Date: August 15, 2012

Subject: Summary of Public Comments on Chromium Electroplating and Steel Pickling

Risk and Technology Review (RTR)

From: Phil Mulrine, EPA/OAQPS/SSPD

To: Docket

The purpose of this memorandum is to summarize and respond to comments received 

from the proposed National Emission Standards for Chromium Emissions from Hard and 

Decorative Chromium Electroplating and Chromium Anodizing Tanks (Chromium 

Electroplating NESHAP, 40 CFR 63, subpart N) and for the Steel Pickling – HCl Process 

Facilities and Hydrochloric Acid Regeneration Plants (Steel Pickling NESHAP, 40 CFR 63, 

subpart CCC) that were not presented in the Federal Register (FR) notice for this action. The 

other comments and responses are shown in the Federal Register notice. 

I. List of Commenters

Table 1 summarizes the commenters who provided comments on the proposed 

Chromium Electroplating and Steel Pickling NESHAP. 

Table 1. Chromium Electroplating, Anodizing and Steel Pickling Commenter Lista

Comment No.b Association Name

0259 Northrop Grumman Shipbuilding, Inc. James R. Thornton

0260/0616

Clean Air Act Services Steering Committee 

(representing the Departments of the Navy, 

Air Force, and Army, other DoD).

Donald R. Schregardus

0272 Regional Air Pollution Control Agency 

(RAPCA)-Ohio

John Paul

0274/0618 New York State Department on 

Environmental Conservation Division of Air 

Resources

David J. Shaw/J. Jared 

Snyder

0275/0615 National Association of Clean Air Agencies 

(NACAA)

G. Vinson Hellwig

Robert H. Colby

0277 Labyrinth Management Group, Inc (LMG), 

for The Electrolizing Corporation of Ohio

Chuck Sisia

0278/0617 North Carolina Department of Environment 

and Natural Resources

Sheila Holman

0285/0296/0619 National Association for Surface Finishing 

(NASF)

Jeffery S. Hannapel

0290/0620 Sierra Club, Earthjustice, et al. Emma Cheuse, James Pew, 

etc.

0291 Air Permitting Forum Shannon S. Broome, 

Teresa A. Gorman, Charles 
2

Comment No.b Association Name

H. Knauss

0609 Indiana Department of Environmental 

Management

Phil Perry

0610 Small Business Administration Office of 

Advocacy

Winslow Sargeant, Sarah 

Bresolin Silver

0613 Alcoa Inc. James D. Jones

0614 American Iron Oxide Company (Amrox) Franz Mullings

0286 American Iron and Steel Institute P. Paganoc

0295 Nucor Corporation E. Hiserc

0614 American Iron Oxide Company F. Mullins a

 Excludes form letter commenters.

b

 Comments 0259 to 0296 apply to October 2010 proposal; Comments 0609 to 0620 apply to 

February 2012 supplemental proposal.

c

 Comments 0286 and 0295 apply to October 2010 proposal.

II. Summary of Comments and Responses – Chromium Electroplating NESHAP

1. General RTR Approach

Comment: Commenter 0285/0296/0619 stated that EPA reversed the proper analysis of 

this rulemaking by first proposing unnecessarily strict standards based on the section 112(d)(6) 

technology review and, after proposing to set new standards under section 112(d)(6), determined 

whether those newly proposed standards should be further revised under CAA section 112(f). 

The commenter added that standards based on section 112(d)(6) were not warranted because 

EPA did not base the proposed lower emission standards on any new technology that has become 

available since the promulgation of the original rule. The commenter stated that EPA should 

have conducted the section 112(f) review of the existing standard first to determine if there was a 

residual risk of concern and should have moved on to the section 112(d)(6) review only if stricter 

standards were warranted based on the results of the section 112(f) review. The commenter 

stated that EPA has previously explained this approach in 69 Fed. Reg. 48351 and that, if EPA 

had first evaluated the existing standards under 112(f), it would have concluded that the existing 

standards were appropriately protective, as it did in October 2010.

Response: We disagree with the commenter’s assertion that EPA should conduct a 

technology review under section 112(d)(6) only if EPA determines that additional controls are 

warranted based on the results of the risk review under section 112(f). This approach would 

appear to eliminate any independent role for section 112(d)(6) because it could not be invoked in 

the absence of a determination that additional controls are needed to address risk. Where 

evaluation of the various health and environmental factors supports adoption of additional 

controls, then section 112(f)(2) provides authority to adopt such requirements. Even if risk 

factors remain the same, changes in costs and performance, or in the availability of control 

technology may be sufficient to determine it is necessary to revise the existing section 112 

standard pursuant to section 112(d)(6). 

We note, however, that although we are not required to consider risk as part of the section 

112(d)(6) review, and we are also not precluded from doing so. Under the CAA, we are required 
3

to perform the risk review under CAA section 112(f)(2) only once, eight years after 

promulgation of the MACT standard. In comparison, we are required to perform the technology 

review under CAA section 112(d)(6) every eight years. Thus, even though we are not 

considering risk as part of the technology review at this stage, we may choose to consider risk as 

we conduct the second round of technology reviews 8 years after this initial round. 

The commenter also states that a section 112(d)(6) revision is not warranted because no 

new technology has been developed since promulgation of the NESHAP. This reading of section 

112(d)(6) is too narrow. Section 112(d)(6) provides that EPA shall revise section 112 standards 

“as necessary (taking into account developments in practices, processes and control 

technologies).” There is nothing in this provision that indicates that EPA is to consider only 

“new” technology that has become available since promulgation of the section 112 standard. 

Rather, it refers to “developments” which refers not only to new technologies, but also 

improvements in existing technologies. We believe “developments” includes new events that 

have resulted in a technology being more economically or technologically feasible. In addition, 

the language refers to practices and processes as well as technologies. Developments in practices 

and processes can include such things as improvements in the control efficiency of an existing 

technology or developments in how a technology is used so that greater reductions may be 

achieved. For example, at the time the NESHAP was promulgated, composite mesh pad systems 

were a new control technology. Since that time, manufacturers of composite mesh pads, as well 

as other types of controls used in the electroplating industry, have continued efforts to improve 

their products. Our analysis of the data indicate that these improvements in the control device 

design result in emissions that are substantially lower than those required at the time we 

established the MACT standards in 1995. 

Comment: Commenter 0285/0296/0619 stated that EPA’s authority under CAA section 

112(d)(6) is limited by the terms of the statute to only making “necessary” revisions to existing 

standards. The commenter added that the term “necessary” in section 112(d)(6) sets a very high 

standard for when changes may be made, and EPA has offered no basis for concluding that its 

proposed changes are “necessary.” The commenter acknowledged that EPA may impose 

additional controls based on the “ample margin of safety” or the 112(d)(6) technology review if 

it meets certain criteria. The commenter believes that with respect to these criteria, EPA has no 

basis to justify new controls for chromium electroplating and anodizing operations because EPA 

has not identified any additional HAPs since the promulgation of the original NESHAP, 

documented any significant improvement in performance for fume suppressants, mesh pads, 

scrubbers, identified any new cost-effective control technologies, and has not identified any cobenefits from the control of criteria pollutant emissions, in addition to chromium emissions.

Response: As explained in the previous response, section 112(d)(6) provides broad 

authority to EPA to review developments that could result in greater emission reductions of 

HAP. In reviewing section 112(d)(2) and (3) standards, and determining whether it is 

“necessary” to revise them under section 112(d)(6), the EPA must evaluate developments in 

practices, processes, and control technologies and in that evaluation, we consider the economic 

and technological feasibility of such developments. Section 112(d)(6) is a continuation of the 

technology-based section 112(d) standard-setting process, and determination is not controlled by 

risk-based considerations. Consequently, the EPA does not interpret CAA section 112 (d)(6) as 
4

requiring that a standard is “necessary” only if justifiable based on public health/risk 

considerations. Although the decision whether to revise a section 112 standard pursuant to 

section 112(d)(6) is not primarily a public health-based determination as is the decision under 

section 112(f), we note that section 112(d)(6) does not preclude consideration of health and 

environmental factors. See NRDC v. EPA, 529 F. 3d 1077, 1084 (D.C. Cir. 2008). We also 

disagree with the comment that suggests that EPA may take action to revise a standard under 

section 112(d)(6) only if the Agency has identified additional HAP or co-benefits from the 

control of criteria pollutant emissions. While those are factors that might play a role in a decision 

whether it is necessary to revise the standard, they are not required conditions for establishing a 

revised standard under section 112(d)(6). As explained in the proposed rule and the preamble 

discussing our final decision, we have concluded that there have been improvements in the 

performance of some of the technologies currently in use to control emissions from chromium 

electroplating sources and we believe that these improvements will result in further emission 

reductions that can be achieved cost-effectively. Thus, we are revising the standard to reflect 

these further cost-effective emission reductions.

Comment: Commenter 0290/0620 suggested that EPA may not rely on the HON 

decision as justification not to perform the updated MACT floor analysis required by CAA 

section 112(d)(6) since the decision explained that its reasoning was based on the fact that 

petitioners had not identified any technological innovations that EPA had overlooked. The 

commenter made the argument that, in this case, there have been developments in practices, 

processes, and control technologies and EPA cannot rely on the HON case to evade its duty to 

satisfy section 112(d)(6). The commenter added that the HON case acknowledges in dicta that 

EPA must review existing floors under the section 112(d)(6) revision, and that using cost as the 

basis for setting section 112(d)(6) standards that reaffirmed existing standards was troublesome 

and contrary to cases holding that costs may not be considered in setting floors. The commenter 

suggested that, based on the record, EPA strengthen the existing MACT floor to ensure it meets 

section 112(d)(3). 

The commenter stated that, for the chromium electroplating source category, EPA has 

recognized that there are significant new technologies that sources are using and that certain 

sources have achieved a level of actual emissions that is less than the allowable emissions under 

the MACT standard. Although the commenter questioned whether these emissions data are 

accurate, the commenter explained that, once EPA has such information, the Agency must factor 

this into the technology review under section 112(d)(6). The commenter noted in particular, that 

plants in California have achieved levels of emissions well below the current emissions limits 

and added that, if EPA had performed the required assessment and included all existing sources, 

including California sources, it is likely that the average emission limitation achieved by the best 

performing 12 percent of the existing sources would be significantly lower than the levels EPA 

chose for the proposed rule and that the limit for new sources in each subcategory also would 

likely be much lower. The commenter stated that EPA has not considered or addressed whether 

the existing MACT floor remains lawful in view of the greater levels of emission reductions that 

have been achieved. According to the commenter, the main thrust of section 112(d)(2) and (3) is 

to require technology-based standards that reflect the maximum achievable degree of emission 

reduction (42 U.S.C. section 7412(d)(2)). Then, section 112(d)(6) serves as an ongoing ratchet to 

continually require EPA to update standards to keep pace with new technology. The commenter 
5

stated that all national emission standards for HAPs must satisfy the requirements of sections 

112(d)(2) and (3), both when set initially and when they are revised and that EPA has no 

justification for failing to recalculate the MACT floors based on new technology and new 

emission reductions now achieved by the source category. The commenter concluded that EPA 

did not review or update the MACT floors for new or existing sources for the Chromium 

Electroplating and Anodizing source category pursuant to section 112(d)(3), but instead looked 

at new developments and performed a cost assessment that made cost (not achievability, as 

required) the central component of the analysis, which the commenter stated, is in violation of 

section 112(d)(6). The commenter recommended that EPA abide by section 112(d)(3) and set 

new MACT floors based on the emission reductions achieved and achievable using the new 

developments without consideration of cost. The commenter stated that because EPA failed to 

calculate a MACT floor, its proposal is unlawful and arbitrary, and it is unlawful for the agency 

to make cost the primary focus of its section 112(d)(6) determination. 

On the other hand, Commenter 0285/0296/0619 agreed with EPA’s conclusion that it 

would be inappropriate for the Agency to import the strict benchmarking required by section 

112(d)(3) into the periodic section 112(d)(6) reviews, and that doing so would create a one way 

ratchet for MACT standards that would be in violation of the clear statutory mandate. The 

commenter noted that the D.C. Circuit has already rejected the argument that section 112(d)(6) 

requires EPA to “completely recalculate the maximum achievable control technology — in other 

words, to start from scratch.” NRDC v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008). The 

commenter added that the setting of a MACT floor under section 112(d) is a one-time 

requirement.

Response: We disagree with the comments suggesting that the EPA must recalculate 

MACT floors under CAA section 112(d)(2)-(3) as part of the section 112(d)(6) review. As 

explained in a prior RTR rulemaking, the EPA does not read 112(d)(6) as requiring a reanalysis 

or recalculation of MACT floors. See National Emission Standards for Coke Oven Batteries (70 

FR 19998-19999, April 15, 2005). We read section 112(d)(6) as providing the EPA with 

substantial latitude in weighing a variety of factors and arriving at an appropriate balance in 

considering revisions to standards promulgated under section 112(d)(2) & (3). Nothing in section 

112(d)(6) expressly or implicitly requires that EPA recalculate the MACT floor as part of the 

section 112(d)(6) review. This position has been upheld by the court. NRDC v. EPA, 529 F.3d 

1077, 1084 (D.C. Cir. 2008). We disagree with the commenters that the court’s decision hinged 

on the fact that for the rulemaking at issue we had not identified any developments in practices, 

processes and control technologies under CAA section 112(d)(6). Rather, the court first states 

“[w]e do not think the words ‘review and revise as necessary’ can be construed reasonably as 

imposing” an obligation to completely recalculate maximum achievable control technology. Id. 

After concluding that the statute does not impose such an obligation, the court then says: “Even 

if the statute did impose such an obligation, petitioners have not identified any post-1994 

technological innovations that EPA has overlooked.” 

Comment: Commenter 0290/0620 pointed out that EPA considered alternatives that 

would have achieved significantly greater emission reductions than what was proposed, but used 

cost effectiveness, and not achievability, as the determining factor to decide what emission limit 

to set among the regulatory options it considered. The commenter also pointed out that EPA‘s 
6

analysis shows that the proposed rules will have very little economic impact on the industry. 

The commenter stated that EPA may not rationally decide that, to be cost effective a rule must 

have virtually no economic impact. The commenter also noted that, for small hard chromium 

electroplaters, EPA concluded that costs and the cost effectiveness are reasonable, but did not 

explain why additional cost to ensure additional emission reductions and additional cancer 

protection would not also be just as reasonable and necessary. The commenter added that EPA 

failed to address the achievability requirement of the statute and suggested that EPA‘s analysis is 

aimed at minimizing costs to the lowest level possible, while still requiring some emission 

reduction, and not setting rules that are truly cost effective. This method, the commenter states, is 

indefensible, arbitrary, and capricious. The commenter stated that EPA must satisfy section 

112(d)(6), which incorporates section 112(d)(2)-(3), and finalize more stringent final standards 

than proposed. The commenter also stated that EPA is allowed to consider cost, but may only do 

so in considering what the maximum degree of reduction in emissions that is achievable. 

Response: To the extent that the commenter is suggesting that the section 112(d)(6) 

review must be a new review under sections 112(d)(2) and (3), we disagree. The initial MACT 

standards established pursuant to sections 112(d)(2) and (3) did incorporate an “achievability” 

component. The commenter is incorrect that section 112(d)(6) incorporates the requirements of 

112(d)(2) & (3) and the court has agreed with EPA’s interpretation that section 112(d)(6) does 

not require a new analysis consistent with those provisions. NRDC v. EPA, 529 F.3d 1077, 1084 

(D.C. Cir. 2008).

The EPA determined long ago that section 112 (d)(6) does not require MACT floors to be 

recalculated, and why EPA’s interpretation that no further floor analysis is required was 

reasonable. See 70 FR at 20008 (April 15, 2005). EPA is not reopening that issue here, or 

otherwise reconsidering its interpretation. Contrary to the position taken by the commenter, the 

argument that we must reset the MACT floor under the section 112(d)(6) review was rejected by 

the D.C. Circuit in the HON opinion. See 529 F. 3d at 1084 (“It is argued that EPA was obliged 

to completely recalculate the maximum achievable control technology-in other words, to start 

from scratch. We do not think the words "review, and revise as necessary" can be construed 

reasonably as imposing any such obligation.”). There is nothing to suggest that the HON Court’s 

ruling that CAA section 112(d)(6) does not require re-calculation of MACT floors was limited to 

instances in which there have not been developments in practices, processes, or control 

technologies.

2. MACT Revisions

Comment: Commenter 0290/0620 stated that EPA unlawfully failed to perform the 

beyond-the-floor analysis required by section 112(d)(6) and section 112(d)(2), which applies to 

all emission standards promulgated under this subsection 112(d). The commenter acknowledged 

that EPA recognized that the industry has achieved significant emission reductions using new 

developments that it identified, but stated that EPA did not consider or determine the maximum 

degree of reduction in emissions now achievable using these developments or other additional 

requirements in the California standards. The commenter stated that, because so many sources 

have already achieved emission reductions well beyond those required by EPA‘s proposed rule, 

the proposed requirements are nowhere near the maximum achievable level, even considering 

cost (as EPA is allowed to do at the beyond-the-floor stage). The commenter added that it does 
7

not appear EPA considered other factors listed in the statute, such as health and environmental 

impacts, as required. The commenter stated that EPA‘s failure to perform the required beyondthe-floor analysis is both unlawful and arbitrary. The commenter also suggested that the 

proposed more stringent surface tension limits should be considered at the “beyond-the-floor” 

stage of its analysis in part due to the non-air quality health and environmental impacts that EPA 

must consider under section 112(d)(2). 

Response: As explained previously, the EPA does not read 112(d)(6) as requiring a 

reanalysis or recalculation of MACT floors nor does it require a “beyond the floor” analysis. It 

logically follows that if MACT floors are not recalculated, the subsequent beyond-the-floor 

analyses that are required when the EPA first establishes MACT standards, also are not required.

Comment: Commenter 0290/0620 stated that EPA has failed to justify setting standards 

for total chromium instead of pollutant-specific standards as required under sections 112(d)(6) 

and (f)(2). The commenter claimed that, under section 112(d), EPA is legally required to set a

limit for each emitted pollutant. The commenter noted that EPA cannot lawfully avoid setting 

pollutant-specific limits for trivalent chromium and hexavalent chromium just because chromium 

compounds are listed under section 112(b)(1). The commenter explained that these hexavalent 

and trivalent chromium are different compounds, have different chemical makeup, and cause 

different health effects. The commenter also pointed out that California Air Resources Board 

(CARB) and South Coast Air Quality Management standards control hexavalent chromium 

directly, not just total chromium, and that EPA has failed to justify not similarly doing so in the 

NESHAP. The commenter noted that EPA has recognized hexavalent chromium is particularly 

responsible for increased cancer risk for this source category. The commenter stated that setting 

a total chromium standard (instead of pollutant-specific standards) will lead to a greater amount 

of risk at some sources, where hexavalent chromium may make up more of the emission stream, 

than at other sources, because of the type of process used.

Response: We agree with the commenter that we have the authority to establish different 

emissions standards for compounds containing hexavalent and trivalent chromium. We also 

agree that hexavalent and trivalent chromium are associated with different health effects and that 

hexavalent chromium is the more toxic species. However, because the emissions of total 

chromium are estimated to be 98 percent hexavalent chromium, a total chromium emissions limit 

is effectively a hexavalent chromium limit for these source categories. The NESHAP established 

emission limits in terms of total chromium, as measured by Methods 306 or 306A. Both of these 

methods measure the total amount of chromium present in the exhaust stream, regardless of the 

form of the emissions (hexavalent or trivalent chromium).

Comment: Commenter 0290/0620 claimed that EPA must assess and consider the 

potential for fugitive emissions and set numerical emission standards that reduce fugitive 

emissions, as well as emissions that are vented to a control device. The commenter explained 

that, in not doing so, EPA has failed to consider the potential for fugitive emissions from this 

source category and to satisfy sections 112(d)(6) and 112(f)(2). The commenter explained that, 

under section 112(f)(2), EPA must fully evaluate the public health and environmental risk 

associated with fugitive emissions, and determine whether standards are needed to provide an 

ample margin of safety. The commenter added that, under section 112(d)(2), EPA must consider 
8

requiring that facilities enclose systems or processes to eliminate emissions, and must consider 

requirements to collect, capture or treat such pollutants when released from a process, stack, 

storage, or fugitive emissions point. 

Response: In both the original MACT standard, and as part of the residual risk and 

technology review, we did consider fugitive emissions from the tanks regulated by the 

Chromium Electroplating NESHAP. We believe that it is not feasible to establish or enforce 

numerical emission standards for the fugitive emission sources associated with chromium 

electroplating and chromium anodizing tanks. Fugitive emissions arise largely from spills of 

chromium-laden liquid that dries and becomes airborne, or from chromium powder that becomes 

airborne. In either case, the frequency and magnitude of emissions are highly variable both 

within a plant on a day-to-day basis and from one plant to the next. Establishing a numerical 

emission limit would require either enclosing and ducting the entire tank area, which would be 

impractical because of worker and equipment movement, or measuring emissions at the building 

exhaust fan exit points. At those locations, the emissions would be highly variable, depending on 

the time and severity of spills, and thus any measurement of emissions would also be highly 

variable. Thus demonstrating compliance with those numerical emission limits would be 

impractical unless emissions were measured continuously. We believe requiring continuous 

monitoring of exhaust fan emissions would be cost-prohibitive. In addition, the NESHAP

requires work practice standards to ensure the proper operation and maintenance of all emission 

control systems. When these systems are operating properly, fugitive emissions are minimized.

As part of our residual risk and technology review, we reviewed whether fugitive emissions 

could be further addressed and we identified housekeeping measures to minimize fugitive 

emissions. In today’s action, we are promulgating those housekeeping measures, which include 

such requirements as installation of splash guards and drip trays, prompt cleanup of spills, 

minimizing overspray, and storage and handling requirements for any substance that contains 

hexavalent chromium. The housekeeping measures being promulgated in this action are 

appropriate work practice standards designed specifically to achieve further reduction of fugitive 

chromium emissions from chromium electroplating processes. 

Comment: Commenter 0290/0620 stated that Section 112 requires EPA to set an 

emission standard to control every emitted hazardous air pollutant. According to the commenter, 

a search of the California emissions inventory for the chromium electroplating and anodizing 

industry produced a list of additional pollutants (other than chromium compounds) that EPA did 

not address or regulate in this rulemaking. The commenter provided a list of the pollutants. The 

commenter added that EPA has recognized that many sources are using wetting agent/fume 

suppressants (WAFS), but believes EPA has not evaluated what other HAPs this may add into 

the emission stream. The commenter further explained that it is unclear why EPA has not 

proposed to set standards to reduce all of these pollutants, as section 112 requires and 

recommended EPA finalize standards for all emitted pollutants from this source category under 

section 112(d).

Response: Chromium compounds are the only HAP on the CAA section 112(b) list that 

are emitted from the chromium electroplating or chromium anodizing tanks, which are the 

emission sources regulated by the Chromium Electroplating NESHAP. Based on the list of 

pollutants provided by the commenter, we believe that the other HAPs referenced by the 
9

commenter are from co-located sources and not from chromium electroplating and anodizing 

tanks, and there are other NESHAP that regulate emissions of those pollutants. For example, the 

Plating and Polishing NESHAP (40 CFR 63, subpart WWWWWW) addresses emissions of 

metal HAP including cadmium, chromium (non-electroplating sources), lead, manganese, and 

nickel. For facilities that perform halogenated solvent cleaning, 40 CFR 63, subpart T, regulates 

emissions of methylene chloride, perchloroethylene, trichloroethylene, 1,1,1-trichloroethane, 

carbon tetrachloride, and chloroform. 

Regarding the use of WAFS, these chemicals are not included on the section 112(b) list 

of HAPs. Based on the material safety data sheets (MSDS) for the formulations of the most 

widely used WAFS, the chemicals do not contain materials listed as hazardous under OSHA 

Hazard Communication Standard (29 CFR 1910.1200). Therefore, we have no reason to believe 

WAFS add other HAPs to the emission stream. While our risk and technology review of the 

Chromium Electroplating NESHAP does not address HAP emissions from sources regulated 

under other NESHAP (and which emissions will be reviewed as part of the risk and technology 

review for those other standards), we did perform, as part of the supplemental proposal, a 

facility-wide risk analysis that considered these other HAP emissions, and the results of that 

analysis are summarized in the February 2012 supplemental proposal and are provided in the 

Residual Risk Assessment for the Chromic Acid Anodizing, Decorative Chromium 

Electroplating, and Hard Chromium Electroplating Source Categories, which is available in the 

rulemaking docket.

Comment: Commenter 0290/0620 stated that, if EPA uses total chromium as a surrogate, 

then it must meet the legal test to use a surrogate under section 112, and EPA has failed to do so 

in the supplemental proposal. The commenter claimed that a surrogate is reasonable only if it 

meets three conditions: (1) the target pollutant/s must invariably be present in the surrogate; 

(2) the control technology used to control the surrogate must indiscriminately capture both the 

surrogate and the target pollutant/s; and (3) control of the surrogate must be the only means by 

which facilities achieve reductions in the target pollutant(s). The commenter commented that 

EPA has not shown that this source meets each factor, particularly in view of the potential 

variety in raw materials (e.g., trivalent vs. hexavalent chromium) and control methods used in the 

past for different subcategories of this source category. The commenter requested the Agency 

investigate whether these factors lead to specific levels of hexavalent chromium emissions that 

are not always proportional to total chromium and fully analyze the reduction methods for 

hexavalent chromium. The commenter ultimately recommended that EPA set a HAP-specific, 

numerical emission standard that limits this (and each other emitted pollutant).

Response: Section 112(b) lists chromium compounds as the HAP which the EPA is 

required to regulate. Therefore, total chromium is not a surrogate pollutant and the commenter’s 

argument is not applicable.

3. General Risk Methodology

Comment: Commenter 0290/0620 stated that the EPA must aggregate health risk for the 

source category and decide whether the total health risk from each pollutant or from all 

pollutants combined is unacceptable. The commenter observed that EPA listed each type of 

health risk, but treated them all separately. The commenter found this determination to be 
10

incomplete and therefore arbitrary and capricious. The commenter also expressed concern that 

the EPA has not combined risks from multiple HAP, thus not assessing cumulative impacts and 

health risk appropriately. The commenter explained that EPA‘s risk assessment only considered 

hexavalent chromium and other chromium compounds and that EPA must assess the risk for all 

emitted pollutants. The commenter noted that the EPA should assess the synergistic, 

carcinogenic (and other) effects of different pollutants, and create a metric to assess the 

cumulative impact of all types of risks. The commenter emphasized that EPA’s failure to assess 

and address cumulative health risks makes it difficult for the public to understand or evaluate 

how EPA reached the proposed acceptability determination. The commenter stated EPA must 

determine whether the risk from the individual or combined pollutants is unacceptable and, if so, 

what standards are needed to provide an ample margin of safety to protect public health. 

The commenter recommended that the EPA aggregate health risk for each pollutant and 

each type of health risk to create a cumulative risk determination for the individual “most 

exposed” to the source category. The commenter also recommended that the EPA create a 

combined health risk metric that accounts for synergistic effects so that the Agency can make an 

acceptability determination that is based on the full picture of health risk and that can be 

compared to other source categories. 

Response: Based on available information, chromium compounds are the only HAP 

emitted from the chromium electroplating and anodizing source categories. Historical data 

indicate that emissions from chromium electroplating sources are almost entirely comprised of 

hexavalent chromium, and we assumed that emissions from all chromium electroplating and 

anodizing sources consisted of 98 percent hexavalent chromium and 2 percent trivalent 

chromium based on these data. The actual speciation of chromium in exhaust streams may vary 

slightly from source to source. The commenter did not identify other pollutants they believe are 

emitted from sources in the chrome source categories. We have not identified any other HAP 

emitted from this source category.

The EPA disagrees that a combined risk metric is appropriate. Depending on whether a 

substance causes cancer and whether its dose-response curve is thought to have a threshold, EPA 

may use either of two approaches in a dose-response assessment. One approach produces a 

predictive estimate (e.g., inhalation cancer risk estimate), and the other produces a reference 

value (e.g., RfC). Historically, the use of a predictive estimate has been limited to cancer 

assessment. That is, dose-response assessments for cancer have been expressed as predictive 

cancer risk estimates based on an assumption that any amount of exposure poses some risk. 

Assessments of effects other than cancer usually have been expressed as reference values at or 

below which no harm is expected. Many substances have been assessed both ways because they 

are associated with both cancer and noncancer effects.

Although cancer and noncancer effects were not considered together with a combined 

risk metric, multiple pollutants causing the same effect or affecting the same target organ were 

combined. Because for carcinogens there is an assumption of a linear dose-response, the cancer 

risks predicted for individual chemicals were added to estimate cumulative cancer risk. This 

approach assumes that the risks associated with individual chemicals in a mixture are additive, 
11

consistent with EPA’s mixtures guidelines.1,2 In rare cases, the chemicals under assessment may 

be evaluated to determine whether effects from multiple chemicals are synergistic (greater than 

additive) or antagonistic (less than additive), although sufficient data for this evaluation are 

usually lacking. For the chrome source categories, hexavalent chromium is the only HAP emitted 

from the categories, so additivity is not relevant, but additivity was used for the facility-wide 

assessments because multiple carcinogens are emitted from some facilities.

In assessing noncancer hazard from chronic exposures, in cases where different pollutants 

cause adverse health effects via completely different modes of action, it may be inappropriate to 

aggregate individual pollutant hazard quotients (HQs). In consideration of these mode-of-action 

differences, the mixtures guidelines support aggregating effects of different substances in 

specific and limited ways. To conform to these guidelines, we aggregated noncancer HQs of 

HAPs that act by similar toxic modes of action, or (where this information is absent) that affect 

the same target organ. This process creates, for each target organ, a target-organ-specific hazard 

index (TOSHI), defined as the sum of hazard quotients for individual HAPs that affect the same 

organ or organ system. This approach was used in both the source category and facility-wide 

assessments of the chrome source categories.

Comment: Commenter 0290/0620 stated that Section 112(f)(2) requires EPA to consider 

all types of public health risk caused or contributed by a source category, but EPA did not assess 

acute health risk at all for the chromium emissions from this source category. The commenter 

noted EPA’s statement that the acute HQ is “NA” or “not applicable” and that “there are no 

HAPs with an acute dose-response benchmark value. Therefore, the commenter stated the EPA

did not perform a quantitative risk assessment for acute exposures to these pollutants.” The 

commenter asserted that the lack of an acute dose-response benchmark value is not a valid 

excuse to fail to assess the acute impact for this source category. The commenter cited the 2008 

ATSDR Toxicological Profile for Chromium in regard to acute exposure impacts. The 

commenter argued that because of the potential for acute impacts in communities that have a 

history of past exposure, the EPA may not lawfully treat the acute risk as zero.

Response: This issue was addressed by the EPA’s Science Advisory Board (SAB) in 

their May 10, 2010 review of EPA’s Risk and Technology Review (RTR) risk assessment 

methodologies.

3 In that review, the SAB Panel recommended that, for HAPs that do not have 

dose-response values from the EPA’s hierarchy list, the EPA should consider and utilize, as 

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

scientific peer review. They further recommended that the inclusion of additional sources of 

dose-response values into the EPA’s hierarchy should be adequately documented in a transparent 

manner in any residual risk assessment case study. We agree with this approach and have 

considered other sources of dose-response data when conducting our risk determinations under

 1 US EPA, 1986. Guidelines for the Health Risk Assessment of Chemical Mixtures. EPA-630-R-98-002. 

http://www.epa.gov/NCEA/raf/pdfs/chem_mix/chemmix_1986.pdf

2 US EPA, 2000. Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures. EPA630/R-00-002. http://www.epa.gov/ncea/raf/pdfs/chem_mix/chem_mix_08_2001.pdf.

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

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

4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf
12

the RTR. However, in some instances no sources of information in addition to the EPA’s 

hierarchy are available.

While the 2008 ATSDR Draft Toxicological Profile for Chromium cited by the 

commenter does discuss a few limited studies of acute effects on humans and animals, that 

document concludes that, “data are not suitable for defining No Observed Adverse Effect Level 

(NOAEL) or Lowest Observed Adverse Effect Level (LOAEL) values for respiratory effects. 

Although longer duration inhalation studies show that the respiratory tract is a sensitive target of 

inhaled chromium (VI), the data are insufficient to determine acute-duration exposure levels that 

would produce respiratory tract, or other effects. In the absence of studies that could be used to 

identify the targets of low level exposure, an acute duration inhalation Minimal Risk Level 

(MRL) for hexavalent chromium was not derived.”

The EPA agrees that we should ultimately develop toxicity values for all HAPs utilizing 

all credible and relevant toxicity information. The need to update assessments with newly 

available data as well as the need to complete toxicological assessments for all HAPs lacking 

dose-response assessments further increases the importance of Agency activities to streamline 

and fully utilize the EPA’s already overloaded Integrated Risk Information System (IRIS) 

program. To that end, the EPA has always prioritized for future IRIS assessments those HAP 

without dose-response values but with the greatest potential for public exposure. 

Comment: Commenter 0290/0620 stated that EPA provided no rational justification for 

its use of the supplementary risk analysis conducted for the October 2010 proposal. In the 

commenter's opinion, EPA used the supplementary analysis only to undermine the results of the 

initial conservative risk analysis, by suggesting that the high rate of cancer risk found for the 

maximum exposed individual in the conservative analysis matters less when compared to the 

estimated 365,100 people that would be exposed to a cancer risk of at least 1-in-1 million, as 

indicated by the supplementary analysis. 

Response: As explained in the preamble for the supplemental proposal, we completely 

revised the risk assessment based on additional information collected on the industry and we are 

relying on that revised risk assessment for this final rule. The comment concerns a risk analysis 

performed for the initial proposal which we are not relying on for our final action and thus is not 

relevant to our final action.

Comment: Commenter 0285/0296/0619 did not agree with EPA’s risk modeling 

procedures and suggested there are systematic errors in using dispersion modeling to predict 

resulting annual average concentrations at receptor sites. The commenter goes on to say that 

EPA’s modeled or predicted concentrations appear to be 3 to 5 times higher relative to the actual 

monitoring results of the 2005 Urban Air Toxics Monitoring Program. The commenter believes 

EPA should, in the risk evaluation performed in this rulemaking, not rely on modeling that 

replicates the errors of the NATA modeling and should explain how the Agency’s risk 

assessment has avoided these errors.

The commenter listed the following factors as possible reasons that may account for 

over-estimated hexavalent chromium concentrations: “worst case” assumptions for modeling 
13

parameters (i.e., stack height, diameter, velocity, and temperature), failure to run 

HEM/AERMOD in a mode that accounts for rapid reduction/reactivity of hexavalent chromium 

or wet/dry deposition, running HEM/AERMOD in “rural” rather than “urban” mode, selecting a 

30 meter default distance from facility stack to property fence line, and not considering the fairly 

rapid reduction of hexavalent chromium in electroplating mists that declines to 85 percent after 

one hour, and to 77 percent after three hours.

The commenter also stated that it is highly improbable that the concentrations of 

hexavalent chromium at MIR sites due to electroplating emissions alone could be higher than 

any observed actual ambient concentrations of hexavalent chromium, which reflect emissions 

from all source types, not just electroplating since surface finishing accounts for less than 1 

percent of total national emissions of hexavalent chromium and chromic acid, as estimated in the 

2005 NEI.

In contrast, other commenters (0274/0618, 0275, 0290/0620) stated that the residual risk 

assessments for the source categories were not conservative enough, especially considering the 

significant public health hazard that emissions from chromium electroplating facilities, including 

hexavalent chromium, can pose.

Response: The EPA believes the comparison of 2005 NATA estimates to 2005 ambient 

monitoring levels is not relevant to the supplemental proposed rule because the NATA estimates 

are based on different emissions data than were used in this rulemaking. The current data set 

relied on for the supplemental proposal is significantly better than the NATA data set and the 

data set we relied on for the 2010 proposal for a number of reasons. The current data set provides 

improved emissions estimates for many facilities, based on actual emissions test data; provides 

actual emissions data for a larger number of facilities than had been modeled for the 2010 

proposal; includes an updated plant list that accounts for facilities that have opened recently and 

eliminates nearly 200 plants that have permanently closed or otherwise permanently stopped 

performing chromium electroplating; includes more plant-specific data on numbers and types of 

electroplating tanks, types of emissions controls, and control system operating parameters; and 

includes corrected geographic locations (latitudes, longitudes) for hundreds of chromium

electroplating and anodizing facilities. 

We agree that the modeling methodology we used for the chrome source categories for 

both the proposal and the supplemental proposal is similar to that used for NATA in that both 

used the HEM-3 exposure model, which utilizes EPA’s preferred dispersion model AERMOD. 

The modeling methodologies used in the risk assessments for the chrome source categories are 

discussed in detail in the risk document for the supplemental proposed rule.4 We disagree that 

such modeling results in significant overestimates or underestimates of concentrations and risks. 

Our dispersion model methodologies were reviewed by SAB as part of their overall review of 

RTR risk assessment methodologies, and their review stated that “...the dispersion modeling for 

primary HAPs used in risk assessments is well developed and appropriate.”5

 4 US EPA. 2012. Draft Residual Risk Assessment for the Chromic Acid Anodizing, Decorative Chromium 

Electroplating, and Hard Chromium Electroplating Source Categories.

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OAR-2010-0600-0179 5 Ibid. 3.
14

We agree that accounting for dry deposition and depletion could result in lower estimated 

air concentrations because mass that is deposited is removed from the plume, resulting in lower 

estimated air concentrations. The impact of deposition for particulate emissions depends on 

multiple factors, including the distance from the source to the receptor, and particle properties. 

The impact on maximum estimated air concentrations and risks likely would be minimal because 

of the short distance between the sources and receptors. At longer distances, the impact would be 

greater, but the extent of that impact is difficult to estimate because we typically do not have 

sufficient particle property data (aerodynamic particle diameters, particle densities, and mass 

fractions) to model deposition. Also, deposited emissions can be resuspended in the air, and 

plume depletion does not account for that.

Regarding the reduction of hexavalent chromium in electroplating mists mentioned by 

the commenter, the impact of such reduction would be minimal on maximum estimated air 

concentrations because the plume would reach many nearby receptors in much less than an hour. 

Finally, the commenter’s assertion that the 30-meter default distance from facility stack to 

presumed property fence line leads to overestimates of modeled concentrations is contrary to the 

purpose of that value. The 30-meter distance is used in HEM-3 to exclude census block receptors 

within that distance because such receptors are likely located within facility boundaries. 

Regarding the comment that our risk assessments are not conservative enough 

considering that the pollutant of concern is hexavalent chromium, we used the RfC and URE 

values from IRIS, which were developed using a rigorous process that consists of the 

development of a draft toxicological review for a chemical; internal and external scientific 

reviews of the draft document; EPA responses to comments from the reviews; and development 

and posting of an IRIS Summary and final toxicological review to EPA's web site. The human 

health reference values (i.e., RfC and URE) that we used for the chromium compounds reflect 

their toxicity, and when used with modeled exposure concentrations, provide reasonable 

estimates of risk.

Comment: Commenter 0615 acknowledged that EPA used allowable emissions in parts 

of the rulemaking but is concerned EPA continues to use actual emissions in parts of its 

assessment. The commenter stated that a risk analysis based on actual emissions from a single 

point in time could underestimate the residual risk from a source category. The commenter 

believes that use of potential or allowable emissions is more appropriate in evaluating residual 

risk since facility emissions could increase over time for a variety of reasons and because major 

source hazardous air pollutant (HAP) thresholds and permits are based on potential-to-emit. The 

commenter stated that limiting the scope of a risk evaluation to actual emissions would be 

inconsistent with the applicability section of Part 63 rules and recommended EPA consider 

potential emissions, rather than actual emissions, as much as possible in evaluating residual risk.

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

and actual emissions in assessing chronic exposure and risk under section 112(f)(2). See, e.g., 

National Emission Standards for Coke Oven Batteries (70 FR 19998-19999, April 15, 2005); 

proposed and final National Emission Standards for Organic Hazardous Air Pollutants from the 

Synthetic Organic Chemical Manufacturing Industry (71 FR 34428, June 14, 2006, and 71 FR 
15

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

inherent in the Benzene NESHAP framework for assessing ample margin of safety. As a general 

matter, modeling allowable emissions levels is inherently reasonable since this reflects the 

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

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

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

(April 15, 2005). The risk assessments for the chrome source categories were conducted using 

actual and allowable emissions, and the results of these assessments were considered in 

determining risk acceptability and ample margin of safety.

Comment: Commenter 0290/0620 stated EPA should consider background levels and/or 

emissions from other sources. The commenter stated that the EPA has failed to satisfy section 

112(f)(2) and has failed to follow scientific recommendations or the best available science 

regarding the need to assess past background exposure as part of the health risk assessment. The 

commenter stated section 112(f) includes recognition of background levels, including 

background levels of past exposures and past pollution. The commenter reminded EPA that the 

SAB has urged EPA to incorporate cumulative risks into its residual risk analysis as section 

112(f)(2) requires, including a full assessment of background and new risk. The commenter 

maintained that the EPA did not evaluate how long existing sources have emitted HAPs at their 

current locations, or the impact of past emissions on current health risk.

The commenter stated that EPA should be considering risk from all sources of 

contaminants, including co-located sources and all types of compounds. The commenter noted 

that EPA has data showing the frequent occurrence of this source category in highly populated, 

urban areas. The commenter stated that EPA has sufficient information to map the number of 

people who live within 50 km of more than one of these facilities, and who are thus subject to a 

double, or greater level of exposure, and a correspondingly greater risk level than EPA has found 

in its single-source exposure analysis. The commenter stated that it would be arbitrary and 

capricious for EPA to fail to fully assess the cumulative impacts faced by the communities it has 

found will experience disproportionate risks from this source category. The commenter stated 

that communities near chromium electroplating facilities are also subject to other types of 

additional harm not considered, including from fugitive emissions and other types of pollution. 

The commenter stated that the EPA should also consider environmental chemical stressors and 

other kinds of stressors that could exist in particular communities, such as poverty. The 

commenter stated that the risk from other sources of HAPs is not zero, for either cancer or noncancer effects, and therefore must be accounted for in the risk assessment. The commenter stated 

that EPA must perform an aggregate analysis in order to assess the full emissions exposure and 

thus the full risk for the maximum exposed individual. The commenter stated that unless it does 

so, EPA has not considered this issue from the perspective of the individuals likely to have the 

maximum level of exposure to this particular type of source category, as required by §112(f)(2). 

The commenter cited statements from the Mineral Wool Production and Wool Fiberglass 

manufacturing NESHAP and EPA’s 2007 resource document on cumulative health risk 

assessment of multiple chemicals, exposures and effects. 6,7 Although the commenter appreciated 

 6 Proposed Rule, 75 Fed. Reg. 65,068, 65,073 (Oct. 21, 2010). 
16

that EPA has considered facility-wide risk in this rulemaking, the commenter believes that 

EPA’s risk assessment is flawed and EPA’s facility-wide risk assessment underestimates the 

total risk faced by the maximum exposed person. According to the commenter, EPA did not 

analyze full HAP exposure, including the baseline level of exposure that is present in the 

environment from sources outside of the source category and not collocated at the same facility.

The commenter suggested that the EPA should follow SAB recommendations to perform 

a sensitivity analysis to identify the major uncertainties in both the human health and ecological 

risk assessments. Further, the commenter recommended that the uncertainties require more 

conservative assessment and more protective action.

The commenter recommended that the EPA perform a cumulative impacts analysis by 

combining current baseline emissions, exposures, and health impacts in addition to those of the 

specific source category EPA is reviewing. As part of this analysis, the commenter added, the 

EPA should aggregate or add the emissions for the most-exposed communities coming from: (1) 

the source category (including all individual sources within it); (2) facility-wide risk from 

collocated sources outside of this category; and (3) all other sources of toxic air pollution in the 

area. The commenter suggested that the EPA aggregate the community‘s exposure and assess the 

full health threats faced by the affected community, including from the sources under review. The 

commenter stated that to perform this step, EPA must also draw on the OEHHA community 

assessment approach. The commenter observed that without a full cumulative risk and impacts 

assessment, EPA fails to gather the necessary information to determine whether stronger 

standards are needed for the Chromium Electroplating source category. The commenter stated 

that a full risk assessment is needed for EPA to be able to prevent unacceptable health risk and 

provide the legally required “ample margin of safety,” 42 U.S.C. § 7412(f)(2).

Another commenter (0278/0617) stated that it is not clear how EPA’s emission 

simulation method accounts for associated health risks to neighboring communities near plants in 

rural areas. 

Response: As an initial matter, we disagree with the commenters to the extent they are 

suggesting that we are required to consider the total risk from all HAP to particular communities 

as part of our section 112(f) review. The focus of section 112(f)(2) is to review the risk posed by 

the emissions of HAP from the “source category” to determine whether it is necessary to revise 

the MACT standard for that source category to ensure an ample margin of safety. While it is true 

that a community-by-community assessment of total risk may be informative and could lead to a 

determination of the primary source of risks within specific communities, such an analysis is 

well beyond the scope of section 112(f)(2). Furthermore, the uncertainties associated with 

sources of emissions outside of the source category under review can be significant. The Act 

establishes a staged approach to performing the residual risk review for the source categories 

regulated under section 112 and we have yet to begin our residual risk review for many of those 

 7 U.S. EPA, Concepts, Methods and Data Sources for Cumulative Health Risk Assessment of Multiple Chemicals, 

Exposures and Effects: A Resource Document, at xxxii (2007), EPA/600/R-06/013F (defining a cumulative risk 

assessment as including “aggregate exposures by multiple pathways, media and routes over time, plus combined 

exposures to multiple contaminants from multiple sources”).
17

source categories. Therefore, we do not even have preliminary inventories, much less more 

refined inventories yet for many source categories. In addition, even assuming we could 

determine the primary source of risks, if those risks are due to sources outside the source 

category being regulated in the immediate regulation or outside the scope of section 112, the 

immediate action would be unable to address those risks. Despite those concerns, however, we 

note that background risks or contributions to risk from other sources, where such information is 

available and reliable, can be one of the relevant factors considered in the AMOS determination, 

along with cost and economic factors, technological feasibility, and other factors. Thus, while we 

are not required (and, indeed, cannot) do a community-by-community analysis of total risk, we 

do consider available information as part of our AMOS analysis.

The EPA disagrees with the comments that we did not consider aggregate or cumulative 

risks. As discussed in detail in the risk document for the supplemental proposed rule,

8 the 

assessments we conducted for the chrome source categories consider the cumulative cancer risks 

from all carcinogens and the cumulative noncancer hazard indices from all non-carcinogens 

(affecting the same target organ system) emitted from sources within each of the chrome 

electroplating and anodizing source categories and also collocated sources at the same facilities. 

However, the commenter is correct that the assessments did not include background risks or 

contributions to risk from sources outside the facilities.

We note that section 112(f)(2) of the CAA expressly preserves our use of the two-step 

process for developing standards to address residual risk and interpret “acceptable risk” and 

“ample margin of safety” as developed in the Benzene NESHAP. In the Benzene NESHAP, EPA 

rejected approaches that would have mandated consideration of background levels of pollution in 

assessing the acceptability of risk, concluding that “...comparison of acceptable risk should not 

be associated with levels in polluted urban air. With respect to considering other sources of risk 

from benzene exposure and determining the acceptable risk level for all exposures to benzene, 

EPA considers this inappropriate because only the risk associated with the emissions under 

consideration are relevant to the regulation being established and, consequently, the decision 

being made.” (54 FR 38044, 38061, September 14, 1989). 

Although not appropriate for consideration in the determination of acceptable risk, we 

note that background risks or contributions to risk from sources outside the facilities under 

review could be one of the relevant factors considered in the AMOS determination, along with 

cost and economic factors, technological feasibility, and other factors. Background risks and

contributions to risk from sources outside the facilities under review were not considered in the 

AMOS determination for these source categories, mainly because of the significant uncertainties 

associated with emissions estimates for such sources.

Comment: Commenter 0290/0620 recommended that the EPA address variability in the 

human response to toxic chemicals by using an additional factor to account for variability in 

chronic non-cancer risk. According to the commenter, the EPA must include this analysis to 

satisfy its responsibility to protect the “individual most exposed” from unacceptable health risk 

under section 112(f). The commenter noted that while the EPA uses an uncertainty factor 

approach to recognize variability, variability is different from uncertainty, and should be treated 

 8 Ibid. 4.
18

differently. The commenter pointed out that the NAS has determined that the difference between 

the median versus higher-end response for cancer may be a factor of 25.9

Response: Regarding noncancer effects, the uncertainty/variability factors that EPA uses 

in operationally deriving the RfD and RfC from experimental data are intended to account both 

for variability and uncertainty. These factors account for (1) variation in susceptibility among the 

members of the human population (i.e., inter-individual or intraspecies variability); (2) 

uncertainty in extrapolating animal data to humans (i.e., interspecies uncertainty); (3) uncertainty 

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

from subchronic to chronic exposure); (4) uncertainty in extrapolating from a LOAEL rather 

than from a NOAEL; and (5) uncertainty associated with extrapolation when the database is 

incomplete.10

Cancer unit risk estimates are derived under the approach that at low doses (i.e., below 

observed data) risk is linear with dose. We use this linear extrapolation as a default approach 

because it generally is considered to be health-protective.

11 The NAS document cited by the 

commenter presents several possible methods for dose-response analysis, including the one 

alluded to by the commenter. We disagree with the commenter’s characterization of the 

document’s statement regarding a factor of 25 ratio between a population median and upper 95th 

percentile as a NAS determination. The NAS committee did not “determin[e]” that a factor of 25 

was the difference between the median versus higher-end response for cancer or any other 

endpoint, nor did the committee make any statements regarding hexavalent chromium. The NAS 

committee’s use of a ratio is simply as an example default assumption in their description of one 

of three conceptual models provided as examples of “unified” approaches (i.e., approaches in 

which cancer and other effects might be assessed in similar manner) for EPA’s consideration of 

such approaches.

 9 S. Janssen et al., NRDC, Issue Paper, Strengthening Toxic Chemical Risk Assessments to Protect Human Health at 

4 (Feb. 2012) (citing NAS, Science and Decisions: Advancing Risk Assessment (2009)).

10 A Review of the Reference Dose and Reference Concentration Process. U.S. Environmental Protection Agency. 

Risk Assessment Forum. EPA/630/P-02/002F. December 2002.

http://www.epa.gov/raf/publications/pdfs/rfd-final.pdf

11 Guidelines for Carcinogen Risk Assessment. U.S. Environmental Protection Agency. Risk Assessment Forum. 

EPA/630/P-03/001F. March 2005.

http://www.epa.gov/raf/publications/pdfs/CANCER_GUIDELINES_FINAL_3-25-05.PDF
19

4. Risk Criteria

Comment: Commenter 0615 points out that in assessing the cancer risks related to the 

source category, EPA used long-term concentrations affecting the most highly exposed census 

block for each facility. The commenter believes this analysis dilutes the effect of sources’ 

emissions by estimating the impact at the centroid of the census block instead of at the property 

line or wherever the maximum exposed individual is. The commenter further noted that even if 

the area near the property line is not developed, over time homes and businesses could locate 

closer to the facility. The commenter added that even if the population distribution is 

homogenous over a census block, this assumption is not necessarily accurate in considering the 

predicted impacts from the location of a source. The commenter believes that using HEM-3, 

EPA can identify the maximum individual risk at any point in a census block that is within a 50-

kilometer radius from the center of the modeled facility. The commenter suggested EPA abandon 

its use of the predicted chronic exposures at the census block centroid and use the truly 

maximum individual risk, irrespective of its location in the census block, in its section 112(f)(2) 

risk assessments.

Response: As we have explained in previous RTRs, such as the SOCMI HON RTR (71 

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

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

identify exposure locations where it may be reasonably expected that an individual will spend a 

majority of his or her lifetime. Further, in determining chronic risks, the EPA believes that it is 

appropriate to use census block information on where people actually reside, rather than points 

on a fence-line, to locate the estimation of exposures and risks to individuals living near such 

facilities.

The commenter is correct that the HEM-3 model can estimate exposures at any location 

within the maximum modeling radius of 50-km recommended for the AERMOD dispersion 

model. However, because nationwide location data for all residences is not readily available, and 

because such data, if available, would result in millions of model receptors that would 

significantly increase model runtimes, we use census blocks as surrogate locations for where 

people reside. Census blocks are the finest resolution available as part of the nationwide 

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

approximately 40 people or about 10 households. In EPA risk assessments, the geographic 

centroid of each census block containing at least one person is used to represent the location 

where all the people in that census block live. The census block centroid with the highest 

estimated exposure then becomes the location of maximum exposure, and the entire population 

of that census block is assumed to experience the maximum individual risk. In some cases, 

because actual residence locations may be closer to or farther from facility emission points, this 

may result in an overestimate or underestimate of the actual annual concentrations (although 

there is no systematic bias for average levels). Given the relatively small dimensions of census 

blocks in densely-populated areas, there is little uncertainty introduced by using the census block 

centroids in lieu of actual residence locations. There is the potential for more uncertainty when 

census blocks are larger, although there is still no bias on average. The EPA concludes that the 

most appropriate locations at which to estimate chronic exposures and risks are the census block 

centroids because: 1) census blocks are the finest resolution available in the national census data, 

2) facility fencelines do not typically represent locations where chronic exposures are likely, and 
20

3) there is no bias introduced into the estimate of the MIR by using census block centroid 

locations.

Comment: Two commenters (0290/0620 and 0285/0296/0619) commented on EPA’s 

criterion of 100-in-1 million for determining when more stringent standards are required. 

Commenter 0290/0620 stated EPA should update the acceptable maximum possible level of risk. 

The commenter stated that the 1988 benchmark of 100-in-1 million is out-dated and contravenes 

the purpose of §112(f)(2), which is to make regulatory changes based on what EPA, and the

public, have learned from the implementation of the MACT standard. The commenter stated that 

the view that a presumptive level of risk of 100-in-1 million may be acceptable has changed 

because the world in which we live has changed. The commenter added that the CAA in 1990 

was amended because risk of death from air pollution at that time was not thought to be 

acceptable. The commenter stated that the available technologies that can reduce health risk must 

be considered, regardless of cost. The commenter added that in the case of chromium 

electroplating, the state of California has already reduced emissions using available technologies. 

Thus, the commenter does not believe it to be acceptable to continue exposing a child today to a 

higher level of risk. The commenter added that, by urging EPA to continue to aspire to reach the 

1-in-1 million level, the court in the HON case implicitly recognized that 100-in-1 million was a 

maximum that EPA should continue to reconsider over time and in context. The commenter 

stated that the EPA must reassess whether a level below 100-in-1 million and closer to the 

aspired goal of 1-in-1 million should be adopted as a more stringent, presumptive outward limit 

for what is considered acceptable. Further, the commenter stated that EPA did not explain why 

the 90-in-1 million cancer risk is acceptable for the chromium electroplating source category. 

Commenter 0274/0618 commented that the residual risk assessment conducted for chromium 

electroplaters is not as highly conservative as stated by the U.S. EPA. The commenter stated that 

the projected inhalation cancer risk of 70- to 90-in-1 million should not be characterized as low.

On the other hand, commenter 0285/0296/0619 agreed with EPA’s conclusion that 

maximum individual risks as high as 100-in-1 million can be presumptively considered “safe” or 

“acceptable.” In order to reach that conclusion, the commenter states that EPA correctly relied on 

the 1987 Vinyl Chloride decision (NRDC, Inc. v. EPA, 824 F.2d 1146 (D.C. Cir. 1987)), and the 

1989 Benzene Rule (54 Fed. Reg. 38,044 (Sept. 14, 1989)), codified by statute under section 

112(f)(2)(B). The commenter further stated that this approach to “residual risk” MACT 

rulemakings has been upheld by the D.C. Circuit, and EPA has been consistently applying it. 

NRDC v. EPA, 529 F3d. 1077 (D.C. Cir. 2008); 77 Fed. Reg. at 1270 – 1272. 

Response: In 1990, Congress codified in section 112(f) of the CAA the approach we use 

for our residual risk analyses (i.e., the Benzene NESHAP, 54 FR 38044). Under that approach, 

the 100-in-1 million cancer risk is not a bright line indicating that risk is “acceptable,” but rather 

we consider this health metric in conjunction with a variety of health factors to determine 

whether the risk is acceptable. Where we conclude that the risk is not acceptable, we cannot 

consider costs in requiring controls to bring risks down to an acceptable level. However, the 

analysis of whether risk is acceptable is not the endpoint. Once we determine that controls are 

sufficient to ensure risk is acceptable, we again review the health metrics in conjunction with 

considering the costs of controls to determine whether additional controls should be required to 

provide an ample margin of safety. The commenter does not provide support for its contention 
21

that “the risk that was acceptable in the world of the 1980s is no longer acceptable in today’s 

world.” Nor does the commenter explain how science has evolved in a way that would 

undermine the codified framework for determining acceptability.

Comment: Commenter 0290/0620 stated that, although in the HON case the D.C. Circuit 

affirmed EPA’s use of certain elements of the Benzene NESHAP, it did not rubber stamp the 

Benzene Rule’s approach in full. The commenter stated that the HON court did not address some 

of the questions raised in this rulemaking. The commenter further stated that it also did not 

broadly hold that EPA can do in every future residual risk rulemaking precisely what it did at 

each step of the Benzene NESHAP.

Response: The commenter’s concerns regarding reliance on the Benzene NESHAP 

presumably refer to our actions under the section 112(f)(2) risk review. We note that section 

112(f)(2)(B) specifically references the Benzene NESHAP as the benchmark for residual risk 

actions and the court in NRDC recognized that. We agree that the court in NRDC did not address 

how EPA should apply the tests in the benzene NESHAP in any future rulemaking actions under 

section 112(f)(2). 

Comment: One commenter (0274/0618) stated that EPA's supplemental risk assessment 

underestimated risk by not adjusting stack parameters, stack diameter, flow rates, and other 

parameters to represent the smaller ventilation systems modeled in the supplemental analysis. 

Instead the commenter stated, EPA modeled smaller sources with the exaggerated flow rates 

characteristic of the model plants, and those higher flow rates result in lower risk.

Response: This comment was submitted on the October 2010 proposed rule. As noted 

previously, for the supplemental proposal, we revised the data and parameters used in the risk 

assessment. The flow rates, stack diameters, plant locations, and other parameters used for the 

supplemental proposal analysis much better reflect the chromium electroplating and anodizing 

industry and take into account source size.

5. Specific Risk Assessment Procedures

Comment: Three commenters (0274/0618, 0275, and 0290/0620) noted that the 

emissions data used in the risk assessment are based on the assumptions that all facilities are in 

compliance with the MACT standard. The commenter stated that because most chromium 

electroplaters are small sources and may not be subject to regular inspections, it may be difficult 

to assume compliance without a comprehensive evaluation of compliance and enforcement 

information. Commenter 0290/0620 asked that the EPA consider the control efficiency for the 

control devices when assessing risk, in the case of the control equipment’s failure. The 

commenter provided an example, that in the case of failure of a control device with 99 percent 

efficiency, the resulting emissions will increase by a factor of 100. The commenter noted that the 

EPA has information in the record showing past non-compliance for this source category.12 The 

commenter stated that EPA’s failing to account for additional risk due to malfunctions or 

violations is unlawful, arbitrary and capricious because it ignores the full risk to the “individual 

most exposed” to the emissions of this source category. Two of the commenters cited a study by 

California's Air Resources Board that reported that many facilities violate provisions of the 

 12 CARB Chrome Plating Rule Effectiveness Study, EPA-HQ-OAR-2010-0600-0069.
22

regulations. One of the commenters stated that, in order to consider the full risk associated with 

emissions from chromium electroplating, EPA must account for a higher potential level of 

emissions above what the MACT allows, including data for SSM emissions and data for 

emissions that exceed the standard. The commenter stated that as part of this, EPA should also 

evaluate how likely pure violations of the standard are. The commenter further stated that as a 

result of these omissions, the proposal is arbitrary and capricious and also fails to satisfy the 

requirement under section 112(f) that EPA address all “emissions from a source in the category 

or subcategory,” whether they are controlled or uncontrolled by the MACT. The commenter also 

stated that EPA has recognized significant uncertainty in the data used, and that EPA must 

perform a robust analysis of risk that starts with accurate, reliable data about the types of 

facilities and their emissions. One commenter stated that, because non-compliance is not factored 

into the analysis, the statement that the RTR results are a highly conservative assessment of risk 

is false.

Response: We disagree with the commenter that emissions associated with MACT 

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

the risk analysis. The purpose of the risk review is to evaluate whether the emission limits should 

be made more stringent to reduce the risk posed after compliance with the underlying MACT 

standards. To the extent that a source is violating the underlying MACT standards, no tightening 

of the emission standard under the residual risk rule will avoid such violations. In other words, a 

source that is violating the MACT emissions standards promulgated under section 112(d) would 

not be any more likely to be able to avoid such violations and comply with presumably more 

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

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

effective means to address violations (regardless of whether they are caused by malfunctions) if 

an emissions event poses a significant health or environmental risk.

Although we disagree that emissions resulting from MACT standards violation should be 

considered as part of the risk review, we believe malfunction events do not contribute 

significantly to cancer or chronic non-cancer risks for the source categories in this rulemaking 

because malfunction events are inherently short-term and infrequent relative to annual operations 

and emissions. The commenter did not supply any data to the contrary. 

Comment: One commenter (0290/0620) recommended that EPA use the Community 

Health Air Pollution Information System (CHAPIS) for locations of chromium electroplating 

facilities throughout the state of California. The commenter included maps showing locations 

and clusters of facilities in southern California, drawn from CHAPIS data. 

Response: Our current chromium electroplating database already includes the street 

address and/or geographic coordinates for most chromium electroplating and anodizing facilities. 

Because of the large number of facilities, it was not possible for us to verify that the geographic 

coordinates for each plant was correct. For those plants with incomplete or missing coordinates

or for which the location was in question, we performed a search of online data databases, 

including EPA’s Envirofacts website, to verify the location and to fill in the missing data. For 

many plants that we believe had relatively high emissions or were high risk plants, we verified 
23

the location using Google maps. We did not see the need to use other databases to further verify 

plant locations.

Comment: One commenter (0285/0296/0619) stated that EPA should use ambient 

chromium concentration estimates from data sources such as the National Air Toxics Assessment 

to address risks based, at minimum, on the research that has already occurred to assess cancer 

risk from toxic air pollution in urban communities nationwide. 

Response: The National Air Toxics Assessment (NATA) is EPA's ongoing 

comprehensive evaluation of air toxics in the U.S. The EPA developed NATA as a screening 

tool for State/Local/Tribal Agencies to prioritize pollutants, emission sources and locations of 

interest for further study in order to gain a better understanding of risks. The NATA provides 

information about emissions, ambient air concentrations, exposures and risks across broad 

geographic areas (such as counties, States and the Nation) at a moment in time. As such, NATA 

helps regulatory agencies identify specific air toxics compounds, and specific source sectors 

(such as stationary sources or mobile sources) which generally produce the highest exposures 

and risks in the country. The NATA assessments are based on assumptions and methods that 

limit the range of questions that can be answered reliably. The results cannot be used to identify 

exposures and risks for specific individuals, or even to identify exposures and risks in small 

geographic regions such as a specific census block. Therefore, NATA estimates are not 

appropriate for use in RTR risk assessments. 

Comment: Commenter 0274/0618 questioned EPA’s treatment of building downwash 

and noted that EPA should not overlook the potential of downwash to produce higher offsite 

concentrations for facilities with short stacks or for densely urbanized areas around facilities. 

Commenter 0274/0618 stated that if EPA had accounted for downwash, the maximum risk 

would have occurred at 100 meters from the plant and would have been much higher. 

Response: We agree that, in certain cases, building downwash can result in higher 

estimated air concentrations near buildings (typically up to five to ten building heights away), 

and that this is one area of uncertainty in our risk assessment. However, the impact of downwash 

on maximum estimated exposures and risks is unlikely to be that significant because the stacks 

(and associated plumes) are already emitted near ground level (stack heights less than 10 m). The 

effects of downwash are most significant with taller stacks because the higher plume is brought 

to the ground nearer the source, with much less space in which to disperse before reaching the 

ground than without downwash, leading to higher ground-level concentrations. 

Comment: Commenter 0274/0618 and 0615 are concerned with EPA’s socio-economic 

analysis including the removal of the 5 km radius. The commenters believe the sole use of a 50 

km radius for a socio-economic analysis is inadequate because it does not consider risks greater 

than 1-in-1 million or consider impacts for individuals living within 5 km of a facility. 

Commenter 0615 added that the results of an analysis that encompasses a larger area can be 

diluted by including population not in the demographic groups most at risk; which is especially 

true at sources located in or next to minority or low-income populations. The commenters 

recommended EPA conduct an analysis at 5 km to assess facility impacts to nearby 

environmental justice communities.
24

Response: In the October 2010 proposed rule for the chrome source categories, we 

performed the demographic analyses using two approaches as examples of how such analyses 

might be developed, and invited public comment on the approaches used and the interpretations 

made from the results. In the first approach, we focused the analysis on the total populations

residing within 5 km of each facility, regardless of their estimated risks, and examined the 

distributions across various demographic groups within those 5 km circles. That analysis was a 

“proximity” analysis in that it considered only the distance from the emission sources to 

surrounding populations, and not the estimated risks to those populations.

In the second approach, we focused the analysis on the populations within 5 km of any 

facility estimated to have exposures to HAP which result in cancer risks of 1-in-1 million or 

greater or non-cancer hazard indices of 1 or greater. We examined the distributions of those risks 

across various demographic groups. In each approach, we compared the percentages of particular 

demographic groups to the total number of people in those demographic groups nationwide. We 

stated in the proposed rule for the chrome source categories that in future rules we planned to 

extend the analyses to cover the entire modeled domain for a facility (50 km radius) to capture 

all individuals with risks of 1-in-1 million or greater or non-cancer hazard indices of 1 or greater. 

We also stated that generally we have found that using a 5 km radius in the analysis will capture 

more than 90 percent of the individuals with cancer risks above 1-in-1 million.

In the February 2012 supplemental proposal for the chrome source categories, our 

demographic analyses included populations within 50 km of each source (including those very 

near the sources) with risks of 1-in-1 million or greater. (77 FR 6628, Feb. 8, 2012). We did not 

include analyses using a 5 km radius in the supplemental proposal. We believe that, where a risk 

assessment has been performed, it is more informative to consider the demographics of all 

populations (including those beyond 5 km) with elevated risks than to limit the demographics 

analysis to populations located within 5 km of a facility. Where risk assessment has been 

performed, all populations with elevated risk are identified, regardless of their proximity to the 

facility. As discussed above, we have found that most exposure locations with the highest 

estimated risks are within 5 km of a facility, so extending the radius to 50 km has little impact on 

an analysis based on risks, but makes more sense because 50 km corresponds to the risk 

modeling radius and includes all populations with elevated risk estimates. Our evaluation of 

demographics did not affect our decisions about acceptability and ample margin of safety of the 

risks associated with these source categories.

Comment: Commenter 0285/0296/0619 stated that the Chromium Electroplating MACT 

standard has been effective in controlling chromium emissions. The commenter noted that over 

the past 15 years, the metal finishing industry has implemented engineering controls and 

management practices to reduce chromium emissions. The commenter explained that there has 

been a 99.9 percent reduction in emissions since the original promulgation of the Chromium 

Electroplating NESHAP. The commenter believes that as a result of these reductions, the risks 

posed by emissions from chromium electroplating and anodizing operations are miniscule. The 

commenter believes that EPA’s emission estimates are high and based on their own estimates 

few, if any, plants would have risk of 1-in-1-million. The commenter stated that the additional 

environmental safeguards provided by the phase-out of PFOS fume suppressants and 
25

implementation of new housekeeping provisions (as clarified in other comments) indicate that no 

new controls are needed to protect the environment or human health from chromium emissions 

from chromium electroplating and anodizing operations. 

Response: We agree with the commenter that nationwide emissions have decreased 

significantly since promulgation of the NESHAP. However, we based our decision to propose 

more stringent limits on the results of the technology and residual risk review and the amount of 

emission reductions already achieved by the industry is not pertinent to whether there is a 

remaining risk and whether there are developments in practices, processes and controls that 

indicate revisions to the standard are necessary. Our basis for determining that additional 

controls are warranted under CAA sections 112(d)(6) and (f)(2) is provided in the preamble to 

the final rule. As explained further in the preamble, we are promulgating lower limits for each of 

the source categories because we believe these lower limits reflect developments in practices, 

processes or control technologies. We are also promulgating these same limits under Section 

112(f) because they will reduce risks and provide an ample margin of safety.

Comment: Commenter 0285/0296/0619 stated that, in 2010, EPA concluded that the 

risks posed by chromium electroplating and anodizing were acceptable and proposed to retain 

the existing emission standards. The commenter stated that the EPA changed its decision in the 

supplemental proposal by significantly reducing emissions limits in spite of EPA’s conclusion 

that the “risks due to the estimates of actual emissions ... are considerably lower than those 

presented in the October 21, 2010 proposal FR notice for hard chromium and decorative 

chromium plants” and “about the same” for chrome anodizing. The commenter explained that, 

initially, EPA estimated that 14 million individuals were exposed to a cancer risk of greater than 

1-in-1 million. The commenter noted that the EPA has significantly reduced its estimate to 

180,000 individuals potentially exposed to a cancer risk of 1-in-1 million. The commenter 

indicated that EPA has been inconsistent in its interpretation of risk results and should not have 

reversed its decision to make no changes to the emission standards.

Response: In both the initial proposal and the supplemental proposal, we proposed that 

the risks posed by this source category after implementation of the MACT standard were 

acceptable. However, for purposes of the second step of the risk analysis, in which we consider 

the cost of controls in addition to considering once again all of the health metrics, we proposed in 

the supplemental proposal that additional controls were needed to provide an ample margin of 

safety. We also proposed that it was necessary to revise the MACT to require these controls as 

part of the technology review, considering the cost effectiveness of the controls. As an initial 

matter, we note that based on updated emissions information and refined analyses, the results of 

our risk assessment for the supplemental proposal indicated that risk was lower than was 

indicated by our 2010 risk assessment, which was the basis for our October 2010 proposal. 

However, for purposes of the supplemental proposal we also considered updated information 

indicating that the existing controls were achieving greater emissions reductions than we had 

previously estimated and that it was feasible and cost-effective to lower the emissions limits and 

achieve further reductions. Thus, although we estimated lower risk from implementation of the 

existing MACT standard for the supplemental proposal, we concluded that increasing the 

stringency of the emission limits was warranted under our both our section 112(d)(6) review and 

the ample margin of safety analysis under section 112(f)(2). We set forth the rationale for our 
26

proposed decision in the supplemental proposal and we maintain that rationale for the 

promulgated limits. Further explanation of the basis for the final standards is provided in the 

Federal Register Notice for this action.

Comment: Commenter 0285/0296/0619 stated that EPA cannot justify imposing any 

new controls for chromium electroplating and anodizing operations because it has concluded 

generally that the risks associated with this proposed rule are acceptable. Specifically the 

commenter noted, EPA has not identified any MIR cancer risks greater than 100-in-1 million, 

and very few greater than 10-in-1 million. The commenter added that the number of individuals 

exposed to a potential cancer risk of 1-in-1 million is 180,000 individuals based on EPA’s 

estimate in the supplemental proposal, and the TOSHI for the rule is well below 1.0, and EPA 

has not identified any significant acute risks or any HAPs that may present multi-pathway risk 

concerns. 

Response: The fact that we concluded that risks are acceptable addressed only the first 

step in the section 112(f)(2) risk review. Once we determine the additional reductions, if any, 

that are necessary to ensure risk is acceptable, where the MIR remains above 1-in-1-million, we 

then look again at the health factors we considered in the risk acceptability determination and 

consider the cost of controls in addition to any other relevant factors. Additionally, under CAA 

section 112(d)(6), we must review developments in practices, processes and control technologies 

to determine whether additional controls are necessary. Under that provision, we focus on 

whether there are developments that can be implemented cost-effectively.

Comment: Commenter 0290/0620 stated that EPA has failed to provide a reasoned 

explanation for its proposed determination that the current level of health risk for Chromium 

Electroplating is acceptable, and that the EPA should find health risk from this source category 

to be unacceptable under section 112(f)(2). The commenter noted that the EPA found cancer risk 

based on allowable emissions is high for each of the subcategories, but still found risk to be 

“acceptable.” 

Response: We explained in the supplemental proposal (77 FR 6648) our reasons for 

finding the risks acceptable. The preamble to the final rule also provides a detailed discussion on 

acceptability and ample margin of safety. 

Comment: Commenter 0290/0620 noted that EPA did not determine what standards 

would “protect the greatest number of persons possible” from an MIR over 1-in-1 million, even 

though EPA has acknowledged that such a determination is required. The commenter noted that 

the EPA did not make a finding that it is not “possible” to protect more people from the risks 

calculated for this source category, but decided, instead, that it is just not cost-effective to do so. 

The commenter added that EPA's cost-effectiveness discussion in the preamble to the proposed 

rule considered only the tons per year (tons/yr) of emission reductions available from new 

technologies. The commenter also stated that EPA did not consider what “the greatest number of 

persons possible” to protect might be. Thus the commenter stated, EPA’s analysis conflicts with 

its own interpretation of the term “ample margin of safety” and its commitment to meet this 

requirement. 
27

Response: As stated in the Benzene NESHAP, in determining the need for residual risk 

standards, we strive to limit to no higher than approximately 1-in-10 thousand 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 and, in the ample margin of safety decision, to protect the greatest 

number of persons possible to an individual lifetime risk level of no higher than approximately 

1-in-1 million. However, in determining whether to require additional standards, these levels are 

not considered rigid lines, and we weigh the cancer risk values with a series of other health 

measures and factors in both the decision regarding risk acceptability and in the ample margin of 

safety determination. If we determine that the risk is unacceptable, we must impose additional 

requirements to reduce emissions without consideration of cost. However, as part of our 

determination of whether standards protect public health with an ample margin of safety, we do 

not look solely at whether technology is “feasible,” but also consider costs. Our ample margin of 

safety analyses are described in details in a response to another comment provided below and in 

the preamble for this final rule. We also consider cost as part of technology review under section 

112(d)(6), which we are required to perform periodically. The preamble to the final rule includes 

a discussion on ample margin of safety and how population risk was considered.

Comment: Commenter 0274/0618 is concerned with the numeric disparity between the 

previous and current socioeconomic analysis for populations where cancer risks are estimated to 

be greater than 1-in-1 million. The commenter stated that neither the decrease in facilities 

considered in the current assessment or the use of 2010 Census data (versus 2000) can account 

for the 99% reduction in total population used in the assessment.

Response: The EPA agrees with the comment that the use of the 2010 (versus 2000) 

Census data and small changes in the number of sources were not the reason for the significant 

decrease in the number of people with estimated cancer risk greater than 1-in-1 million. The 

reason for the decrease is the significant decrease in estimated emissions based on updated and 

more accurate emissions information we received between the 2010 proposal and the 

supplemental proposal. We believe the current data set to be significantly better than the data set 

we relied on for the 2010 proposal for a number of reasons, as discussed elsewhere in this 

document and in the supplemental proposal FR Notice (77 FR 6648).

Comment: Commenters 0274/0618 and 0290/0620 suggested that the EPA, like 

California, set standards that require greater protection and specific action to occur when 

facilities are located near “sensitive receptors” such as schools and day care facilities. 

Commenter 0290/0620 claimed that EPA has not discussed setting standards that similarly 

consider the location of such receptors, despite the fact that chrome facilities are frequently 

located in city neighborhoods containing “sensitive receptors.” The commenter provided an 

example from Philadelphia, and emphasized that because of the greater health risk to children, 

EPA must consider requiring stricter limits for facilities located near such receptors.

Commenter 0274/0618 noted that the California Air Resources Board's (CARB) Chrome 

Plating Rule Effectiveness Study Report highlighted the issue that chromium electroplating 

operations are typically small facilities often located in low-income areas. The commenter stated 

that another CARB study found elevated cancer risk from a compliant chromium electroplater, 

and that fugitive dust laden with hexavalent chromium was an important source of emissions that 
28

likely contributed to the elevated cancer risk. The commenter noted that the results of this study 

prompted CARB to update their regulations adding stricter controls for facilities in proximity to 

sensitive receptors. Based on CARB’s recommendation to prohibit the sitting of new chromium 

electroplaters within 1,000 feet of sensitive land uses, the commenter suggested that EPA 

evaluate impacts to sensitive receptors within 1,000 feet of chromium electroplating facilities. 

The commenter stated that the Agency should evaluate the use of distance to receptors as a 

parameter in all RTR assessments and consider the promulgation of additional pollution control 

requirements on facilities with impacts on these locations which exceed a 10-in-1 million cancer 

risk. Commenter 0290/0620 stated that, in its final rule, EPA should prohibit new sources from 

being sited within a specific distance, 150 meters or more, of a residence, school, or nursing 

home, or require additional controls and reporting for facilities that are located close to 

residences and vulnerable populations. The commenter stated that the EPA should also consider 

barring facilities within 1,000 feet of a sensitive receptor.

Response: The EPA believes that, in a national-scale assessment of lifetime inhalation 

exposures and health risks from facilities in a source category, it is appropriate to identify 

exposure locations where it may be reasonably expected that an individual will spend a majority 

of his or her lifetime. The EPA uses census block information on where people actually reside, 

rather than points on or near a fenceline, to locate the estimation of exposures and risks to 

individuals living near such facilities. As noted by the commenter, chrome electroplating 

facilities are typically located in urban areas. In such areas of high population density, census 

blocks are typically small, so the centroid location that we use as a surrogate for the residences in 

the block would not be substantially distant from other locations in the block. Therefore, 

although we do not consider lifetime exposures at locations other than the census block 

centroids, the centroid locations would be very near the locations noted by the commenter 

(schools, nursing homes) where exposure durations would be much less than a lifetime.

Comment: One commenter (0290/0620) stated that costs alone are insufficient 

justification to preclude setting more stringent standards when the purpose of §112(f)(2) is to 

provide an “ample margin of safety.” The commenter stated that in the “ample margin” analysis, 

in order to find whether a balance favors economics over human health, EPA must explain why a 

level of cost is too high when weighed against the reductions in cancer risk to an MIR of 6-in-1 

million. The commenter stated that EPA‘s cost-based determination is irrational and unsupported 

on the record. The commenter noted that EPA‘s proposed rule under section 112(f)(2) just 

repeats EPA‘s proposal under section 112(d)(6) and that sections 112(d)(6) and (f)(2) set 

different tests and require different analyses. The commenter disagreed with EPA’s reliance on 

an analysis under section 112(d)(6) to satisfy its section 112(f)(2) responsibility; the commenter 

stated that EPA must satisfy each statutory test in its own right. The commenter asked for 

information on how the EPA reached its ample margin of safety determination that addresses the 

section 112(f)(2) health-focused inquiry, instead of the EPA’s relying on and repeating the costbased analysis it used for its section 112(d)(6) rulemaking. According to the commenter, EPA‘s 

own cost-effectiveness analysis is unlawful and arbitrary and capricious because it ignores the 

achievements made in California, which show it is both cost-effective and necessary to require 

greater emission reductions than EPA has proposed. The commenter asserted that the EPA 

should, at minimum, follow the California example to ensure an additional “margin of safety” for 
29

affected people who live or visit schools, day care centers, or other sensitive receptors that are 

located close to Chromium Electroplating or Anodizing sources.

The commenter further stated that the EPA failed to consider and make public health the 

primary focus as required by section 112(f)(2). The commenter claimed that the EPA used cost 

as the key factor to decide what standards to set. The commenter noted that to reach this 

conclusion, EPA cited the analysis performed under section 112(d)(6) in which it focused on the 

cost per pound of hexavalent chromium or chromium compounds reduction.13 The commenter 

asserted that the EPA’s proposal does not provide an analysis of the ample margin of safety in 

terms of public health. 

Response: In the ample margin of safety decision step under CAA section 112(f)(2), the 

agency again considers all of the health risks and other health information considered in the first 

step (acceptability determination). Beyond that information, additional factors relating to the 

appropriate level of control are considered, including costs and economic impacts of controls, 

technological feasibility, uncertainties and any other relevant factors. 

In this rulemaking for the chromium electroplating and anodizing source categories, 

under our ample margin of safety analysis, we evaluated various options to reduce emissions and 

risks, and the costs, economic impacts and other factors associated with those options. In the 

supplemental proposal we presented the costs and economic impacts of various options and 

summarized the risk reductions that would be achieved with the proposed limits. Since proposal, 

we updated and revised the estimated costs and economic impacts of the various options (details 

are in the Revised Procedures for Determining Control Costs and Cost Effectiveness for 

Chromium Electroplating and Anodizing, which is available in the docket). As part of our 

AMOS analysis in the preamble to this final rule, we evaluated the costs, economic impacts and 

risk reductions that would be achieved for each option for each of the categories and 

subcategories (i.e., large hard chromium electroplating, small hard chromium electroplating, 

decorative electroplating and chromic acid anodizing). The results of this analysis and our 

conclusions are described in the preamble for this final rule.

Comment: Commenter 0290/0620 suggested that the EPA consider setting an absolute 

hexavalent chromium mass emission limit, not just concentration-based limits. The commenter 

observed that the proposed emission concentration-based limits do not set any absolute limit on 

the total amount of hexavalent chromium that can come from a given source; rather, the more 

tanks a source has, the more emissions it may release. The commenter argued that, under section 

112(f)(2), the EPA must ensure against “unacceptable” risk and provide an “ample margin of 

safety to protect public health,” and consider the greater amount of emissions that can occur from 

multiple tanks. The commenter recommended that the EPA set an absolute limit for each facility, 

in addition to a concentration-based limit, to ensure that no individual facility causes emissions 

that reach an extreme level that can cause grave harm and serious health risks to the local 

community. The commenter noted that California’s mg/amp-hr standard is likely to be more 

protective than a concentration-based standard because it limits the source‘s overall hourly 

 13 77 Fed. Reg. at 6648 (discussing “the controls, measures, and costs reviewed under the technology review”); id. 

(stating its proposal “after evaluating the costs and feasibility of possible options to reduce emissions in our 

technology review”). 
30

emissions from one tank or many, while EPA‘s concentration-based standard does not ensure 

absolute pollution control above any level.

Response: We note that based on the information we have gathered for chromium 

electroplating facilities over the past 20 years, there is nothing to suggest that any facility is 

adding multiple tanks and significantly increasing the level of absolute emissions or that new, 

large facilities are being constructed. Many of the existing facilities are located in areas that do 

not provide the space for the type of expansion the commenter speculates about. The commenter 

does not provide any examples where this has occurred. For that reason, we do not believe that 

setting an absolute limit on facilities is necessary to address risk under CAA section 112(f)(2). 

Furthermore, we note that setting an absolute emission limit is not practical. Since risk is 

a function of emission rate, release height, meteorology and proximity to populations, 

establishing such an absolute emissions limit would require either a plant-specific emission limit 

for each facility based on that facilities emissions and distance to the surrounding population, or 

identifying the one facility that is located closest to populations or sensitive receptors and 

determining the maximum emission rate for that facility and applying that rate to all facilities in 

the source category. In either case, the circumstances could change from year-to-year

We disagree with the comment that a mg/amp-hr format would be more protective. When 

developing the NESHAP, we considered adopting the mg/amp-hr format. We concluded that 

such a format would be appropriate if emissions always tracked process rate (e.g., as process rate 

increased, emissions also increased). However, the data indicated that was not the case for 

certain types of emission controls and therefore, process rate (ampere hours) was not a reliable 

indicator of controlled emissions, and we decided that emission concentration was a more 

appropriate format for the standard.

Finally, we note that the mg/amp-hr format used in California also is not an absolute 

emission limit, but allows plants with more tanks to have higher emissions. If a plant added 

several more tanks, the facility’s process rate would increase and thus, it would be allowed to 

increase emissions proportionally. 

6. Environmental Justice

Comment: One commenter (0290/0620) stated that EPA should use the National 

Academy of Sciences current recommendations on how to appropriately address environmental 

justice. The commenter stated that the residual risk analysis requires a fresh look at whether there

is a need for more stringent pollution controls to protect public health and the environment,

including a current look at what the contemporary view of “acceptable” risk is, in relation to 

environmental pollution.

Response: Per the EPA’s “Interim Guidance on Considering Environmental Justice 

During the Development of an Action,” the agency is encouraging rule writers and policy makers 

to look at the whole range of relevant factors that impact communities and population groups 

when crafting rules. With regard to how the agency conducts its analysis, the EPA is continuing 

to discuss and pilot approaches that are consistent with the agency’s responsibilities regarding 

environmental justice as outlined in EO 12898. For this rule, we performed a demographic 
31

analysis to determine the potential impacts to different demographic groups, and that analysis is 

in the docket. While we analyzed the demographic makeup of the at-risk populations 

surrounding the facilities within the source category addressed by this rule making, we ultimately 

concluded the risks were acceptable for all population groups and that the proposed limits would 

protect public health with an ample margin of safety.

With regard to determining the acceptable levels of risk, first we note that in 1990 

Congress codified in section 112(f) (2)(B) of the CAA the approach we use for our residual risk 

analyses. Under that approach, the 100-in-1 million cancer risk is not a bright line indicating that 

risk is “acceptable.” Rather, we consider this health metric in conjunction with a variety of health 

factors to determine whether the risk is acceptable. Where we conclude that the risk is not 

acceptable, we cannot and do not consider costs in requiring controls to bring risks down to an 

acceptable level. However, the analysis of whether risk is acceptable is not the endpoint. Once 

we determine that controls are sufficient to ensure that risk is acceptable, we again review the 

health metrics in conjunction with the costs of controls, technical feasibility, and other relevant 

factors, to determine whether additional controls should be required to provide an ample margin 

of safety, as described in more detail in responses provided above. 

The EPA also does not accept that the language in the en banc Vinyl Chloride opinion 

regarding risks “acceptable in the world in which we live,” 824 F. 2d at 1165, dictates any 

particular quantitative result based on societal preference – especially when the court, in using 

this language, was indicating that risk-based standards for hazardous air pollutants did not need 

to be risk-free. Moreover, the commenter does not support its contention that people are now 

unwilling to accept a level of risk that was acceptable at the time the CAA was amended in 1990. 

Nor does the commenter support how science has evolved in a way that would undermine the 

statutorily codified framework for determining risk acceptability. 

Comment: Commenter 0274/0618 is concerned with the failure of the assessment to 

identify enhanced safety measures (e.g., stricter controls) to address the disproportionate socioeconomic impact found for both hard and decorative electroplaters. The commenter did not 

support the conclusion that the disproportionate impacts to populations at cancer risks above 1-

in-1 million are acceptable, and requested that EPA’s Office of Environmental Justice 

participate in the evaluation of potential disproportionate impacts in some communities. 

Response: The EPA’s Office of Environmental Justice has actively participated in the 

development of this rule. For the reasons provided in the preamble to the proposed and final 

rules, we have determined that the standards we have adopted provide an ample margin of safety 

for all proximate populations, including minority and low-income populations. 

Comment: Three commenters (0272, 0274/0618, and 0290/0620) expressed concern that 

the residual risks identified by EPA are highly disproportionate to individuals who are 

minorities, below the poverty level, and/or do not have a high school diploma. Commenter 

0290/0620 stated that urban and minority populations face a disproportionate risk from other 

pollution hazards and EPA should provide protections beyond the MACT. The same commenter 

stated that a community in good health with higher income that does not have numerous other 

polluting facilities might well be willing to tolerate an additional cancer case every 1.25 years 
32

(i.e., every 15 months). According to Commenter 0290/0620, adding this risk of an extra cancer 

case into minority populations and urban communities, which are already at a serious pollution 

and health disadvantage, should be considered unacceptable. The commenter also stated that 

EPA does not incorporate into the risk assessment the significantly higher likelihood that 

minority communities are exposed to cancer risk from chromium electroplating sources. The 

commenter stated that EPA must consider the disproportionate impact on minority individuals 

and communities in deciding whether the likelihood of cancer risk to them is still acceptable. The 

commenter stated that to satisfy the requirements of the Clean Air Act and address the aims of 

EPA’s Environmental Justice guidance, EPA should incorporate elements of the cumulative risk 

assessment methodology that it has already developed into its residual risk analysis, considering 

population groups exposed at average levels and those in the high-end portions of the risk 

distribution, the exposed population as a whole, and important subgroups or life stage strata of 

the population (e.g., children) or other highly susceptible groups. The commenter stated that

EPA must incorporate into its risk analysis and its proposed rule both (1) the vulnerability of 

certain individuals to higher risk (such as due to age or early exposure, or due to multiple or 

cumulative exposures to the source category’s emissions), and (2) the unacceptability of 

disparities in risk based on race or income level. The commenter stated that appropriate analysis 

of these factors will show that there is a higher overall level of risk that is likely to occur to the 

maximum exposed individual, and that this level of risk is not acceptable. The same commenter 

added that considering these factors and performing these analyses also must be part of the 

ample margin of safety inquiry and it is neither acceptable nor just to subject certain people, 

based on race or income level, to a disproportionate risk of cancer from air pollution caused by 

chromium electroplating emissions. 

Response: We have responded to many of the concerns raised by this commenter in the 

preamble to the final rule or in this document, in particular those comments that suggest that we 

must analyze risk from all sources that affect individuals in communities in which chromium 

electroplating and anodizing facilities are located. It appears the commenter is suggesting that 

minority and low income individuals experience a disproportionate risk because these 

individuals are more likely to live in areas where they are exposed to pollutants from a variety of 

sources. As we have explained previously, section 112(f) requires EPA to review the risk posed 

from the source category at issue. 

We acknowledge that population subgroups, including children, may have the potential 

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

susceptibility to the toxicant. As we have noted elsewhere in the record for this action, as part of 

the 112(f) review, we do account for such vulnerabilities and we also consider the risk posed due 

to multiple or cumulative exposures where multiple sources within the source category may 

impact the same geographic area. For the dose-response component of HAP assessments for 

RTR, we use exposure reference concentrations and unit risk estimates (UREs) that are expressly 

derived with the objective of protecting sensitive populations and lifestages, including children.

14

7. Emission Data Quality and Completeness

Comment: Several commenters (0274/0618, 0275/0615, 0278/0617, 0285/0296/0619, 

and 0290/0620) took issue with EPA's approach to estimate actual emissions for the October 

 14 Ibid. 10.
33

2010 proposal. Three commenters disagreed specifically on the model plant approach to 

modeling risk. Two commenters stated that the default assumptions used by EPA in modeling its 

estimates to predict inhalation cancer risk underestimated the risk, and that EPA should reevaluate the risk assessment using accurate emissions data and source parameter information. 

One commenter stated that this underestimation occurred because the analysis relied on a default 

model plant to assign the necessary stack parameters to conduct the modeling analysis. The 

commenter stated that the use of model plant parameters for the chromium electroplating 

facilities clearly limited EPA's ability to accurately estimate the risk associated with hexavalent 

chromium emissions. The commenter believed the conservative approach (that that EPA 

requested comment on), which assigned emission rates of 9.26 lbs/yr (lbs/yr) for hard chromium 

electroplaters, 2.26 lbs/yr for decorative chromium electroplaters, and 0.44 lbs/yr for chromium 

anodizing, is probably a more accurate determination of the risks faced by communities exposed 

to hexavalent chromium emissions from chromium electroplaters in compliance with the 

NESHAP.

One commenter stated that EPA overestimated chromium emissions by at least one order 

of magnitude. The commenter stated that if EPA corrected the average per-plant chromium 

emissions estimate to 0.5 lbs/yr, very few facilities would be expected to have an MIR above 1-

in-1 million, and the number of individuals subject to risk associated with chromium emissions 

would be more than an order of magnitude less than EPA’s estimate of 14 million. The 

commenter believes that the number of individuals exposed to a risk of 1-in-1 million could be 

considerably less than 400,000. Finally, the commenter noted that, as part of the proposed 

rulemaking, EPA acknowledged that the residual risk from chromium emissions from chromium 

electroplating and anodizing operations appears to be acceptable. The commenter noted that EPA 

requested comments on its more conservative risk modeling approach with 14 million 

individuals potentially exposed to a cancer risk of 1-in-1 million from chromium emissions. The 

commenter stated that this conservative approach does not appear to be realistic or supported by 

the available data and analysis.

One commenter remarked that the estimates of 9.26 lbs/yr of chromium emissions for 

hard chromium electroplating operations and 2.65 lbs/yr for decorative electroplating operations 

are substantially higher than all but a handful of the largest facilities. The commenter noted that 

EPA attributed the 9.26 lb/yr emission rate to any facility that performs hard chromium 

electroplating, even if the hard chromium electroplating operation was a small percentage of the 

overall chromium electroplating or anodizing operations at the facility. The commenter also 

noted that EPA attributed the highest emissions rate of 9.26 lbs/yr to any facility for which it did 

not have complete information. The commenter stated that, based on these assumptions, EPA 

inflated the number of facilities with hard chromium electroplating operations to over 1,200 of 

the 1,634 facilities, instead of a more realistic estimate of less than 800 facilities. The commenter 

further stated that EPA compounded its errors, resulting in a substantial over-estimate of 

chromium emissions and the associated risk. The commenter recommended that EPA use 

estimates of 0.5 lbs/yr of chromium emissions as a conservative estimate of average annual 

facility emissions, resulting in a national estimate of 0.409 tons/yr of chromium emissions. 

One commenter stated that EPA’s conclusions in regard to the emission factor data used 

for the “conservative” analysis are not supported by EPA’s own data in the record that shows 
34

that the Agency has actual, higher emission data for certain facilities and that it believes potential

emissions per facility could run even higher. The commenter provided the example of a large 

plant, which was determined to have the potential to emit 23.6 lbs/yr for the sake of the initial 

analysis, although EPA had previously concluded for the original MACT that this could be as 

high as 35.3 lbs/yr, and, according to the model plant data memorandum, the largest facility’s 

emissions number is 31.2 lbs/yr. The commenter provided other examples of apparent 

inconsistencies in the analysis data, including using a lower emission factor for the majority of 

facilities for which it had no emission data, including for large facilities. The commenter stated 

that, in its supplementary analysis, EPA created different, smaller emission factors for a modeled 

data set of facilities for which it has no actual emission data. The commenter stated that the 

emissions are underestimated because, for the weighted average that EPA uses, the number of 

small plants overwhelms the larger plants, causing the emission factor used for all hard 

chromium electroplaters in this analysis to dramatically underestimate the emissions from larger 

plants, and thus the health risk. A commenter recommended that EPA revise the risk assessment 

based on actual source and emissions data rather than using "model plant" data. 

One commenter stated that EPA's estimates that were used as the basis for the 2010 

proposal do not reflect the effective controls and management practices that the industry has 

implemented to reduce chromium emissions. The commenter stated that chromium emissions 

data reported from individual facilities are significantly lower than EPA’s estimated emissions 

and the emissions for the model plants. Further, the commenter argued that, based on CARB's 

estimates for total chromium emissions in California, and assuming that metal finishing 

operations in California represent more than 10 percent of the national chromium electroplating 

and anodizing production in the U.S., national chromium emissions from the metal finishing 

industry would be significantly less than 0.5 tons/yr. The commenter noted that EPA labeled 19 

facilities located in California as “highest risk,” and indicated those plants account for over 180 

pounds of chromium emissions each year. The commenter stated that this estimate for these 

facilities is significantly more than CARB’s estimate of 4 lbs/yr of chromium emissions from all 

electroplating and anodizing operations in California.

Response: These comments primarily concern the emission estimates that we developed 

for the October 2010 proposed rule. As explained in more detail in the February 2012 

supplemental proposal, we obtained a substantial amount of improved emissions data after the 

2010 proposal and recalculated the emissions estimates because of concerns about their 

accuracy. See 77 FR 6632. Much of the information we relied on at the time of the October 2010

proposal was emissions information that was available at the time we initially promulgated the 

NESHAP and thus the emissions data did not reflect reductions required by the existing MACT 

standard. The Simulation of Actual and Allowable Emissions for Chromium Electroplating

document explains in detail the analysis we performed for the February 2012 supplemental 

proposal. The data used and the analyses performed to estimate nationwide emissions for the 

February 2012 supplemental proposal more accurately reflect emissions following promulgation 

of the NESHAP because it uses actual post-MACT data. In addition, it accounts for variations in 

the parameters that determine annual emissions rates. Instead of relying upon model plants as we 

did for the October 2010 proposal, we used a Monte Carlo approach to simulate actual 

emissions. The simulation model used the pool of available data on actual emissions 

concentrations, exhaust flow rates, and annual operating hours for each process type (hard 
35

chromium electroplating, decorative chromium electroplating, and chromium anodizing). We 

believe that the resulting emissions estimates simulated by the model relied on for the February 

2012 supplemental proposal are much more representative of actual emissions on average and 

also are more representative of the variability of emissions from plant to plant. 

To the extent that the commenters are suggesting that we use actual data for all facilities, 

we note that is not feasible or realistic. We estimate that there are over 1,300 sources subject to 

the NESHAP nationwide and the large majority are small businesses that do not have the 

capability, and many facilities are not required, to estimate annual emission levels.

Comment: Commenter 0274/0618 stated that EPA should better illustrate where the 

California facilities fit within EPA’s determination of emission limits for each source category. 

The commenter believes that California plants could be included into the analysis in “Procedures 

for Determining Control Costs and Cost Effectiveness for Chromium Electroplating 

Supplemental Proposal” by using default stack parameters to convert California’s production 

based emissions into concentration based emissions. The commenter stated that by not including 

California plants EPA is not considering 25 percent of American chromium electroplating 

facilities.

On the other hand, Commenter 0285/0296/0619 supported EPA’s decision to exclude 

California facilities from the analysis because they are not representative of chromium 

electroplating and anodizing facilities nationwide.

Response: Regarding the suggestion by Commenter 0274/0618, we point out that

emissions data in the mg/A-hr format cannot be converted directly to concentration format 

(mg/dscm) without making several assumptions about production rates. Electroplating and 

anodizing exhaust or ventilation systems are generally sized according to tank surface area, and 

there is no correlation between surface area and production rate. Furthermore, there are large 

variations in rectifier capacity (amperes) and throughput (ampere-hours) for each process type. 

Although we can make informed assumptions about exhaust flow rate for a specified size of tank 

(surface area), we believe that any assumptions made about production rates would render the 

emissions conversions (from mg/A-hr to mg/dscm) uncertain. As supported by Commenter 

0285/0296/0619, we maintain that the data for facilities located in California are not 

representative of plants located in other States with respect to modeling emissions from facilities 

located outside of California. Nevertheless, available information indicates that the emissions 

and emissions concentrations are generally quite lower on average at the California facilities 

compared to facilities in other States. There are more than 150 facilities in California. Based on 

available information, we believe that all facilities in California already have emissions 

concentrations well below the limits being promulgated in today’s action and will need no 

additional controls to meet the promulgated limits in this rule. This fact provides further support 

that the limits we are promulgating in today’s action are feasible and achievable for plants in 

other States. 

Comment: Commenter 0285/0296/0619 points out that EPA stated that it did not include 

California facilities as part of the analysis for estimating allowable emissions, but yet the 

facilities with the highest MIRs for allowable emissions for decorative and anodizing were 
36

nearly all in California. The commenter believes allowable emissions in California should be 

significantly lower due to stringent state air emission limits for hexavalent chromium. 

Response: We recognize that the State regulations in California are generally more 

stringent than in other States. However, for purposes of allowable emissions, we consider the 

emissions allowed based on implementation of the NESHAP in order to determine whether the 

NESHAP should be tightened. As to whether we considered allowable emissions for plants in 

California, the commenter misinterpreted EPA’s statement; we did evaluate allowable emissions 

as well as the MIR for such plants based on the allowable emissions. 

For purposes of calculating allowable emissions for plants in California, we did not have 

adequate data to perform simulations of emissions similar to the simulations we performed for 

plants in other States. That is, we did not have data on emissions concentrations, exhaust flow 

rates, annual hours of operation, or mass emission rates; for the most part, we had data only on 

annual production (ampere-hours per year) and emissions as a function of rectifier output 

(milligrams per ampere hour). We decided instead to use the mean of the simulated allowable 

emissions for the non-California plants to represent allowable emissions for the plants located in 

California. We believed this approach would provide estimates that are conservatively high for 

plants in California (considering state controls), but obviously not as high as allowable emissions 

for many plants. We agree with the commenter that many of the highest MIR values based on 

allowable emissions were for decorative chromium electroplating and chromium anodizing 

plants in California. The MIR values are not simply a measure of emissions, but are significantly 

influenced by the location of populations relative to emission sources. Many of the plants in 

California are located in more urban settings than those in other States. For example, 

approximately 18 of the decorative chromium plants located outside of California had higher 

emissions than the value used for decorative chromium plants located in Californian (0.93 lb/yr), 

yet only two of those plants had MIR values among the highest 25, whereas 19 of the highest 25 

MIR values were associated with plants in California. Proximity to populations is the reason why 

so many plants in California had high MIR values.

Comment: Commenter 0290/0620 noted that EPA did not provide emission 

concentration information for California in the record and found this to be a problematic 

omission that undermines the ability for meaningful notice-and-comment under 42 U.S.C. 

§7607(d). The commenter acknowledged that EPA provided annual average total emissions for 

California facilities which they believe show that California plants have achieved levels of 

emissions well below the levels outside of California.

Response: The state-imposed emissions limits in California are expressed in units of 

mg/A-hr and the facilities report their emissions in those units. Although we have some emission 

test reports that also report emissions in units of concentration, most of the emission data for 

California are reported as mg/A-hr. The concentration data we have for California plants are 

included in the individual docket files received from South Coast Air Quality Management 

District (AQMD) and the Bay Area AQMD, but we did not compile the data into a single table.

Comment: One commenter (0290/0620) stated that EPA has used actual emission data 

(not measured data, but based on emission factor estimates) that suggest that numerous facilities 
37

are not currently emitting at the full level allowed under the existing MACT standard, but at a 

lower level, presumably because they are using technologies or practices that allow them to 

reduce emissions further. However the commenter noted that, EPA predicts that requiring 

retrofits with HEPA filters would still impact over half of the industry. The commenter thinks 

that EPA's conclusion about the number of facilities that would be impacted by a requirement to 

install HEPA filters is inconsistent with EPA's data on actual emissions and the data on facilities 

operating in California, many of which have already installed such controls.

Response: Based on the data collected following the October 2010 proposal, we agree 

with the commenter that many facilities are operating well below the current emission limits and, 

in many cases, more than 10 times below that limit. In addition, those data have enabled us to 

better estimate the number of plants in the U.S. that use HEPA filters, as well as other types of 

controls such as composite mesh pads (CMPs), to comply with the NESHAP. Our updated 

estimates of the impacts of the amendments to the NESHAP indicate that far fewer plants, if any, 

would be required to install HEPA filters to comply with the more stringent emission limits.

Comment: One commenter (0290/0620) questioned EPA’s definition of MACTallowable emissions, stating that EPA’s definition does not ensure a complete picture of the true 

maximum potential emissions. The commenter stated that EPA actually did not use the truly 

allowable or maximum potential of which EPA is aware, and the proposal preamble does not 

make clear whether the maximum potential includes the level of emission that was allowed under 

the old version of the MACT (which exempted malfunctions from the standard) or under the new 

version of the MACT (under which malfunctions will violate the standard). The commenter 

asked that EPA address this question in the final rule. The commenter also stated that EPA did 

not use the maximum allowable emission levels for large or medium sources, attributing instead 

a median modeled level for medium sized plants to both large and medium plants. The 

commenter stated that EPA fails to explain how this emissions factor could allow EPA to address 

the risk of the maximum exposed individual, when EPA is aware of at least five facilities that 

actually emit more than this factor.

The same commenter stated that EPA underestimated the facility emissions factor that 

EPA used to assess risk and to estimate a 90-in-1 million maximum lifetime individual cancer 

risk for the hard chromium electroplating category. 

Response: The revised risk assessment relied on for the supplemental proposal includes a 

separate data set to model MACT allowable emissions. That data set was developed by scaling 

up actual emissions data, where available, to the corresponding emission limit. For example, if 

actual data showed that a large hard chromium electroplating plant was operating at 0.0075 

mg/dscm (i.e., at one-half the emission limit), the MACT allowable emissions for that specific 

plant was estimated by doubling the actual annual emissions for the plant. For those plants for 

which we did not have actual emissions data, we used a Monte Carlo approach to simulate 

allowable emissions. For that approach, we used the pool of actual emissions data, substituted 

actual emissions concentrations with the emissions limits, and then simulated allowable 

emissions (see Revised Simulation of Actual and Allowable Emissions for Chromium 

Electroplating Facilities, which can be found in the docket for this rulemaking). We believe this 

approach provides representative estimates for allowable emissions nationwide. The final 
38

amendments eliminate the exemption for malfunctions. Therefore, emissions exceedances that 

occur during periods of malfunction are considered to be violations and our assessment of 

allowable emissions do not include emissions during malfunctions, which are not allowed under 

the MACT standard.

Comment: Commenter 0278/0617 reviewed the data on 12 hard chrome and decorative 

electroplating permitted facilities in North Carolina and found that two facilities would not meet 

the revised emissions or surface tension limits. The commenter explained that one of the two 

facilities uses a wet scrubber and the other uses a packed bed mist eliminator, but both facilities 

would have to replace existing controls in order to comply. The commenter is concerned that the 

proposed emission limits are based on a small amount of actual data that could result in an 

unrepresentative distribution of technically feasible options for affected facilities and could lead 

to infeasible and burdensome requirements for facilities whose emissions are higher than the 

proposed limits. The commenter noted that EPA used actual emissions and process data for only 

two of the thirteen facilities in NC for which risk was assessed and that 80 percent of the data 

used to calculate the revised emission limits was simulated. The commenter requested that EPA 

re-examine the methodology employed to simulate emissions and use a larger data set based on 

actual emission performance of different types of controls. 

Response: As an initial matter, we note that it is difficult to address the situation 

presented by the comments because the commenter provided limited facts. However, the concern 

raised – that some sources may not be able to meet the emission limit through existing controls -

is not inconsistent with our determination that not all facilities will be able to comply based on 

existing processes. However, that does not mean that sources with existing controls would need 

to replace such controls. 

These findings are consistent with our overall analysis that over 80 percent of facilities 

already meet the lower emissions limits and will need no additional controls and no additional 

reductions to meet the lower emissions limits. With regard to the two facilities in North Carolina 

that apparently do not currently meet the limits, they can reduce their emissions and comply with 

the lower limits either through improving their add-on controls or by adding fume suppressants. 

For example, our data indicate that about 15 percent of chromium electroplating tanks are 

controlled with a combination of add-on controls, such as packed bed scrubbers, and fume 

suppressants and that the purpose of the fume suppressant is to further reduce emissions to 

ensure compliance and to improve indoor air for the workers. Consequently, we believe that 

many existing plants that could not meet the proposed emission limits solely through the use of 

add-on controls, could do so through the addition of fume suppressants without having to replace 

their primary add-on control device.

Regarding the data set used as the basis for the supplemental proposal, the analysis and 

decision to propose more stringent emissions and surface tension limits were based on the 

available data. We agree that having additional data is desirable, but we do not believe that the 

outcome of our analysis would have been significantly different. Regarding the more stringent 

emissions limits, we believe we had enough data on hard chromium electroplating sources (75 

data points for large hard chromium, 38 data points for new small hard chromium, and 35 data 

points for existing small hard chromium) to characterize the industry with reasonable certainty. 
39

The data also were consistent with respect to the percentage of plants that would meet the more 

stringent emission limits. The data are from sources located in 19 states and we believe they 

represent a random sampling. We had fewer data points for decorative chromium electroplating 

and only one data point for chromium anodizing, but those data also consistently showed that the 

majority of sources would meet the more stringent emissions limits. Additional chromium 

anodizing data we have collected since the supplemental proposal also support this conclusion. 

We also point out that the proposed emission limits were not based on simulated emissions, as 

suggested by the commenter; the simulated emissions data were used only to assess nationwide 

risk associated with emissions from chromium electroplating and chromium anodizing sources. 

Regarding the more stringent surface tension limits, the proposed limits were based on 

data from 15 plants and were relatively consistent. We have no reason to believe additional data 

would have materially changed the outcome of our analysis.

Comment: Commenter 0285/0296/0619 stated that, after spot checking the operating 

hours EPA used to estimate actual annual emissions for 170 non-California facilities, they found 

several errors in the data. The commenter checked EPA’s data on operating hours specifically for 

the anodizing and decorative chrome facilities for which EPA claims to have used information 

on the facility’s operating hours in estimating a facility’s actual emissions and concluded that 

EPA’s data on operating hours appeared to be inaccurate/wrong for 16 among these 21 facilities. 

The commenter believes the net result of these errors overstated these facilities’ operating hours, 

actual emissions, and in turn results in over-estimating emissions for the remaining 1,149 nonCA facilities comprising the remainder of the industry.

Response: We have reviewed the data identified by the commenter and compared it with 

information submitted by the commenter. Most of the errors concern operating hours that did not 

account for the percentage of time the rectifiers were energized. We have made corrections to the 

data to ensure that the operating hours for each plant accounts for rectifier operation. We also 

have used the revisions to operating hours and other changes to the available data, as discussed 

in the responses to other comments on data issues, to re-simulate emissions for those facilities for 

which actual data were not available. 

Comment: Two commenters (0274/0618, and 0275) stated that EPA based its risk 

assessment on source data for only 166 facilities out of approximately 1,770 covered by the 

MACT standard, which is an insufficient number. Commenter 0278/0617 agreed and stated that 

basing risk estimates for the Chromium Electroplating source categories on a small database of 

actual data increases the uncertainty in those risk estimates.

Response: First, we note that gathering actual emissions data for sources in this source 

category is difficult because they are primarily small businesses and they are not subject to 

routine testing of emission levels. Furthermore, because the plants in question are area sources,

they are not required to submit annual emissions inventory reports. As a result, most emissions 

information must be obtained directly from state agency permit files, which is a time-consuming 

process. We agree with the commenters that the data set used to model risk for the October 2010 

proposal was limited. Prior to issuing the supplemental proposal, we conducted extensive data 

gathering to acquire data that were more accurate and to develop a data set that is more 
40

representative of the chromium electroplating industry. At the time of the supplemental proposal, 

we had actual source data from 198 facilities out of 1,454 plants, and for purposes of the final 

rule we have obtained emissions data for 25 additional plants. Moreover, many plants have 

closed, so the total number of facilities is now estimated to be about 1,350 plants. Therefore, we 

now have data for about 223 facilities out of 1,350 plants, and the data we have now are more 

representative than the data we had in 2010. While there will always be uncertainties in any risk 

analysis that we perform, we believe that we have relied on the best information available to the 

Agency and thus have minimized the uncertainties to the extent feasible at this time. 

Comment: One commenter (0290/0620) stated that, when EPA has so little data about 

the industry, it is arbitrary and capricious for EPA to assume that any one of the facilities for 

which it has data is the largest or worst-performing facility. The commenter stated that EPA does 

not have enough data to conclude that any of the facilities that the Agency has data for is the 

largest and worst-performing. The commenter stated that a further indicator of uncertainty is that 

EPA has stated that the largest facility that it has actual data for is reported to be closed, and EPA 

is considering removal of that facility from its risk assessment. The commenter noted that if this 

is a large facility of “allowable” emissions, it represents a data point that EPA must take into 

consideration in its residual risk analysis as part of the maximum potential emissions to which an 

individual person is exposed. The commenter stated that ignoring a facility that closes during the 

course of a rulemaking could allow industry to cook the risk numbers by engaging in a 

temporary shut-down, and then reopening a badly performing facility after EPA’s rulemaking is 

complete in order to evade stronger standards.

Response: This comment was received shortly after the 2010 proposal. As explained 

previously, since the October 2010 proposal, we collected data on several hundred additional 

facilities. For each of those facilities, we estimated annual emissions to be at least several pounds 

less than the facility that we believe has the greatest emissions, so none of those data leads us to 

believe that there are facilities in operation with greater emissions. However, the approach used 

to simulate emissions for purposes of the supplemental proposal did result in comparable annual 

emissions (approximately 10 lbs/yr) for two plants and greater annual emissions for three other 

plants, and we used those greater emission rates in our risk modeling. Given that the simulation 

approach accounts for the variability in emissions, and that one of the data points used in the 

analysis was for the plant we believe to have the highest emissions, it is expected that at least one 

plant would be simulated as having even greater emissions, which was the case. Therefore, we 

believe the results of our risk assessment account for other plants that could have greater 

emissions than the plant we have identified as being the largest emitter in the industry.

We understand the commenter’s concern regarding facilities that may close down 

temporarily. We have not excluded any facilities from our analysis unless we have concluded 

that they have permanently shut down.

Comment: Commenter 0285/0296/0619 recognized that EPA has gathered more facility 

data since the 2010 proposal, but is still concerned with the quality of the data EPA used in the 

rulemaking, adding that much of the data is more than 15 years old and generated prior to the 

amendments to the NESHAP and changes to OSHA’s workplace exposure standard for 

hexavalent chromium. The commenter stated that there are a number of inconsistencies in the 
41

data and that EPA has not only relied upon limited and flawed data, but has also chosen to 

“stretch” the data beyond its logical and reasonable limits. The commenter believes imposing 

new regulatory standards based on unreliable data creates an unnecessary and unwarranted 

burden on an industry that serves several critical supply chains (such as military, aerospace and 

automotive) and is experiencing significant economic challenges. Commenter 0285/0296/0619 

believes that the major reason why EPA has insufficient information is the Agency’s failure to 

conduct a recent Information Collection Request (ICR) or industry survey. The commenter stated 

that EPA’s failure to collect the data necessary to support this rulemaking, and nonetheless 

proposing to impose stricter standards even after it concluded that emissions were lower than 

previously estimated, is an arbitrary and capricious exercise of the Agency’s authority.

Commenter 0290/0620 stated that EPA needs to use the section 114 information collection 

process to provide more accurate data and to fill in the data gaps for this source category.

Response: We agree with the commenter that conducting industry-wide ICRs is an 

effective method for obtaining detailed information on an industry, and we did consider an ICR 

for the chromium electroplating source categories. However, we decided against taking such 

action for two reasons: we believed that doing so would have put a significant burden on 

hundreds of small facilities, and we believed our approach of requesting the needed data from 

permitting agencies in States with the largest numbers of facilities would provide adequate data. 

As noted in the preamble to the supplemental proposal, we contacted 26 State and local agencies 

for information. Although not all of the contacted agencies provided data, those that did respond 

provided us with information which they believed was representative of the industry. We agree 

that some of the emissions test data are more than 15 years old. However, since the NESHAP 

requires only a one-time performance test, those data are likely the only data available for many 

of those facilities. Furthermore, the fact that the data are old does not necessarily mean that the 

data are not representative. We recognize that the OSHA standard for worker exposure has been 

revised since some the data were compiled, but it is our understanding that changes in the OSHA 

rule were largely addressed through better room ventilation and improved housekeeping and not 

by making changes to electroplating tank control systems. Finally, we disagree with the 

comment that we have stretched the data beyond the logical and reasonable limits. The 

procedures we have used to represent the operation and emissions for chromium electroplating 

plants and estimate emissions are no different than the methodologies and statistical procedures 

we have used for several other industries to fill data gaps.

Comment: One commenter (0290/0620) stated that, because chromium electroplating 

facilities are not subject to monitoring requirements under the MACT, the NEI data appear to be 

generated purely using emission factors, rather than actual measurement of emissions. The 

commenter stated that this makes the data even less reliable, and EPA may not rationally use 

them as the sole basis for its assessment of emissions during the residual risk assessment. The 

commenter added that, both for the “conservative” and “supplementary” analyses in the 2010 

proposal, EPA relied in part on 2005 NEI data, which are industry-generated and not verified in 

many states. The commenter stated that for the residual risk review, it is arbitrary and capricious 

for EPA to rely solely on industry-reported unverified emissions. The commenter also noted that 

EPA’s own Office of the Inspector General has reviewed the NEI data and found not only 

problems with accuracy, but also that there are significant data gaps. 
42

Response: This comment concerned the October 2010 proposal. As a general matter, we 

disagree with the commenter. The commenter provided no basis for the statement that the NEI 

data for these source categories are generated using emission factors, and we do not believe that 

is generally the case. While we agree that the NEI data do have some problems with accuracy, 

we believe that is true with any database of emissions data. While we relied on the NEI database 

as the starting point for residual risk analyses, we also made great efforts to check and verify the 

data to the extent possible by trying to collect additional information and independently confirm 

any data that does not appear to be reasonable. In addition, we disagree with the suggestion that 

industry-generated data are not reliable. In many cases, the industry is the only sources for the 

relevant information. Again, however, experts within the Agency review the data prior to our 

relying on it for our analyses. For example, emissions greater than about 6 lbs/yr for hard 

chromium electroplating plants, and emissions greater than about 4 lbs/yr for other types of 

plants are scrutinized because few plants emit more than these amounts. On the other end of the 

scale, it is common for plants to electroplate infrequently, and data points for emissions 

significantly less than 0.1 lb/yr are common and reasonable. As the starting point, the revised 

risk assessment used for the supplemental proposal also relied upon NEI data, and industrygenerated data for actual emissions. We then enhanced the data set with data obtained from State 

and local agencies as described in the responses above. Where actual emissions test data were 

available, we calculated annual emissions based on measured concentrations and exhaust flow 

rates. Where we used NEI data to supplement the actual data set, we reviewed those data to 

determine if they are reasonable when compared to data from other similar plants. We rejected 

any such data that did not appear to be representative. For those facilities for which actual data 

were not available, we used a Monte Carlo approach, which utilized actual data on emissions 

concentrations and exhaust flow rates to simulate emissions.

Comment: Commenter 0285/0296/0619 stated they were unable to find all of the 

supporting documentation in the docket for facility emissions estimates that EPA noted as 

coming from state and local regulatory agencies. The commenter identified three specific plants 

that were spot-checked for supporting documentation in the rulemaking docket. The commenter 

believes that if these data were estimated or were not directly provided by local agencies the 

EPA should not claim the data to be a facility-specific estimate of annual emissions provided by 

a State or local agency.

Response: Regarding the three facilities identified by the commenter, emission estimates 

for two plants (Jobsite, Inc. and Starrett Company), were taken from the NEI database. The 

estimates for these plants are indicated “as reported” in the Industry Profile Memorandum. Prior 

to being included in the analysis, these and other NEI data were screened to determine if they 

were reasonable, and it was concluded that 2.7 lbs/yr for a large hard chromium plant (Jobsite) 

and 4.0 lbs/yr for a decorative chromium plant were reasonable. Regarding the third facility 

(Dover Industrial Chrome) identified by the commenter, the basis for the estimated emissions of 

4.76 lbs/yr is provided in three documents included in the docket for the October 2010 proposal: 

Document Nos. EPA-HQ-OAR-2010-0600-0096, EPA-HQ-OAR-2010-0600 -0115, and the 

attachment to EPA-HQ-OAR-2010-0600-0115, which are the operating permit, emission test 

summary, and the plant’s permit renewal application, respectively.

8. Facility-Specific Data
43

Comment: One commenter (0274/0618) stated that an example of potential 

underestimation involves a large hard chromium electroplater in New York that was identified as 

an unknown electroplater in the August 27, 2010, analysis and assigned an emission rate of 

1.1 lbs/yr. The commenter stated that this facility has emissions of 10.0 lbs/yr at the MACT 

allowable emissions rate for large chromium electroplaters. The commenter noted that this value 

is actually higher than the 2.24 lbs/yr assigned to known hard chromium electroplaters. The 

commenter stated that this source has installed redundant air pollution controls (a packed bed 

scrubber followed by a composite mesh pad system) to achieve the MACT allowable emission 

rate of 0.015 mg/dscm. The commenter stated that the modeling of this facility at the unrealistic 

low emission rate (1.1 lbs/yr) and large flow rate (962.8 dscm/minute) results in extremely low 

risk in a very densely populated urban area. The commenter’s risk evaluation of the facility 

indicated an 8-in-1 million maximum individual cancer risk at the property line, calling into 

question the results in the draft residual risk assessment.

Response: The commenter did not provide specific information about which chromium 

electroplater in New York they were concerned about. In response to this comment, EPA 

contacted the New York Department of Environmental Conservation for information about 

facilities in the State. The agency provided additional information for several plants in the State, 

but it was not possible to identify the plant in question. However, for the supplemental proposal,

we simulated allowable emissions for two facilities in New York who have emissions greater

than 10 lbs/yr, with an MIR value of 40-in-1 million for one of the facilities. Therefore, we 

believe that our revised risk assessment addresses the commenter’s concern that we 

underestimated emissions and risk.

Comment: Three commenters (0259, 0278/0617, 0285/0296/0619) provided data on 

specific facilities to update EPA's list of plants in operation and the type of chromium 

electroplating performed. In addition, Commenter 0285/0296/0619 provided updated emission 

estimates for several facilities that EPA had identified as being high risk. Commenter 0259 

provided test results for chromium electroplating process operations at the commenter’s facility. 

The commenter also provided production rates of hard and decorative chromium electroplating 

conducted by the commenter over the eight-year period from 2003 through 2010, which is 

representative of normal operation. The commenter also provided other information about the 

facility's chromium electroplating operation. Another commenter (0278/0617) pointed out that 

reliable data for the facilities in North Carolina can be found in the state's emissions inventory.

Response: To the extent possible, we used all of the data provided by the commenters in 

the revised risk assessment and impacts analyses that was performed for the supplemental 

proposal and in finalizing the amendments to the NESHAP. We also performed an extensive data 

gathering effort in which we requested State agencies to provide data on actual emissions and 

facility design and operation. Altogether, 28 State and local agencies were contacted, and 

24 agencies provided data. Data were collected on a total of 346 plants and, where there were 

adequate data, actual emissions were calculated. The resulting data set represents a significant 

improvement over the data set used as the basis for the October 2010 proposal.
44

Comment: Commenter 0278/0617 stated that according to the NCDAQ database, there 

are 30 facilities in NC subject to the Chromium Electroplating NESHAP; 10 of which match 

EPA’s list of 17 facilities in NC that are subject to the rule. 

Response: The 17 facilities are based on the plant list provided by DENR in Feb 2011. 

We subsequently contacted NC DENR and spoke to the contact listed in the comment. He could 

not provide any more information on the number of NC facilities. Based on our information, we 

believe our list of 17 facilities is valid. We subsequently contacted NC DENR and spoke to the 

contact listed in the comment. He was not aware of any other chromium electroplating facilities 

operating in North Carolina.

Comment: Commenter 0285/0296/0619 reviewed EPA’s annual actual emissions for 

Chrome Crankshaft Co. of Illinois, which was based on stack flow, operating hours, and average 

emissions concentration from a stack test report. The commenter noted issues with the age of the 

test report, the calculation of the stack flow and emission concentrations, and the “stress test” 

operating conditions during the test. The commenter also speculated that the facility may have 

changed their process and control equipment since that time. The commenter believes EPA’s 

calculations over-estimate this facility’s current actual annual emissions.

Response: The approach used by EPA in estimating actual emissions for any facility was 

to use the available data and make reasonable assumptions to fill in any data gaps needed to 

complete the estimate. In this case, the basis for the emission estimate is a series of tests 

conducted in 2001 and documented in an emissions test summary provided by the State agency. 

Since chromium electroplating plants are required to perform a one-time test, the 2001 tests were 

the only test data available. If the plant had changed process and control equipment, as suggested 

by the commenter, the plant would have been required to perform new emission tests and the 

results of those tests would have been provided by the State agency. Since the test summary did 

not include exhaust flow rates, a representative rate of 11,090 dry standard cubic feet per minute 

(DSCFM) was used. This flow rate is based on the available data for small hard chromium 

plants. The commenter is correct that estimating emissions on a flow-weighted average would be 

more representative, but as noted above, flow rate data were not available. The annual operating 

hours also were based on average hours for small hard chromium electroplating plants. The 

commenter stated that the operating conditions during the test might not have been representative 

of normal operating conditions. However, it is common practice for performance tests to be 

conducted with sources operating at high production rates to help ensure compliance with 

emission standards at all times, and the results of such testing reflect the best available data for 

estimating emissions.

The commenter raised general concerns about the accuracy of the data we relied on and 

developed, but provided no different data that it claims should be used instead. We continue to 

believe that the emissions estimate for the Chrome Crankshaft facility was made using the best 

available data.

9. Emissions Simulations

Comment: Commenter 0285/0296/0619 suggested that EPA used imputed, inaccurate 

“facility-specific” data to calculate emissions estimates for the remaining 1,149 facilities for 
45

which the Agency had no site-specific information. In addition, the commenter points out that for 

many of these facilities, EPA has no information on their size or on the plating processes that 

they conduct. The commenter stated that due to confusing and sometimes conflicting 

documentation in the record, it is difficult to understand and then comment on how EPA 

performed the “extrapolation” of emissions.

Response: The purpose of the emissions simulations was to provide a reasonable 

estimate of nationwide emissions and an estimate of the nationwide distribution of those 

emissions for evaluating nationwide risk. The emissions simulated for a specific plant are not 

meant to be an accurate estimate of emissions for that specific plant. Rather, the simulated values 

are to be considered in the aggregate. We agree with the commenter that we did not have sitespecific data on plant size and process for many of the plants and that is precisely why we 

decided to use an emissions simulations approach to estimate emissions. The emissions 

simulations use data on the parameters that determine emissions (exhaust flow rate, emissions 

concentration, and hours of operation) that span the range of typical values for those parameters. 

Values for the parameters are then randomly assigned to plants to determine an estimated 

emission rate for a plant. 

As for the accuracy of the data, we have taken into account specific comments we have 

received regarding the data and have performed additional risk modeling based on the revised 

input data. It is true that we used average (“imputed”) values for some parameters, but doing so 

is a common practice and we fail to see how that would render the data unrepresentative. We 

reject the commenter’s suggestion that we had no site-specific information for all of the plants 

for which emissions were simulated. For many of these plants, we had data on the process and 

we incorporated that information into the simulations. The Simulation of Actual and Allowable 

Emissions for Chromium Electroplating Facilities document, which can be found in the 

rulemaking docket, explains the procedures and data used for the emissions simulations.

Comment: Commenter 0278/0617 agreed that the random sampling methods used for 

simulating emissions data was appropriate, but believes the technical support documentation 

should include discussions of confidence intervals, uncertainty, or limitations. The commenter 

explained that it is unclear whether these simulated emissions are representative of actual 

emissions or produce a conservative estimate of risk. The commenter encourages EPA to provide 

more detail to the technical support document that would lend validity to the random sampling 

methods use, the representativeness of the emissions, and the risk calculated.

Response: We have revised the supporting memorandum that describes the methodology 

used and have included the statistical parameters (e.g., confidence intervals) mentioned by the 

commenter (see Revised Simulation of Actual and Allowable Emissions for Chromium 

Electroplating Facilities in the docket for this rulemaking). We believe the revised memorandum 

addresses the commenter’s suggestions.

Comment: Commenter 0278/0617 pointed out that the random sampling method used to 

simulate emissions does not distinguish between facilities that use control devices and those that 

use fume suppressants. The commenter encourages EPA to provide additional information on the 
46

number of facilities that use control devices and the type of control devices, as well as, data on 

which type of control devices are likely to meet the revised emission limit of 0.015 mg/dscm. 

Response: The purpose of the emissions simulations was to estimate annual emissions 

for those plants for which actual emissions data were unavailable. Thus, the simulated emissions 

are not associated with any specific type of emission control method or device. Regarding the 

types of control devices used, the commenter is referred to the Profile of Chromium 

Electroplating Processes and Emissions document (Profile), which can be found in the 

rulemaking document. Tables 10 through 12 of the Profile provide information on the types and 

numbers of emission controls used. Tables 1 through 4 of the Profile show the available emission 

concentration data and the control methods used when each source was tested. These data 

indicate the emissions concentrations achieved in practice by most types of emission controls.

Comment: Commenter 0285/0296/0619 believes that EPA’s methodology for estimating 

emissions for the non-California facilities demonstrates lack of knowledge about the specific 

chromium electroplating and anodizing operations and provides no useful information or any 

reasonable simulation or prediction of actual emissions from facilities. As a result, the 

commenter believes the results from this process cannot be used reliably to impose additional 

regulatory controls on chromium electroplating and anodizing operations and that EPA could 

have produced more reliable results if it had focused on other more relevant variables such as 

facility size and chromium processes for the Monte Carlo analysis.

Response: The commenter misunderstands the purpose of the Monte Carlo analysis. The 

analysis was used to estimate nationwide emissions and to assess nationwide risk. The emissions 

simulations derived using the Monte Carlo analysis was not used to develop the more stringent 

emissions and surface tension limits. Instead, we used the available emissions data on chromium 

electroplating facilities to develop the proposed emissions limits, and we used the available data 

on concurrent measurements of surface tension and emissions to develop the proposed surface 

tension limits. Contrary to the commenter’s statements, the Monte Carlo analysis and the 

analyses used to develop the proposed emissions and surface tension limits actually did account 

for facility size and chromium processes.

Comment: Commenter 0285/0296/0619 stated that EPA appears to have used Monte 

Carlo procedures only to estimate what the “n” emission values would be if there were “n” plants 

in a subcategory (hard chrome/large, hard chrome/small, etc.). The commenter stated that EPA 

used the Monte Carlo analysis for a less important uncertainty in the analysis, and did not use it 

on the major uncertainty which is what subcategory an unknown plant really is in. The 

commenter is also concerned with the alphabetical approach by which emissions estimates were 

assigned but recognized that the “alphabetical” process does not necessarily bias the overall 

emissions estimates high or low. 

Response: Contrary to what the commenter states, a key step in the methodology used to 

simulate emissions using the Monte Carlo approach was to assign a process type to each of the 

unknown plants, while ensuring that the total number of plants in each subcategory matched our 

best estimate of the number of plants nationwide. This step is shown in Figure 1 of the 

Simulation of Actual and Allowable Emissions for Chromium Electroplating Facilities 
47

document, which can be found in the rulemaking docket. In addition, Attachment 1 to Simulation 

document shows the process assignments for each plant that was simulated. 

The commenter is incorrect that emissions were assigned to plants in alphabetical order. 

On the other hand, the commenter is correct that assigning emissions to plants alphabetically 

does not bias the overall emissions.

Comment: Commenter 0285/0296/0619 believes that EPA may have identified most of 

the facilities in the “unknown” categories as hard chromium and that since the highest emissions 

are expected from hard chromium processes, EPA’s apparent assumptions for “unknown” 

facilities would tend to over-estimate emissions significantly.

Response: The commenter is incorrect in stating that the majority of the unknown 

facilities were assumed to be hard chromium electroplating plants in the analysis. Of the 

unknown plants, approximately 13 percent were modeled as chromium anodizing, 41 percent as 

decorative chromium electroplating, 14 percent as large hard chromium electroplating, and 31 

percent as small hard chromium electroplating plants.

10. Surface Tension Data Analysis

Comment: Commenter 0285/0296/0619 stated that EPA has limited data on the use of 

fume suppressants to reduce emissions. The commenter believes that EPA attempted to correlate 

the surface tension levels observed with the emissions limits measured with very limited and 

flawed data. The commenter also noted that too much of the data is based on single facilities or 

on facilities that contain a secondary control device in addition to a fume suppressant. 

Commenter 0285/0296/0619 added that there is no quantitative data that show how much 

emissions reduction could be expected from the use of a specific amount of fume suppressants. 

Response: We disagree that the data used to develop the revised surface tension limits 

were inadequate or flawed. The analysis was performed using data for multiple tanks at 

15 different facilities. We believe that the resulting data set was adequate to develop revised 

limits. We also note that our analysis accounted for the level of uncertainty in the data as a 

function of the number of data points. Thus, even if we had fewer data points to analyze, we 

believe the methodology used would have provided a valid result. We acknowledge that we used 

multiple data points for some facilities. However, we fail to see how that nullifies the outcome of

the analysis. Regarding the comment that some of the data are based on tanks with a secondary 

control device, the commenter did not specifically identify any such facilities. We note that in 

those cases, the tests were performed upstream of the additional control and did not impact 

emissions. 

Comment: Commenter 0290/0620 suggested that there are uncertainties in the 

methodology EPA has used to try to translate the proposed concentration-based emission limits 

into surface tension limits. The commenter noted that EPA’s analysis concludes that emissions 

are a function of the surface tension, regardless of the specific chemicals used, but emphasizes 

that there was no data available for chromium anodizing. Commenter 0290/0620 also pointed out 

that EPA has analyzed how effectively the use of surface tension limits can translate to a 

particular concentration of emissions; but has not demonstrated that they can achieve that 
48

concentration with the same degree of certainty as an emission limit subject to monitoring and 

testing requirements. Commenter 0290/0620 believes that EPA’s lack of data and the multiple 

assumptions used to turn the emission concentration-based limit into a surface tension limit 

added significant uncertainty that may lead to a surface tension limit that does not actually 

control emissions to the same extent as a concentration-based limit. The commenter stated that if 

EPA sets surface tension limits they must be at least equivalent to or more protective than the 

concentration based limits.

Response: We agree with the commenter that there are uncertainties in the analysis used 

to develop the revised surface tension limits just as there are uncertainties inherent in any such 

analysis of data. We disagree with the commenter’s assertion that we tried to translate 

concentration-based limits into surface tension limits. What our analysis did was to compare 

concurrently measured emissions concentration and surface tension data and determine the 

emissions concentration that corresponds to specific surface tension values, taking into account 

the uncertainties in the data. We acknowledge that the dataset used for the analysis did not 

include data on chromium anodizing. Although the bath formulation is not exactly the same for 

chromium anodizing as for chromium electroplating, the principle bath constituent is the same, 

namely chromic acid. Furthermore, the mechanism, by which reduced surface tension results in 

lower emissions, should not be significantly affected by the type of bath. Reducing the surface 

tension results in smaller gas bubbles, which rise to the surface more slowly and burst with less 

energy, thereby generating less chromic acid mist. With respect to monitoring, the NESHAP 

already requires periodic monitoring of surface tension by any facility that elects to comply with 

the surface tension limits. We believe the monitoring requirements provide adequate assurance 

that surface tension levels are maintained below the limits specified in the NESHAP. We agree 

that the surface tension limits must be equivalent to or more protective than the emission limits 

and we believe our analysis shows that the surface tension limits will maintain emissions below 

the emissions concentration limits.

11. Compliance Provisions

Comment: Commenter 0609 remarked on the requirements of §63.343(c) for 

establishing operating limits for pressure drop across control devices. The commenter explained 

that the NESHAP allows for facilities to conduct a single compliance test or multiple 

performance tests. The commenter stated that, if a single performance test is performed, the 

compliant range is based on the average pressure drop measured during the test ± 1 or 2 inches of 

water column, depending on the type of control device. The commenter added that, for cases 

when the plant performs multiple performance tests, the NESHAP specifies the compliant range 

to be equal to the range demonstrated by the performance tests. The commenter believes that the 

± 1 or 2 inches of water column provision should also apply in these cases. Commenter 0609 

also suggested adding a requirement that the pressure drop across control devices be greater than 

zero inches of water column because a pressure drop of zero indicates no resistance and is 

therefore unacceptable.

Response: This comment is on a section of the rule which was not part of the proposal or 

supplemental proposal. The provision referenced by the commenter was established as part of the 

initial MACT rule. We did not propose to revise this provision in either the 2010 proposal or the 

2012 supplemental proposal. The purpose of the provision is to allow for the typical variability in 
49

pressure drop measurements without causing an exceedance of the operating limit. The 

commenter does not state a substantive basis for suggesting that we revise the existing rule to 

apply the ± 1 or 2 inches of water column provision where multiple performance tests are 

performed. We disagree on the need to specify that the pressure drop must be greater than zero

because any add-on control that reduces chromium electroplating emissions would have a 

pressure drop greater than zero.

Comment: Commenter 0613 stated that the proposed amendments fail to address how 

plants that use emission elimination devices (EEDs) to control emissions from affected sources

can comply with the emissions limits and what type of monitoring is required for such sources. 

The commenter noted that, despite EPA’s statement to the contrary in the October 2010 

proposal, EEDs are in use at chromium electroplating facilities, as evidenced by the multiple 

Regional Office approvals for alternative test procedures for EEDs. Another commenter (0272) 

stated that one facility in commenter’s jurisdiction is currently using EEDs on several sources to 

comply with Subpart N and the EEDs appear effective in controlling chromium emissions. 

Commenter 0613 noted that, although the supplemental proposal addresses revised emission 

limits and compliance options, no provisions for EEDs were proposed. The commenter 

recommended that EPA amend the NESHAP to specify compliance provisions that address the 

unique characteristics of EEDs and added that doing so would reduce the administrative burdens 

on state and local agencies associated with evaluating case-by-case requests for approval of 

EEDs.

Response: Although we did not propose amending the NESHAP to address EEDs, we 

did request comment on their use. Emission elimination devices are membrane covers that are 

impervious to chromium mist and essentially eliminate emissions when in place (i.e., when the 

tank is covered). Currently, the NESHAP does not specify provisions for demonstrating 

compliance, or monitoring emissions, when EEDs are used. We acknowledge that EEDs are still 

in use by some chromium electroplating sources. However, our understanding is that the use of 

these devices is minimal, has not significantly increased in recent years, and there is no reason to 

believe that their use will increase. As the commenters recognize, the NESHAP currently allows 

facilities who would like to install EEDs the option of applying for approval on a case-by-case 

basis. We believe that, given the relatively low numbers of EEDs that are installed on an annual 

basis, it is not necessary to add special provisions to the NESHAP to accommodate their use.

Comment: Commenter 0285/0296/0619 stated that the supplemental proposal does not 

identify any new procedures for demonstrating ongoing compliance with the NESHAP emissions 

limits using a combination of add-on control device and fume suppressants. The commenter 

noted that if facilities can continue to demonstrate compliance by maintaining the pressure drop 

across the control equipment within the specific range, then the use of fume suppressants to 

achieve compliance would be irrelevant. Similarly the commenter noted that, if EPA requires 

facilities that use fume suppressants with control equipment to achieve the new proposed 

emissions limits to measure surface tension, then the emissions limits would be irrelevant. The 

commenter believes this demonstrates that EPA’s proposed emission limits and technology 

options to achieve them are not feasible and note the new standards present an implementation 

and enforcement nightmare for facilities and regulatory officials to measure compliance. The 
50

commenter recommended that before proceeding with this rulemaking, EPA address these

enforcement and implementation issues and provides a reasonable and workable solution.

Response: Monitoring requirements for sources that comply with the emissions limits 

using a combination of one or more add-on control device and fume suppressants are already 

addressed in §63.343(c)(7). This paragraph of the NESHAP clearly states that, in such cases, the 

monitoring requirements for the add-on control device specified in §63.343(c)(1) through (4) and 

the monitoring requirements for fume suppressants specified in §63.343(c)(5) and (6) both apply. 

Therefore, no changes to the NESHAP are needed to address these types of control system 

combinations. As noted previously, using a combination of one or more add-on control devices

and fume suppressants to meet the emissions limits is a relatively common practice and we are 

unaware of any implementation or enforcement issues that have arisen to date. 

Comment: Commenter 0260/0616 remarked that facilities should not be required to 

keep records of every occurrence or action taken to demonstrate compliance with the proposed 

housekeeping practices. The commenter stated that the requirement to clean surfaces and clean 

up spills should be included in the Operation and Maintenance Plan, but recordkeeping should 

not be imposed for these actions. The commenter added that the recordkeeping burden would be 

excessive if operators had to create a record for every drop of any chromium containing 

substances that is spilled at an affected facility. To address housekeeping issues, the commenter 

recommended the following changes to the proposed rule text:

Revise paragraph §63.342(f)(3)(i)(F) as follows:

"(F) The plan shall include the housekeeping procedures specified in Table 2 of this section. ** 

add the new text: Owners or operators must incorporate these measures into their standard 

operating procedures but are not required to keep detailed records.**"

Revise paragraph §63.342(f)(3)(i) as follows: 

* * *

(A) The plan shall specify the operation and maintenance criteria for the affected source, the addon air pollution control device (if such a device is used to comply with the emission limits), and 

the process and control system monitoring equipment, and shall include a standardized checklist 

to document the operation and maintenance, ** add new text: excluding housekeeping 

measures**, of this equipment.

Revise §63.346(b)(2) as follows:

(2) Records of all maintenance, ** add the new text: excluding housekeeping measures**,

performed on the affected source, the add-on air pollution control device, and monitoring 

equipment;

Response: We agree with the commenter that the requirements to clean surfaces and 

clean up spills should be included in the Operation and Maintenance Plan, as was proposed. We 

also agree that is unnecessary to maintain records of routine housekeeping procedures. As a 
51

result, we have revised §63.346(b)(2) in the final rule to exempt routine housekeeping practices 

from recordkeeping..

12. Cost Methodology

Comment: Commenter 0285/0296/0619 believes that EPA’s conclusion that controls 

(based primarily on the use of fume suppressants) with a cost effectiveness of $18,000 per pound 

are reasonable contradicts the October 2010 proposal that concluded a cost effectiveness of 

$18,000 per pound for HEPA filters would not reduce risks at reasonable costs. Additionally, the 

commenter noted that although EPA reported the cost effectiveness of $18,000 per pound in the 

2010 proposal, it should have been $9,000 per pound instead. The commenter further explained 

that EPA failed to incorporate the cost of new control devices and retro fit equipment 

appropriately in the cost analysis of the supplemental proposal and noted that EPA has already 

determined in the October 2010 proposal that such add-on controls and retrofits were not cost 

effective, and there is no evidence in the record to support a change in EPA’s position.

Response: In determining whether a regulatory alternative is reasonable, we consider 

several metrics, including cost effectiveness, total capital cost, total annualized costs, emissions 

reductions, and number of plants impacted, especially for the chromium electroplating and 

anodizing source categories since many are small businesses. For the 2010 proposal, we 

evaluated the costs of installing only HEPA filters throughout the entire industry. For the 2012 

supplemental proposal, we conducted a new analysis that estimated the actual number of plants 

that would meet the proposed emission and surface tension limits, the number of plants that 

would have to improve their controls, and the likely methods those plants would use to comply 

with the moderately more stringent standards. As a result, we estimated that a far fewer number 

of plants would be impacted. Although the cost effectiveness may have been comparable to the 

results for the 2010 proposal, the capital costs, total annualized costs and number of plants 

potentially impacted were significantly less for the proposed requirements in the supplemental 

proposal, and the requirements in the final rule. For example, a comparison of total capital costs 

is shown in the following table. Furthermore, we recently reevaluated the costs of requiring 

HEPA filters for all hard chromium electroplating sources. Based on this analysis we believe we 

underestimated the cost-effectiveness in the 2010 proposal for requiring HEPA filters for all such 

plants. We now estimate the cost-effectiveness would be at least $27,000 per pound.

Type of Facility

Table A.7

2010 Proposal

Capital Cost

HEPA Retrofit 

($ Millions)

Table 7

Supplemental 

Proposal

Capital Cost

Proposed 

Options ($ 

Millions)

Large Hard Chromium Electroplating 35.1 1.8

Small Hard Chromium Electroplating 66.0 1.4

Decorative Chromium Electroplating 109.0 0.18

Chromium Anodizing 43.9 0.25
52

Comment: Commenter 0290/0620 disagreed with EPA’s cost effectiveness analysis of 

different regulatory options and believes EPA failed to provide a reasoned explanation for 

choosing different acceptable levels of cost-effectiveness and levels of emission reduction for 

each subcategory. The commenter gave an example by comparing the option selected for large 

hard chromium electroplating, with a cost effectiveness of $18,100/lb, to the option selected for 

small hard chromium electroplating, with a cost effectiveness of $15,800/lb for the example of 

the options. The commenter claimed that EPA’s proposal fails to satisfy the required statutory 

test of maximum achievability, it also does not appear to be based on any other intelligible, 

objective, rational standard by which it would be possible to understand or assess the agency‘s 

decision required by Section 112(d).

Response: While it is true that the proposed emissions limits differ in terms of cost 

effectiveness, we selected the options by considering other factors, such as capital costs, 

emissions reductions, and number of facilities impacted. We also note that, from a practical 

perspective, regulatory options do not realistically represent a continuum of emissions limits and 

cost effectiveness. Thus, there may not be an option for one source category (e.g., large hard 

chromium electroplating) that is an exact match with respect to same cost effectiveness and 

emissions reductions values for a different source category (e.g., small hard chromium 

electroplating). We believe the selected options are comparable in terms of cost effectiveness, 

even if they are not exactly the same value.

Regarding the commenter’s statement about maximum achievability, the initial MACT 

standards established pursuant to sections 112(d)(2) and (3) did incorporate an “achievability” 

component. As explained elsewhere in this document, Section 112(d)(6) does not require us to 

repeat our section 112(d)(2) & (3) review.

Comment: Commenter 0285/0296/0619 disagreed with EPA’s estimates of stack testing 

costs. The commenter stated that EPA has calculated the annualized costs of stack testing by 

assuming that a stack test is good for 15 years, so the costs were amortized over 15 years at an 

interest rate of 7 percent. The commenter believes the cost of stack tests would be 30 percent 

higher for a period of 10 years and 130 percent higher for a period of 5 years. The commenter 

also disagreed with EPA’s estimates of facilities that need stack tests pursuant to the proposed 

rule. The commenter stated that there are approximately 700 to 950 hard chromium facilities and 

that, to demonstrate compliance with the new proposed limits, many more facilities would 

appear to need a new stack test than have been estimated by EPA.

Response: The commenter is correct that stack tests costs would be higher if annualized 

over a 10-year or 5-year period. However, the chromium electroplating NESHAP requires a onetime emission test, rather than periodic testing at 10 or 5 year intervals, as assumed by the 

commenter. We decided to annualize the cost over a 15-year period because we believe that 

period represents the lifetime of an electroplating source and/or control system.

Regarding the number of facilities that would have to conduct performance tests, the 

commenter appears to assume that most, if not all, hard chromium electroplating tanks would

have to be tested. However, the proposed amendments include a waiver for any source test that 

was performed after January 25, 1995 (the original promulgation date for the NESHAP), 
53

provided that the source uses the same emissions controls and is operated as during the initial 

performance date. Thus, we estimate that the majority of facilities would not have to conduct a 

performance test.

Comment: Commenter 0274/0618 questioned the analysis for the nationwide costs and 

cost effectiveness of the regulatory control options for chromium electroplating facilities. The 

commenter requested an explanation of whether the cost analysis is for onetime cost for 

facilities, or if it considers the recurring cost associated with HEPA filters. The commenter stated 

that a more realistic approach would be a cost analysis that evaluates the potential cost to a 

facility rather than the cost per reduction of HAP emissions.

Response: The costs estimates developed for both the October 2010 proposal and for the 

supplemental proposal include capital (one-time costs) and annualized costs. Annualized costs 

include recurring costs, such as the costs for operation and maintenance, and the annualized 

capital costs of new emissions controls that would be needed to comply with the proposed 

requirements.

Comment: Commenter 0274/0618 recommended that EPA should consider using the 

cost per pound rather than cost per ton for HAPs to obtain a more realistic cost figure. 

Response: For the February 2012 supplemental proposal, the cost-effectiveness for each 

regulatory option considered is presented in units of cost per pound.

13. Costs and Economic Impacts

Comment: Commenter 0285/0296/0619 stated that EPA did not conduct a Small 

Business Regulatory Enforcement Fairness Act (SBREFA) panel pursuant to its obligations 

under the Regulatory Flexibility Act. The commenter stated that in preparation for the 

supplemental proposal, and the new revisions to surface tension levels and emission limits, the 

commenter urged EPA to conduct a SBREFA panel to review EPA’s data and to assess the 

potential impacts of the proposed changes on small business. The commenter added that EPA 

began the administrative process for convening a SBREFA panel, but at the “eleventh hour” 

reversed course, concluding that the supplemental proposal would not have a significant impact 

on a substantial number of small entities, and declined to convene a SBREFA panel. The 

commenter believes EPA’s justification for the decision was partly due to time constraints and 

the Agency’s failure to adhere to its own rulemaking schedule and deadlines. The commenter 

stated that The Small Business Administration (SBA), Office of Advocacy, along with NASF, 

opposed EPA’s decision not to convene a SBREFA panel.

Commenter 0610 believes that EPA’s statement that the proposed amendments would not 

have a significant impact on a substantial number of small entities lacks a factual basis. The 

commenter explained that, in order to meet the requirements of the Regulatory Flexibility Act 

(RFA), the certification must include a description of the affected entities, as well as the 

anticipated impacts that clearly justify a finding of “no significant impact” and EPA has not done 

so.
54

One commenter (0277) stated that the costs to implement the proposed housekeeping 

requirements would trigger the Regulatory Flexibility Act (RFA) because it would have a 

significant economic impact on a substantial number of small entities. Another commenter 

(0285/0296/0619) stated that any requirement to install additional controls on chromium 

electroplating facilities would trigger the RFA. The commenter added that requirements to install 

control equipment would not be necessary, practical, or economically feasible.

Response: Given the compressed rule development schedule, EPA initiated the SBREFA 

panel early to ensure sufficient time to conduct and complete the panel. Shortly after initiating 

the panel, EPA performed a screening analysis for impacts on all affected small entities by 

comparing compliance costs to average sales revenues by employment size category. From the 

screening analysis, the Agency estimated that under the main options being considered for the 

proposal that approximately 96% of all affected facilities would have a cost-to-sales ratio less 

than 1 percent. Based on the screening analysis, the Agency concluded that the proposal would 

not have a significant economic impact on a substantial number of small entities and determined 

that the SBREFA panel was not needed. Additional details on our analysis of the economic 

impacts of the final rule amendments on small entities can be found in the Economic Impact 

Analysis for Risk and Technology Review: Chromium Electroplating and Chromic Acid 

Anodizing Source Categories, which is available in the docket. It should be noted that we did 

include the costs associated with the final housekeeping requirements in our economic impacts 

analysis. Regarding the assertion by Commenter 0277 that the proposed housekeeping measure 

would have a significant economic impact on a substantial number of small entities, the 

commenter did not provide any support for their claims that substantively addresses the 

determination that EPA made that the proposed requirements would not have a significant effect 

on a substantial number of small businesses.

Comment: Commenter 0290/0620 acknowledged that it may be valid to recognize that 

plants that have already achieved greater reductions should incur no cost under EPA‘s new rules, 

but it is not lawful or rational for EPA to ignore the fact that hundreds of facilities have achieved 

those reductions when it is making a decision what standards to set nationally. The commenter 

believes that in performing its cost-based analysis for other plants, EPA did not consider the 

California experience. The commenter claimed that it was arbitrary and capricious for EPA to 

fail to consider the record of success in California, what the cost actually was for California 

facilities to comply, whether the California rules that have now been implemented were cost 

effective, whether facilities were able to comply, and the overall success in implementing the 

California rules. 

Response: EPA recognizes the limits set forth in California and analyzed comparable 

standards when evaluating and setting limits for this rulemaking. However, EPA does not have 

adequate information on the cost or cost effectiveness for facilities in California to comply with 

the California standards and is not aware of any cost studies related to the California standards. 

Nevertheless, EPA did evaluate the costs of requiring HEPA filters on all hard chromium 

facilities, which would be similar to California requirements and based on that analysis, EPA 

estimates the cost effectiveness would be at least $27,000 per pound.
55

Comment: Commenter 0290/0620 disagreed with EPA's conclusion that requiring plants 

to retrofit HEPA filters would not be cost effective. The commenter indicated that California 

determined that only 40 percent of the industry there (89 of 226 facilities) would incur 

significant capital costs from its rule, because so many were already in substantial compliance. 

Response: The analysis used to estimate the costs associated with the supplemental 

proposal, took into account the estimated number of existing facilities that currently would meet 

the revised emission limits, as well as the estimated number of plants that would have to install 

new controls or otherwise reduce emissions, and the likely emission control method adopted by 

those plants. As part of the cost analysis, we assumed that some facilities that require additional 

control would install HEPA filters. However, we believe that most facilities that would need to 

reduce emissions to comply with the more stringent emissions limits could do so through the use 

of fume suppressants or by retrofitting CMPs. As described elsewhere in this document and in 

the cost analysis technical document (i.e., Revised Procedures for Determining Control Costs 

and Cost Effectiveness for Chromium Electroplating and Anodizing, which is available in the 

docket), we estimate that requiring HEPA filters for all hard chromium plants would have costs 

effectiveness of at least $27,000 per pound.

Comment: Two commenters (0274/0618, 0290/0620) disagreed with EPA’s cost analysis 

for HEPA filters, and provided several reasons to argue that the use of HEPA filters are cost 

effective. Both commenters cited the economic analysis conducted by CARB in their "Proposed 

Amendments to the Hexavalent Chromium Airborne Toxic Control Measure for Chrome Plating 

and Chromic Acid Anodizing Operations" report. Commenter 0274/0618 stated that the CARB 

assessment looked at the cost of installing HEPA filters, but their analysis considered the 

expected first year, capital and annual recurring costs. The commenter provided example costs 

for small and large hard chromium electroplaters. The commenter stated that in CARB's 

assessment, the costs reflect actual purchasing cost for a facility. Additionally the commenter 

noted that CARB acknowledged that not all facilities would be required to install HEPA filters if 

other control methods are effective. The commenter stated that CARB's assessment concludes 

that HEPA filters are cost effective, yet the EPA's assessment concluded otherwise. Commenter 

0290/0620 stated that EPA concluded that the cost-to-sales ratio change that would occur if it 

required HEPA filters would be 8 to 22 percent for more than half of the facilities. By contrast

the commenter noted, California found that the profitability decline could be as low as 3 percent. 

The commenter stated that the significant range in these numbers suggests variability from the 

differences for a small number of outlier facilities, which means that a few facilities that may 

well not be profitable or efficient already are likely distorting the cost-to-sales ratio analysis. The 

commenter recommended that EPA perform an analysis of businesses that would incur 

substantial costs if it intends to rely on costs in this manner and determine if there would be any 

significant impact on employment; business creation, elimination or expansion; or business 

competitiveness.

Response: These comments were made on the October 2010 proposal. At that time, we 

estimated the costs for installing HEPA filters across the board on all plants. Based on the high 

capital costs and other factors, we rejected that option. For our revised cost analysis for the final 

rule, we used an approach that is more discriminating in terms of the type of emission control 

that a specific plant would likely need to comply with the more stringent emissions limits that 
56

were proposed in the February 2012 supplemental proposal. That is, we looked at the available 

data, and, instead of assuming that all plants would need to retrofit additional controls, we 

determined whether each existing source for which we had data could meet the more stringent 

emission limits with its current control system, assuming a margin of compliance. If so, we did 

not estimate additional control costs for those sources. Based on available data, we estimate that 

more than 85 percent of existing plants that choose to comply with the rule by meeting the 

concentration based emissions limits already meet the lower emissions limits and will need no 

additional emissions reductions. If we determined a source would need additional control, we 

considered how close the source operated to the more stringent emission limit. If the source 

operated slightly above the more stringent limit, we assumed, for sources other than large hard 

chromium electroplating tanks, that most sources (80 to 90 percent) could use fume suppressants 

to achieve slightly lower emissions to comply with the emissions limits. For large hard 

chromium electroplating sources, we estimate that over 85% of existing large hard chromium 

plants already meet the limit and therefore would not need additional controls. For the other 15 

percent (or less) of large hard chromium plants that may need to reduce their emissions to meet 

the lower emissions limit, we assumed that 10 percent of these plants could meet the final limits 

using fume suppressants and that approximately 80 percent of these sources would install a CMP 

and the remaining sources would install a HEPA filter. This is similar to CARB’s conclusion that 

not all sources would need to install a HEPA filter to comply with the CARB ATCM. In 

addition, we did conclude that HEPA filters would be a cost-effective option to comply with the 

emission limits incorporated in the final rule for the small subset of large hard chromium 

electroplating plants that may need a HEPA filter to achieve the limits. Finally, our economic 

impact analysis, which is summarized in Economic Impact Analysis for Risk and Technology 

Review: Chromium Electroplating and Chromic Acid Anodizing Source Categories and is 

available in the docket, describes our assessment of the impacts on affected businesses.

Comment: Commenter 0285/0296/0619 stated that the proposed new source emissions 

limits could be problematic for facilities, particularly hard chromium facilities and is concerned 

that the stringent new source emissions limits will discourage new production and job creation 

for chromium electroplating and anodizing operations

Response: We disagree that the new source emission limits will discourage new

production and job creation. For the 148 hard chromium electroplating sources for which EPA 

has emissions data, 58% of the sources already meet the 0.006 mg/dscm new source limit. These 

data clearly indicate that the new source emission limit is quite achievable. Additionally, it is less 

expensive to install add-on controls on a new system than to retrofit controls on an existing 

system, and therefore the cost impacts for new facilities are lower. 

Comment: One commenter (0285/0296/0619) stated that national chromium emissions 

have been reduced because of the recent economic downturn and increased global competition. 

Over the past decade, approximately 20 to 30 percent of metal finishing facilities have been 

forced to close. The commenter stated that fewer facilities generate fewer total chromium 

emissions. The commenter concluded that these factors have effectively reduced chromium 

emissions from electroplating and anodizing operations to well below 0.5 tons/yr.
57

Response: We agree that economic factors have affected the chromium electroplating 

industry. To the extent that we know of facilities that have permanently closed, we did not 

include them in our analysis. We updated our emissions data set considering closures and other 

information. Nevertheless, we assess both actual and allowable emissions in the RTR. Our 

evaluation of both actual and allowable emissions helps ensure that we appropriately evaluate the 

health risks from the industry over the long term rather than looking at just how the industry may 

be affected at a particular moment in time.

Comment: One commenter (0290/0620) asked EPA to recognize and address the 

environmental harm these chromium electroplating and anodizing sources pose. The commenter 

stated that as part of considering adverse environmental effects, EPA must consult with the Fish 

and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) under 16 U.S.C. 

1536(a)(2) because emissions from these source categories could affect endangered and 

threatened species.

Response: For the steel pickling, chromium electroplating and chromium anodizing 

source categories, EPA considered effects to the environment separately from human health risk 

in order to determine whether it is necessary to set a more stringent standard to prevent an 

adverse environmental effect. The results of our analyses are presented below.

For steel pickling, in considering effects to the environment, the EPA first determined 

that some HAPs of potential concern with respect to the environment are emitted from sources in 

this category. We call these eco HAPs, and the eco HAPs that are emitted from steel pickling are 

hydrogen chloride (HCl) and chlorine (Cl2). Other eco HAPS, such as certain persistent, 

bioaccumulative HAP (PB-HAP) and hydrogen fluoride (HF) are not emitted from steel pickling 

operations. We included HCl and Cl2 in our environmental analysis because we determined that 

they have the potential to cause adverse environmental effects. These pollutants are very reactive 

and, therefore, have the potential to cause adverse effect to ecological receptors by direct contact. 

The Agency also determined that there was at least some potential for exposures to 

environmental receptors, because the presence of such receptors around the sources in this 

category cannot be ruled out. The EPA then looked at emissions of the eco HAPs, including the 

highest-emitting facility for each HAP and the total emissions of each HAP from the source 

category. The results are presented in the table below:

Emissions of Eco HAPs from the Steel Pickling Source Category (post-RTR)*

Pollutant

Category emissions 

(tpy)

Number of facilities 

in category reporting 

emissions Emissions for highestemitting facility (tpy)

HCl 248 75 24

Cl2 2.8 5 0.9

*For the baseline risk assessment, which is described in the Residual Risk Assessment for the 

Steel Pickling Source Category document, we estimated total emissions to be 247 tpy of HCl and 

18 tpy of chlorine. However, given the amendments promulgated in today’s action, which will 

achieve a 15 tpy reduction of chlorine emissions, the post RTR chlorine emissions are estimated 

to be 2.8 tpy.
58

Based on the emission estimates shown above, the EPA determined that the emission 

levels of these pollutants are low. For instance, compared to the 2008 NEI for point sources, 

estimates of nationwide HCl emissions from this source category are about 0.17 percent of the 

total. For Cl2, this source category accounts for about 0.18 percent of the nationwide emission 

totals. Based on the low emissions from the steel pickling source category, the Agency would not 

expect an environmental effect to occur.15 Finally, even though the Agency does not expect an 

environmental effect to occur, we evaluated requiring additional controls to reduce these HAP 

emissions, but we did not identify any additional technology that could reduce emissions.

For the chromium electroplating and anodizing source categories, the EPA examined the 

potential for emissions of eco HAPs. As mentioned earlier, those eco HAPs include certain PBHAP and acid gases. Data show that none of the 14 PB-HAP are emitted. In addition, precursors 

of HF, HCl, and chlorine (acid gases) are not introduced in the chromium electroplating process, 

which is a process that uses highly refined materials of known composition. Because these 

precursors are not present in the process and must be present for the acid gases to be emitted, it is 

reasonable to conclude that HF, HCl, and chlorine cannot be emitted from these sources. 

Because of the absence of HAP that present ecological concerns, the EPA determined that the 

standards for the chromium electroplating source categories would have no effect on the 

environment.

In addition, the Agency does not have information, nor did the commenter provide 

information to support the position that emissions of chromium from chromium electroplaters 

would result in environmental effects. With regard to the environment, the limited available 

information on the persistence and bioaccumulation of hexavalent chromium suggests that there 

is no indication of the biomagnifications of hexavalent chromium along the aquatic food chain, 

and that chromium has low mobility for translocation from roots to above ground parts of plants. 

(ATSDRs Tox profile 2008 http://www.atsdr.cdc.gov/toxprofiles/tp7.pdf).

Because our analyses show no environmental effect from these source categories, we 

disagree with the commenter’s statement that the EPA must consult with the FWS and the 

NMFS under 16 U.S.C. 1536(a)(2). 

Comment: Commenter 0285/0296/0619 suggested EPA has under-estimated compliance 

costs by underestimating the number of facilities that do not meet the proposed limits by 

assuming that only facilities exceeding 85 percent of the proposed new emissions limits would 

need to reduce emissions or make adjustments to meet the new proposed emission limits. The 

commenter stated EPA provided no data in the record to support the 85 percent value for 

estimating compliance and that EPA’s assumption fails to take into account the variability over 

time regarding a facility’s emissions concentration. Based on this variability, the commenter 

recommended EPA should set a compliance margin of 50 percent based on typical variability in 

stack test results or provide some evidence to support this narrow compliance margin. 

 15 However, we do note that the EPA’s current ability to evaluate the potential for ecological effects is 

limited, and we are working to improve the Agency’s capacity in this regard. The results of our effort to 

improve these capabilities will be particularly important for source categories where emissions of eco 

HAPs are at a level that may be of concern.
59

Response: We agree with the commenter that a plant owner or operator may want to 

operate with a larger compliance margin than at 85 percent of the emission limit. However, the 

85 percent value used in the analysis is not a compliance margin, as inferred by the commenter. 

This value simply was used to estimate additional existing plants that might decide to, or be 

required to, install additional controls. Under the proposed amendments, plants could use the 

results of their previous performance tests to demonstrate compliance with the more stringent 

limits (with a few exceptions). Thus, even a plant whose previous performance test indicated that 

the plant was operating at 95 percent of the more stringent limit would not be required to install 

additional controls, provided they were still operating the source and were using the same 

emission controls as during the performance test. Furthermore, even for sources that do need to 

test, the rule only requires a one-time test. So, as long as the performance test is no higher than 

the emissions limit, all the source needs to do after that test to remain in compliance is to do the 

basic control device monitoring (such as take pressure drop readings). 

Comment: Commenter 0285/0296/0619 did not agree with EPA’s calculation of 

emissions reductions. The commenter stated that EPA estimate is off by at least an order of 

magnitude, and should be 18 lbs/yr instead of the 208 lbs/yr estimated by EPA. The commenter 

estimated that this change would revise the cost effectiveness to approximately $180,000 per 

pound. For the facilities used as the basis for estimating the impacts for the supplemental 

proposal, the commenter estimated total nationwide emissions reductions to be 91 lbs/yr, 

compared to EPA’s estimated reductions of 208 lbs/yr. The commenter added that baseline 

emissions should be actually be 228 lbs/yr, rather than the 1,138 lbs/yr estimated by EPA, and if 

the same percent reduction is applied to a baseline of 228 lbs/yr, total reductions would be only 

18 lbs/yr. With respect to emissions reductions achieved by reducing the surface tension in tanks 

using fume suppressants, the commenter stated that reduction in surface tension does not equate 

to a linear reduction in emissions, but assumed a linear relationship to calculate emissions 

reduction of 5.7 to 11.1 percent. Assuming these percent reductions applied to all of the affected 

decorative chromium electroplating and chromium anodizing plants, the commenter stated that 

the emissions reductions would be 24 lbs/yr for decorative and 6 lbs/yr for chromium anodizing 

plants. For all hard chromium electroplating plants, the commenter assumed the same percent 

reduction (i.e., 5.7 to 11.1 percent) for all sources regardless of the type of control device or 

method (i.e., for tanks that would be controlled with fume suppressants and for tanks that would 

retrofit add-on controls). After applying these percent reductions to the average emission rates, 

the commenter estimated emissions reductions to be 31 lbs/yr for large hard chromium and 30 

lbs/yr for small hard chromium electroplating plants based on EPA’s estimated baseline of 1,138 

lbs/yr.

The commenter’s estimate of baseline emissions (208 lbs/yr) is based on a combination 

of estimates, which, according to the commenter are 80 percent less than EPA’s estimated 

baseline emissions. Specific factors considered by the commenter in making this estimate were:

estimated number of facilities that have closed, estimated number of facilities that do not use 

hexavalent chromium, and revised emissions estimates.

Response: After reviewing the commenter’s emissions reductions estimates, we have 

concluded that there is no basis for the assumptions and methodology used by the commenter. 

Regarding estimated baseline emissions, we disagree with how the commenter used the data 
60

collected by the commenter. We do not question the data indicating that several plants that have 

closed and several other plants that do not perform chromium electroplating or anodizing, and 

we have revised our database and baseline emissions to account for these changes by removing 

those plants and their associated emissions. However, we do not agree that the percentages of 

closed plants and of plants that do not perform chromium electroplating or anodizing determined 

by the commenter can be applied across the board to all plants nationwide. It is unclear how the 

commenter determined which plants to contact and whether there was any bias in that selection.

Furthermore, although we recognize that the chromium electroplating industry has not shown 

much, if any growth in several years, it is not appropriate to assume that no new plants have 

opened during that period, as assumed by the commenter.

Regarding the emissions reductions achieved by lowering the surface tension, the 

commenter first states that the relationship is not linear, yet then assumes a linear relationship to 

estimate reductions. Our methodology for estimating emissions reductions achieved from

reducing the surface tension is based on the data presented in the Development of Revised 

Surface Tension Limits for Chromium Electroplating and Anodizing Tanks Controlled with 

Wetting Agent Fume Suppressants document, which is available in the docket for this 

rulemaking. Those data indicate that reducing surface tension to the proposed levels would 

achieve a 15 percent reduction in emissions. With respect to the estimated emissions reductions 

for hard chromium electroplating plants with add-on control devices, there is no basis for the 

commenter’s assumption that the emissions reductions achieved using add-on controls can be 

estimated using the percent change in surface tension for sources that are controlled with fume 

suppressants. The assumptions used in our analysis to estimate emissions reductions are provided 

in the Revised Procedures for Determining Control Costs and Cost Effectiveness for Chromium 

Electroplating Supplemental Proposal document, which is available in the docket for this 

rulemaking. As explained in that document, we estimated emissions reductions based on the 

incremental increase in control efficiency of additional controls over existing emission controls. 

We continue to believe that using incremental control efficiencies is an appropriate method for 

estimating emissions reductions.

Regarding the revised emissions data provided by the commenter, we have developed a

revised database to account for the revisions that were documented or that we were otherwise 

able to verify. We note that, for several plants, the commenter assumed that actual emissions 

were either exactly 10 percent or exactly 33 percent of our estimated emissions, which suggests 

that the commenter did not receive actual data from the facilities regarding their emissions but 

estimated emissions by applying an arbitrary factor to our estimates. We further note that for

most of these plants, the emissions used for the supplemental proposal were simulated and not 

actual measured emissions. Since the simulated emissions were developed for estimating 

nationwide risk and impacts, rather than plant-specific estimates, applying an arbitrary 10 

percent or 33 percent factor to simulated emissions further calls into question the estimates 

provided by the commenter.

Finally, as explained previously, we have performed an emissions simulations using

some of the data provided by the commenter (as described in the previous paragraph) and other 

information obtained since the supplemental proposal. Based on those results and data, we 

estimate baseline emissions for the chromium electroplating and anodizing industry to be 955 
61

lbs/yr. Documentation for this revised estimate of baseline emissions can be found in the Revised 

Procedures for Determining Control Costs and Cost Effectiveness for Chromium Electroplating 

and Revised Simulation of Actual and Allowable Emissions for Chromium Electroplating 

Facilities, which are available in the docket for this rulemaking.

Comment: Commenter 0285/0296/0619 believes reduction of surface tension levels may 

not reduce emissions at all and will yield little, if any environmental benefit or risk reductions, 

particularly with the use of non-PFOS fume suppressants. The commenter stated that, while most 

facilities should be able to meet the new levels with PFOS-based fume suppressants, several 

facilities have expressed concerns that the lower surface tension levels will provide no 

environmental benefit or risk reduction and will eliminate a much-needed margin of compliance. 

The commenter goes on to say that to maintain the same margin of compliance, facilities may 

have to add more fume suppressants. The commenter stated that the added costs to ensure 

continued compliance with a sufficient buffer does not appear to be warranted given the minimal 

environmental benefits or risk reductions, if any that are expected from this change. The 

commenter believes that EPA has not provided any documentation or data in the record to 

demonstrate that the proposed changes to the surface tension levels will provide any measurable 

benefits (i.e., emissions reductions).

Commenter 0610 stated that EPA did not collect adequate data on the costs of non-PFOS 

WAFS and how quickly non-PFOS WAFS are depleted in chromium electroplating tanks. The 

commenter recommended that EPA delay further action on the NESHAP until the Agency can 

complete a full review of the feasibility of, and costs to small businesses associated with using 

non-PFOS WAFS to meet the proposed surface tension limits. Commenter 0285/0296/0619 

similarly believes that non-PFOS WAFS are significantly more expensive to use than EPA 

claims. 

Response: We based our decision to propose lower surface tension limits on an analysis 

of actual surface tension and emissions data. The data show that reducing surface tension from 

the current levels of 45 dynes/cm (stalagmometer data) or 35 dynes/cm (tensiometer data) to 40 

dynes/cm (with stalagmometer) or 33 dynes/cm (with tensiometer), will achieve an emissions 

reduction of approximately 15 percent and that is the value we used in our estimates of emissions 

reductions and cost effectiveness. The commenter provides no substantive information to refute 

that analysis but merely makes general statements of disagreement. We agree with the 

commenter that additional fume suppressant will be needed to maintain the lower surface tension 

levels and we have accounted for the additional fume suppressant use in our cost estimates. 

Finally, we disagree with the commenter that we have not provided documentation on the 

emissions reductions that are expected from the reduced surface tension levels. The rulemaking 

docket includes memoranda that provide data on emissions, costs, and reductions associated with 

the proposed limits. (See Development of Revised Surface Tension Limits for Chromium 

Electroplating and Anodizing Tanks Controlled with Wetting Agent Fume Suppressants and 

Procedures for Determining Control Costs and Cost Effectiveness for Chromium Electroplating 

Supplemental Proposal in the docket for this rulemaking.)

Following the supplemental proposal, we collected additional information on several 

chromium electroplating plants located in Minnesota that have been using non-PFOS fume 
62

suppressants for several years. The facilities have reported no significant problems in switching 

from PFOS-based to non-PFOS-based fume suppressants and also reported no significant 

difference in costs between the two types of fume suppressants. In addition, none of the facilities 

reported significant problems related to depletion of non-PFOS chemicals in electroplating baths. 

Therefore, we believe the data are adequate and support our conclusion that requiring non-PFOS 

fume suppressants will not create a significant impact on a substantial number of small entities. 

Additional details on the use of non-PFOS fume suppressants in Minnesota can be found in the 

Information on non-PFOS Fume Suppressants in Minnesota Chromium Electroplating Facilities

document in the docket for this rulemaking.

14. Compliance Options

Comment: Commenter 0285/0296/0619 stated that contrary to EPA’s assumptions, all 

facilities would need to use add-on controls or retrofit existing controls to meet the new proposed 

emissions limits because add-on controls are a critical component for meeting the current 

NESHAP standards (particularly for hard chromium facilities), and would also be a critical 

component for meeting the new proposed emissions limits. The commenter recommended that 

EPA include the additional costs of add-on controls and retrofits in its cost analysis for all 

facilities that need to reduce emissions or make adjustments to meet the proposed emissions 

limits. The commenter believes that when these costs are included, the analysis will demonstrate 

that EPA technology options are not cost effective.

Response: We disagree with the commenter’s assertion that all facilities will need to 

install additional controls to meet the proposed emission limits. Our analysis of the data indicates 

that most facilities already meet the proposed limits. Our cost analysis clearly includes additional 

costs for those facilities that we expect will be unable to meet the revised emission limits without 

additional control measures, such as retrofitting add-on controls or introducing the use of fume 

suppressants. The commenter provides no substantive information that refutes our analysis.

Comment: One commenter (0285/0296/0619) stated that HEPA filters are not costeffective and additional add-on controls are not feasible because many facilities control 

chromium emissions effectively through the use of mist suppressants without the need for 

control equipment. The commenter further stated that since the promulgation of the 1995 

Chromium Electroplating MACT standard and the 2004 amendments, no new control 

technologies have been developed or identified to control chromium emissions.

Response: We agree with the commenter that no “new” types of controls have been 

identified for chromium electroplating sources since promulgation of the MACT standard. 

However, as we have discussed in previous responses, for purposes of the residual risk and 

technology reviews, we look at developments in processes, process and controls since 

promulgation of the MACT and are not limited to reviewing “new control technologies. We 

disagree with the commenter's conclusion that add-on controls, are not cost-effective. Our 

analysis indicates that retrofitting add-on controls is not unreasonably expensive for existing 

plants that currently use only WAFS for controlling emissions from chromium electroplating 

tanks. In addition, our analysis also indicates that many plants that currently use WAFS can meet 

the more stringent emission limits without additional controls. (See Revised Procedures for 
63

Determining Control Costs and Cost Effectiveness for Chromium Electroplating and Anodizing, 

which can be found in the docket for this rulemaking.) 

Comment: Commenter 0285/0296/0619 stated that non-PFOS fume suppressants are still 

a technology in transition and are not a simple “drop-in” replacement for PFOS fume 

suppressants. 

Response: The EPA contacted several facilities in Minnesota that have switched from a 

PFOS-based fume suppressant to a non-PFOS fume suppressant and asked them to describe the 

transition and any problems they experienced. All the facilities that responded performed a slide 

conversion in order to transition to a non-PFOS fume suppressant. In the slide conversion 

method, a facility stops adding PFOS-based fume suppressant and begins adding non-PFOS 

fume suppressant. This method allows the PFOS concentration in the solution to reduce over 

time without having to empty and replace the contents of the tank. The facilities worked closely 

with the fume suppressant suppliers during the conversion. None of the plants that responded had 

any downtime due to the conversion and overall stated the slide conversion was a simple 

adjustment. 

Comment: Commenter 0285/0296/0619 believes non-PFOS fume suppressants do not 

perform in the same manner as PFOS fume suppressants, particularly with respect to reducing 

emissions. The commenter provided a case study of a Texas facility that observed a significant 

decline in controlling emissions with the use of non-PFOS fume suppressants. The commenter 

suggested that the results from this case study are consistent with the anecdotal information that 

NASF has received regarding benchmarking trials with non-PFOS fume suppressants within the 

industry. The commenter also listed one closed facility in Minnesota that used a non-PFOS fume 

suppressant and had average surface tension levels of about 30 dynes/cm but also had a few 

surface tension measurements above the proposed limit of 33 dynes/cm. 

Response: The Texas facility in the case study uses high hardness dense chromium and a 

low-temperature (136°F to 140°F), multi-state surface finishing process. EPA believes this 

process is not typical or representative of most hard chromium electroplating operations. 

Nevertheless, all facilities will have the option to use add-on control devices or WAFs or a 

combination of the two approaches to limit emissions. Also, for those facilities that choose to use 

WAFS, facilities will have 3 years to determine an effective non-PFOS fume suppressant, and 

can petition for an additional year. EPA acknowledges that some facilities may need additional 

time to test and refine the use of non-PFOS fume suppressants and such facilities could request 

an additional year for compliance pursuant to CAA section 112(h)(3)(B). Additionally, it may be 

that fume suppressants will not work for a limited set of facilities and such facilities may need to 

use add-on controls.

With regard to the Minnesota facility, the commenter does not identify why the facility in 

Minnesota that closed had a few surface tension measurements above the levels in the 33 

dynes/cm. Nevertheless, most of the facility’s measurements were below 33 dynes/cm and the 

facility maintained an average surface tension of about 30 dynes/cm. We again note that we have 

contacted several other facilities in Minnesota, none of which has had issues in switching to a 

non-PFOS fume suppressant or in controlling surface tension levels. We also reviewed and 
64

analyzed two recent studies (i.e., a German study and Danish study) that evaluated the 

effectiveness of non-PFOS based WAFS compared to PFOS-based WAFS. The Danish study 

results indicate that the non-PFOS based WAFS performed as well or better than the PFOS based 

WAFS at reducing chromium emissions. The results of the German study were less clear. For 

example, a new experimental product that is not commercially available seemed to actually 

increase emissions. However, with regard to the commercially available products, the authors 

concluded that the PFOS and non-PFOS products both reduced emissions by more than 95 

percent (see the technical memo Comparison of Studies on Non-PFOS Fume Suppressant 

Performance, which is available in the docket for more information).

Comment: Commenter 0285/0296/0619 stated that EPA offers no proof to support 

claims that the new source emissions limit can be achieved for decorative and anodizing by 

maintaining the new surface tension level. The commenter stated that EPA has not provided any 

data in the record to demonstrate that the proposed limit is feasible for new hard chromium 

facilities. The commenters focused on EPA’s need to reassess its claims regarding the use of

non-PFOS fume suppressants and stated EPA has not provided any evidence in the record that 

non-PFOS fume suppressant can effectively reduce emissions to meet the new proposed 

emissions limits. The commenter feels that as a result, non-PFOS fume suppressants are not a 

technologically or economically feasible option for ensuring compliance with the new proposed 

emissions limits.

Response: First, any new source has the option to comply with the rule by either 

maintaining the surface tension levels or by meeting the emissions limits. The data from 

Minnesota and from the chemical companies (e.g., Atotech) indicate that surface tension levels 

of 33 dynes/cm (as measured with a tensiometer) are achievable. Regarding those plants that 

choose to comply by meeting the emissions limits, based on the data we have, facilities can meet 

the emissions limits with readily available control devices (such as CMPs or HEPA filters). Our 

analysis of the available data on surface tension indicates that maintaining surface tension below 

40 dynes per centimeter (when measured using a stalagmometer) or 33 dynes/cm (when 

measured using a tensiometer) will ensure emissions remain below 0.0055 mg/dscm, which is 

below the revised emission limit of 0.006 mg/dscm. The analysis and results are documented in 

Development of Revised Surface Tension Limits for Chromium Electroplating and Anodizing 

Tanks Controlled with Wetting Agent Fume Suppressants, which can be found in the rulemaking 

docket.

Comment: Commenter 0290/0620 pointed out that, if, as EPA states, surface tension 

limits lead to emission control that is equivalent to that of the emission concentration-based 

limits, then there is no need to set an alternative limit for surface tension. The commenter added

that although EPA should require actual measurement of emissions coming from the sources to 

ensure compliance, EPA could also consider using surface tension as one method of assessing 

compliance with the concentration-based limits (as long as it is actually equivalent). The 

commenter suggested that, since some sources may need to use WAFS and other controls to 

achieve the emission standards, then EPA should require surface tension limits in addition to 

those standards. The commenter noted that then instead of a potential loophole that does not 

satisfy section 112, surface tension limits could serve as an important additional protection and 

backstop to the core emission standards (but not the only compliance option).”
65

Response: While we have phrased the regulation as establishing surface tension limits as 

an “alternative to” the emission limit, as we have provided above, compliance with the surface 

tension limits will ensure compliance with the emission limits and it is appropriate to consider 

the surface tension limits as a means of demonstrating compliance with the emission limit. We 

do not believe it is necessary, however, to revise the long-standing structure of the MACT rule to 

define it as a required compliance method in addition to complying with the emissions limit 

rather than as an alternative to meeting the emissions limit. We are unclear what point the 

commenter is making in the last sentence. To the extent some sources need both WAFS and 

control equipment to meet the emission limit, there is no need to establish a surface tension limit 

for such sources. Rather, where emission control equipment is used as the sole or partial means 

of complying with the MACT rule, the source must demonstrate compliance by meeting the 

applicable emission limit. Surface tension limits were developed as an alternative means for 

complying with the MACT rule when they are the sole means of compliance. 

Comment: Commenter 0285/0296/0619 stated that with respect to the hard chromium 

facilities that would need to reduce emissions or make adjustments to meet the proposed 

emission limits, EPA “assumes” that most facilities “would achieve these extra reductions with 

the addition of fume suppressants.” Commenter 0285/0296/0619 points out that some facilities 

cannot use fume suppressants because of operational considerations such as the size of tanks, 

configuration of tanks, and the mechanics of the plating process and that some plants are not 

currently using fume suppressants because of operational, product quality or cost considerations. 

The commenter stated that EPA has continued to acknowledge this limitation on the use of fume 

suppressants, but appears to ignore it as it insists that fume suppressants, which are not a new 

technology, are the answer for all facilities to meet the proposed limits. The commenter 

concludes that facilities that can use fume suppressants beneficially in their operations are 

currently using them and believes EPA’s solution to start using fume suppressants or using more 

fume suppressants is misguided and without merit, and is not supported by evidence in the 

record.

Response: Based on available data, more than 85 percent of existing large hard 

chromium plants already meet the limit of 0.011 mg/dscm and therefore will not need to add 

WAFS or retrofit controls. Those 85 percent (or more) plants will have no additional control 

costs. For the 15 percent (or less) of plants that will need to achieve reductions, we have revised 

our costs analysis using the assumption that all of the existing large hard chromium 

electroplating plants that cannot currently meet the revised emission limit of 0.011 mg/dscm will 

have to retrofit add-on controls. 

For small hard chromium electroplating plants we also estimate that more than 85 percent 

of existing plants already meet the limit and will need no additional controls. For the 15 percent 

(or less) of plants that will need to achieve reductions, we have assumed that 20 percent of 

affected existing facilities will have to retrofit add-on controls. We believe this assumption 

accounts for facilities that may not be able to use fume suppressants. The available data indicates 

that approximately 15 percent of plants outside of California currently use fume suppressants in 

combination with add-on controls, and, in California, the percentage is believed to be greater 

than 15 percent. On the other hand, the commenter provides no data to support the statement that 
66

any plant that can use fume suppressants is already using fume suppressants. To the contrary, our 

data show that all types of plants (hard chromium electroplating, decorative chromium 

electroplating, and chromium anodizing) use fume suppressants to complement the reductions 

achieved by add-on controls. In addition, several of the plants that would marginally exceed the 

more stringent emission limits are not using fume suppressants currently. Therefore, there is no 

reason to assume that none of these plants could introduce fume suppressants to the 

electroplating tanks, as stated by the commenter.

15. Housekeeping Requirements

Comment: Commenters 0277 and 0285/0296/0619 commented on the burden associated 

with some of the specific housekeeping practices proposed. Regarding Item No. 1 of proposed 

Table 2 to §63.342, which would require storing substances containing hexavalent chromium in 

an enclosed area, Commenter 0277 stated that, if cabinets are required, the facility would incur 

costs of approximately $4,500 for cabinets with sufficient capacity to contain the maximum 

amount of inventory that could potentially be onsite. In addition the commenter stated that, the 

use of such cabinets would then limit the amount of inventory that the facility could purchase 

and would take up valuable floor space in an already limited amount of storage area. The 

commenter added that the real costs and operational disruption that would result from the use of 

storage cabinets would be unacceptable in light of there being no apparent advantage over 

placement of containers inside a containment area within a building. Commenter 

0285/0296/0619 stated that, if the proposed measure required storage of all such substances in 

cabinets, there would be considerable costs to retrofit a facility or to purchase and install such 

drum storage cabinets, and that EPA has not taken such costs into consideration. The commenter 

added that such additional controls and costs are unnecessary. 

Regarding requirement No. 2, for minimizing spills from dragout, Commenter 0277 

stated that neither of the proposed compliance options is feasible at the commenter's facility 

without capital investment of more than $100,000. The commenter suggested allowing a third 

compliance option to collect and treat dragout in an onsite wastewater treatment plant and/or 

dispose of solution that drips or drains from parts as they are being removed from tanks. 

According to the commenter, this option would be far less burdensome. 

Regarding requirement No. 5, to clean surfaces on a weekly basis, Commenter 0277 

stated that cleaning elevated surfaces would require specialized equipment (lifts, booms, etc) and 

require an estimated 12 man-hours per week. The commenter stated that weekly cleaning of the 

wastewater collection pits would only be feasible if the use of a hose is permitted, and could be 

accomplished with an acceptable number of man hours. However the commenter stated that, 

hosing out the pits would generate approximately 1,000 gallons of additional wastewater that 

would need to be processed by the wastewater treatment operation (and its associated operator). 

In the event that hosing was not allowed the commenter noted that, cleaning the pits would entail 

removal of several hundred linear of feet of floor grates and a confined space entry. The 

commenter further stated that this work could only be conducted on the weekend when the 

facility is not staffed, due to the safety hazard that would be created by removing the floor grates. 

The commenter stated that the additional labor and operating costs associated with a broad 

interpretation of this requirement could range from $24,000 to $50,000 per year at his plant. 
67

Regarding requirement No. 6, to install a physical barrier to separate buffing, grinding, 

and polishing operations from chromium electroplating or anodizing operations, the same 

commenter (0277) stated that, if the intent was to totally enclose these operations, the proposed 

rule does not address the capital costs for meeting this requirement. The commenter stated that, 

at his facility, these capital costs could exceed $250,000 in construction of new areas and 

physical barriers (i.e., walls).

Three commenters (0260/0616, 0277, and 0285/0296/0619) commented about the 

proposed housekeeping practices specified in Table 2 to §63.342. All three commenters stated 

that the proposed requirements needed clarification to ensure that they are not interpreted too 

broadly and are not overly burdensome. Commenter 0260/0616 remarked that the proposed 

housekeeping measures are unnecessary and should be eliminated. Commenter 0277 stated that 

the proposed measures are ambiguous and will result in actions that, although beyond the 

intended scope of the rule, will be necessary for mitigating the potential for enforcement or 

litigation. The commenter added that the proposed requirements will result in regulatory burdens 

and costs not properly considered by EPA. The commenter offered several suggestions for 

reducing the burden associated with implementing the proposed measures. Commenter 

0285/0296/0619 stated that, although the proposed requirements appear generally to be 

consistent with good management practices for chromium electroplating and anodizing 

operations, several clarifications are needed to ensure that facilities can implement the 

housekeeping practices effectively without overly broad and unnecessarily strict interpretations 

of the requirements.

Response: The final rule includes several changes to the housekeeping requirements that 

we believe address the commenters’ concerns. Regarding Item No. 1, the final rule allows 

chromium-containing substances to be stored in an enclosed container, an enclosed storage area, 

or a building; thus, it will not be necessary to store the substances in a cabinet. Regarding Item 

No. 2, the final rule allows collection and treatment in an onsite wastewater treatment plant. 

Regarding Item No. 5, the final rule clarifies and limits which surfaces must be cleaned; that is, 

only surfaces contaminated with hexavalent chromium from materials used in an affected tank. 

The final rule also allows rinsing surfaces and collecting the liquid in a wastewater collection 

system. Regarding Item No. 6, the requirement has been clarified to apply only for buffing or 

polishing operations located in the same room as an affected tank and clarifies that a plastic strip 

curtain is acceptable; the rule does not require construction of enclosed of walls or other types of 

enclosures. Additionally, in response to these and other comments on the proposed amendments 

we have made several changes to clarify and simplify the housekeeping measures incorporated in 

the final rule. The specific changes are described in our responses to the specific comments on 

each of the housekeeping measures, as described in the following paragraphs.

Comment: One commenter (0260/0616) questioned the need to establish housekeeping 

requirements if the purpose is to minimize fugitive emissions, as stated in the preamble to the 

proposed amendments. The commenter pointed out that fugitive emissions are already 

minimized by efforts implemented to minimize occupational exposures regulated by 29 CFR 

1910 and the hazardous waste management requirements of 40 CFR 262. For this reason the 

commenter believes, EPA should not impose measures that are adequately addressed by other 

regulations. The commenter added that, if occupational exposures in the shop are regulated to an 
68

acceptable level, it is not clear how the level of fugitive emissions that migrate out of the shop 

would present an unacceptable risk to the public.

Response: We understand that occupational exposures to chromium at chromium 

electroplating plants are addressed under 29 CFR 1910, and that §1910.1026(j) specifies 

housekeeping requirements. We have not determined that fugitive emissions present an 

unacceptable risk to public health. Rather we proposed and are finalizing the housekeeping 

requirements under the technology review provision of section 112(d)(6) because these 

procedures are cost effective and will result in emission reductions.

Comment: Three commenters (0260/0616, 0277, and 0285/0296/0619) requested 

clarification of the term "enclosed storage area" as it related to the requirement in item No. 1 of 

Table 2 to §63.342 for storing substances that contain hexavalent chromium. Commenters 0277 

and 0285/0296/0619 stated that a common practice is to store such materials in a building with 

secondary spill containment or other spill and release prevention measures, but it is unclear if 

such a practice would satisfy the proposed requirement. Commenter 0260/0616 stated that, while 

electroplating operations are underway, such substances often are placed temporarily in or 

around the shop and that the building surrounding the electroplating processes should qualify as 

an enclosed storage area.

Commenter 0260/0616 remarked that the proposed storage requirement should be revised 

to clarify that it is limited to substances used in chromium electroplating and anodizing tanks, 

and should not apply to other substances such as surface coatings, solvents, sealers, adhesives, 

and greases. Otherwise the commenter noted, the requirement could lead to inappropriate 

enforcement actions. The same commenter also commented that the phrase "at all times" is too 

narrow as this requirement could not be met while transferring material to and from the 

container. The commenter provided the following revised text to the storage requirements 

specified in Item 1 of Table 2 to §63.342:

For You must: At this minimum frequency

1. Any substance used in an 

affected chromium 

electroplating or anodizing 

tank that contains hexavalent 

chromium.

(a) Store the substance in a 

closed container in an 

enclosed storage area or 

building; AND

At all times except when 

transferring the substance to 

and from the container.

(b) Use a closed container 

when transporting the 

substance from or within the 

enclosed storage area or 

building.

Whenever transporting 

substance, except when 

transferring the substance to 

and from the container.

Response: We agree with the commenters that buildings with secondary containment or 

other spill and release prevention measures would satisfy the proposed requirement and we have 

revised the requirement accordingly. We do not agree with Commenter 0260/0616 that the 

building surrounding the electroplating processes could serve as the enclosed storage area. The 

final housekeeping requirements continue to require storage of such materials except when 

transferring the substance to and from the container. We agree with the suggested changes by 
69

Commenter 0260/0616 to clarify that the storage requirements would not apply when 

transferring substances containing hexavalent chromium. We also agree with the commenter 

concerning the clarification that the proposed storage requirements apply only to substances used 

in chromium electroplating or anodizing processes, and we have revised the requirements 

accordingly.

Comment: Commenters 0260/0616, 0277, and 0285/0296/0619 pointed out that the 

proposed requirement specified in Item No. 2 of Table 2 to §63.342, which would require 

minimizing spills from dragout by installing drip trays or collecting and returning dripped or 

spilled tank solution to the tank, are not practical at many facilities. The commenter stated that 

in many cases, drip trays cannot be installed due to the positioning of the electrical bus and Vblocks on the tank structure; drip trays also can interfere with the workers' ability to move racks 

into and out of tanks. Commenters 0277 and 0285/0296/0619 suggested that the final rule 

provide facilities the option of collecting dragout in pits and sumps surrounding tanks that 

contain hexavalent chromium, and then periodically pumping out the sump contents and 

processing it through the facility's wastewater treatment operation. Commenter 0260/0616 

remarked that the proposed requirement is not necessary because facilities already have a 

substantial economic incentive to minimize dragout due to the cost of the tank chemicals. All 

three commenters noted that the option of collecting and returning dripped solution to the tank is 

not recommended in many situations due to the possibility of contamination. Commenter 

0260/0616 suggested that a process engineer or operator be allowed to determine whether any 

dragout should be returned to the tank or handled as a waste to avoid contaminating the entire 

chromium electroplating or anodizing bath. Commenter 0277 added that the requirement to 

reuse the solution after it has been captured appears to be arbitrary and does not present any 

reduced likelihood of the creation of fugitive dust, as is the stated intention of the proposed 

housekeeping requirements. One commenter (0260/0616) provided the following revised text to 

the requirements specified in Item 2 of Table 2 to §63.342:

For You must: At this minimum 

frequency

2. Each affected tank, to minimize 

spills of bath solution that result 

from dragout.

Note: This measure does not require 

the return of contaminated bath 

solution to the tank. This 

requirement only applies “as the 

parts are removed from the tank.” 

Once away from the tank area, any 

spilled solution would be handled in 

accordance with housekeeping 

measure.

(a) Install drip trays that 

collect and return to the tank 

any bath solution that drips 

or drains from parts as the 

parts are removed from the 

tank;

OR

Prior to operating the 

tank.

(b) Contain and return to the 

tank all solution that drains 

or drips from parts as the 

parts are removed from the 

tank.

Whenever removing parts 

from an affected tank.

Response: We agree with the commenters that the proposed requirement should allow 

for situations where drip trays are not practical and we have revised the proposed requirements to 

allow facilities to collect dragout using other methods, such as by using pits and sumps. We also 
70

agree with the commenters that the proposed practice should not require returning dragout 

liquids to the electroplating or anodizing tank and have revised the requirement to allow other 

options. We also agree with the other clarifications suggested by Commenter 0260/0616 

regarding when the requirement would apply and how spilled solution should be handled and we 

have incorporated the suggested changes into the final housekeeping practices.

Comment: Commenter 0260/0616 commented that the proposed requirement specified in 

Item No. 3 of Table 2 to §63.342, which would require installing splash guards to minimize 

overspray, should be revised to ensure that splash guards are only required when spraying parts 

to remove excess chromic acid. The commenter added that the requirement should also recognize 

that a splash guard may not be 100 percent effective and that it is not feasible to require 

“any...liquid” be returned to the tank. In addition, the commenter stated that the proposed 

requirement should be revised to ensure that it does not prevent a facility from performing spray 

operations over rinse tanks located near the electroplating or anodizing tanks. The commenter 

included the following recommended changes to this requirement:

For You must: At this minimum 

frequency

3. Each spraying operation for 

removing excess chromic acid from 

parts removed from and occurring 

over an affected chromium 

electroplating or anodizing tank. 

Note: this measure does not require 

facilities to perform spraying 

operations but rather specifies a 

practice to follow during spraying 

operations.

Install a splash guard to minimize 

overspray during spraying 

operations and to ensure that any 

hexavalent chromium laden liquid 

captured by the splash guard is 

returned to the affected chromium

electroplating or anodizing tank.

Prior to any such 

spraying operation.

Response: We agree with the commenter and have revised the housekeeping practices

related to spraying to clarify that it applies only to spraying operations over an affected tank and 

that the liquid captured by the splash guard must be returned to the affected tank.

Comment: Commenter 0260/0616 commented on the requirement specified in Item No. 

4 of Table 2 to §63.342, which would require affected facilities to clean up or contain all spills of 

hexavalent chromium substances within 1 hour. The commenter stated that, to meet a similar 

requirement under California's ATCM for Chromium Plating and Chromic Acid Anodizing 

Facilities, a facility had to cover all surfaces with metallic silver barrier paper to ensure that all 

drips are contained and cleaned up within the specified time period. The commenter stated that 

the proposed requirement does not specify what amount constitutes a spill, which locations are 

covered by the requirement, and does not define the terms “cleaned up,” “contained,” and “spill." 

According to the commenter, the proposed requirement could result in a violation if a facility 

spills a drop of deionized water, coffee, or soda. The commenter pointed out that facilities 

already have a substantial economic incentive to clean up spills and minimize fugitive emissions 

to prevent workers from being exposed to chromium laden dust caused by poor housekeeping. 

The commenter suggested that the proposed language be clarified to limit it to substances used in 
71

chromium electroplating and anodizing tanks. The commenter also stated that drippings that fall 

into a basement, secondary containment, or other collection device should meet the obligation to 

contain spills, and these containment areas should not need to be cleaned within 1 hour. The 

commenter pointed out that it may not be safe to send employees into the subfloor areas to clean 

up spills while the chromium electroplating process tanks are in operation. The commenter noted 

that if EPA were to extend this measure to the subfloor areas, the time limit should be revised to 

require cleanup upon completion of the electroplating or anodizing operation, or at the end of the 

shift, whichever comes first. The commenter provided the following revised text to the 

requirements specified in Item 4 of Table 2 to §63.342:

For You must: At this minimum 

frequency

4. Each operation that involves 

the handling or use of any 

substance used in an affected 

chromium electroplating or 

anodizing tank that contains 

hexavalent chromium.

Begin clean up, or otherwise 

contain, all spills of the 

substance. Note: substances that 

fall or flow into drip trays, pans, 

sumps or other containment areas 

are not considered spills.

Within 1 hour of the 

spill.

Commenter 0285/0296/0619 suggested that the proposed requirement be revised to 

“Initiate clean up or containment of all spills of the substance within one hour of discovering the 

spill.” According to the commenter, this modest change can ensure that spills are promptly 

cleaned and contained without imposing an impractical burden on facilities. 

Response: Based on the commenters' comments, we have revised the proposed 

housekeeping practice to clarify that it applies only to substances used in an affected chromium 

electroplating or anodizing tank; that it does not include material that is caught or collected by a 

drip pan, sump, or other containment or collection structure or device designed to collect 

electroplating tank liquid, and that the cleanup must be initiated within 1 hour of the spill.

Comment: Three commenters (0260/0616, 0277, and 0285/0296/0619) submitted 

comments on the proposed requirement specified in Item No. 5 of Table 2 to §63.342, which 

would require weekly cleaning of all surfaces on which hexavalent chromium dust could 

potentially accumulate. The commenters stated that, as proposed, the requirement could apply to 

any surface within the facility; they requested that the final rule clarify and limit the surfaces to 

which the requirement would apply. Commenter 0277 suggested the requirement be limited to 

surfaces that can be cleaned with reasonable effort and for which there is a reasonable 

expectation that the dust would be disturbed. The commenter stated that would exclude light 

fixtures, duct work, or any surfaces associated with a building’s structural components. 

Commenter 0285/0296/0619 added that cleaning such remote and elevated surfaces would 

require specialized equipment (e.g., lifts, booms, etc.) and require significant compliance costs 

that have not been accounted for by EPA. Commenter 0260/0616 stated that surfaces inside of 

the tank, the rim, ventilation duct work, and ancillary equipment connected to the electroplating 

tank are not feasible to clean. Commenter 0285/0296/0619 requested that the requirement be 

limited to “all surfaces within the storage areas, open floor space, walkways around affected 

tanks, or readily accessible surfaces contaminated with hexavalent chromium dust.” 
72

Commenters 0260/0616 and 0285/0296/0619 commented on the proposed cleaning 

methods for surfaces with accumulated hexavalent chromium dust. Commenter 0260/0616 stated 

that an additional method for cleaning potentially contaminated surfaces under 5.(a) should be a 

washdown of the surfaces with potable water. The commenter stated that many facilities are 

designed and constructed to collect, store, and/or treat washdown water potentially contaminated 

with hexavalent chromium. The commenter noted that washdown of potentially contaminated 

surfaces until no discoloration of the washdown water is visible should provide a level of 

fugitive dust control equal to wet mopping. Commenter 0285/0296/0619 stated that, while 

facilities should implement these cleaning methods effectively, this requirement should not be 

interpreted to include a strict performance standard such as no visible signs of any chromium. 

For example the commenter noted, it is not practical to remove all “chrome staining” in areas 

around the electroplating tanks (not to mention the fact that such stains do not pose any 

environmental or health concerns). The commenter requested that EPA clarify this provision so 

that compliance can be achieved through reasonable and practical good management practices.

Commenter 0260/0616 remarked that some facilities conduct chromium electroplating or 

anodizing on an infrequent basis, with the majority of their electroplating operations involving 

the electrodeposition of other metals, such as copper and nickel. The commenter stated that these 

“job shop” type facilities should not be subject to the weekly cleaning requirement for calendar 

weeks in which no chromium electroplating or anodizing operation have taken place at the 

affected source. Additionally the commenter stated that, it may be appropriate to provide an 

alternative requirement to perform the cleaning after a specified period of operation of one or 

more chromium electroplating or anodizing tanks. The commenter provided the following 

revised text to address all of his concerns with the proposed requirements specified in Item 5 of 

Table 2 to §63.342:

For You must: At this minimum frequency

5. All sSurfaces within the 

enclosed storage area, open 

floor area, walkways around 

affected tanks, or any surface 

potentially contaminated with 

hexavalent chromium from 

materials used in an affected 

chromium electroplating or 

anodizing tank that 

accumulates or potentially 

accumulates dust.

(a) Clean the surfaces using 

one or more of the following 

methods:

(i) HEPA vacuuming; 

(ii) Hand-wiping with a damp 

cloth;

(iii) Wet mopping;

(iv) Hose down or rinse with 

potable water into a 

wastewater collection system;

(v) Other cleaning method

approved by the permitting 

agency; OR

At least once every 7 days if 

one or more chromium plating 

or anodizing tanks were used, 

or at least after every 40 hours 

of operating time of one or 

more affected chromium 

plating or anodizing tanks, 

whichever interval is later.

(b) Apply a non-toxic 

chemical dust suppressant to 

the surfaces.

According to manufacturer’s 

recommendations.
73

Response: We agree with the clarifications suggested by Commenter 0260/0616 and 

believe those clarifications also address the concern of Commenter 0285/0296/0619 regarding 

weekly cleaning of surfaces. We have revised the proposed housekeeping requirement, as 

suggested by Commenter 0260/0616.

Comment: Two commenters (0277 and 0285/0296/0619) commented on the proposed 

requirement specified in Item No. 6 of Table 2 to §63.342, which would require installing a 

physical barrier to separate buffing, grinding, and polishing operations from chromium 

electroplating or anodizing operations. Both commenters stated that such barriers would obstruct 

workers' ability to move parts into and out of the buffing and polishing areas. Commenter 0277 

added that the proposed requirement would present a safety hazard by impairing visibility, 

particularly when moving large parts or equipment through the polishing and buffing area. The 

commenter noted that, although the polishing and buffing operations at his facility are not 

surrounded on all sides by a barrier, there is no line of sight between those operations and the 

chromium electroplating and anodizing operations. The commenter believes that having no line 

of sight between these operations should be adequate for reducing the likelihood of 

contamination associated with these operations. Commenter 0285/0296/0619 requested that EPA 

clarify the definition of “physical barrier” in the context of this requirement with the following 

regulatory language: “separate the operation from any affected electroplating or anodizing 

operation by a reasonable distance or other measure from the buffing, grinding, or polishing 

operations, or by installing a physical barrier such as plastic strip curtains."

Response: We agree with the commenters' remarks regarding physical barriers, and we 

have revised the proposed housekeeping practice to require a physical barrier if the polishing or 

buffing operations are located in the same room as chromium electroplating or anodizing tanks.

16. Restriction on Use of PFOS to Meet the MACT

Comment: One commenter (0285/0296/0619) suggested that EPA eliminate or revise the 

provisions pertaining to the use of fume suppressants that contain perfluoro-octyl sulfonates 

(PFOS). The commenter explained that because PFOS is not listed under Section 112 of the 

CAA as a HAP, it would be more appropriate to regulate the production and use of PFOS under 

the Toxic Substances Control Act. 

Response: The commenter is correct that PFOS-based fume suppressants are not listed as 

HAP under section 112(b); however, we did not propose to regulate PFOS as a section 112(b) 

HAP. Rather, as proposed, under Section 112(d)(6) of the CAA we are restricting the use of 

PFOS-based fume suppressants as a means for complying with the MACT rule requirements 

because of the adverse non-air quality health and environmental impacts. In the years since 

promulgation of the original rule, non-PFOS-based fume suppressants have emerged as a costeffective alternative to PFOS-based fume suppressants. The available data, described previously 

and documented in the rulemaking docket, indicate that the current generation of non-PFOS 

fume suppressants is comparable to PFOS-based fume suppressants in terms of cost and 

performance. We consider these improvements to non-PFOS-based fume suppressants to be the 

type of development that can be considered under section 112(d)(6). In light of the adverse 

impacts associated with PFOS-based fume suppressants, and that non-PFOS fume suppressants 

are available and cost effective, we believe restricting their use as a means of complying with the 
74

MACT is necessary pursuant to section 112(d)(6).

Comment: One commenter (0285/0296/0619) stated that if PFOS is regulated under the 

Clean Air Act, EPA should revise the proposed rule language to allow the continued use of 

unexpired PFOS-based fume suppressants that have already been purchased: To reduce the 

ultimate ecosystem loading of the PBT chemical, production and introduction into commerce 

must be restricted, rather than require that usable PFOS-based fume suppressants be managed as 

waste after some future arbitrary date. The commenter suggested the following changes:

63.342(c)(1) * * * 

(iv) After [Insert date 3 years from after the date of publication of the final rule 

amendments in the Federal Register], the owner or operator of an affected open surface 

hard chromium electroplating tank shall not add PFOS-based fume suppressants 

purchased after [Insert date of publication of the final rule amendments in the Federal 

Register] to any affected open surface hard chromium electroplating tank.

* * * * *

(2) * * *

(vi) After [Insert date 3 years from after the date of publication of the final rule 

amendments in the Federal Register], the owner or operator of an affected enclosed hard 

chromium electroplating tank shall not add PFOS-based fume suppressants purchased 

after [Insert date of publication of the final rule amendments in the Federal Register] to 

any affected enclosed hard chromium electroplating tank.

* * * * *

(d) * * *

(3) After [Insert date 3 years from after the date of publication of the final rule 

amendments in the Federal Register], the owner or operator of an affected decorative 

chromium electroplating tank or an affected chromium anodizing tank shall not add 

PFOS-based fume suppressants purchased after [Insert date of publication of the final 

rule amendments in the Federal Register] to any affected decorative chromium 

electroplating tank or chromium anodizing tank.

(e) * * *

(2) After [Insert date 3 years from after the date of publication of the final rule 

amendments in the Federal Register], the owner or operator of an affected decorative 

chromium electroplating tank using a trivalent chromium bath shall not add PFOS-based 

fume suppressants purchased after [Insert date of publication of the final rule 

amendments in the Federal Register] to any affected decorative chromium electroplating 

tank.

Response: EPA believes the 3 year compliance period is more than enough time to use 

existing stocks of PFOS-based fume suppressants that a facility may have. We disagree with the 

revisions the commenter has suggested as it may encourage facilities to purchase extra new 

PFOS-based fume suppressant for immediate use and hold on to existing stocks of PFOS-based 

fume suppressant for use after the 3 year compliance period. 

Comment: Several commenters (0272, 0285/0296/0619) supported EPA's proposal to 

eliminate PFOS-based wetting agents due to its persistence, bioaccumulation, and toxic 
75

characteristics, and noting that the proposed phase-out of PFOS fume suppressants is a 

reasonable requirement that is protective of the environment and human health.

Response: We acknowledge the commenters' support.

17. Other Comments

Comment: Commenter 0290/0620 claimed surface tension limits appear to lead to 

stronger protection for workers inside a facility, by keeping emissions in the tanks, instead of 

having them escape into a building. The commenter believes EPA should evaluate the impacts 

on workers’ health of using surface tension limits, in addition to emission concentration-based 

limits. The commenter believes if requiring WAFS, measured through surface tension, would 

better protect workers’ health, this provides further reason to require surface tension limits in 

addition to emission limits.

Response: We agree with the commenter that the use of WAFS can provide additional 

worker protection as a co-benefit along with reducing emissions. However, the commenter 

appears to be suggesting that EPA’s regulations address worker safety and health. Those issues 

are within the jurisdiction of OSHA, not EPA.

Comment: Commenter 0278/0617 noted that a new affected source would have the 

added expense of possibly using an add-on control device to meet the 0.006 mg/dscm limit, but a 

new affected source also has the option of using a fume suppressant containing a wetting agent. 

The commenter recommended that EPA define a minimum control technology requirement for 

new sources that would limit the need for stack testing. 

Response: We do not believe it is appropriate to require a specific control technology in 

place of an emission limit. We believe it is important that sources ensure emissions are below 

specified levels and we cannot be assured that use of a specific control technology would achieve 

that. We further note control technologies are a “one-size-fits-all” approach and some new 

sources could incur higher costs by installing a mandated control technology than they would 

incur if they could choose a different method of compliance. 

Comment: One commenter (0272) recommended amending Method 306B by 

incorporating the surface tension measurement procedure for stalagmometers specified by 

Appendix 8 of the California's ATCM for Chromium Plating and Chromic Acid Anodizing 

Facilities. 

Response: Both the October 2010 proposal and the supplemental proposal were written 

to incorporate the procedure referenced by the commenter into the revisions to Method 306B as 

recommended by the commenter and we are finalizing those provisions as proposed.

Comment: Commenter 0609 suggested revising the definitions of existing affected 

sources and new affected source in §63.341(a). The commenter noted that rectifiers and 

ancillary equipment are integral to the process and should be included in the definitions.
76

Response: EPA did not propose changes to the definition of existing and new affected 

sources and does not agree with the commenter’s suggested revisions. 

Comment: Commenter 0285/0296/0619 recognized EPA’s court-ordered deadline for the 

issuance of the final rule and EPA’s consideration of additional information (provided it is 

submitted within a reasonable time period after the close of the comment period), but does not 

agree with EPA’s denial of NASF’s request for an extension of the comment period. The 

commenter believes additional time to review and evaluate the data in the record would have 

provided EPA with more effective feedback on the technical support for the proposed revisions. 

The commenter also stated they did not have enough time to review and evaluate all the data and 

analysis provided by EPA and that they will continue to work with EPA officials to identify 

issues with the data, analysis, and methodologies used. 

Response: As explained in our response to the commenter’s request, the deadline to 

conduct the additional analyses and finalize the amendments, as required by our Consent Decree

deadline, prevented us from extending the comment period. However, we considered the 

information received after the March 26, 2012 comment period deadline, to the extent possible.

Comment: One commenter (0278/0617) recommended that EPA submit an inventory for 

the state to review prior to making any policy decisions regarding this source category. 

Response: As described previously, we contacted 26 states and local agencies to request 

additional information on the industry. Those requests were sent to the states with the largest 

numbers of chromium electroplating plants, and we included in those requests an inventory of 

plants in each state. Therefore, for the majority of plants in the U.S. we did send an inventory to 

the respective state agency and specifically requested that they review the list. In addition, for 

both the October 2010 proposal and the supplemental proposal, we included a complete list of 

plants. For the October 2010 proposal, we specifically requested comments on the plant list. 

Thus, each state agency had the opportunity to review those lists and inventories.

Comment: More than 10,000 commenters submitted their comments through a mass 

comment campaign sponsored by Earth Justice, and an additional 63 citizens expressed general 

concern over emissions from the chromium electroplating industry. See Appendix A for the 

summary of citizen and mass comment campaign commenters. The commenters believe that 

evaluating health impacts on a healthy adult is insufficient and unrealistic and recommend that 

EPA evaluate health impacts on children, the elderly, and other vulnerable populations. The 

commenters stated that EPA must consider the cumulative impacts of exposure to toxic air 

pollution on the people with low-income and minority individuals that live in denser urban areas, 

where chromium electroplaters and other sources are overburdening them with toxic air 

pollution. The commenters support the removal of the malfunction exemption, but believe that 

the affirmative defense approach leaves a major loophole in the deterrent effect and value of the 

standard. The commenters recommended that EPA strengthen the final standard. 

Response: The EPA acknowledges the general concerns of the commenters regarding

the results of the RTR review and the proposed amendments to the Chromium Electroplating 

NESHAP, and responses to comments elsewhere in this document respond to those concerns.
77

III. Summary of Comments and Responses – Steel Pickling NESHAP

1. Startup, Shutdown, and Malfunction

Comment: Commenter 0286 stated that EPA is proposing to change longstanding 

provisions without any justification of its authority to make the changes and without apparent 

factual analysis of the statutory criteria for standard-setting. The commenter also asserts that 

EPA does not have the authority to impose more stringent requirements (by requiring that 

emission limits apply during times of SSM). The commenter stated:

“While EPA does not make the distinction clearly in the proposed rule, the 

proposed SSM provisions, unlike the remainder of the proposed rule, are changes 

to existing MACT standards that EPA promulgated previously pursuant to CAA 

section 112 (d)(2)-(3) for the six NESHAP categories. The Clean Air Act does not 

contemplate, however, EPA returning to previously issued MACT standards to 

improve them or bring them up-to-date...EPA did not invoke its section 112(d)(6) 

authority to support the proposed SSM provisions (see, e.g., 75 Fed. Reg. at 

65,074 cols. 1-2), but even if it had, section 112 (d)(6) does not provide broad 

authority to reconsider aspects of previously issued MACT standards unrelated to 

“developments in practices, processes, and control technologies.” Thus, EPA 

cannot simply change its mind about what standards are required to comply with 

CAA section 112 (d)(2)-(3), nor can it recalculate a MACT floor based on 

subsequent performance. Cf. NRDC v. EPA, 529 F.3d 1077, __(D.C. Cir. 2008) 

(rejecting contention that CAA section 112(f) requires EPA to “start from 

scratch” and develop new MACT standards).

Commenter 0286 further asserts that imposing more stringent requirements to existing 

NESHAPs based on the previous MACT floor would not only be inconsistent with the 

technology review and residual risk authority cited above, but “also with Congress’s desire for 

finality evident in the judicial review provisions of CAA section 307(b). Challenges to MACT 

standards needed to be raised within 60 days of their promulgation.” The commenter notes that 

regulated facilities have made capital investments and developed operating procedures to meet 

the existing MACT standards, and that “the CAA does not allow EPA simply to revisit the 

analysis and decisions involved in developing emission standards that meet the requirements of 

CAA section 112(d)(2)-(3)”. 

Commenter 0295 stated that extending the MACT standards to periods of startup, 

shutdown , and malfunction violates the CAA because the original standards expressly excluded 

SSM and EPA’s database and analyses excluded periods of SSM, and EPA has not conducted a 

new 112 (d) analysis to support standards during periods of SSM. Commenter 0295 also stated 

that they oppose EPA’s repeal, without meaningful discussion, of the flexibility previously 

granted to vary from the manufacturer’s recommendations.

Response: In Medical Waste Institute v. EPA, 645 F. 3d 420, 425-27 (D.C. Cir. 2011), 

the D.C. Circuit held that EPA may permissibly amend improper MACT determinations, 

including amendments to improperly promulgated floor determinations, using its authority under 
78

section 112 (d) (2) and (3). The absence of standards for these HAP is not proper. National Lime, 

233 F. 3d at 633-34; see also Medical Waste Incinerator, 645 F. 3d at 426 (resetting MACT 

floor, based on post-compliance data, permissible when originally-established floor was 

improperly established, and permissibility of EPA’s action does not turn on whether the prior 

standard was remanded or vacated).

Similarly, the D.C. Circuit’s December 9, 2011decision in Portland Cement Ass’n v. 

EPA (D.C. Cir. No. 10-1358) confirms that EPA is not constrained by section 112 (d)(6) and it 

may reassess its standards more often, including revising existing floors if need be. Slip op. p. 

17. The commenters are thus incorrect that section 112 (d)(6) provides the exclusive authority to 

address standards that apply during SSM events.

Comment: Commenter 0295 stated that extending the MACT standards to periods of 

startup, shutdown, and malfunction violates the CAA because the original standards expressly 

excluded SSM and EPA’s database and analyses excluded periods of SSM, and EPA has not 

conducted a new 112 (d) analysis to support standards during periods of SSM. Commenter 0295 

also stated that they oppose EPA’s repeal, without meaningful discussion, of the flexibility 

previously granted to vary from the manufacturer’s recommendations.

Response: Under CAA section 112(d)(2), the EPA must promulgate technology-based 

standards that reflect the maximum degree of emission reductions of HAP achievable (after

considering cost, energy requirements, and non-air quality health and environmental impacts). 

Nothing in the CAA or its legislative history suggests that EPA is prohibited from reviewing and 

revising MACT standards, except as part of the CAA section 112(d)(6) or CAA section 112(f)

reviews. Where we identify emission points that were erroneously not previously regulated under 

a MACT rule, we may identify MACT floor and beyond-the-floor control options for existing 

and new sources. An agency generally remains free to revise improperly promulgated or

otherwise unsupportable rules, even in the absence of a remand from a Court. United Gas 

Improvement Co. v. Callery Props., Inc., 382 U.S. 223, 229 (1966) (‘‘An agency, like a court, 

can undo what is wrongfully done by virtue of its order.’’); Macktal v. Chao, 286 F.3d 822, 825–

26 (5th Cir. 2002) (‘‘[I]t is generally accepted that in the absence of a specific statutory 

limitation, an administrative agency has the inherent authority to reconsider its decisions.’’).

Agencies have particularly broad authority to revise their regulations to correct their errors. Last 

Best Beef, LLC v. Dudas, 506 F.3d 333, 340 (4th Cir. 2007); Friends of the Boundary 

WaterWilderness v. Bosworth, 437 F.3d 815, 823 (8th Cir. 2006) (‘‘It is widely accepted that an 

agency may, on its own initiative, reconsider its interim or even final decisions, regardless of 

whether the applicable statute and agency regulations expressly provide for such review.’’) 

(citations omitted). Moreover, an agency may reconsider its methodologies and application of its

statutory requirements and may even completely reverse course, regardless of whether a court 

has determined that its original regulation is flawed, so long as the agency explains its bases for 

doing so. Motor Vehicle Mfrs. Ass’n v. State Farm Mutual Auto Ins. Co., 463 U.S. 29,

42 (1983); FCC v. Fox Television Stations, Inc., 129 S. Ct. 1800, 1810 (2009); Nat’l Cable & 

Telecomms. Ass’n v. Brand X Internet Servs., 545 U.S. 967, 981–82 (2005) (internal citations

omitted): (‘‘’An initial agency interpretation is not instantly carved in stone. On the contrary, the 

agency must consider varying interpretations and the wisdom of its policy on a continuing basis,’ 
79

Chevron, supra at 863–864, for example, in response to changed factual circumstances, or a 

change in administration. That is, no doubt, why in Chevron itself, this Court deferred to

an agency interpretation that was a recent reversal of agency policy.’’)

Comment: Two commenters (0286 and 0295) argued that the EPA does not have 

continuous section 112-compliant standards. Commenters 0286 and 0295 stated that under CAA 

section 112(d)(2), MACT standards must be “achievable”; a limit that applies during SSM events 

has not been demonstrated to be achievable by the best-performing 12% of units in the source 

category. Commenter 0295 argued that Sierra Club v. EPA holds that “Congress has required 

that there must be continuous section 112-compliant standards.” Sierra Club, slip op. at 15, but 

that the EPA does not have continuous section 112-complaint standards.

Commenter 0295 asserts that the proposal to extend the existing standards to periods of 

startup and shutdown potentially invalidates the existing standards, as these periods should have 

been included in determining the “best performing” source for purposes of determining the 

MACT floor and then MACT. The commenter observes that the existing standards were not 

developed with consideration of SSM, and these standards are acceptable if they apply

continuously, except during SSM. The commenter stated that extending the standards to cover 

startup and shutdown extends the existing standards without compliance with the applicable 

Clean Air Act section 112(d) requirements.

According to commenter 0295, under the rationale used in the Sierra Club decision, 

extending the Steel Pickling MACT standards to cover SSM periods constitutes a reopening of 

the Steel Pickling MACT standards. The commenter asserted that once reopening occurs, the 

existing standards are subject to invalidation for failing to meet the “continuous” requirement 

established by the court in Sierra Club as that standard applies to startup, shutdown and 

malfunction, which have never been addressed. Further, EPA has no reasonable prospect of 

saving these standards should it proceed because all of the emissions data available to EPA 

excludes SSM emissions, due to the requirements of 40 C.F.R. § 63.7(e)(1). The commenter 

recommends that the EPA withdraw this rule, gather the information necessary to establish SSM 

limits under Section 112(d) or (h), and then re-propose a rule aimed exclusively at addressing 

SSM periods.

As incorporated by reference, commenter 0295 adopted the comments in docket EPAHQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 as follows:

One commenter (91.1) recommended that EPA conduct stack testing during startup and 

shutdown events, but also acknowledged that emissions testing during startup and shutdown will 

not be an option in all cases. The commenter (91.1) stated that if the Proposed Regulations are 

adopted, EPA should be able to use continuous monitoring data to set alternative emission 

standards that apply during startup and shutdown, or conclude that sources with the identified 

control technology will be able to meet emission limitations established for normal operations 

during startup and shutdown periods, as well. The commenter (91.1) suggested that continuous 

monitoring data during some SSM events should be possible for the next review of emission 

standards, from those facilities that opt to use the continuous emission monitor option in the 

Proposed Rule, since the Proposed Rule would require such facilities to operate and report data 
80

from continuous monitors even during SSM events other than during monitor malfunction or 

downtime. The commenter (91.1) also suggested that EPA could study facilities’ operational logs 

to determine an averaging time for an emission standard sufficiently long that typical startups 

and shutdowns would not cause an exceedance of the standard. The commenter (91.1) further 

suggested that EPA might determine, based on infeasibility of collecting representative data 

during startup and shutdown events, that it is necessary and appropriate to promulgate a design, 

equipment, work practice, or operational standard, pursuant to CAA section 111(h) and/or 

section 302(k), in lieu of deriving limitations on the mass or concentration of pollutants emitted 

during startup or shutdown. 

One commenter (91.1) recommended EPA revise the proposed standards to account 

better for SSM events, rather than rely on an affirmative defense to make up for its failure to do 

so.

Commenter 0295 finds that the EPA’s definition of a malfunction does not match the 

definition of process interruptions that would be excluded during a stack testing program. The 

commenter stated that the EPA cannot exclude non-optimal periods in setting the standards if the 

standards will apply to those periods unless it exempts them from the standards, which it has 

refused to do for any interruption that does not qualify as a “malfunction.” The commenter asks 

that the EPA address how its approach, which collects data only from “normal” operations 

exclusive of SSM or process interruption, can be reconciled with the requirements of Clean Air 

Act section 112(d) that the data be “achieved,” demonstrated in practice, and from the best 

performing source(s).

Response: 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 startup, shutdown, and malfunction (SSM). Sierra Club v. 

EPA, 551 F.3d 1019 (D.C. Cir. 2008), cert. denied, 130 S. Ct. 1735 (2010). Specifically, the 

Court vacated the SSM exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), that 

was part of a regulation, commonly referred to as the “General Provisions Rule,” that the EPA 

promulgated under CAA section 112. When incorporated into CAA section 112(d) regulations 

for specific source categories, these two provisions exempted sources from the requirement to 

comply with the otherwise applicable CAA section 112(d) emission standard during periods of 

SSM.

We have eliminated the SSM exemption for Steel Pickling facilities in this rule. 

Consistent with Sierra Club v. EPA, the EPA has established standards in this rule for all periods 

of operation. We have also revised Table 1 to subpart CCC (the General Provisions table) in 

several respects. For example, we have eliminated the incorporation of the General Provisions’ 

requirement that the source develop an SSM plan. We have also eliminated or revised certain 

recordkeeping and reporting that related to the SSM exemption. The EPA has attempted to 

ensure that we have not included in the regulatory language any provisions that are 

inappropriate, unnecessary, or redundant in the absence of the SSM exemption. 

In establishing the standards in this rule, the EPA has taken into account startup and 

shutdown periods and we are not promulgating separate emission standards for periods of startup 
81

and shutdown for the Steel Pickling source categories in this rule because we believe compliance 

with the standards is achievable during these periods.

Information on periods of startup and shutdown in the industry indicate that emissions 

during these periods do not increase. Furthermore, all processes are controlled and these controls 

would not typically be affected by startup or shutdown. Therefore, the EPA is not adopting 

separate standards for periods of startup and shutdown.

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 

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

during periods of malfunction be factored into development of CAA section 112 standards. 

Under section 112, emissions standards for new sources must be no less stringent than the level 

“achieved” by the best controlled similar source and for existing sources generally must be no 

less stringent than the average emission limitation “achieved” by the best performing 12 percent 

of sources in the category. There is nothing in section 112 that directs the agency to consider 

malfunctions in determining the level “achieved” by the best performing or best controlled 

sources when setting emission standards. Moreover, while the EPA accounts for variability in 

setting emissions standards consistent with the section 112 case law, nothing in that case law 

requires the agency to consider malfunctions as part of that analysis. Section 112 uses the 

concept of “best controlled” and “best performing” unit in defining the level of stringency that 

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 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) (EPA typically has wide latitude in determining the extent of data-gathering 

necessary to solve a problem.) We generally defer to an agency's decision to proceed on the basis 

of imperfect scientific information, rather than to "invest the resources to conduct the perfect 

study". See also, Weyerhaeuser v Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) (“In the nature of 

things, no general limit, individual permit, or even any upset provision can anticipate all upset 

situations. After a certain point, the transgression of regulatory limits caused by ‘uncontrollable 

acts of third parties,’ such as strikes, sabotage, operator intoxication or insanity, and a variety of 

other eventualities, must be a matter for the administrative exercise of case-by-case enforcement 

discretion, not for specification in advance by regulation.”). In addition, the goal of a best 

controlled or best performing source is to operate in such a way as to avoid malfunctions of the 

source and accounting for malfunctions could lead to standards that are significantly less 

stringent than levels that are achieved by a well-performing non-malfunctioning source. The 

EPA’s approach to malfunctions is consistent with CAA section 112 and is a reasonable 

interpretation of the statute. In a separate response to comment, we respond to comments that 
82

emissions during malfunctions should be accounted for in assessing risk pursuant to CAA 

section 112 (f)(2).

In the event that a source fails to comply with the applicable CAA section 112(d) 

standards as a result of a malfunction event, the EPA would determine an appropriate response 

based on, among other things, the good faith efforts of the source to minimize emissions during 

malfunction periods, including preventative and corrective actions, as well as root cause analyses 

to ascertain and rectify excess emissions. The EPA would also consider whether the source's 

failure to comply with the CAA section 112(d) standard was, in fact, “sudden, infrequent, not 

reasonably preventable” and was not instead “caused in part by poor maintenance or careless 

operation.” 40 CFR 63.2 (definition of malfunction).

Finally, the EPA recognizes that even equipment that is properly designed and 

maintained can sometimes fail and that such failure can sometimes cause an exceedance of the 

relevant emission standard. (See, e.g., State Implementation Plans: Policy Regarding Excessive 

Emissions During Malfunctions, Startup, and Shutdown (September 20, 1999); Policy on Excess 

Emissions During Startup, Shutdown, Maintenance, and Malfunctions (February 15, 1983).) The 

EPA is therefore adding to the final rule an affirmative defense to civil penalties for exceedances 

of emission limits that are caused by malfunctions. 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 have added 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 63.552 (see 40 CFR 22.24). The criteria ensure that the 

affirmative defense is available only where the event that causes an exceedance of the emission 

limit meets the narrow definition of malfunction in 40 CFR 63.2 (sudden, infrequent, not 

reasonable preventable and not caused by poor maintenance and or careless operation). For 

example, to successfully assert the affirmative defense, the source must prove by a 

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 

63.552 and to prevent future malfunctions. For example, the source must prove by a 

preponderance of the evidence that “[r]epairs were made as expeditiously as possible when the 

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

to minimize the impact of the excess emissions on ambient air quality, the environment and 

human health....” In any judicial or administrative proceeding, the Administrator may challenge 

the assertion of the affirmative defense and, if the respondent has not met its burden of proving 

all of the requirements in the affirmative defense, appropriate penalties may be assessed in 

accordance with CAA section 113 (see also 40 CFR 22.27). 

The EPA is including an affirmative defense in the final rule in an attempt to balance a 

tension, inherent in many types of air regulations, 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 
83

emission standards that “limit the quantity, rate, or concentration of emissions of air pollutants 

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

standard”). See generally Sierra Club v. EPA, 551 F.3d 1019, 1021 (D.C. Cir. 2008). Thus, the 

EPA is required to ensure that section 112 emissions limitations are continuous. The affirmative 

defense for malfunction events meets this requirement by ensuring that even where there is a 

malfunction, the emission limitation is still enforceable through injunctive relief. While 

“continuous” limitations, on the one hand, are required, there is also 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, 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.

Comment: Commenter 0286 stated that the proposed rule takes an unreasonable 

approach concerning the obligations of the source during periods of SSM. The commenter 

noted, 

“For example, the existing MACT standards in part 63 subpart U contain

numerous provisions that are different from what EPA proposes to replace them 

with. The statement that ‘the owner or operator shall implement, to the extent 

reasonably available, measures to prevent or minimize excess emissions to the 

extent practical’ would be eliminated, and in its place would be a condition for

the affirmative defense that the ‘frequency, amount, and duration of the excess

emissions (including any bypass) were minimized to the maximum extent 

practicable during periods of such emissions.’ Compare 40 C.F.R. 

§63.480(j)(4) with proposed section 63.480(j)(4)(i)(C). A provision prohibiting 

a source from shutting down control equipment under certain circumstances 

(proposed section 63.480(j)(3)) would no longer be qualified, as it is in the 

current rule, that this prohibition does not apply if the compliance equipment is

shut down ‘to avoid damage due to a contemporaneousstart-up, shutdown, or 

malfunction of the affected source or portion thereof’ or to avoid damage to 

monitoring equipment. See 40 C.F.R. § 63.480(j)(3). It is not clear whether 

EPA means by these changes to say, for example, that control equipment must

not be shut down even when continued operation will damage it, or whether the 
84

differences are unintended.”

Commenter 0286 argued that EPA must demonstrate how the revised standards reflect 

the performance actually achieved by the best-performing sources, or meet the criteria for 

beyond-the-floor standards. Commenter 286 also notes that EPA has several options for setting 

MACT standards for SSM periods, including establishing work practice standards under CAA 

section 112(h).

Response: With respect to the commenter‘s suggestion to establish work practice 

standards for malfunctions, EPA‘s approach to malfunctions is the same irrespective of the form 

of the standard at issue. See response provided above regarding malfunctions. 

The EPA recognizes that even equipment that is properly designed and maintained can 

fail and that such failure can cause a violation of the relevant emission standard. The EPA is 

including an affirmative defense in the final rule as we have in other recent section 111, section 

112, and section 129 rules so as to balance the tension, inherent in many types of air regulation, 

to ensure adequate compliance while simultaneously recognizing that despite the most diligent of 

efforts, emission limits may be exceeded under circumstances beyond the control of the source. 

The EPA must establish emission standards that “limit the quantity, rate, or concentration of 

emissions of air pollutants on a continuous basis.” 42 U.S.C. § 7602(k) (defining “emission 

limitation and emission standard”). See generally Sierra Club v. EPA, 551 F.3d 1019, 1021 (D.C. 

Cir. 2008) (emissions limitations under both must continuously apply and meet minimum 

stringency requirements, even during periods of startup, shutdown and malfunction). Thus, the 

EPA is required to ensure that emissions limitations are continuous. The affirmative defense for 

malfunction events meets this requirement by ensuring that even where there is a malfunction, 

the emission limitation is still enforceable through injunctive relief.

While “continuous” limitations, on the one hand, are required, there is also case law 

indicating that in some situations it is appropriate for the EPA to account for the practical 

realities of technology. For example, in Essex Chemical v. Ruckelshaus, 486 F.2d 427, 433 (D.C. 

Cir. 1973), the D.C. Circuit acknowledged that in setting standards under CAA section 111 

“variant provisions” such as provisions allowing for upsets during startup, shutdown and 

equipment malfunction “appear necessary to preserve the reasonableness of the standards as a 

whole and that the record does not support the ‘never to be exceeded’ standard currently in 

force.” See also, Portland Cement Association v. Ruckelshaus, 486 F.2d 375 (D.C.Cir. 1973). 

Though intervening case law such as Sierra Club v. EPA and the CAA 1977 amendments calls 

into question the relevance of these cases today, they support the EPA’s view that a system that 

incorporates some level of flexibility is reasonable. The affirmative defense simply provides for 

a defense to civil penalties for excess emissions that are proven to be beyond the control of the 

source. By incorporating an affirmative defense, the EPA has formalized its approach to upset 

events. In a Clean Water Act setting, the Ninth Circuit required this type of formalized approach 

when regulating “upsets beyond the control of the permit holder.” Marathon Oil Co. v. EPA, 564 

F.2d 1253, 1272-73 (9th Cir. 1977). 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 
85

“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. 

Moreover, even if malfunctions were considered a distinct operating mode, we believe it 

would be impracticable to take malfunctions into account in setting CAA section 112 standards. 

As noted above, by definition, malfunctions are sudden and unexpected events, and it would be 

difficult to set a standard that takes into account the myriad different types of malfunctions that 

can occur across all sources in the category. Moreover, malfunctions can vary in frequency, 

degree, and duration, further complicating standard setting.

Comment: Commenters 0295 and 0286 assert that the EPA does not discuss startup and 

shutdown and whether the standards are achieved in practice, as required by Clean Air Act 

section 112(d)(2) (for floor), or are “achievable,” as required by section 112(d)(1) (for above the 

floor determinations). 

Commenter 0295 disagrees with the EPA’s assertion that, “any emissions that occur 

during malfunctions do not need to be factored into the development of CAA section 112(d) 

standards, which, once promulgated, apply at all times.” 75 Fed. Reg. at 65074. 

The commenter notes that the EPA has a statutory requirement to consider “the emission 

control that is achieved in practice by the best controlled similar source.” The commenter argues 

that the EPA’s interpretation of “best performing” leads to the absurd result that a source with a 

very high level of control that functions only a small percent of the time, and fails to function 

well the rest of the time, establishes the level of control. The commenter states that this turns the 

concept of “demonstrated in practice” and “achieved” or “achievable” on its head.

As incorporated by reference, commenter 0295 adopted the comments in docket EPA-HQ-OAR2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 as follows:

One commenter (91.1) argued, by virtue of the variability analysis itself, the Proposed 

Standards are representative of emissions achieved during normal (very stable) operations and 

are not representative of emissions during SSM events (which can be highly variable). The 

commenter (91.1) stated that the variability EPA used in setting the Proposed Standard reflects at 

most only the normal variation in emissions experienced during normal operations because the 

analysis was performed on emissions data from performance tests, when the source is being 

operated at normal levels and when efforts are being made to maintain steady-state conditions. 

The commenter (91.1) purported that since performance test data are not collected during SSM 

events, the variability factors EPA derived to establish the Proposed Standards could not possibly 

incorporate emissions variability experienced during SSM events. Commenter (91.1) stated that 

for these same reasons, EPA’s attempt to consider variability in setting emission standards does 

not eliminate the need for different standards that apply during malfunctions.

Response: We acknowledge the commenters for their suggestion on further data 

gathering. We know of no facilities in this source category that currently conduct continuous 

emissions monitoring. For the reasons explained above, EPA is not promulgating a separate 

emission standard for the source category that applies during periods of startup and shutdown. 

With regard to malfunctions, see response provided above.
86

In today’s rule, the EPA is finalizing the proposed affirmative defense language for 

exceedances of the numerical emission limits that are caused by malfunctions. As explained at 

proposal, the EPA recognizes that even equipment that is properly designed and maintained can 

fail and that such failure can cause an exceedance of the relevant emission standard. The EPA is 

including an affirmative defense in the final rule as we have in other recent section 112 and 

section 129 rules so as to balance the tension, inherent in many types of air regulation, to ensure 

adequate compliance while simultaneously recognizing that despite the most diligent of efforts, 

emission limits may be exceeded under circumstances beyond the control of the source. The 

EPA must establish emission standards that “limit the quantity, rate, or concentration of 

emissions of air pollutants on a continuous basis.” 42 U.S.C. § 7602(k)(defining “emission 

limitation and emission standard”). See generally Sierra Club v. EPA, 551 F.3d 1019, 1021 (D.C. 

Cir. 2008) (emissions limitations under CAA section 112 must both continuously apply and meet 

section 112’s minimum stringency requirements, even during periods of startup, shutdown and 

malfunction). Thus, the EPA is required to ensure that section 112 emissions limitations are 

continuous. The affirmative defense for malfunction events meets this requirement by ensuring 

that even where there is a malfunction, the emission limitation is still enforceable through 

injunctive relief. While “continuous” limitations, on the one hand, are required, there is also case

law indicating that in some situations it is appropriate for the EPA to account for the practical 

realities of technology. For example, in Essex Chemical v. Ruckelshaus, 486 F.2d 427, 433 (D.C. 

Cir. 1973), the D.C. Circuit acknowledged that in setting standards under CAA section 111 

“variant provisions” such as provisions allowing for upsets during startup, shutdown and 

equipment malfunction “appear necessary to preserve the reasonableness of the standards as a

whole and that the record does not support the ‘never to be exceeded’ standard currently in 

force.” See also, Portland Cement Association v. Ruckelshaus, 486 F.2d 375 (D.C.Cir. 1973). 

Though intervening case law such as Sierra Club v. EPA and the CAA 1977 amendments calls 

into question the relevance of these cases today, they support the EPA’s view that a system that 

incorporates some level of flexibility is reasonable. The affirmative defense simply provides for 

a defense to civil penalties for excess emissions that are proven to be beyond the control of the 

source. By incorporating an affirmative defense, the EPA has formalized its approach to upset 

events. In a Clean Water Act setting, the Ninth Circuit required this type of formalized approach 

when regulating “upsets beyond the control of the permit holder.” Marathon Oil Co. v. EPA, 564 

F.2d 1253, 1272-73 (9th Cir. 1977). See also, Mont. Sulphur & Chem. Co. v. United States EPA, 

2012 U.S. App. LEXIS 1056 (Jan 19, 2012)(rejecting industry argument that reliance on the 

affirmative defense was not adequate). But see, Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 

1057-58 (D.C. Cir. 1978) (holding that an informal approach is adequate). The affirmative 

defense provisions give the EPA the flexibility to both ensure that its emission limitations are 

“continuous” as required by 42 U.S.C. §7602(k), and account for unplanned upsets and thus 

support the reasonableness of the standard as a whole. 

As also explained at proposal, 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. As the EPA further explained, accounting for malfunctions would 

be difficult, if not impossible, given the myriad different types of malfunctions that can occur 

across all sources in the category and given the difficulties associated with predicting or 

accounting for the frequency, degree, and duration of various malfunctions that might occur. The 
87

EPA’s rationale for its approach to malfunctions is not based on the criteria that must be met to 

justify a work practice standard under CAA section 112(h). Section 112 (h) (2) provides that 

such a finding must be based on a determination that “a hazardous air pollutant or pollutants 

cannot be emitted through a conveyance designed and constructed to emit or capture such 

pollutant, or that any requirement for, or use of, such a conveyance would be inconsistent with 

any Federal, State or local law” or “the application of measurement methodology to a particular 

class of sources is not practicable due to technological and economic limitations.” Thus, section 

112(h) “allows EPA to substitute work practice standards for emission floors only if measuring 

emission levels is technologically or economically infeasible.” Sierra Club v. EPA, 479 F. 2d 

875, 880 (D.C. Cir. 2007). Further, setting work practice standards under section 112 presents 

the same issues as setting numerical emission limits given the varied nature of malfunctions. In 

any event, the commenter has not provided support for its assertion that it would not be 

technically feasible to accurately measure emissions and impracticable to enforce numeric 

emissions limits during malfunction and breakdown. Sources in this category can and do operate 

multiple measurement systems that measure different parameters at different points in their 

production processes and on affected sources and control equipment. While direct measurement 

of some factors may or may not take place during certain malfunctions, the EPA is not persuaded 

that sources could be left with no means whatsoever to determine whether they stayed in 

compliance during a malfunction. Sources may use other available means (including engineering 

judgment) or information to demonstrate that the source complied with the standard.

Comment: As incorporated by reference, commenter 0295 adopted the comments in 

docket EPA-HQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 

as follows. Commenter 0286 also presented these views.

One commenter (91.1) argued that EPA provides no explanation of how it determined 

that malfunctions are not a distinct operating mode; and EPA offers no explanation of how it 

determined that, even though it believes malfunctions are not a distinct operating mode, 

emissions during malfunctions should not be used to characterize the source’s operating mode. 

The commenter (91.1) agreed with EPA’s conclusion that the factual complexity of differing 

processes and of the severity, frequency, and duration of malfunctions makes standard-setting 

difficult. The commenter (91.1) stated that it is often impossible to gather emission data during 

malfunctions (either for standard-setting or for compliance demonstration purposes). The 

commenter (91.1) stated that malfunctions are by definition unexpected, so it is not possible to 

plan to have test equipment in place to measure emissions when one occurs; and even if test or 

monitoring equipment is in place, emissions during malfunctions often are not routed to a stack 

where they can be measured, and upsets during stack testing invalidate the test results under 

EPA’s approved test methods.

One commenter (91.1) asserted that EPA is going beyond the MACT floor without 

making the demonstrations that the statute and case law require EPA to make in order to impose 

beyond-the-floor MACT standards. The commenter (91.1) stated that this is especially obvious 

when one considers the multitude of conditions EPA proposes to impose on sources during 

malfunctions, in order to be excused from civil penalties: EPA makes no attempt to justify those 

conditions as reasonable, taking into consideration the cost of achieving such emission reduction, 
88

and any non-air quality health and environmental impacts and energy requirements (referenced 

CAA section 129(a)(2)).

Response: EPA is not setting a beyond-the-floor standard. For the reasons described in 

the above responses, EPA‘s approach to malfunctions is consistent with section 112 and is a 

reasonable interpretation of the statute. Even if malfunctions were considered a distinct operating 

mode, we believe it would be impracticable to take malfunctions into account in setting CAA 

section 112 standards. As noted above, by definition, malfunctions are sudden and unexpected 

events, and it would be difficult to set a standard that takes into account the myriad different 

types of malfunctions that can occur across all sources in the category. Moreover, malfunctions 

can vary in frequency, degree, and duration, further complicating standard setting. In light of the 

Sierra Club decision, EPA proposed to require that sources be in continuous compliance with 

emissions limits at all times, even during SSM and are finalizing in this action. 

Comment: As incorporated by reference, commenter 0295 adopted the comments in 

docket EPA-HQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 

as follows. Commenter 0286 provided these arguments as well.

One commenter (91.1) provided examples where courts have recognized that a 

technology based standard discards its fundamental premise when it ignores the limits inherent in 

technology (NRDC v. EPA, 859 F.2d 156, 208 (D.C. Cir. 1988)). The commenter (91.1) stated 

that the D.C. Circuit recognized, in Portland Cement Ass'n v. Ruckelshaus, 486 F.2d 375, 398 

(D.C. Cir. 1973), a decision reviewing standards under CAA section 111, that startup and upset 

conditions due to plant or emission device malfunction, is an inescapable aspect of industrial life 

and that allowance must be made for such factors in the standards that are promulgated (Id. at 

399). Similarly, the commenter (91.1) mentioned Essex Chem. Corp. v. Ruckelshaus, 486 F.2d 

427, 432 (D.C. Cir. 1973), cert. denied, 416 U.S. 969 (1974), another section 111 case, the court 

held that SSM provisions are necessary to preserve the reasonableness of the standards as a 

whole (Id. at 433). The commenter (91.1) also mentioned National Lime Ass‘n v. EPA, 627 F.2d 

416 (D.C. Cir. 1980), another case reviewing emission standards promulgated under CAA 

section 111, the court held CAA technology-based standards must be capable of being met under 

most adverse circumstances which can reasonably be expected to recur, such as during periods of 

SSM (627 F.2d at 431 n.46).

Commenter 0286 made similar comments and also provided additional examples. The 

commenter cited the Clean Water Act requirementsthat EPA establish technology-based 

effluent limitations based on the best available control technology. The commenter stated that 

knowing that there would be periods where a discharger, even with “exemplary use of” the 

identified best technology, would exceed the effluent limitations because of conditions “beyond 

the control of the permit holder,” EPA violated the Clean Water Act by failing to provide an 

“upset provision” to address those periods. Marathon Oil Co. v. EPA,

564 F.2d 1253, 1273-74 (9th Cir. 1977). Commenter 2086 also cites e.g., NRDC v. EPA, 859 

F.2d at 207 (distinguishing between technology-based effluent limitations, where some provision

for “upsets” is required, and water-quality-based effluent limitations, which are tied to achieving

water quality standards rather than based on available technology, and therefore need not include

an upset provision).
89

Response: There is nothing in the plain language of the statute or in case law addressing 

section 112 that directs the Agency to consider malfunctions in determining the level achieved 

by the best performing sources for purposes of setting standards under section 112. As explained 

in the preamble and elsewhere in this response to comment document, EPA‘s approach to 

malfunctions is a reasonable interpretation of the requirements of section 112. The relevance of 

Portland Cement and Essex Chem Corp. is questionable in light of subsequent case law and the 

1977 amendments to the Clean Air Act‘s definition of emission standard requiring that such 

standards be continuous. Further, the NRDC case interprets provisions of the Clean Water Act 

that are different in nature than provisions governing standards under section 112 of the Clean 

Air Act.

In any event, even if those cases are relevant, EPA‘s overall approach to malfunction 

events in this rule, including the promulgation of an affirmative defense, is consistent with the 

approach set forth in EPA’s 1972 proposed rules cited favorably in Portland Cement and Essex 

Chemical in that both EPA’s approach today and in 1972 impart a construction of 

"reasonableness" to the standards as a whole and adopts a more flexible system of regulation 

than can be had by a system devoid of "give." (Portland Cement at 399). Portland Cement and 

Essex criticized EPA regulations that contained no specific provisions to address malfunctions 

and EPA‘s assertion that malfunctions would be dealt with by the informal exercise of discretion 

in the Agency‘s enforcement activities. Those decisions did not require exemptions or less 

stringent standards for malfunction events as the commenter suggests. EPA‘s approach to 

malfunctions goes further than reliance on the informal exercise of enforcement discretion in that 

it includes regulatory provisions establishing an affirmative defense to civil penalties for 

exceedances of emission limits that are caused by malfunctions.

As noted above, the NRDC v EPA, 859 F. 2d 156, 207(D.C. Cir. 1988) case cited by the 

commenter is not on point and the discussion of technology-based standards is dicta. 

Nevertheless, EPA‘s approach to malfunctions is consistent with the NRDC decision. The 

NRDC decision does not require exemptions or less stringent standards for malfunctions either. 

Further, the regulatory affirmative defense included in today‘s final rule is consistent with the 

case cited in the NRDC decision; Marathon Oil Co. v. EPA, 564 F.2d 1253, 1272 (9th Cir. 

1977). The court in Marathon Oil held that EPA must formalize its approach to upsets under the 

Clean Water Act. The affirmative defense does so. But see, Weyerhaeuser v Costle, 590 F.2d 

1011, 1057-58 (D.C. Cir. 1978) (holding that an informal approach is adequate).

At proposal we explained that the D.C. Court had recently vacated the SSM exemption 

contained in 40 C.F.R. § 63.6(f)(1) and § 63.6(h)(1) that are part of the section 112 regulations 

commonly referred to as the General Provisions (GP) rule. Sierra Club v. EPA, 551 F.3d 1019 

(D.C. Cir. 2008) cert. denied, 130 S. Ct 1735 (2010). We further explained that when 

incorporated into section 112(d) regulations for specific source categories, these two provisions 

exempt sources from the requirement to comply with otherwise applicable MACT standards 

during periods of SSM. We also explained that because the Steel Pickling NESHAP relied on 

the GP rule for SSM provisions (40 C.F.R. §§ 63.1194 and 63.1386(c), respectively) we were 

proposing to set standards that applied during SS periods for these source categories. (76 Fed. 

Reg. at 72775). EPA does not claim that the Sierra Club case constrains its authority to prescribe 
90

unique standards for SSM periods. Rather EPA’s view is that this decision calls into question the 

legality of source category-specific SSM exemptions in rules promulgated pursuant to section 

112.

One commenter asserted that in National Lime Ass‘n v. EPA, 627 F.2d 416 (D.C. Cir. 

1980), (the commenter asserted that) the court held that “CAA technology-based standards must 

be capable of being met under most adverse circumstances which can reasonably be expected to 

recur, such as during periods of SSM (627 F.2d at 431 n.46).” The EPA disagrees that periods of 

SSM were referenced in that context, noting that the commenter added the phrase “such as 

during periods of SSM” where the phrase was not present in the opinion. Further, the EPA 

disagrees that such periods were contemplated by the court in that context. 

Taken in the appropriate context, the language cited by the commenter supports the 

EPA’s view that MACT standards adopted with an appropriate level of leeway for variation in 

normal operations is sufficient to meet the requirement of the CAA that standards be"... based on 

the emission levels achieved through the application of MACT floor technologies and account 

for variation in the process and in the air pollution control device effectiveness." 64 Fed. Reg. 

31,916 (June 14, 1999) (quoting Sierra, 167 F.3d at 665), 

Comment: As incorporated by reference, commenter 0295 adopted the comments in 

docket EPA-HQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 

as follows:

Commenter 0091 questions the EPA’s legal authority in the CAA to shift the burden to 

the regulated community of proving (or disproving) essential elements of an alleged violation. 

The commenter believes that the statute is silent as to the issue and “the ordinary default rule [is] 

that plaintiffs bear the risk of failing to prove their claims.” Shaeffer v. Weast, 546 U.S. 49 

(2005), quoting McCormick on Evidence §337, at 412. (“The burdens of pleading and proof with 

regard to most facts have and should be assigned to the plaintiff who generally seeks to change 

the present state of affairs and who therefore naturally should be expected to bear the risk of 

failure or proof or persuasion”); C. Mueller & L. Kirkpatrick, Evidence § 3.1, p. 104 (3d ed. 

2003) (“Perhaps the broadest and most accepted idea is that the person who seeks court action 

should justify the request, which means that the plaintiffs bear the burdens on the elements in 

their claims”). 

The commenter notes that while the Supreme Court has recognized exceptions such as 

affirmative defenses, the commenter asserts that courts retain the authority to establish such rules 

unless Congress acts to delegate that authority. In this instance, according to the commenter, the 

EPA has not provided any statutory authority, nor any real justification, for requiring a source to 

prove its innocence; moreover, to fully demonstrate its innocence within 30 days of the event, 

without even being charged. The commenter stated that if the EPA adopts an approach along the 

lines of the proposed affirmative defense, it should be stated instead in terms that, once a source 

has claimed that its excess emissions were related to a malfunction, it will not be considered to 

be in violation of the standards unless the enforcement authority demonstrates that the source is 

not entitled to claim the malfunction.
91

Commenter 0286 also provided these comments, and noted that the preamble to the 

proposed rule does not give any explanation for why the affirmative defense would not apply to 

injunctive relief

Commenter 0286 believes that the proposed changes inappropriately shift the burden to 

the source to disprove alleged violations during malfunctions, and the limitations and 

requirements in the proposed rule are unreasonable and impracticable.

Response: The EPA disagrees with comments that criticize the affirmative defense for 

shifting the burden of proof. The affirmative defense does not require a facility to prove its 

innocence rather than requiring an enforcement authority to prove a violation of the CAA or 

change the burden of proof with respect to establishing a violation. The affirmative defense 

applies to penalties and thus is only utilized where a violation has been established. The burden 

of proof remains with the plaintiff in an enforcement action. See, e.g., 40 C.F.R. 22.24. If a 

violation has been established and a source wishes to assert the affirmative defense with respect 

to penalties, the source does bear the burden of establishing that the elements of the affirmative 

defense have been met. This burden-shifting is appropriate because the source is in a better 

position to determine the facts required to establish the defense. See, e.g., Arizona Pub. Serv. Co. 

v. EPA, 562 F.3d 1116, 1120, 1129-30 (10th Cir. 2009) (rejecting industry challenge to the 

EPA’s use of an affirmative defense to address excess emissions during malfunction events).

Comment: As incorporated by reference, commenter 0295 adopted the comments in 

docket EPA-HQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 

as follows. Commenter 0286 reiterated these comments. The commenter (91.1) disagreed with 

EPA‘s affirmative defense option and argued that inclusion of the affirmative defense does not 

cure EPA’s failure to set emission standards that are achievable during SSM events. The 

commenter (91.1) urged EPA to promulgate an emission standard that eliminates the situation 

where a source sometimes will be unable to comply with the Proposed Standards because of 

malfunctions, even if their equipment is properly designed and maintained, through no fault of 

the source. The commenter (91.1) recommended that sources be subject to differentiated 

requirements, achievable with the identified best technology, during SSM events. The 

commenter (91.1) argued that the proposed affirmative defense shifts the burden to the source to 

prove that a myriad number of criteria are met and actions were taken by the source (which bear 

no direct relation to the statutory factors for performance standards under CAA sections 111 and 

129), in order to avoid civil penalties.

Commenter 0295 stated that EPA should extend the affirmative defense to injunctive 

relief. The commenter argues that the EPA provides no rationale for its decision to exclude 

injunctive relief. The commenter notes that costs to a defendant of defending an injunctive relief 

action are equal to those to a penalty action. According to the commenter, if a defendant acted 

properly to claim the affirmative defense, it is unclear, under the balancing of equities test 

employed in equity, that injunctive relief could be granted.

Commenter 0295 recommends that the EPA clarify that the affirmative defense covers all 

enforcement and citizen suit actions, regardless of what entity brings the action. The commenter 

proposed that claims for statutory penalties of whatever type should be covered by the 
92

affirmative defense. The commenter asks that the EPA reword the affirmative defense to state 

that a source is “not in violation” if it meets the requirements of the affirmative defense.

Commenter 0295 also stated that the EPA’s policy of placing sources continuously outof-compliance, and using “enforcement discretion,” violates fundamental concepts of due 

process. The commenter asks that the EPA explain why it is not bound to “anticipate all upset 

situations” which may be dealt with by “enforcement discretion.” The commenter objects to the 

use of enforcement discretion, stating that it allows the EPA to be entitled to exercise a 

prerogative that is denied to every other agency and instrumentality of government in the United 

States.

As incorporated by reference, commenter 0295 adopted the comments in docket EPAHQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 as follows. 

Commenter 0286 also provided these comments.

One commenter (91.1) stated that it is not clear what the affirmative defense covers. In 

the Proposed Rule, EPA stated that the affirmative defense is “to a claim for civil penalties for 

exceedances of such standards that are caused by malfunction, as defined in section 60.2.” The 

commenter (91.1) asked whether the term “civil penalties,” which is not defined in the Proposed 

Rule, is intended to apply as well to a “civil administrative penalty” imposed by EPA under 

CAA section 113(d) (the term “civil penalty” in other contexts means only penalties imposed by 

a court). The commenter (91.1) also asked whether the affirmative defense apply to 

“noncompliance penalties” under CAA section 120 (which apply, inter alia, to noncompliance 

with a section 111 NSPS). The commenter (91.1) stated that to meet the purported purpose of the 

affirmative defense, which is to provide relief from emission limitations that cannot be met at 

times even with equipment that is properly designed and maintained (see 75 Fed. Reg. 63,283 

col. 2), the affirmative defense would need to apply to civil and administrative penalties, 

including noncompliance penalties.

Commenter (91.1) also pointed out that the preamble to the Proposed Rule does not give 

any explanation for why the affirmative defense would not apply to injunctive relief. The 

commenter (91.1) added that if in fact the excess emissions associated with the equipment or 

process failure are not reasonably preventable, then there is no apparent reason why injunctive 

relief should not be available either. The commenter (91.1) stated, as a matter of law, injunctive 

relief may not be available in cases where a civil penalty cannot be imposed (See Sierra Club v. 

Otter Tail Power Co., 615 F.3d 1008 (8th Cir. 2010)); under concurrent remedy doctrine, 

injunctive relief for a CAA violation is barred when civil penalty is barred by statute of 

limitations. The commenter (91.1) argued that maintaining liability for injunctive relief renders 

the affirmative defense particularly ineffective with respect to citizen suits. The commenter 

(91.1) stated that if the source is even potentially subject to injunctive relief, and therefore could 

be required to pay the citizen-plaintiff’s attorneys fees even if the source successfully 

demonstrated that it otherwise qualified for the affirmative defense, then the affirmative defense 

would not accomplish EPA’s stated objective of providing relief in situations where the emission 

limitations cannot be met despite proper design and operation of process and control equipment. 

Moreover, the commenter (91.1) contended that EPA has provided no analysis that would 

supersede its previous and long-standing determination that it is not desirable to rely on 
93

enforcement, rather than regulatory language, to address the inability to comply with section 111 

performance standards during SSM events (referenced 37 Fed. Reg. 17,214, 17,214 (Aug. 25, 

1972). See also Marathon Oil Co. v. EPA, 564 F.2d at 1273). 

The commenter (91.1) recommended EPA, at a minimum, state that the affirmative 

defense applies to civil penalties, civil administrative penalties, noncompliance penalties, and 

injunctive relief. The commenter (91.1) also recommended that EPA reword the “affirmative 

defense,” so that it stated that a source “will not be deemed in violation of” the Part LLLL or Part 

MMMM standards for excess emissions unless the event, and the source’s response to the event, 

do not meet the criteria spelled out in the regulations (referenced Cf. 40 CFR §80.613); 

configured in that way, this provision for malfunction should be called something other than an 

“affirmative defense,” such as an “alternative standard for SSM events”. The commenter (91.1) 

stated that if EPA refuses to set alternative emission standards that apply during SSM periods 

and continues to rely instead on the proposed affirmative defense, the affirmative defense must 

be substantially modified for it to provide any significant relief. The commenter (91.1) stated that 

the affirmative defense needs to state clearly that a source that qualifies for the affirmative 

defense shall not be deemed to have violated the applicable standards during that time; if EPA 

does that, it may be unnecessary to state also that the affirmative defense relieves the source 

from liability for all types of penalties and injunctive relief (save criminal penalties), but that 

should be the clear effect of qualifying for the affirmative defense.

Response: With respect to malfunctions, as explained in the proposed and final rules and 

in more detail elsewhere in this response to comment document, EPA has determined that CAA 

section 112 does not require that emissions that occur at such times be factored into development 

of CAA section 112 standards and that it is reasonable not to do so.

The EPA also disagrees with comments that criticize the affirmative defense for shifting 

the burden of proof. The affirmative defense does not require a facility to prove its innocence 

rather than requiring an enforcement authority to prove a violation of the CAA or change the 

burden of proof with respect to establishing a violation. The affirmative defense applies to 

penalties and thus is only utilized where a violation has been established. The burden of proof 

remains with the plaintiff in an enforcement action. See, e.g., 40 C.F.R. 22.24. If a violation has 

been established and a source wishes to assert the affirmative defense with respect to penalties, 

the source does bear the burden of establishing that the elements of the affirmative defense have 

been met. This burden-shifting is appropriate because the source is in a better position to 

determine the facts required to establish the defense. See, e.g., Arizona Pub. Serv. Co. v. EPA, 

562 F.3d 1116, 1120, 1129-30 (10th Cir. 2009) (rejecting industry challenge to the EPA’s use of 

an affirmative defense to address excess emissions during malfunction events).

The affirmative defense applies to civil penalties, including civil administrative penalties 

and penalties under section 120, but does not apply to injunctive relief or criminal penalties. The 

affirmative defense is available in any civil action to enforce the standards set forth in this rule, 

whether such action is brought by EPA, a state or local authority or a citizen. EPA agrees that in 

some cases, injunctive relief may not be appropriate if all the criteria of the affirmative defense 

have been satisfied. In such cases, liability for attorney’s fees is not a real issue. However, some 

form of injunctive relief may be appropriate. The Sierra Club v. Otter Tail Power Co case cited
94

by commenters is not on point and does not undermine EPA’s ability to limit the affirmative 

defense to penalty claims. The concurrent remedy doctrine provides that where a party's legal 

remedies are time-barred a party's concurrent equitable claims generally are barred. The 

affirmative defense is not a time-bar to civil penalties. EPA does not intend to provide an 

affirmative defense to criminal charges as the very nature of criminal charges is that there is 

alleged to be a knowing violation (CAA Section 113(c)(1-3), or a knowing or negligence release 

that threatens imminent danger to persons (CAA Section 113(c)(4)and (5)). In these 

circumstances, it is likely that the source did not do all that could be done to prevent the excess 

emissions. However, if there are circumstances that justify a knowing release as is suggested by 

the commenter, such circumstances can be raised in any enforcement action and may be the basis 

for a defense.

Further, the EPA’s view is that the affirmative defense is consistent with CAA sections 

113(e) and 304. Section 304 gives district court’s jurisdiction “to apply appropriate civil 

penalties.” Section 113(e)(1) identifies the factors that the Administrator or a court shall take into 

consideration in determining the amount of a penalty to be assessed only after it has been 

determined that a penalty is appropriate. The affirmative defense regulatory provision is not 

relevant to the amount of any penalty to be assessed under section 113(e) because if a court 

determines that the affirmative defense elements have been established, then a penalty is not 

appropriate and penalty assessment pursuant to the section 113(e)(1) factors does not occur.

In exercising its authority under section 112 to establish emission standards (at a level that meets 

the stringency requirements of section 112), the EPA necessarily defines conduct that constitutes 

a violation. The EPA’s view is that the affirmative defense is part of the emission standard and 

defines two categories of violation. If there is a violation of the emission standard and the source 

demonstrates that all the elements of the affirmative defense are met, only injunctive relief is 

available. All other violations of the emission standard are subject to injunctive relief and 

penalties. The CAA does not require that all violations be treated equally. Further, a citizen suit 

claim under section 304 allows citizens to commence a civil action against any person alleged to 

be in violation of “an emission standard or limitation under this chapter.” The CAA, however, 

allows the EPA to establish such “enforceable emission limitations.” Thus, the citizen suit 

provision clearly contemplates enforcement of the standards that are defined by the EPA. As a 

result, where the EPA defines its emissions limitations and enforcement measures to allow a 

source the opportunity to prove its entitlement to a lesser degree of violation (not subject to 

penalties) in narrow, specified circumstances, as the EPA did here, penalties are not 

“appropriate” under section 304. The EPA’s view is that an affirmative defense to civil penalties 

for exceedances of applicable emission standards during periods of malfunction appropriately 

balances competing concerns. On the one hand, citizen enforcers are concerned about additional 

complications in their enforcement actions. On the other hand, industrial sources are concerned 

about being penalized for violations caused by malfunctions that could not have prevented and 

were otherwise appropriately handled (as reflected in the affirmative defense criteria). The EPA 

has utilized its Section 301(a)(1) authority to issue regulations necessary to carry out the Act in a 

manner that appropriately balances these competing concerns.

The affirmative defense is available in any action to enforce the standards set forth in this 

rule, whether such action is brought by EPA, a state or local authority or a citizen. Although the 

preamble‘s reference to the ―Administrator‖ may have caused some confusion, there is nothing 
95

in the language of the regulatory text establishing the affirmative defense that suggests that the 

affirmative defense is limited to EPA enforcement actions.

Comment: As incorporated by reference, commenter 0295 adopted the comments in 

docket EPA-HQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 

as follows. Commenter 0286 reiterated these comments. One commenter (91.1) stated that it is 

unclear how the affirmative defense would apply to enforcement actions by state and local 

governments, or to private citizen enforcement actions under CAA section 304. The commenter 

(91.1) stated that the preamble to the Proposed Rule, for example, speaks only in terms of 

application of the affirmative defense in an EPA enforcement action (See, e.g., 75 Fed. Reg. at 

63,283 co. 2). The commenter (91.1) recommended that an affirmative defense should clearly 

state that it is applicable to enforcement actions by states or citizen-suit plaintiffs, as well.

Response: The affirmative defense is available in any action to enforce the standards set 

forth in this rule, whether such action is brought by EPA, a state or local authority or a citizen. 

Although the preamble‘s reference to the ―Administrator may have caused some confusion, 

there is nothing in the language of the regulatory text establishing the affirmative defense that 

suggests that the affirmative defense is limited to EPA enforcement actions.

Comment: As incorporated by reference, commenter 0295 adopted the comments in 

docket EPA-HQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 

as follows. Commenter 0296 also provided these comments. 

One commenter (91.1) said that EPA needs to substantially revise and streamline the 

proposed affirmative defense for it to be of practical value, and argued that many aspects of the 

affirmative defense would make it unavailable as a practical matter for many, if not most 

malfunctions. The commenter (91.1) stated that many of these limitations on the affirmative 

defense also are not directly related to the question of whether an exceedance of the emission 

limitations due to a malfunction should be excused. One commenter (91.1) stated that several of 

the conditions for establishing an affirmative defense use phrases that are subject to a wide range 

of interpretations, and that on their face do not recognize any need for reasonableness or costeffectiveness. The commenter asked how will the enforcement authority, or a judge, determine 

whether “proper design” or “better operation and maintenance practices” could have prevented a 

malfunction whether a recurring malfunction is a result of “inadequate design” whether repairs 

were made “as expeditiously as possible” whether the source took “all possible steps” to 

minimize the impact of the excess emissions and whether emissions control systems “were kept 

in operation if at all possible” The commenter (91.1) argued that at a minimum, the vague and 

unqualified descriptors in the criteria for demonstrating the affirmative defense will inevitably 

lead to varying conclusions as to whether a violation has occurred, resulting in inconsistency 

from one jurisdiction to the next.

Response: EPA does not agree that the affirmative defense criteria are overly vague and 

will result in varying interpretations. Courts are well equipped and often do evaluate and apply 

criteria that are subject to differing interpretations. Many of the conditions were modeled after 

the conditions of the affirmative defense in EPA‘s SIP SSM policy, which several states have 

adopted into their SIPs.
96

We do not have any indication that parties to enforcement proceedings have had any 

significant difficulties applying the terms of these SIP affirmative defenses. (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)). Other conditions are modeled after a Federal 

Implementation promulgated by EPA. (40 C.F.R. 50.1312). EPA‘s view is that use of consistent 

terms in establishing affirmative defense regulations and policies across various CAA programs 

will promote consistent implementation of those rules and policies. However, EPA agrees that 

some of the terms or phrases in the regulatory text establishing the affirmative can be revised or 

streamlined to some extent. Such revisions are discussed elsewhere in this response to comment 

document.

Comment: Commenter 0295, noting that the data set EPA has used to set the Steel 

Pickling MACT standards does not include startup and shutdown emissions, suggests that the 

EPA should extend an affirmative defense for unavoidable startups and shutdowns where the 

facility owner or operator has taken all reasonable and prudent steps to minimize emissions in 

accordance with good air pollution control practice.

As incorporated by reference, commenter 0295 adopted the comments in docket EPAHQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 as follows. 

Commenter 0286 also provided this comment. 

One commenter (91.1) stated that EPA’s rationale for excluding startup and shutdown 

events from the proposed affirmative defense is unclear. The commenter (91.1) argued that if 

EPA persists in its proposal not to provide separate emission limitations for startup and 

shutdown, and if in fact excess emissions from a source cannot reasonably be avoided during a 

startup or shutdown, not because of failure of a process or equipment but because of the nature of 

conditions while starting up or shutting down the source, there is no apparent reason why EPA 

would not provide the same kind of affirmative defense that it proposes to provide for 

malfunctions.

Response: EPA is promulgating the affirmative defense for malfunctions only, not for 

periods of startup and shutdown. As explained earlier in this document, EPA believes that 

malfunction events should be treated differently than periods of startup and shutdown, which are 

predictable and routine aspects of a source‘s operations. In contrast, EPA does not view 

malfunctions as a distinct operating mode. Because startup and shutdown periods are part of a 

source‘s normal operations, the same approach to compliance with, and enforcement of, 

applicable emissions standards during those periods should apply as otherwise applies during a 

source‘s operations. Further, as explained above, periods of startup and shutdown – but not 

malfunctions -- are taken into account when establishing section 112 emissions standards. For 

these reasons, EPA does not believe it is appropriate to apply the affirmative defense provision to 

startup and shutdown periods.

Finally, the EPA does not consider affirmative defense an appropriate means to regulate 

emissions during startup and shutdown. If any source in this category had submitted valid data 
97

demonstrating that because “...of the nature of conditions while starting up or shutting down...” 

compliance with the normal operating standards during startup or shutdown was impracticable, 

the EPA would have considered proposing standards applicable to startup, shutdown, or both. 

Comment: As incorporated by reference, commenter 0295 adopted the comments in 

docket EPA-HQ-OAR-2009-0559-0091.1, and summarized in EPA-HQ-OAR-2009-0559-0171 

as follows. Commenter 0286 also provided these comments. 

One commenter (91.1) said the requirement in the proposed rule (75 FR 65068) to notify 

the Administrator by telephone or fax as soon as possible, but no later than two business days 

after the malfunction begins, and then to submit a written report within 30 days of the initial 

occurrence of the malfunction that demonstrates, “with all necessary supporting documentation,” 

that the source met all of the multitude of criteria for the affirmative defense, is unreasonable and 

unnecessary. The commenter (91.1) stated that it is novel at best for a person to be determined to 

have acted unlawfully unless the person has submitted his entire defense before he is even 

notified of a potential enforcement action. The commenter (91.1) stated that in many cases, it 

would be obvious to the enforcement authority (not “the Administrator”), based on the kind of 

short malfunction or deviation report that sources already submit under many air programs, that 

an exceedance of the Proposed Standards resulted from an unforeseen and unavoidable 

equipment failure or process upset. The commenter (91.1) contended that it is extremely 

inefficient and burdensome for both sources and regulators to require a complete justification of 

the affirmative defense before the enforcement authority has indicated any need for further 

investigation. Additionally, the commenter (91.1) stated that allowing only 30 days to provide 

the kind of extensive documentation required by the affirmative defense as currently written, 

including a completed root cause analysis, is unreasonable. The commenter (91.1) recommended 

ninety days as the minimum time that should be allowed, unless EPA substantially streamlines 

the criteria for the affirmative defense.

Response: The requirement to notify the Administrator of an exceedance during a 

malfunction is reasonable and consistent with many other upset and malfunction notification 

requirements that have been applied without significant difficulty. (See, e.g. 40 CFR 

63.6(e)(3)(iv)). 

Comment: Commenter 0286 stated that EPA’s claim that the proposed rule would 

reduce the reporting burden associated with SSM events is misleading. The commenter notes 

that while the proposed rule would eliminate application of certain recordkeeping and reporting 

requirements in the NESHAPs General Provisions related to SSM, they will be replaced by a 

much more onerous reporting requirement for any source wishing to claim an affirmative 

defense. The commenter claimed that both the overly broad set of conditions that must be 

demonstrated in a report documenting eligibility for the affirmative defense, and the 

requirement that all of the information be submitted before any enforcement action has been 

commenced would greatly expand reporting and recordkeeping associated with SSM events.

Thus, commenter 0286 stated that EPA needs to prepare an Information Collection Request for

the SSM portion of the proposed rule and otherwise comply with the Paperwork Reduction Act.
98

Response: The rule reduced the reporting burden related to SSM because the owner 

operator is no longer required to have an SSM plan, and the decision to assert affirmative 

defense is at the discretion of the source. To assert affirmative defense is not a requirement for 

compliance. As stated previously, the affirmative defense applies to penalties and thus is only 

utilized where a violation has been established. The burden of proof remains with the plaintiff in 

an enforcement action. See, e.g., 40 C.F.R. 22.24. If a violation has been established and a source 

wishes to assert the affirmative defense with respect to penalties, the source does bear the burden 

of establishing that the elements of the affirmative defense have been met. This burden-shifting 

is appropriate because the source is in a better position to determine the facts required to 

establish the defense. See, e.g., Arizona Pub. Serv. Co. v. EPA, 562 F.3d 1116, 1120, 1129-30 

(10th Cir. 2009) (rejecting industry challenge to the EPA’s use of an affirmative defense to 

address excess emissions during malfunction events). Thus, the overall reporting for SSM events 

will be reduced under the rule. 

2. Residual Risk

Comment: Commenters 0286 and 0295 support EPA’s conclusions based on the residual 

risk and technology review. The commenters concur that the existing standards adequately 

minimize risk and no revisions to the existing standards are needed. 

Response: We agree with the commenters that the existing standards for Steel Pickling –

HCl Process Facilities and Hydrochloric Acid Regeneration Plants do not need to be revised for 

the purposes of reducing risks under Section 112(f).

Comment: Commenter 0290/0620 stated that each of the problems discussed in regard to 

Chrome Plating apply to EPA’s residual risk assessment and risk determination for the Steel 

Pickling source category. The commenter stated that EPA failed to fully assess the health risk, its 

determination that risk is “acceptable” and that no revisions are needed to provide an “ample 

margin of safety to protect public health is unlawful, arbitrary, and capricious.. 

Response: The responses to the commenter’s problems with EPA’s Steel Pickling

residual risk assessment are the same as the responses to the commenter’s problems in regard to 

the Chrome Plating residual risk assessment as discussed in this document.
99

Appendix A Summary of Citizen and Mass Comment Campaign Commenters

Chromium Electroplating Commenter Lista

Comment No.b Name

0266 Anonymous 

0267 Anonymous 

0268 Anonymous 

0269 Anonymous 

0270 C. Lish

0282 Anonymous public comment

0299 Mass Comment Campaign sponsored by Earthjustice (10,294)

0302 A. Leary

0303 J. Lang

0304 T. B. Griswold

0305 R. Miller

0306 L. Jobe

0307 A. Byrne

0308 J. Boone

0309 W. Lachman

0310 M. Breton

0311 Dr. C. Leman

0312 K. Shimata

0313 V. Harris

0314 D. Aikins

0315 T. Imajo

0316 P. Crouser

0317 A. Kay

0318 L. Koelle

0319 S. Sanders

0320 M. Fogg

0321 B. Browing

0322 G. Sferra

0323 K. B. Russell

0324 J. Gau

0325 N. Gladfelter

0326 K. Van Dame

0327 S. Kauffman

0328 P. B. La Point

0329 C. O. Dietrich
100

Comment No.b Name

0330 E. Zenker

0331 M. Reid

0332 C. Schmalz

0333 S. Chickman

0334 S. Tims

0335 R. Bixby

0336 C. Woodcock

0337 M. Nola

0338 Dr. R. Philbrick

0339 A. Saga

0340 L. Thompson

0341 H. Curtler III

0342 S. and D. Anthes

0343 K. Rowlett

0344 S. McKee

0345 Dr. D. Johnson

0346 C. A. Morey, Jr.

0347 G. and F. Alderson

0348 J. Unruh

0349 Z. Daluz

0351 J. Mortensen

0352 N. Brothers

0353 J. Robinson

0354 D. Briscoe

0355 R. Rodarte

0356 J. Harmer

0357 C. Mead

0358 R. Ruggles a

 Includes form letter commenters.

b

 Comments 0266 to 0358 apply to October 2010 proposal.