furnaces at 3 

facilities that do not meet this proposed chromium emission 

limit. In their responses to the survey conducted by the 

industry, facilities stated the tested furnaces were 

representative of the untested furnaces. However, furnace 

construction materials (refractory composition) were not one of 

the factors considered in determining representativeness.

After the completion of the survey conducted by industry, 

we received information that emissions testing for chromium may 

not necessarily be representative of other furnaces that were 

not tested. Therefore, we based our assessment of the impacts 

upon the tested furnaces only, and did not include in that 

assessment untested furnaces.

Based on this approach, we anticipate that all 29 wool 

fiberglass manufacturing facilities currently operating in the 

United States will be affected by these proposed amendments, 2

of the 29 wool fiberglass manufacturing facilities currently 

operating in the United States will install air pollution 

controls, and that one facility will reconstruct a furnace to 

comply with these proposed amendments. Additionally, industry 

has stated that no major wool fiberglass residential insulation 

sources will still exist in this source category by the time the 

proposed rules are promulgated. If their predictions come to 
Page 181 of 242

pass, we estimate that two facilities will be affected by these 

proposed amendments; these are pipe insulation facilities.

However, any major sources still in operation at the time the 

amendments are promulgated will be affected by this rule. One

new facility was recently built, but no facilities are expected 

to be constructed in the foreseeable future.

B. How are the impacts for this proposal evaluated?

For the proposed Wool Fiberglass Manufacturing NESHAP 

amendments, the air quality, water quality, solid waste, and 

energy impacts were determined based on the need for additional 

control technologies and actions required to meet the proposed 

emissions limits. The Economic Impact Analysis considered annual 

sales and revenue data from the facilities within this source 

category and their ability to meet the proposed amendments. The 

following sections discuss the cost, environmental, and economic 

impacts to the Wool Fiberglass Manufacturing source category.

(Economic Impact Analysis for the Mineral Wool and Wool 

Fiberglass RTRs. US EPA. October 2011.)

C. What are the air quality impacts?

The EPA estimated the emissions reductions that are 

expected to result from the proposed amendments to the 1999 MACT 

rule compared to the 2010 baseline emissions estimates. A 

detailed documentation of the analysis can be found in: Cost 

Impacts of the Revised NESHAP for the Wool Fiberglass 
Page 182 of 242

Manufacturing Source Category. We expect reductions of 

formaldehyde, phenol and methanol, and chromium compounds.

Emissions of formaldehyde, PM, and HAP metals from wool 

fiberglass manufacturing have declined over the last 12 years as 

a result of federal rules, state rules and on the industry’s own 

initiative. The current proposal is not expected to yield 

emission reductions for formaldehyde, phenol, or methanol from 

their current levels. However, the proposed amendments are 

expected to discourage facilities in the wool fiberglass 

industry from reintroducing formaldehyde to their production 

lines. In addition, the proposed chromium compound emission 

limit would prevent emissions of chromium compounds in the 

future and discourage the replacement of currently operating 

furnaces with those constructed of high chromium refractory 

bricks.

Based on the emissions data available to the EPA, we 

believe that all affected facilities will be able to comply with 

the proposed emissions limits for formaldehyde, phenol, 

methanol, HF, and HCl without additional controls. Additional 

controls are required for major sources with high-chrome 

refractories. Additionally, as discussed in Section X.J of this 

preamble, the EPA has determined that the proposed rule will not 

have disproportionately high and adverse human health or 

environmental effects on minority or low-income populations. 
Page 183 of 242

D. What are the water quality and solid waste impacts?

We anticipate water quality and solid waste impacts may 

result from the disposal of high chrome refractories in 

landfills or in other areas that are not designed or permitted 

to receive hexavalent chromium waste. Water quality and solid 

waste impacts are also possible from potential reuse of spent 

high chrome refractory products. Because of their durability, we 

believe that use of refractory bricks made with high chrome 

content are becoming widespread52, (Chromium in Refractories)

11,

as their use can nearly double the life of glass furnaces (Notes 

of April 14, 2011, Certainteed; Region 7 Certainteed Notes; 

August 31, 2011 Meeting)12,13,35. When glass furnaces reach the end 

of their useful life and must be rebuilt, the high chrome 

refractory brick from demolition of the old furnace is typically 

discarded, as it typically cannot be used in new furnace 

construction. As for any industrial waste, the bricks from an 

old glass furnace would, when discarded, potentially be subject 

to the Resource Conservation and Recovery Act (RCRA) and its 

regulations.

Additionally, NaOH scrubber solids are expected to contain 

high levels of hexavalent chromium removed from furnace 

emissions. The proper disposal procedures for hexavalent 

 

52 Excel spreadsheet provided by North American Insulation 

Manufacturers Association (NAIMA). Non-CBI NAIMA Response to 

Cr Emissions 8.11.11. 
Page 184 of 242

chromium-contaminated waste are provided under RCRA regulations 

(40 CFR 262.11).

E. What are the secondary impacts?

Indirect or secondary air quality impacts include impacts 

that will result from the increased electricity usage associated 

with the operation of control devices, as well as water quality 

and solid waste impacts that might occur as a result of these 

proposed actions. We estimate the proposed amendments will not 

result in any significant secondary impacts from the 

requirements of the Mineral Wool MACT amendments because 

facilities can meet the COS limits without installing RTOs. We 

do not anticipate significant secondary impacts from the 

proposed amendments to the Wool Fiberglass MACT.

F. What are the energy impacts?

Energy impacts in this section are those energy 

requirements associated with the operation of emission control 

devices. Potential impacts on the national energy economy from 

the proposed amendments to the Wool Fiberglass MACT are expected 

to be minimal and will not result in a significant increase in

national energy demand.

G. What are the cost impacts?

The capital costs for each facility were estimated based on 

the ability for each facility to meet the proposed emissions 

limits for PM, chromium compounds, HF, HCl, formaldehyde, 
Page 185 of 242

phenol, and methanol. The memorandum, Cost Impacts of the 

Revised NESHAP for the Wool Fiberglass Manufacturing Source 

Category, includes a complete description of the cost estimate 

methods used for this analysis and is available in the docket.

Under the proposed amendments, the majority of wool fiberglass 

facilities are not expected to incur any capital costs to comply 

with the proposed emissions limits. The total costs estimated 

for compliance with the amendments proposed in this action are

$60,000 for compliance testing on glass-melting furnaces and 

$52,000 for compliance testing on the FA manufacturing line for 

pipe insulation products. The total annualized costs for the 

proposed rule are estimated at $112,000 (2010 dollars). Table 14 

provides a summary of the costs and emission reductions 

associated with the proposed amendments if the three facilities 

with high levels of hexavalent chromium install controls or 

reconstruct furnaces to meet the emission limits of the proposed 

rule. Because the industry is undergoing the phaseout of HAP 

binders, no major sources are expected to exist by the 

compliance deadline for this proposed rule, and no costs to 

industry beyond testing would be incurred. However, in the event 

that the three facilities that do not now meet the chromium 

compounds limit were to remain major sources, we estimated the 

annualized control costs as between $100,000 to $300,000 per 

furnace, depending on which of two options is used. Eleven 
Page 186 of 242

hundred (1100) pounds of chromium compounds per year would be 

reduced at three major sources in the industry, 913 pounds of 

this from a single facility. Hexavalent chromium is 92% of the 

total chromium compounds emitted from wool fiberglass furnaces. 

Actual facility costs would be determined by the number of 

furnaces, the associated level of Cr emissions, and the major 

source status of the facility.

Table 14. Estimated Costs and Reductions for the Proposed 

Wool Fiberglass Manufacturing Standards in this Action

Proposed 

Amendment

Est.Capi

tal Cost 

($MM)

Est. Annual 

Cost ($MM)

Total HAP 

Emissions 

Reductions 

(pounds per 

year)

Cost 

Effecti

veness 

in $ 

per 

pound

No. 

Faciliti

es

Change out 

of 

refractory 

brick lining

6.0 0.3 900 333 1

Installation 

of NaOH 

scrubber

.25 .1 70 1400 2

Additional 

testing and 

monitoring 

for glassmelting 

furnaces

0 0.06 N/A N/A

Additional 

testing and 

monitoring 

for FA lines 

for pipe 

insulation 

products

0 0.052 N/A N/A

H. What are the economic impacts?
Page 187 of 242

We performed an economic impact analysis for the wool fiberglass 

industry using the annual compliance costs estimated for this 

proposed rule (Economic Impact and Initial Regulatory 

Flexibility Analysis for the Proposed Mineral Wool and Wool 

Fiberglass Risk and Technology Review)43. The impacts to 

producers affected by this proposed rule are annualized costs of 

less than 0.1 percent of their revenues using the most current 

year available for revenue data. With the responsiveness of wool 

fiberglass demand and supply at less than 1:1 compared to a 

price change, and with the change in product price as 

approximated by the cost to revenue ratio at less than 0.1 

percent, for this ratio is the maximum price change that

producers may face, it is expected that wool fiberglass price 

and output changes will be less than 0.1 percent. Hence, the

overall economic impact of this proposed rule should be low on 

the affected industry and its consumers. For more information, 

please refer to the Economic Impact Analysis for this proposed 

rulemaking that is available in the public docket. (Economic 

Impact Analysis for the Mineral Wool and Wool Fiberglass RTRs. 

US EPA. October 2011.)

I. What are the benefits?

As stated in section X.C., we expect emissions reductions of PM, 

phenol, formaldehyde, methanol, and chromium compounds. We have 
Page 188 of 242

not quantified the monetary benefits associated with these

reductions.

J. What demographic groups might benefit the most from this 

regulation?

For the proposed wool fiberglass rule, the EPA has 

determined that the current health risks posed to anyone by 

emissions from this source category are acceptable. However, 

there are about 849,000 people nationwide that are currently 

subject to health risks which are non-negligible (i.e., cancer 

risks greater than 1-in-1 million) due to emissions from this 

source category. We performed an analysis of the demographic 

makeup of these 849,000 people. The demographic distribution of 

this “at-risk” population is similar to the national 

distribution of demographics for all groups except for the 

“minority” group (defined as total population minus the white 

population), which is 11 percent greater than its corresponding 

national percentage. See the Risk and Technology Review –

Analysis of Socio-Economic Factors for Populations Living Near 

Wool Fiberglass Facilities in the docket for additional details 

on the demographic analysis.

The EPA has determined that the current health risks posed 

to anyone by emissions from this source category are acceptable.

Therefore, the EPA has determined that the proposed rule will 
Page 189 of 242

not have disproportionately high and adverse human health or 

environmental effects on minority or low-income populations.

XI. Request for Comments

We are soliciting comments on all aspects of this proposed 

action. All comments received during the comment period will be 

considered. In addition to general comments on this proposed 

action, we are also interested in any additional data that may 

help to address emissions of chromium compounds from wool 

fiberglass manufacturing furnaces, such as speciation of the 

different types of chromium compounds that may be used in the 

manufacture of refractory bricks, shapes, and castables; and the 

properties of different chromium compounds when exposed to 

temperatures exceeding 15000C. Specifically, we are interested in 

data we can use to support any of the proposed alternatives and 

new data that could support an alternative not proposed in these

actions. We are also interested in additional data that may help 

to reduce the uncertainties inherent in the risk assessments and 

other analyses. We are specifically interested in receiving 

corrections to the site-specific emissions profiles used for 

risk modeling. Such data should include supporting documentation 

in sufficient detail to allow characterization of the quality 

and representativeness of the data or information. Section VII

of this preamble provides more information on submitting data.

XII. Submitting Data Corrections
Page 190 of 242

The site-specific emissions profiles used in the source 

category risk and demographic analyses are available for 

download on the RTR web page at: 

http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. The data files 

include detailed information for each HAP emissions release 

point for the facility included in the source category.

If you believe that the data are not representative or are 

inaccurate, please identify the data in question, provide your 

reason for concern, and provide any “improved” data that you 

have, if available. When you submit data, we request that you 

provide documentation of the basis for the revised values to 

support your suggested changes. To submit comments on the data 

downloaded from the RTR Web page, complete the following steps:

1. Within this downloaded file, enter suggested revisions 

to the data fields appropriate for that information. The data 

fields that may be revised include the following:

Data Element Definition

Control Measure Are control measures in place? 

(yes or no)

Control Measure Comment

Select control measure from list 

provided, and briefly describe 

the control measure

Delete Indicate here if the facility or 

record should be deleted

Delete Comment Describes the reason for deletion

Emissions Calculation Method 

Code For Revised Emissions

Code description of the method 

used to derive emissions. For 

example, CEM, material balance, 

stack test, etc.

Emissions Process Group

Enter the general type of 

emissions process associated with 

the specified emissions point
Page 191 of 242

Data Element Definition

Fugitive Angle

Enter release angle (clockwise 

from true North); orientation of 

the y-dimension relative to true 

North, measured positive for 

clockwise starting at 0 degrees 

(maximum 89 degrees)

Fugitive Length

Enter dimension of the source in 

the east-west (x-) direction, 

commonly referred to as length 

(ft)

Fugitive Width

Enter dimension of the source in 

the north-south (y-) direction, 

commonly referred to as width 

(ft)

Malfunction Emissions Enter total annual emissions due 

to malfunctions (tpy)

Malfunction Emissions Max 

Hourly

Enter maximum hourly malfunction 

emissions here (lb/hr)

North American Datum

Enter datum for 

latitude/longitude coordinates 

(NAD27 or NAD83); if left blank, 

NAD83 is assumed

Process Comment Enter general comments about 

process sources of emissions

REVISED Address Enter revised physical street 

address for MACT facility here

REVISED City Enter revised city name here

REVISED County Name Enter revised county name here

REVISED Emissions Release 

Point Type

Enter revised Emissions Release 

Point Type here

REVISED End Date Enter revised End Date here

REVISED Exit Gas Flow Rate Enter revised Exit Gas Flowrate 

here (ft3/sec)

REVISED Exit Gas Temperature Enter revised Exit Gas 

Temperature here (F)

REVISED Exit Gas Velocity Enter revised Exit Gas Velocity 

here (ft/sec)

REVISED Facility Category 

Code

Enter revised Facility Category 

Code here, which indicates 

whether facility is a major or 

area source

REVISED Facility Name Enter revised Facility Name here

REVISED Facility Registry 

Identifier

Enter revised Facility Registry 

Identifier here, which is an ID 

assigned by the EPA Facility 

Registry System

REVISED HAP Emissions 

Performance Level Code

Enter revised HAP Emissions 

Performance Level here
Page 192 of 242

Data Element Definition

REVISED Latitude Enter revised Latitude here 

(decimal degrees)

REVISED Longitude Enter revised Longitude here 

(decimal degrees)

REVISED MACT Code Enter revised MACT Code here

REVISED Pollutant Code Enter revised Pollutant Code here

REVISED Routine Emissions Enter revised routine emissions 

value here (tpy)

REVISED SCC Code Enter revised SCC Code here

REVISED Stack Diameter Enter revised Stack Diameter here 

(ft)

REVISED Stack Height Enter revised Stack Height here 

(ft)

REVISED Start Date Enter revised Start Date here

REVISED State Enter revised State here

REVISED Tribal Code Enter revised Tribal Code here

REVISED Zip Code Enter revised Zip Code here

Shutdown Emissions Enter total annual emissions due 

to shutdown events (tpy)

Shutdown Emissions Max 

Hourly

Enter maximum hourly shutdown 

emissions here (lb/hr)

Stack Comment Enter general comments about 

emissions release points

Startup Emissions Enter total annual emissions due 

to startup events (tpy)

Startup Emissions Max Hourly Enter maximum hourly startup 

emissions here (lb/hr)

Year Closed Enter date facility stopped 

operations

2. Fill in the commenter information fields for each 

suggested revision (i.e., commenter name, commenter 

organization, commenter email address, commenter phone number, 

and revision comments).

3. Gather documentation for any suggested emissions 

revisions (e.g., performance test reports, material balance 

calculations).

4. Send the entire downloaded file with suggested revisions 

in Microsoft® Access format and all accompanying documentation 
Page 193 of 242

to Docket ID Number EPA-HQ-OAR-2010-1041 for the Mineral Wool 

Production source category and Docket ID number EPA-HQ-OAR-2010-

1042 for the Wool Fiberglass Manufacturing source category

(through one of the methods described in the ADDRESSES section 

of this preamble). To expedite review of the revisions, it would 

also be helpful if you submitted a copy of your revisions to the 

EPA directly at RTR@epa.gov in addition to submitting them to 

the docket.

5. If you are providing comments on a facility, you need 

only submit one file for that facility, which should contain all 

suggested changes for all sources at that facility. We request 

that all data revision comments be submitted in the form of 

updated Microsoft® Access files, which are provided on the RTR 

Web Page at: http://www.epa.gov/ttn/atw/rrisk/rtrpg.html.

XIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and 

Executive Order 13563: Improving Regulation and Regulatory 

Review

Under Executive Order 12866 (58 FR 51735, October 4, 1993), 

this action is a significant regulatory action because it raises 

novel legal and policy issues. Accordingly, the EPA submitted 

this action to the Office of Management and Budget (OMB) for 

review under Executive Orders 12866 and 13563 (76 FR 3821, 

January 21, 2011) and any changes made in response to OMB 
Page 194 of 242

recommendations have been documented in the docket for this 

action.

B. Paperwork Reduction Act.

The information collection requirements in this rule have 

been submitted for approval to the OMB under the Paperwork 

Reduction Act, 44 U.S.C. 3501 et seq. The Information Collection 

Request (ICR) documents prepared by the EPA have been assigned 

EPA ICR numbers 1799.06 for Mineral Wool Production and 1160.10 

for Wool Fiberglass Manufacturing. The information collection 

requirements are not enforceable until OMB approves them. The 

information requirements are based on notification, 

recordkeeping, and reporting requirements in the NESHAP General 

Provisions (40 CFR part 63, subpart A), which are mandatory for 

all operators subject to national emissions standards. These 

recordkeeping and reporting requirements are specifically 

authorized by CAA section 114 (42 U.S.C. 7414). All information 

submitted to the EPA pursuant to the recordkeeping and reporting 

requirements for which a claim of confidentiality is made is 

safeguarded according to agency policies set forth in 40 CFR 

part 2, subpart B.

For this proposed rule, the EPA is adding affirmative 

defense to the estimate of burden in the ICRs. To provide the 

public with an estimate of the relative magnitude of the burden 

associated with an assertion of the affirmative defense position 
Page 195 of 242

adopted by a source, the EPA has provided administrative 

adjustments to these ICRs to show what the notification, 

recordkeeping and reporting requirements associated with the 

assertion of the affirmative defense might entail. The EPA’s 

estimate for the required notification, reports and records for 

any individual incident totals $3,141 and is based on the time 

and effort required of a source to review relevant data, 

interview plant employees, and document the events surrounding a 

malfunction that has caused an exceedance of an emissions limit.

The estimate also includes time to produce and retain the record 

and reports for submission to the EPA. The EPA provides this 

illustrative estimate of this burden because these costs are 

only incurred if there has been a violation and a source chooses 

to take advantage of the affirmative defense.

Given the variety of circumstances under which malfunctions 

could occur, as well as differences among sources' operation and 

maintenance practices, we cannot reliably predict the severity 

and frequency of malfunction-related excess emissions events for 

a particular source. It is important to note that the EPA has no 

basis currently for estimating the number of malfunctions that 

would qualify for an affirmative defense. Current historical 

records would be an inappropriate basis, as source owners or 

operators previously operated their facilities in recognition 

that they were exempt from the requirement to comply with 
Page 196 of 242

emissions standards during malfunctions. Of the number of excess 

emissions events reported by source operators, only a small 

number would be expected to result from a malfunction (based on 

the definition above), and only a subset of excess emissions 

caused by malfunctions would result in the source choosing to 

assert the affirmative defense. Thus, we believe the number of 

instances in which source operators might be expected to avail 

themselves of the affirmative defense will be extremely small.

For this reason, we did not estimate any such occurrences for 

all sources subject to subparts DDD and NNN over the 3-year 

period covered by these ICRs. We expect to gather information on 

such events in the future and will revise this estimate as 

better information becomes available.

We estimate 7 regulated entities are currently subject to 

subpart DDD and will be subject to all proposed standards. The 

annual monitoring, reporting, and recordkeeping burden for this 

collection (averaged over the first 3 years after the effective 

date of the standards) for these amendments to subpart DDD

(Mineral Wool Production) is estimated to be $85,348 per year.

This estimate includes performance tests, notifications, 

reporting, and recordkeeping associated with the new 

requirements for COS, HF, and HCl from cupolas and formaldehyde, 

phenol, and methanol from combined collection and curing oven 

designs. The total burden for the Federal government (averaged 
Page 197 of 242

over the first 3 years after the effective date of the standard) 

is estimated to be 22 hours per year at a total labor cost of 

$970 per year. Burden is defined at 5 CFR 1320.3(b).

We estimate 29 regulated entities are currently subject to 

subpart NNN and only 2 will be subject to all proposed 

standards. The annual monitoring, reporting, and recordkeeping 

burden for this collection (averaged over the first 3 years 

after the effective date of the standards) for these amendments 

to subpart NNN (Wool Fiberglass Manufacturing) is estimated to 

be $14,000 per year. This estimate includes performance tests, 

notifications, reporting, and recordkeeping associated with the 

new requirements for PM, chromium compounds, HF, and HCl from 

glass-melting furnaces and formaldehyde, phenol, and methanol 

from both RS and FA manufacturing lines. The total burden for 

the Federal government (averaged over the first 3 years after 

the effective date of the standard) is estimated to be 6.3 hours 

per year at a total labor cost of $283 per year.

An agency may not conduct or sponsor, and a person is not 

required to respond to, a collection of information unless it 

displays a currently valid OMB control number. The OMB control 

numbers for the EPA's regulations in 40 CFR are listed in 40 CFR 

part 9. When these ICRs are approved by OMB, the agency will 

publish a technical amendment to 40 CFR part 9 in the Federal 

Register to display the OMB control numbers for the approved 
Page 198 of 242

information collection requirements contained in the final 

rules.

To comment on the agency's need for this information, the 

accuracy of the provided burden estimates, and any suggested 

methods for minimizing respondent burden, the EPA has 

established a public docket for this rule, which includes this 

ICR, under Docket ID number EPA-HQ-OAR-2010-1041 for the Mineral 

Wool Production source category and Docket ID number EPA-HQ-OAR2010-1042 for the Wool Fiberglass Manufacturing source category. 

Submit any comments related to the ICRs to the EPA and the OMB. 

See the ADDRESSES section at the beginning of this notice for 

where to submit comments to the EPA. Send comments to the OMB at 

the Office of Information and Regulatory Affairs, Office of 

Management and Budget, 725 17th Street, NW, Washington, DC 

20503, Attention: Desk Office for the EPA. Since the OMB is 

required to make a decision concerning the ICR between 30 and 60 

days after [INSERT THE DATE OF PUBLICATION OF THIS PROPOSED RULE 

IN THE FEDERAL REGISTER], a comment to OMB is best assured of 

having its full effect if the OMB receives it by [INSERT THE 

DATE 30 DAYS AFTER THE DATE OF PUBLICATION IN THE FEDERAL 

REGISTER]. The final rule will respond to any OMB or public 

comments on the information collection requirements contained in 

this proposal.

C. Regulatory Flexibility Act.
Page 199 of 242

The RFA generally requires an agency to prepare a 

regulatory flexibility analysis of any rule subject to notice 

and comment rulemaking requirements under the Administrative 

Procedure Act or any other statute unless the agency certifies 

that the rule will not have a significant economic impact on a 

substantial number of small entities. Small entities include 

small businesses, small organizations, and small governmental 

jurisdictions.

For purposes of assessing the impacts of this proposed rule 

on small entities, small entity is defined as: (1) a small 

business as defined by the SBA’s regulations at 13 CFR 121.201; 

(2) a small governmental jurisdiction that is a government of a 

city, county, town, school district or special district with a 

population of less than 50,000; and (3) a small organization 

that is any not-for-profit enterprise that is independently 

owned and operated and is not dominant in its field. For this 

source category, which has the NAICS code 327993 (i.e., Mineral 

Wool Production and Wool Fiberglass Manufacturing), the SBA 

small business size standard is 500 employees according to the 

SBA small business standards definitions. 

After considering the economic impacts of this proposed 

rule on small entities in the Mineral Wool Production and Wool 

Fiberglass Manufacturing source categories, I certify that this 

action will not have a significant economic impact on a 
Page 200 of 242

substantial number of small entities. Five of the 6 Mineral Wool 

Production parent companies affected are considered to be small 

entities per the definition provided in this section. However, 

we estimate that this proposed action will not have a 

significant economic impact on those companies. The impact of 

this proposed action on these companies will be an annualized 

compliance cost of less than one percent of its revenues. Only

one of the five small parent companies is expected to have an 

annualized compliance cost of greater than one percent of its 

revenues. All other affected parent companies are not small 

businesses according to the SBA small business size standard for 

the affected NAICS code (NAICS 327993). One Wool Fiberglass 

Manufacturing facility is considered to be owned by a small 

business, but this facility will not experience an impact from 

this proposed rule. We have determined that the impacts do not 

constitute a significant economic impact on a substantial number 

of small entities in the Wool Fiberglass Manufacturing source 

category (See: Economic Impact and Small Business Analysis for 

the proposed Mineral Wool and Wood Fiberglass Production Source 

Categories NESHAP).

Although this proposed rule will not have a significant 

economic impact on a substantial number of small entities, the 

EPA nonetheless has tried to reduce the impact of this rule on 

small entities. For more information, please refer to the 
Page 201 of 242

economic impact and small business analysis that is in the 

docket. We continue to be interested in the potential impacts of 

the proposed rule on small entities and welcome comments on 

issues related to such impacts.

D. Unfunded Mandates Reform Act.

This proposed rule does not contain a Federal mandate under 

the provisions of Title II of the UMRA of 1995 , 2 U.S.C. 1531-

1538 for State, local, or tribal governments or the private 

sector. The proposed rule would not result in expenditures of 

$100 million or more for State, local, and tribal governments, 

in aggregate, or the private sector in any 1 year. The proposed 

rule imposes no enforceable duties on any State, local or tribal 

governments or the private sector. Thus, this proposed rule is 

not subject to the requirements of sections 202 or 205 of the 

UMRA.

This proposed rule is also not subject to the requirements 

of section 203 of UMRA because it contains no regulatory 

requirements that might significantly or uniquely affect small 

governments because it contains no requirements that apply to 

such governments nor does it impose obligations upon them.

E. Executive Order 13132: Federalism.

This proposed rule does not have federalism implications.

It will not have substantial direct effects on the States, on 

the relationship between the national government and the States, 
Page 202 of 242

or on the distribution of power and responsibilities among the 

various levels of government, as specified in Executive Order 

13132. None of the facilities subject to this action are owned 

or operated by State governments, and, because no new 

requirements are being promulgated, nothing in this proposed 

rule will supersede State regulations. Thus, Executive Order 

13132 does not apply to this proposed rule.

In the spirit of Executive Order 13132, and consistent with 

the EPA policy to promote communications between the EPA and 

State and local governments, the EPA specifically solicits 

comment on this proposed rule from State and local officials.

F. Executive Order 13175: Consultation and Coordination with 

Indian Tribal Governments.

This proposed rule does not have tribal implications, as 

specified in Executive Order 13175 (65 FR 67249, November 9, 

2000). Thus, Executive Order 13175 does not apply to this 

action.

The EPA specifically solicits additional comment on this 

proposed action from tribal officials.

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks.

This proposed rule is not subject to Executive Order 13045 

(62 FR 19885, April 23, 1997) because it is not economically 

significant as defined in Executive Order 12866.
Page 203 of 242

H. Executive Order 13211: Actions Concerning Regulations That 

Significantly Affect Energy Supply, Distribution, or Use.

This action is not a “significant energy action” as defined 

under Executive Order 13211, “Actions Concerning Regulations 

That Significantly Affect Energy Supply, Distribution, or Use” 

(66 FR 28355, May 22, 2001), because it is not likely to have 

significant adverse effect on the supply, distribution, or use 

of energy. This action will not create any new requirements and 

therefore no additional costs for sources in the energy supply, 

distribution, or use sectors.

I. National Technology Transfer and Advancement Act.

Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (NTTAA), Public Law No. 104-113 (15 

U.S.C. 272 note), directs the EPA to use VCS in its regulatory 

activities unless to do so would be inconsistent with applicable 

law or otherwise impractical. VCS are technical standards (e.g., 

materials specifications, test methods, sampling procedures, and 

business practices) that are developed or adopted by voluntary 

consensus standards bodies. NTTAA directs the EPA to provide 

Congress, through OMB, explanations when the agency decides not 

to use available and applicable VCS. 

The proposed rule involves technical standards. Therefore, 

the requirements of the NTTAA apply to this action. We conducted 

searches for the RTR for the Mineral Wool Production and Wool 
Page 204 of 242

Fiberglass Manufacturing NESHAP through the Enhanced NSSN 

Database managed by the American National Standards Institute 

(ANSI). We also contacted VCS organizations and accessed and 

searched their databases.

Under 40 CFR part 63 subpart DDD, searches were conducted 

for EPA Methods 5, 318, and 320 of 40 CFR Part 60, Appendix A. 

Under 40 CFR part 63 subpart NNN, searches were conducted for 

EPA Methods 5, 318, 320, 29, and 0061 of 40 CFR Part 60, 

Appendix A. No applicable voluntary consensus standards were 

identified for EPA Method 318 and SW-846 Method 0061. 

One voluntary consensus standard ASTM D6348-03(2010), 

Determination of Gaseous Compounds by Extractive Direct 

Interface Fourier Transform (FTIR) Spectroscopy is acceptable as 

an alternative to Method 320 for both subparts DDD and NNN, but 

with several conditions: (1) The test plan preparation and 

implementation in the Annexes to ASTM D6348-03, Sections A1 

through A8 are mandatory; and (2) In ASTM D6348-03 Annex A5 

(Analyte Spiking Technique), the percent R (percent R) must be 

determined for each target analyte (Equation A5.5). In order for 

the test data to be acceptable for a compound, percent R must be 

70 percent ≥ R ≤ 130 percent. If the percent R value does not 

meet the criterion for a target compound, the test data is not 

acceptable for that compound and the test must be repeated for 

that analyte (i.e., the sampling and/or analytical procedure 
Page 205 of 242

should be adjusted before a retest). The percent R value for 

each compound must be reported in the test report, and all field 

measurements must be corrected with the calculated percent R 

value for that compound by using the following equation: 

Reported Result = (Measured Concentration in the Stack x 

100)/percent R.

In addition, ASTM D6784-02(2008), Standard Test Method for 

Elemental, Oxidized, Particle-Bound and Total Mercury Gas 

Generated from Coal-Fired Stationary Sources (Ontario Hydro 

Method) is acceptable as an alternative to Method 29 in the 

subpart NNN rule. 

The search identified four other VCS that were potentially 

applicable for the Mineral Wool Production rule in lieu of EPA 

reference methods. However, after reviewing the available 

standards, EPA determined that four candidate VCS (ASTM 

D3685/D3685M-98 [2005], ISO 9096:1992 [2003], CAN/CSA Z223.1-

M1977, ANSI/ASME PTC 38 1980 [1985]) identified for measuring 

emissions of pollutants or their surrogates subject to emission 

standards in the rule would not be practical due to lack of 

equivalency, documentation, validation data and other important 

technical and policy considerations. 

Under the Wool Fiberglass rule, the search identified six 

other VCS that were potentially applicable in lieu of EPA 

reference methods (EN 13211:2001, CAN/CSA Z223.26-M1986, ASTM 
Page 206 of 242

D3685/D3685M-98 [2005], ISO 9096:1992 [2003], CAN/CSA Z223.1-

M1977, and ANSI/ASME PTC 38 1980 [1985]). However, the EPA 

determined that these methods would not be practical due to lack 

of equivalency, documentation, validation data and other 

important technical and policy considerations.

The VCS searches are documented in the Voluntary Consensus 

Standard Results for the Risk and Technology Review for the 

Mineral Wool NESHAP and the Voluntary Consensus Standard Results 

for the Risk and Technology Review for the Wool Fiberglass 

NESHAP memorandums as provided in the docket.

The EPA welcomes comments on this aspect of the proposed 

rulemaking and, specifically, invites the public to identify 

potentially-applicable VCS and to explain why such standards 

should be used in this regulation.

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations.

Executive Order 12898 (59 FR 7629, February 16, 1994) 

establishes federal executive policy on EJ. Its main provision 

directs federal agencies, to the greatest extent practicable and 

permitted by law, to make EJ part of their mission by 

identifying and addressing, as appropriate, disproportionately 

high and adverse human health or environmental effects of their 
Page 207 of 242

programs, policies and activities on minority populations and 

low-income populations in the United States.

For the proposed mineral wool rule, the EPA has determined 

that the rule will not have disproportionately high and adverse 

human health or environmental effects on minority or low-income 

populations, because it increases the level of environmental 

protection for all affected populations without having any 

disproportionately high and adverse human health or 

environmental effects on any population, including any minority 

or low-income population.

For the proposed wool fiberglass rule, the EPA has 

determined that the current health risks posed to anyone by 

emissions from this source category are acceptable. Therefore, 

the EPA has determined that the proposed rule will not have 

disproportionately high and adverse human health or 

environmental effects on minority or low-income populations. =.
National Emission Standards For Hazardous Air Pollutants From 

Mineral Wool Production and Wool Fiberglass Manufacturing:

Page 208 of 242

The comments reflect interagency review of the draft rule under

EOs 12866 and 13563. They are subject to further policy review.

List of Subjects in 40 CFR Part 63

Environmental protection, Air pollution control, 

Incorporation by reference, Mineral wool, Wool fiberglass, 

Reporting and recordkeeping requirements.

____________________________

Dated:

____________________________

Lisa P. Jackson,

Administrator.
Page 209 of 242

For the reasons stated in the preamble, part 63 of title 

40, chapter I, of the Code of Federal Regulations is proposed to 

be amended as follows:

PART 63—[AMENDED]

1. The authority citation for part 63 continues to read as 

follows:

Authority: 42 U.S.C. 7401, et seq.

Subpart DDD – [AMENDED]

2. Section 63.1178 is amended by revising paragraph (a)(2) and 

adding requirements for HF and HCl in paragraphs (a)(3) and 

(a)(4). 

§63.1178 For cupolas, what standards must I meet?

* * * * *

(a) * * *

(2) Limit emissions of carbonyl sulfide (COS) from each 

existing, new, or reconstructed cupola to the following:

(i) 3.3 lb of COS per ton of melt or less for existing 

cupolas.

(ii) 0.017 lb of COS per ton of melt or less for new or 

reconstructed cupolas. 

(3) Limit emissions of hydrogen fluoride (HF) from each 

existing, new, or reconstructed cupola to 0.014 lb of HF per ton 

of melt or less.
Page 210 of 242

(4) Limit emissions of hydrogen chloride (HCl) from each 

existing, new, or reconstructed cupola to 0.0096 lb of HCl per 

ton of melt or less.

* * * * *

3. Section 63.1179 is amended by revising the section title to 

read as follows: §63.1179 For combined collection/curing 

operations, what standards must I meet?; revising the emission 

requirements for formaldehyde and adding language for phenol and 

methanol to paragraphs (a) and (b) to read as follows:

§63.1179 For combined collection/curing operations, what 

standards must I meet?

(a) You must control emissions from each existing and new 

combined collection/curing operations by limiting emissions of 

formaldehyde, phenol, and methanol to the following:

(1) For combined drum collection/curing operations:

(i) 0.067 lb of formaldehyde per ton of melt or less, 

(ii) 0.0023 lb of phenol per ton of melt or less, and 

(iii) 0.00077 lb of methanol per ton of melt or less. 

(2) For combined horizontal collection/curing operations:

(i) 0.054 lb of formaldehyde per ton of melt or less, 

(ii) 0.15 lb of phenol per ton of melt or less, and 

(iii) 0.022 lb of methanol per ton of melt or less. 

(3) For combined vertical collection/curing operations:

(i) 0.46 lb of formaldehyde per ton of melt or less, 
Page 211 of 242

(ii) 0.52 lb of phenol per ton of melt or less, and 

(iii) 0.63 lb of methanol per ton of melt or less. 

(b) You must meet the following operating limits for each 

combined collection/curing operations subcategory:

* * * * *

4. Section 63.1180 is amended by revising the compliance dates 

in paragraphs (a) and (b), removing paragraphs (a)(1) and 

(a)(2), revising paragraph (d), and adding paragraph (e) on 

affirmative defense to read as follows:

§63.1180 When must I meet these standards?

(a) Existing cupolas and combined collection/curing 

operations. (1) Except as noted in paragraph (2) of this 

section, the compliance date for an owner or operator of an 

existing plant or source subject to the provisions of this 

subpart is June 2, 2002 or June 3, 2003 if you applied for and 

received a one-year extension under section 112(i)(b)(3)(B) of 

the Act.

(2) The compliance dates for existing plants and sources 

are:

(i) [INSERT DATE 3 YEARS AFTER PUBLICATION OF THE FINAL 

RULE IN THE FEDERAL REGISTER] for cupolas and combined 

collection/curing operations subject to emission limits in 

§§63.1178 and 63.1179 which became effective [INSERT DATE OF 

PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER].
Page 212 of 242

(ii) [INSERT DATE OF PUBLICATION OF THE FINAL RULE IN THE 

FEDERAL REGISTER] for the provisions related to malfunctions and 

affirmative defense provisions of paragraph (e) of this section

and the electronic reporting provisions of §§63.1192(d) and 

63.1193(b)(1) and (g). 

* * * * *

(b) New and reconstructed cupolas and combined 

collection/curing operations. For affected sources that 

commenced construction or reconstruction after [INSERT DATE OF 

PUBLICATION OF THIS PROPOSED RULE IN THE FEDERAL REGISTER], you 

must demonstrate compliance with the requirements of this 

subpart no later than the effective date of the rule or upon 

start-up. 

* * * * *

(d) See §63.1197 for requirements during startups and

shutdowns.

(e) Affirmative Defense for Exceedance of Emissions limits

During Malfunction. In response to an action to enforce the 

standards set forth in this subpart, you may assert an 

affirmative defense to a claim for civil penalties for 

exceedances of such standards that are caused by malfunction, as 

defined at §63.2. Appropriate penalties may be assessed, 

however, if you fail to meet your burden of proving all of the 
Page 213 of 242

requirements in the affirmative defense. The affirmative defense 

must not be available for claims for injunctive relief.

(1) To establish the affirmative defense in any action to 

enforce such a limit, you must timely meet the notification 

requirements in §63.1191 of this subpart, and must prove by a 

preponderance of evidence that:

(i) The excess emissions: 

(A) Were caused by a sudden, infrequent, and unavoidable 

failure of air pollution control and monitoring equipment, 

process equipment, or a process to operate in a normal or usual 

manner; and

(B) Could not have been prevented through careful planning, 

proper design or better operation and maintenance practices; and 

(C) Did not stem from any activity or event that could have 

been foreseen and avoided, or planned for; and

(D) Were not part of a recurring pattern indicative of 

inadequate design, operation, or maintenance.

(ii) Repairs were made as expeditiously as possible when 

the applicable emissions limitations were being exceeded. Offshift and overtime labor were used, to the extent practicable to 

make these repairs; and

(iii) The frequency, amount and duration of the excess 

emissions (including any bypass) were minimized to the maximum 

extent practicable during periods of such emissions; and
Page 214 of 242

(iv) If the excess emissions resulted from a bypass of 

control equipment or a process, then the bypass was unavoidable 

to prevent loss of life, personal injury, or severe property 

damage; and

(v) All possible steps were taken to minimize the impact of 

the excess emissions on ambient air quality, the environment and 

human health; and

(vi) All emissions monitoring and control systems were kept 

in operation if at all possible, consistent with safety and good 

air pollution control practices; and

(vii) All of the actions in response to the excess 

emissions were documented by properly signed, contemporaneous 

operating logs; and

(viii) At all times, the affected source was operated in a 

manner consistent with good practices for minimizing emissions; 

and

(ix) A written root cause analysis has been prepared, the 

purpose of which is to determine, correct, and eliminate the 

primary causes of the malfunction and the excess emissions 

resulting from the malfunction event at issue. The analysis must

also specify, using best monitoring methods and engineering 

judgment, the amount of excess emissions that were the result of 

the malfunction.
Page 215 of 242

(2) Notification. The owner or operator of the affected

source experiencing an exceedance of its emissions limit(s) 

during a malfunction, must notify the Administrator by telephone 

or facsimile transmission as soon as possible, but no later than 

two business days after the initial occurrence of the 

malfunction, s/he wishes to be able to use an affirmative 

defense to civil penalties for that malfunction. The owner or 

operator seeking to assert an affirmative defense, must also 

submit a written report to the Administrator within 45 days of 

the initial occurrence of the exceedance of the standards in 

this subpart. This report must demonstrate that the 

owner/operator met the requirements set forth in paragraph (e) 

of this section and must include all necessary supporting 

documentation. The owner or operator may seek an extension of 

this deadline for up to 30 additional days by submitting a 

written request to the Administrator before the expiration of 

the 45 day period. Until a request for an extension has been 

approved by the Administrator, the owner or operator is subject 

to the requirement to submit such report within 45 days of the 

initial occurrence of the exceedance.

* * * * *

5. Section 63.1182 is amended by revising the section heading 

and introductory paragraph, revising paragraph (a) to clarify 

that the term ‘incinerator’ means ‘regenerative thermal 
Page 216 of 242

oxidizer’, removing all CO emission limits and associated 

language, and adding language for COS, HF, and HCl by revising 

paragraph (b) to read as follows:

§63.1182 How do I comply with the carbonyl sulfide, hydrogen 

fluoride, and hydrogen chloride standards for existing, new, and 

reconstructed cupolas?

To comply with the COS, HF, and HCL standards, you must 

meet the following:

* * * * *

(a) Install, calibrate, maintain, and operate a device that 

continuously measures the operating temperature in the firebox 

of each thermal incinerator. For the purposes of this rule, the 

term ‘incinerator’ means ‘regenerative thermal oxidizer’ (RTO).

(b) Conduct a performance test as specified in §63.1188 of 

this subpart that shows compliance with the COS, HF, and HCl 

emissions limits while the device for measuring incinerator 

(regenerative thermal oxidizer) operating temperature is 

installed, operational, and properly calibrated. Establish the 

average operating temperature based on the performance test as 

specified in §63.1185(a) of this subpart.

6. Section 63.1183 is amended by revising the section heading 

and introductory paragraph, and revising paragraphs (b) and (d) 
Page 217 of 242

to include formaldehyde, phenol, and methanol standards for 

combined collection/curing operations to read as follows:

§63.1183 How do I comply with the formaldehyde, phenol, and 

methanol standards for existing, new, and reconstructed combined 

collection/curing operations?

To comply with the formaldehyde, phenol, and methanol standards, 

you must meet all of the following:

* * * * *

(b) Conduct a performance test as specified in §63.1188 of 

this subpart while manufacturing the product that requires a 

binder formulation made with the resin containing the highest 

free-formaldehyde content specification range. Show compliance 

with the formaldehyde, phenol, and methanol emissions limits

while the device for measuring the control device operating 

parameter is installed, operational, and properly calibrated. 

Establish the average operating parameter based on the 

performance test as specified in §63.1185(a) of this subpart.

* * * * *

(d) Following the performance test, monitor and record the 

free-formaldehyde content of each resin lot and the formulation 

of each batch of binder used, including the formaldehyde, 

phenol, and methanol content.

* * * * *
Page 218 of 242

7. Section 63.1188 is amended by revising paragraphs (b), (c), 

(d), (e), and (f) to read as follows:

§63.1188 What performance test requirements must I meet?

* * * * *

(b) Conduct a performance test, consisting of three test 

runs, for each cupola and/or combined collection/curing 

operation subject to this subpart at the maximum production rate 

to demonstrate compliance with each of the applicable emissions 

limits in §§63.1178 and 63.1179 of this subpart.

(c) Following the initial performance or compliance test to 

be conducted within 120 days of [INSERT PROMULGATION DATE OF THE 

RULE] you must conduct a performance test to demonstrate 

compliance with each of the applicable emissions limits in 

§§63.1178 and 63.1179 of this subpart at least once every 5 

years and as often as the raw material ingredients change by 

more than 10 percent of those processed during the previous 

performance test.

(d) Measure emissions of PM, COS, HF, and HCl from each 

existing, new, or reconstructed cupola.

(e) Measure emissions of formaldehyde, phenol, and methanol 

from each existing, new, or reconstructed combined 

collection/curing operation.

(f) Measure emissions at the outlet of the control device 

for PM, COS, HF, HCl, formaldehyde, phenol, or methanol. 
Page 219 of 242

* * * * *

8. Section 63.1189 is amended by revising paragraph (g) and 

adding paragraph (i) to read as follows:

§63.1189 What test methods do I use?

* * * * *

(g) Method 318 in appendix A to this part for the 

concentration of formaldehyde, phenol, methanol, or COS.

* * * * *

(i) Method 26A or 320 in appendix A to this part for the 

concentration of HF and HCl.

* * * * *

9. Section 63.1190 is amended by revising paragraph (b) to 

include COS, HF, HCl, formaldehyde, phenol and methanol; 

revising the definition of the variable molecular weight (MW) in 

paragraph (b) to include the molecular weights for COS, HF, HCl, 

formaldehyde, phenol and methanol; and removing paragraph (c) to 

read as follows:

§63.1190 How do I determine compliance?

* * * * *

(b) Using the results from the performance tests, you must 

use the following equation to determine compliance with the COS, 

HF, HCl, formaldehyde, phenol, and methanol numerical emissions 

limits:
Page 220 of 242

* * * * *

MW = Molecular weight of measured pollutant, g/g-mole:

COS = 60.07, HF = 20.01, HCl = 36.46, Formaldehyde = 30.03, 

Phenol = 94.11, Methanol = 32.04.

* * * * *

10. Section 63.1191 is amended by revising the introductory 

paragraph to read as follows:

§63.1191 What notifications must I submit?

You must submit written or electronic notifications to the 

Administrator as required by §63.9(b)-(h) of the general 

provisions in subpart A of this part. Electronic notifications 

are encouraged when possible. These notifications include, but 

are not limited to, the following:

* * * * *

11. Section 63.1192 is amended by revising paragraph (d) to read 

as follows: 

§63.1192 What recordkeeping requirements must I meet?

* * * * *

(d) Records must be maintained in a form suitable and 

readily available for expeditious review, according to §63.10 of 

the General Provisions that are referenced in Table 3 to this 

subpart. Electronic recordkeeping is encouraged. 

* * * * *
Page 221 of 242

12. Section 63.1193 is amended by redesignating paragraphs (b) 

through (f) as paragraphs (c) through (g), and adding paragraphs

(b) and (g) to read as follows:

* * * * *

(b)(1) As of January 1, 2012 and within 60 days after the 

date of completing each performance test, as defined in §63.2, 

and as required in this subpart, you must submit performance 

test data, except opacity data, electronically to the EPA’s 

Central Data Exchange by using the ERT (see 

http://www.epa.gov/ttn/chief/ert/erttool.html/) or other 

compatible electronic spreadsheet. Only data collected using 

test methods compatible with the ERT are subject to this 

requirement to be submitted electronically into the EPA’s 

WebFIRE database.

* * * * * 

(g) All reports required by this subpart not subject to the 

requirements in paragraph (b) of this section must be sent to 

the Administrator at the appropriate address listed in §63.13. 

If acceptable to both the Administrator and the owner or 

operator of a source, these reports may be submitted on 

electronic media. The Administrator retains the right to require 

submittal of reports subject to paragraph (b) of this section in 

paper format. 
Page 222 of 242

13. Section 63.1196 is amended by deleting the definitions for 

“CO” and “formaldehyde”, adding definitions for “affirmative 

defense” and “combined collection/curing operations”, and 

revising the definition for “incinerator” to read as follows:

§63.1196 What definitions should I be aware of?

* * * * *

Affirmative defense means, in the context of an enforcement 

proceeding, a response or defense put forward by a defendant, 

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

merits of which are independently and objectively evaluated in a 

judicial or administrative proceeding.

Combined collection/curing operations means the combination 

of fiber collection operations and curing ovens used to make 

bonded products.

Incinerator means an enclosed air pollution control device 

that uses controlled flame combustion to convert combustible 

materials to noncombustible gases. For the purposes of this 

rule, the term ‘incinerator’ means ‘regenerative thermal 

oxidizer’ (RTO).

* * * * *

14. Section 63.1197 is amended by adding requirements for 

startups and shutdowns to read as follows:

§63.1197 Startups and shutdowns. 
Page 223 of 242

(a) The provisions set forth in this subpart apply at all 

times.

(b) The owner or operator must not shut down items of 

equipment that are utilized for compliance with this subpart.

(c) Table 1 to subpart DDD summarizes the emissions limits

during startups and shutdowns for existing, new, and 

reconstructed cupolas.

Table 1 to Subpart DDD-Emissions limits During Startups and 

Shutdowns for Existing, New, and Reconstructed Cupolas, pound of

pollutant per hour

Pollutant

Emission Limit (lb/hr)

Existing Cupolas

New and 

Reconstructed 

Cupolas

PM 1.0 1.0

COS 32 0.17

HF 0.13 0.13

HCl 0.092 0.092

(d) Table 2 to subpart DDD summarizes the emissions limits

during startups and shutdowns for existing, new, and 

reconstructed combined collection/curing operations.

Table 2 to Subpart DDD-Emissions limits During Startups and 

Shutdowns for Existing, New, and Reconstructed Combined 

Collection/Curing Operations, pound of pollutant per hour

Design Pollutant Emission Limit 

(lb/hr)

Vertical Formaldehyde 4.5

Phenol 5.0

Methanol 6.0

Horizontal Formaldehyde 0.52

Phenol 1.4

Methanol 0.21

Drum Formaldehyde 0.64

Phenol 0.022

Methanol 0.0074
Page 224 of 242

* * * * *

15. Table 1 to subpart DDD of part 63 is redesignated as Table 3 

to subpart DDD of part 63 and amended to read as follows:

Table 3 to Subpart DDD of Part 63—Applicability of General 

Provisions (40 CFR Part 63, Subpart A) to Subpart DDD of Part 63

Reference Applies to 

subpart DDD

Comment

63.1 Yes

63.2 Yes

63.3 Yes

63.4 Yes

63.5 Yes

63.6(a), (b), (c) Yes

63.6(d) No Section reserved.

63.6(e)(1)(i) No See 63.1180 for 

general duty 

requirement.

63.6(e)(1)(ii) No

63.6(e)(1)(iii) Yes

63.6(e)(2) No Section reserved.

63.6(e)(3) No

63.6(f)(1) No

63.6(g) Yes

63.6(h) No No opacity limits in 

rule.

63.6(i) Yes

63.6(j) Yes

§63.7(a)-(d) Yes

§63.7(e)(1) No See 63.1180

§63.7(e)(2)-(e)(4) Yes

63.7(f), (g), (h) Yes

63.8(a)-(b) Yes

63.8(c)(1)(i) No See 63.1180 for 

general duty 

requirement.

63.8(c)(1)(ii) Yes

63.8(c)(1)(iii) No
Page 225 of 242

Reference Applies to 

subpart DDD

Comment

63.8(c)(2)-(d)(2) Yes

63.8(d)(3) Yes, except 

for last 

sentence

63.8(e)-(g) Yes

63.9(a),(b),(c),(e),(g),(h)(1)th

rough (3), (h)(5) and (6), (i) 

and (j)

Yes

63.9(f) No

63.9(h)(4) No Reserved

63.10 (a) Yes

63.10 (b)(1) Yes

63.10(b)(2)(i) No

63.10(b)(2)(ii) No See 63.1193(c) for 

recordkeeping of 

occurrence and 

duration of 

malfunctions and 

recordkeeping of 

actions taken during 

malfunction. 

63.10(b)(2)(iii) Yes

63.10(b)(2)(iv)-(b)(2)(v) No

63.10(b)(2)(vi)-(b)(2)(xiv) Yes

63.(10)(b)(3) Yes

63.10(c)(1)-(9) Yes

63.10(c)(10)-(11) No See 63.1192 for 

recordkeeping of 

malfunctions. 

63.10(c)(12)-(c)(14) Yes

63.10(c)(15) No

63.10(d)(1)-(4) Yes

63.10(d)(5) No See 63.1193 for 

reporting of 

malfunctions.

63.10(e)-((f) Yes

63.11 No Flares will not be 

used to comply with 

the emissions limits

63.12 to 63.15 Yes
Page 226 of 242

* * * * *

Subpart NNN – [AMENDED]

16. Section 63.1381 is amended by adding a definition for 

“affirmative defense” and revising the definition for 

“incinerator”.

§63.1381 Definitions.

* * * * *

Affirmative defense means, in the context of an enforcement 

proceeding, a response or defense put forward by a defendant, 

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

merits of which are independently and objectively evaluated in a 

judicial or administrative proceeding.

Incinerator means an enclosed air pollution control device 

that uses controlled flame combustion to convert combustible 

materials to noncombustible gases. For the purposes of this 

rule, the term ‘incinerator’ means ‘regenerative thermal 

oxidizer’ (RTO).

* * * * *

17. Section 63.1382 is amended by revising paragraph (a) to 

include revised emissions limits for PM; adding emissions limits

for chromium compounds, hydrogen fluoride, and hydrogen 

chloride; revising formaldehyde emissions limits; and adding 
Page 227 of 242

emissions limits for phenol and formaldehyde; and revising 

paragraph (b)(6) to include phenol and methanol.

§63.1382 Emission standards.

(a) Emissions limits

(1) Glass-melting furnaces. On and after the date the 

initial performance test is completed or required to be 

completed under §63.7 of this part, whichever date is earlier, 

(i) the owner or operator of each existing glass-melting 

furnace must not discharge or cause to be discharged into the 

atmosphere in excess of:

(A) 0.014 pound (lb) of particulate matter (PM) per ton of 

glass pulled;

(B) 0.0020 lb of hydrogen fluoride (HF) per ton of glass 

pulled; and 

(C) 0.0015 lb of hydrogen chloride (HCl) per ton of glass 

pulled. 

(D) 0.00006 lb of chromium (Cr) compounds per ton of glass 

pulled (60 lb per million tons glass pulled).

(ii) the owner or operator of each new or reconstructed 

glass-melting furnace must not discharge or cause to be 

discharged into the atmosphere in excess of:

(A) 0.0018 lb of PM per ton of glass pulled; 

(B) 0.00078 lb of HF per ton of glass pulled; and 

(C) 0.00078 lb of HCl per ton of glass pulled. 
Page 228 of 242

(D) 0.00006 lb of Cr compounds per ton of glass pulled (60

lb per million tons glass pulled).

(2) Rotary spin manufacturing lines. On and after the date 

the initial performance test is completed or required to be 

completed under §63.7 of this part, whichever date is earlier, 

(i) the owner or operator of each existing rotary spin (RS)

manufacturing line must not discharge or cause to be discharged 

into the atmosphere in excess of:

(A) 0.17 lb of formaldehyde per ton of glass pulled;

(B) 0.19 lb of phenol per ton of glass pulled; and 

(C) 0.48 lb of methanol per ton of glass pulled.

(ii) the owner or operator of each new or reconstructed RS

manufacturing line must not discharge or cause to be discharged 

into the atmosphere in excess of:

(A) 0.020 lb of formaldehyde per ton of glass pulled;

(B) 0.0011 lb of phenol per ton of glass pulled; and 

(C) 0.00067 lb of methanol per ton of glass pulled.

(3) Flame attenuation manufacturing lines. On and after the 

date the initial performance test is completed or required to be 

completed under §63.7 of this part, whichever date is earlier, 

(i) the owner or operator of each existing flame 

attenuation (FA) manufacturing line that produces heavy-density 

wool fiberglass and/or pipe insulation must not discharge or 

cause to be discharged into the atmosphere in excess of:
Page 229 of 242

(A) 5.6 lb of formaldehyde per ton of glass pulled;

(B) 1.4 lb of phenol per ton of glass pulled; and 

(C) 0.50 lb of methanol per ton of glass pulled. 

(ii) the owner or operator of each new or reconstructed FA

manufacturing line that produces heavy-density wool fiberglass

and/or pipe insulation must not discharge or cause to be 

discharged into the atmosphere in excess of:

(A) 3.3 lb of formaldehyde per ton of glass pulled;

(B) 0.46 lb of phenol per ton of glass pulled; and 

(C) 0.50 lb of methanol per ton of glass pulled. 

(b) * * * 

(6) The owner or operator must operate each control device

used to control formaldehyde, phenol, and methanol emissions 

from forming or curing such that any three-hour block average 

temperature in the firebox does not fall below the average 

established during the performance test as specified in 

§63.1384.

* * * * *

18. Section 63.1383 is amended by revising paragraph (f) to read 

as follows:

§63.1383 Monitoring requirements.

* * * * *
Page 230 of 242

(f) The owner or operator who uses a control device to 

control HAP emissions from a glass-melting furnace, RS 

manufacturing line, or FA manufacturing line must install, 

calibrate, maintain, and operate a monitoring device that 

continuously measures an appropriate parameter that is 

correlated to the emission limit performance test.

* * * * *

19. Section 63.1384 is amended by revising the E, C, and MW 

variables in equation (2) in paragraph (c), and adding 

paragraphs (d) and (e) to read as follows:

§63.1384 Performance test requirements.

* * * * *

(c) To determine compliance with the emission limit for 

formaldehyde, phenol, or methanol for RS manufacturing lines and 

FA manufacturing lines, and for chromium compounds, HF, or HCl

for glass-melting furnaces, use the following equation:

* * * * *

E = Emission rate of formaldehyde, phenol, methanol, chromium 

compounds, HF, or HCl, kg/Mg (lb/ton) of glass pulled;

C = Measured volume fraction of formaldehyde, phenol, methanol, 

chromium compounds, HF, or HCl, ppm;
Page 231 of 242

MW = Molecular weight of formaldehyde, 30.03 g/g-mol; molecular 

weight of phenol, 94.11 g/g-mol; molecular weight of methanol, 

32.04 g/g-mol; molecular weight of chromium compounds tested in

g/g-mol; molecular weight of HF, 20.0064 g/g-mol; molecular 

weight of HCl, 36.4611 g/g-mol.

(d) Following the initial performance or compliance test to 

be conducted within 90 days of [INSERT PROMULGATION DATE OF THE 

RULE] to demonstrate compliance with the chromium compounds 

emissions limit specified in §63.1382(a)(1)(D) or (a)(ii)(D), 

you must conduct an annual performance test for chromium 

compounds emissions from each glass-melting furnace (no later 

than 12 calendar months following the previous compliance test). 

(e) Following the initial performance or compliance test to 

demonstrate compliance with the PM, HF, HCl, formaldehyde, 

phenol, and methanol emissions limits specified in §63.1382, you 

must conduct a performance test to demonstrate compliance with 

each of the applicable PM, HF, HCl, formaldehyde, phenol, and 

methanol emissions limits in §63.1382 of this subpart at least 

once every 5 years and as often as raw material inputs change by 

more than 10 percent following the previous test.

* * * * *

20. Section 63.1385 is amended by revising the requirements for 

test methods in paragraphs (a)(5) and (a)(6), and adding 

requirements for test methods in paragraphs (a)(11) and (a)(12).
Page 232 of 242

§63.1385 Test methods and procedures.

* * * * *

(a) * * *

(5) Method 5 and Method 202 (40 CFR part 60, appendix A) 

for the concentration of total PM including condensibles. Each 

run must consist of a minimum run time of 2 hours and a minimum 

sample volume of 60 dry standard cubic feet (dscf). The probe 

and filter holder heating system may be set to provide a gas 

temperature no greater than 177±14oC (350±25oF);

(6) Method 318 (appendix A of this subpart) for the 

concentration of formaldehyde, phenol, and methanol. Each run 

must consist of a minimum run time of 2 hours;

* * * * *

(11) Method 0061 (appendix A of this subpart) for the 

concentration of chromium compounds and hexavalent chromium. 

Each run must consist of a minimum run time of 1 hour.

(12) Method 26A or Method 320 (appendix A of this subpart) 

for the concentration of HF and HCl. Each run must consist of a 

minimum run time of 1 hour.

* * * * *

21. Section 63.1386 is amended by revising the notification 

dates in paragraphs (a)(2), (a)(3), and (a)(4); revising 

recordkeeping requirements in paragraphs (d)(ii) and (d)(iii), 

and adding paragraph (d)(2)(x); adding electronic reporting 
Page 233 of 242

language in paragraph (f); and adding in requirements for 

affirmative defense for exceedances of emissions limits during 

malfunction to paragraph (g).

§63.1386 Notification, recordkeeping, and reporting 

requirements.

(a) * * *

(2) Notification that a source is subject to the standard, 

where the initial startup is before [INSERT DATE OF PUBLICATION 

OF THIS PROPOSED RULE IN THE FEDERAL REGISTER].

(3) Notification that a source is subject to the standard, 

where the source is new or has been reconstructed the initial 

startup is after [INSERT DATE OF PUBLICATION OF THIS PROPOSED 

RULE IN THE FEDERAL REGISTER], and for which an application for 

approval of construction or reconstruction is not required;

(4) Notification of intention to construct a new affected

source or reconstruct an affected source; of the date 

construction or reconstruction commenced; of the anticipated 

date of startup; of the actual date of startup, where the 

initial startup of a new or reconstructed source occurs after 

[INSERT DATE OF PUBLICATION OF THIS PROPOSED RULE IN THE FEDERAL 

REGISTER], and for which an application for approval or 

construction or reconstruction is required (See §63.9(b)(4) and 

(5) of this part);

* * * * *
Page 234 of 242

(d) * * *

(1) * * *

(ii) The owner or operator may retain records 

electronically, on a computer or labeled computer disks, or on 

paper; and

(iii) The owner or operator may report required information 

on paper or on a labeled computer disk using commonly available 

and EPA-compatible computer software. Electronic notifications 

are encouraged when possible.

* * * * *

(2) * * *

(x) You must report total chromium and hexavalent chromium 

emissions from glass-melting furnaces using Method 0061. 

* * * * *

(f)(1) As of January 1, 2012 and within 60 days after the 

date of completing each performance test, as defined in §63.2, 

and as required in this subpart, you must submit performance 

test data, except opacity data, electronically to the EPA’s 

Central Data Exchange by using the ERT (see 

http://www.epa.gov/ttn/chief/ert/erttool.html/) or other 

compatible electronic spreadsheet. Only data collected using 

test methods compatible with ERT are subject to this requirement 

to be submitted electronically into the EPA’s WebFIRE database.
Page 235 of 242

(2) All reports required by this subpart not subject to the 

requirements in paragraph (f)(1) of this section must be sent to 

the Administrator at the appropriate address listed in § 63.13. 

If acceptable to both the Administrator and the owner or 

operator of a source, these reports may be submitted on 

electronic media. The Administrator retains the right to require 

submittal of reports subject to paragraph (f)(1) of this section 

in paper format. 

(g) Affirmative Defense for Exceedance of Emission Limit 

During Malfunction. In response to an action to enforce the 

standards set forth in this subpart, you may assert an 

affirmative defense to a claim for civil penalties for 

exceedances of such standards that are caused by malfunction, as 

defined at §63.2. Appropriate penalties may be assessed, 

however, if you fail to meet your burden of proving all of the 

requirements in the affirmative defense. The affirmative defense 

must not be available for claims for injunctive relief.

(1) To establish the affirmative defense in any action to 

enforce such a limit, you must timely meet the notification 

requirements in §63.1386 of this subpart, and must prove by a 

preponderance of evidence that:

(i) The excess emissions: 

(A) Were caused by a sudden, infrequent, and unavoidable 

failure of air pollution control and monitoring equipment, 
Page 236 of 242

process equipment, or a process to operate in a normal or usual 

manner; and

(B) Could not have been prevented through careful planning, 

proper design or better operation and maintenance practices; and 

(C) Did not stem from any activity or event that could have 

been foreseen and avoided, or planned for; and

(D) Were not part of a recurring pattern indicative of 

inadequate design, operation, or maintenance.

(ii) Repairs were made as expeditiously as possible when 

the applicable emissions limitations were being exceeded. Offshift and overtime labor were used, to the extent practicable to 

make these repairs; and

(iii) The frequency, amount and duration of the excess 

emissions (including any bypass) were minimized to the maximum 

extent practicable during periods of such emissions; and

(iv) If the excess emissions resulted from a bypass of 

control equipment or a process, then the bypass was unavoidable 

to prevent loss of life, personal injury, or severe property 

damage; and

(v) All possible steps were taken to minimize the impact of 

the excess emissions on ambient air quality, the environment and 

human health; and
Page 237 of 242

(vi) All emissions monitoring and control systems were kept 

in operation if at all possible, consistent with safety and good 

air pollution control practices; and

(vii) All of the actions in response to the excess 

emissions were documented by properly signed, contemporaneous 

operating logs; and

(viii) At all times, the affected source was operated in a 

manner consistent with good practices for minimizing emissions; 

and

(ix) A written root cause analysis has been prepared, the 

purpose of which is to determine, correct, and eliminate the 

primary causes of the malfunction and the excess emissions 

resulting from the malfunction event at issue. The analysis must

also specify, using best monitoring methods and engineering 

judgment, the amount of excess emissions that were the result of 

the malfunction.

(2) Notification. The owner or operator of the affected 

source experiencing an exceedance of its emissions limit(s) 

during a malfunction, must notify the Administrator by telephone 

or facsimile transmission as soon as possible, but no later than 

two business days after the initial occurrence of the 

malfunction, if he/she wishes to be able to use an affirmative 

defense to civil penalties for that malfunction. The owner or 

operator seeking to assert an affirmative defense must also 
Page 238 of 242

submit a written report to the Administrator within 45 days of 

the initial occurrence of the exceedance of the standards in 

this subpart. This report must demonstrate that the 

owner/operator has met the requirements set forth in paragraph 

(g) of this section and must include all necessary supporting 

documentation. The owner or operator may seek an extension of 

this deadline for up to 30 additional days by submitting a 

written request to the Administrator before the expiration of 

the 45 day period. Until a request for an extension has been 

approved by the Administrator, the owner or operator is subject 

to the requirement to submit such report within 45 days of the 

initial occurrence of the exceedance. 

* * * * *

22. Section 63.1387 is amended by revising the compliance dates

in paragraph (a) to read as follows:

§63.1387 Compliance dates.

(a) * * *

(1) Except as noted in paragraph (2) of this section, the 

compliance date for an owner or operator of an existing plant or 

source subject to the provisions of this subpart is [INSERT DATE 

OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER].

(2) The compliance dates for existing plants and sources 

are:
Page 239 of 242

(i) [INSERT DATE 1 YEAR AFTER PUBLICATION OF THE FINAL RULE

IN THE FEDERAL REGISTER] for glass-melting furnaces, rotary spin 

manufacturing lines, or flame attenuation manufacturing lines

subject to emission limits in §63.1382(a) which became effective 

[INSERT DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL 

REGISTER].

(ii) [INSERT DATE OF PUBLICATION OF THE FINAL RULE IN THE 

FEDERAL REGISTER] for the provisions related to malfunctions and 

affirmative defense provisions of §63.1386(g) and the electronic 

reporting provisions of §63.1386(d) and (f). 

* * * * *

23. Section 63.1388 is amended by adding requirements for 

startups and shutdowns to read as follows:

§63.1388 Startups and shutdowns. 

(a) The provisions set forth in this subpart apply at all 

times.

(b) The owner or operator must not shut down items of 

equipment that are required or utilized for compliance with the 

provisions of this subpart during times when emissions are being 

routed to such items of equipment, if the shutdown would 

contravene requirements of this subpart applicable to such items 

of equipment. This paragraph does not apply if the owner or 

operator must shut down the equipment to avoid damage due to a 
Page 240 of 242

contemporaneous startup or shutdown, of the affected source or a 

portion thereof.

(c) Table 1 to subpart NNN summarizes the emissions limits

during startups and shutdowns of glass-melting furnaces.

Table 1 to Subpart NNN-Emissions limits During Startups and 

Shutdowns of Glass-Melting Furnaces (lb/hr)

Pollutant Existing 

Furnaces

New and Reconstructed 

Furnaces

PM 0.25 0.033

Chromium Compounds 0.0019 0.0019

HF 0.036 0.014

HCl 0.026 0.014

(d) Table 2 to subpart NNN summarizes the emissions limits

during startups and shutdowns of rotary spin (RS) manufacturing 

lines.

Table 2 to Subpart NNN-Emissions limits During Startups and 

Shutdowns of Rotary Spin (RS) Manufacturing Lines (lb/hr)

Pollutant Existing RS 

Lines

New and Reconstructed 

RS Lines

Formaldehyde 3.1 0.36

Phenol 3.4 0.019

Methanol 8.8 0.012

(e) Table 3 to subpart NNN summarizes the emissions limits

during startups and shutdowns of flame attenuation (FA) 

manufacturing lines.

Table 3 to Subpart NNN-Emissions limits During Startups and 

Shutdowns of Flame Attenuation (FA) Manufacturing Lines (lb/hr)

Pollutant Existing FA 

Lines

New and Reconstructed 

FA Lines

Formaldehyde 100 60

Phenol 25 8

Methanol 9 9
Page 241 of 242

24. Table 1 to Subpart NNN of Part 63 is redesignated as Table 4 

to Subpart NNN of Part 63 and amended to read as follows:

Table 4to Subpart NNN of Part 63—General Provisions 

Applicability to Subpart NNN

Reference Applies to 

subpart NNN

Comment

63.1 Yes

63.2 Yes

63.3 Yes

63.4 Yes

63.5 Yes

63.6(a), (b), (c) Yes

63.6(d) No Section reserved.

63.6(e)(1)(i) No See 63.1382(b) for 

general duty 

requirement.

63.6(e)(1)(ii) No

63.6(e)(1)(iii) Yes

63.6(e)(2) No Section reserved.

63.6(e)(3) No

63.6(f)(1) No

63.6(g) Yes

63.6(h) No No opacity limits in 

rule.

63.6(i) Yes

63.6(j) Yes

§63.7(a)-(d) Yes

§63.7(e)(1) No See 63.1382(b)

§63.7(e)(2)-(e)(4) Yes

63.7(f), (g), (h) Yes

63.8(a)-(b) Yes

63.8(c)(1)(i) No See 63.1382(b) for 

general duty 

requirement.

63.8(c)(1)(ii) Yes

63.8(c)(1)(iii) No

63.8(c)(2)-(d)(2) Yes

63.8(d)(3) Yes, except 

for last 

sentence
Page 242 of 242

Reference Applies to 

subpart NNN

Comment

63.8(e)-(g) Yes

63.9(a),(b),(c),(e),(g),(h)(1)thr

ough (3), (h)(5) and (6), (i) and 

(j)

Yes

63.9(f) No

63.9(h)(4) No Reserved

63.10 (a) Yes

63.10 (b)(1) Yes

63.10(b)(2)(i) No

63.10(b)(2)(ii) No See 63.1386 for 

recordkeeping of 

occurrence and 

duration of 

malfunctions and 

recordkeeping of 

actions taken during 

malfunction. 

63.10(b)(2)(iii) Yes

63.10(b)(2)(iv)-(b)(2)(v) No

63.10(b)(2)(vi)-(b)(2)(xiv) Yes

63.(10)(b)(3) Yes

63.10(c)(1)-(9) Yes

63.10(c)(10)-(11) No See 63.1386 for 

recordkeeping of 

malfunctions. 

63.10(c)(12)-(c)(14) Yes

63.10(c)(15) No

63.10(d)(1)-(4) Yes

63.10(d)(5) No See 63.1386(c)(2) for 

reporting of 

malfunctions.

63.10(e)-((f) Yes

63.11 No Flares will not be 

used to comply with 

the emissions limits

63.12 to 63.15 Yes