National Emission Standards for Hazardous Air 

Pollutant Emissions: Ferroalloys Production

Summary of Public Comments and Responses on Proposed Rule 

(76 FR 72508, November 23, 2011) and Supplemental Proposal 

(79 FR 60238, October 6, 2014)

U.S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Sector Policies and Programs Division

Research Triangle Park, NC 27711
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Table of Contents

1.0 EMISSION ESTIMATES USED IN RISK MODELING .................................................. 9

1.1 Methodology to Estimate Baseline and Control Scenario Emissions.............................. 9

1.2 Method to Estimate Fugitive Emissions is Flawed ........................................................ 13

1.3 Stack Testing Data Used in Estimating Emissions ........................................................ 16

1.3.1 Nickel Speciation of Emissions.............................................................................. 18

1.3.2 Treatment of Non-detects ....................................................................................... 19

1.4 Use of Allowable vs. Actual Emissions......................................................................... 20

2.0 EPA RISK ASSESSMENT ............................................................................................... 23

2.1 Dose-Response Values................................................................................................... 23

2.1.1 Chronic Dose-Response Values.............................................................................. 23

2.1.2 Acute Dose-response Values .................................................................................. 42

2.2 Chronic Risk Assessment Issues.................................................................................... 45

2.2.1 Census Block Centroids.......................................................................................... 45

2.2.2 Activity Patterns and Exposure............................................................................... 47

2.2.3 Respirable Emissions.............................................................................................. 52

2.2.4 Cumulative Risk...................................................................................................... 53

2.2.5 Chronic risk assessment results .............................................................................. 58

2.3 Acute Risk Assessment Issues ....................................................................................... 58

2.4 Facility-wide Risk Assessment ...................................................................................... 60

2.5 Multipathway and Environmental Effects...................................................................... 62

2.5.1 Multipathway .......................................................................................................... 62

2.5.2 Environmental Effects ............................................................................................ 70

2.6 Environmental Justice Assessment Issues...................................................................... 71
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2.7 Other Modeling Methodology Issues............................................................................. 75

2.8 Community Health Impacts and Concerns..................................................................... 80

2.8.1 Community Issues................................................................................................... 80

2.8.2 Local Resident Concerns Regarding Health and Air Quality................................. 85

3.0 DECISION......................................................................................................................... 88

3.1 Finding of Unacceptable Risk is Justified...................................................................... 88

3.2 Finding of Unacceptable Risk is Not Justified............................................................... 90

3.3 Finding of Acceptable Post-Control Risk is Deficient................................................... 92

3.4 The Rule Does Not Provide an Ample Margin of Safety .............................................. 98

4.0 PREVIOUSLY UNREGULATED POLLUTANTS AND EMISSION POINTS AND 

TECHNOLOGY REVIEW......................................................................................................... 100

4.1 Regulating Previously Unregulated Pollutants and Emission Points........................... 100

4.2 Technology Review...................................................................................................... 102

4.3 Stack Emission Limits.................................................................................................. 109

4.4 Object to UPL Methodology........................................................................................ 112

4.5 Emission Averaging Across Multiple Furnaces........................................................... 115

4.6 Fugitive Emissions Capture ......................................................................................... 116

4.6.1 Total Negative Pressure Enclosure ....................................................................... 116

4.6.2 Enhanced Local Capture Option........................................................................... 120

4.7 Ambient Air Monitoring Option .................................................................................. 124

4.7.1 Activated Carbon Injection .......................................................................................... 127

4.7.2 Mercury Control.................................................................................................... 128

4.7.3 Formaldehyde Control .......................................................................................... 128

4.8 Opacity Standards ........................................................................................................ 129

4.9 Fugitive Dust................................................................................................................ 135
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4.10 Format of the Regulation.............................................................................................. 136

4.10.1 Need to Retain Subcategories............................................................................... 136

4.10.2 Concentration Format is Not Appropriate ............................................................ 136

4.10.3 PM Cannot be Used as a Surrogate....................................................................... 138

4.11 Compliance Testing Requirements .............................................................................. 140

4.12 Monitoring, Reporting and Recordkeeping Requirements .......................................... 142

4.13 Compliance Date .......................................................................................................... 147

5.0 ECONOMIC IMPACTS OF PROPOSED RULE........................................................... 151

5.1 Impacts on Economy and National Interests ................................................................... 151

5.2 Benefits Analysis.......................................................................................................... 156

5.2.1 Regulatory Comments .......................................................................................... 156

5.2.2 Methodology Comments....................................................................................... 158

5.2.3 Uncertainties in the Benefits Analysis.................................................................. 160

5.2.4 Limits of Statistical Analysis................................................................................ 162

6.0 STARTUP, SHUTDOWN AND MALFUNCTION (SSM) PERIODS AND 

AFFIRMATIVE DEFENSE....................................................................................................... 164

6.1 SSM.............................................................................................................................. 164

6.2 Affirmative Defense..................................................................................................... 172

7.0 OTHER COMMENTS..................................................................................................... 179

7.1 Overall Support ............................................................................................................ 179

7.2 Request for Extension/Additional Review................................................................... 179

7.3 Object to Additional Testing or Data Gathering .......................................................... 181

7.4 Citizen Involvement in the Rulemaking Process ......................................................... 181

7.5 Other............................................................................................................................. 182
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Purpose and Background

The EPA proposed amendments to the National Emissions Standards for Hazardous Air 

Pollutants (NESHAP) for ferroalloys production facilities to address the results of a residual risk 

and technology review on November 23, 2011. Fifty-five public comments (from 41 

commenters) were received during the comment period. In addition, both companies that would 

be affected by the final rule submitted supplemental comments in July 2012 as well as additional 

supporting information, such as new test data, in the summer and fall of 2012. Other commenters 

met with us in person or via teleconference to reiterate their earlier comments. On October 6, 

2014, the EPA published a supplemental proposal that addressed many of the key issues brought 

up by commenters on the 2011 proposed rule. Twenty-seven comments (from 20 commenters) 

were received during the comment period for the 2014 supplemental proposal. The purpose of 

this document is to summarize the comments received on the 2011 proposed rule and 2014 

supplemental proposal that were not addressed in the promulgation preamble.

Commenters

Commenter Name

Document Id a

EPA-HQ-OAR2010-0895-XXXXDate

American Chemistry Council (ACC) 0076 2/1/12

American Iron and Steel Institute (AISI) 0271, 0275 12/24/14

Anonymous (Afscmewv@aol.com) 0086 2/1/12

Anonymous (SSkal@aol.com) 0081 2/1/12

Anonymous Public Comment 0257 

0258 

0261 

0268

11/28/14 

12/4/14 

12/17/14 

12/20/14

Karin Arnold 0102 2/1/12

Albert Arnone 0260 12/17/14

Caroline Beidler 0089 2/1/12

Sherri Biegeleisen 0103 2/1/12

Ellyn Burnes 0077 2/1/12

CC Metals and Alloys, LLC (CCMA) 0069 1/31/12

Coalition for Responsible Waste Incineration (CRWI) 0071 2/1/12

Kathleen Davies 0104 2/1/12

Earthjustice (on behalf of Neighbors for Clean Air, Ohio Citizen Action 

and Sierra Club)

0107 through 0114 

0276 

0277 

0278

2/1/12 

12/24/14 

12/29/14 

1/15/15

Attachments/supporting materials to comment letter 0301

0373

0042

2/18/15

2/12/15

1/21/15

Eramet Marietta Inc. (EMI) 0051, 0052 

0059 

12/12/11 

12/28/11 
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Commenter Name

Document Id a

EPA-HQ-OAR2010-0895-XXXXDate

0106 

0122 

0251 

0253 

0256 

0272, 0273

2/1/12 

8/28/12 

10/28/14 

11/4/14 

11/28/14 

12/24/14

Felman Production Inc. (Felman) 0053 

0073 

0123 

0252 

0269

0274 (copy of 0269)

12/15/11 

2/1/12 

8/28/12 

10/29/14 

12/20/14

12/24/14

Brian Gath 0093 2/1/12

Sharon Growick 0096 2/1/12

Roger Hall 0101 2/1/12

Emily Haynes 0087 2/1/12

J. Harris 0084 2/1/12

Industrial Energy Consumers of America (IECA) 0263 

0267

12/19/14 

12/20/14

Julia E. Johnson 0082 2/1/12

Brian Kuru 0095 2/1/12

Manganese Interest Group (MIG) 0055 

0067, 0070 

0266

12/19/11 

1/31/12 

12/20/14

Kenneth Marantz 0088 2/1/12

Terry Martin 0079 2/1/12

National Association of Clean Air Agencies (NACAA) 0065 1/25/12

North American Metals Council (NAMC) 0072 2/1/12

David Neubauer 0092 2/1/12

Nickel Producers Environmental Research Association, Inc. (NiPERA) 0066 

0264

1/31/12 

12/19/14

Melissa Ochal 0083 2/1/12

Ohio Citizen Action (OCA) 0068 

0105 

0270

1/25/12 

2/1/12 

12/24/14

Ohio Environmental Protection Agency (Ohio EPA) 0265 12/19/14

The Residual Risk Coalition (R2C) 0075 2/1/12

June Robb 0078 2/1/12

Barbara Stewart 0098 2/1/12

Patrick Stewart 0090 2/1/12

Scott Strickler 0099 2/1/12

SSM Coalition 0074 2/1/12

James Thiel 0094 2/1/12
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Commenter Name

Document Id a

EPA-HQ-OAR2010-0895-XXXXDate

RoseMarie E. Thomas 0097 2/1/12

University of Cincinnati, College of Medicine 0085 2/1/12

Virtual Technology, LLC 0262

0279

12/19/14

2/5/15

Washington County 0247 10/14/14

West Virginia Department of Environmental Protection (WV DEP) 0255 11/20/14

Dawn Wittberg 0091 2/1/12

Richard A. Wittberg 0100 2/1/12

Kim and Dan Wolford 0080 2/1/12
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Issues Raised by Commenters

1.0 EMISSION ESTIMATES USED IN RISK MODELING

1.1 Methodology to Estimate Baseline and Control Scenario Emissions

Comment: In response to the 2011 proposal, two commenters (0122, 0123) recommended

changes to the methodology used to estimate emissions from each of the plants. One commenter 

(0122) suggested that stack emissions from control devices be based on all recent performance 

tests, not just the 2010 tests conducted for the EPA prior to proposal. The commenter (0122) also 

suggested that the furnace 1 control device emissions be based upon the baghouse that is 

currently in operation, not the scrubber that was previously in place. Additionally, the 

commenter (0122) pointed out that furnace 1 tapping baghouse emissions were excluded from 

the baseline file included in the proposal docket. 

The commenters (0122, 0123) recommended replacing the mass balance approach described by 

the EPA at proposal to estimate emissions from tapping and crushing/screening with the use of 

applicable emission factors. The commenters (0122, 0123) also suggested replacing the casting 

emission factor used by the EPA at proposal with a different emission factor. The commenters 

(0122, 0123) suggested estimating tapping fugitive emission using an uncontrolled PM emissions 

factor of 0.29 lb/ton, based on AP-42, Table 12.5-1 for “BOF Tapping, at building monitor” with 

maximum process rate information provided by the plants. The commenters (0122, 0123) 

suggested estimating casting emissions using an uncontrolled PM emissions factor of 0.056 

lb/ton, based on AP-42, Table 12.5-1 for “Hot metal transfer, at building monitor” with 

maximum process rate information provided by the plants. The commenters (0122, 0123) also 

recommended estimating uncontrolled emissions from their crushing and screening operations 

using PM10 emission factors for metallic minerals processing as presented in AP-42, Table 

11.24-2 with maximum process rates.

In their comments on the supplemental proposal, commenter 0272 noted that the EPA used AP42 emission factors developed for basic oxygen furnaces (BOF) to estimate fugitive emissions 

from ferroalloy operations. This section included “at the source” and “at the monitor” emission 

factors to estimate ferroalloy production process fugitive emissions, and the EPA chose to use 

the “at the source” emission factors, which produced estimated emission rates about three times 

higher than “at the monitor” factors. The commenter (0272) believes that the “correct” choice of 

emission factors are the ones that produce predicted emissions closest to real air data. The 

availability of real world data means that it is possible in this rulemaking for EPA to use each set 

of factors in its model and determine objectively which set produces results that better match 

reality. The commenter (0272) stated that using the BOF “at the monitor” emission factors 

overestimates actual air concentrations, but less than the “at the source” emissions factors and 

that even with this correction, the EPA’s model remains very conservative. The commenter 

(0272) therefore recommended that the EPA adjust its modeling assumptions to use the BOF “at 

the monitor” emission factors.
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One commenter (0122) stated that the EPA’s characterization of the removal of material from the 

MOR process is incorrect because it equates that operation to tapping of an active furnace. 

Therefore, according to the commenter (0122), it is more correct to characterize these emissions 

using the hot metal transfer emission factors. The commenter (0122) added that the emissions 

should be calculated when the ladle from the furnace process is poured into the MOR and again 

when the treated material (post-MOR processing) is cast.

In supplemental comments to their original comments, two commenters (0122, 0123) provided 

revised estimates of manganese emissions for both a baseline scenario and an “enhanced control” 

scenario. These estimates and the associated emission estimation methodology are located in the 

project docket. As described by the commenters (0122, 0123), the manganese emissions are 

based on each plant's estimate of a “worst-case” ratio of PM to manganese emissions (41 percent 

at EMI and 23 percent at Felman for most operations except for 52.9 percent for 

crushing/screening operations). Based on their calculations, both commenters (0122, 0123) 

concluded that their proposed “enhanced local capture” scenarios would collectively reduce 

emissions from the affected sources by 95 percent.

Based on the commenters’ (0122, 0123) engineering studies of baseline capture efficiencies, they 

also recommended changes to some of the capture efficiency assumptions made in the proposal 

analysis conducted by the EPA. In most cases, the commenters (0122, 0123) suggested 

efficiencies that are less than the efficiencies estimated by the EPA.

The commenter (0272) acknowledged that mathematical modeling is necessary to fill gaps when 

actual data is unavailable. However, the commenter (0272) stated that the EPA should not ignore 

nor allow modeling to trump real world data when it is available, as the commenter contends 

occurred here in developing the 2014 proposal.

Response: We agree that certain changes should be made to the emission estimation 

methodology based on these comments. First, we have developed a new baseline scenario that 

included modeling emissions from the current furnace 1 baghouse at EMI instead of the 

previously used scrubber. We also believe that it is appropriate to use a broader range of PM and 

HAP stack test data to estimate control device stack emissions to reflect potential operational 

variability. 

Regarding the use of emission factors, we recognize that emission factors are commonly used by 

plants to estimate emissions from their processes and that they can have a higher degree of 

precision and accuracy than a mass balance approach. We reviewed the factors suggested by the 

commenters and agree that the use of the BOF tapping and hot metal transfer as surrogates for 

ferroalloys tapping and casting is appropriate, given the absence of AP-42 factors specific to 

ferroalloys. However, we disagree with the use of the “at the monitor” factors suggested by the 

commenters. 
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First, we note that these emission factors were not based on emissions collected at the roof 

monitor, but instead collected in hoods or ductwork located above the actual emission source and 

estimates of assumed capture efficiency were made to estimate the “uncontrolled” portion. This 

differs from a measurement of actual emissions at the roof monitor. Second, the respective BOF 

tapping and hot metal transfer tables each show a second emission factor associated with each 

operation (“at the source”). For tapping the factor is 0.291 lb/ton and for hot metal transfer the 

factor is 0.19 lb/ton. These factors are also based on tests that sampled the air inside a hood or 

duct (albeit one that was probably closer to the source of the emissions than the so-called “at the 

monitor” collection sites) with assumptions made about capture efficiency to determine 

uncontrolled emissions. We decided to use the higher emission factors (EFs) in our calculations 

because we believe they more accurately reflect actual emissions from these sources. 

Furthermore, given that there are some uncertainties regarding these emissions, we believe it is 

appropriate to use the more conservative estimates to error on the side of public health 

protection. Further explanation of the EFs and our rationale for choosing these EFs are provided 

in the document titled Revised Development of the Risk and Technology Review (RTR) 

Emissions Dataset for the Ferroalloys Production Source Category for the 2014 Supplemental 

Proposal, which is provided in the docket for this action.

In their proposed emission estimation procedures, the commenters assumed that use of the 

tapping emission factor suffices to estimate all fugitive emissions from the furnaces, which 

implies that there are no fugitive emissions from the main furnace hood (e.g., primary 

emissions). During a subsequent conversation, the commenters stated that they believe the main 

furnace hoods capture 100 percent of furnace emissions except during upset events 

(malfunctions). However, we believe that an assumption of 100 percent capture is too high and 

have retained the assumption that there are some primary furnace fugitive emissions although we 

did assume a slightly higher capture efficiency (and thus lower emissions) of the main furnace

hood (up from 95 to 98 percent) since the 2011 proposal.

We note that the EPA’s estimates of casting emission at proposal were based on an emissions 

factor contained in a previous RACM determination from the state of Ohio. However, upon 

closer examination, we were unable to sufficiently document this emission factor and decided 

that the use of the BOF factor is more defensible.

For crushing and screening emissions, we determined that use of more recently updated emission 

factors from the crushed stone AP-42 (give table) should be considered as well. We identified 

candidate emission factors and consulted with the plants regarding their application to specific 

equipment operated at each plant. Based on this process, the plants submitted revised estimates 

of crushing and screening emissions that we included in our final modeling files.

We agree that the commenter’s (EMI2) description of the MOR process better characterizes the 

nature of emissions from that source, and we have revised the emission estimation procedures 

accordingly.
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Regarding the issue of the ratio of PM to manganese emissions, we believe that the use of stack 

test data is a better methodology to estimate the actual emissions from the plants. For example, 

we have stack test data from the furnaces that show the PM, manganese and other HAP 

emissions from the control device stacks. We think that furnace emissions are a better surrogate 

for estimating the ratios of PM to manganese for tapping fugitive emissions (where we lack 

tapping baghouse data) and casting fugitive emissions than a generic “worst-case” value. 

Similarly, we have stack data from the MOR baghouse and crushing and screening operations 

that we think are a better surrogate for MOR fugitives and crushing and screening fugitives, 

respectively.

With regard to capture efficiencies, for the 2014 supplemental proposal and the final rule, we 

developed estimates of capture efficiency for each of the processes based on site visits, 

observations, and engineering judgement provided by several EPA engineers. The capture 

efficiency assumptions, and explanation of how they were developed, are described in more 

detail in the document titled Revised Development of the Risk and Technology Review (RTR) 

Emissions Dataset for the Ferroalloys Production Source Category for the 2014 Supplemental 

Proposal, which is provided in the docket for this action. 

Comment: Commenter 0073 disagrees with the EPA’s proposal to regulate all furnace types and 

products as part of the same category, noting significant differences in feedstocks, processes, 

operations and emissions. Specifically, the commenter (0073) notes that emissions from 

ferromanganese operations contain a different HAP profile than those from silicomanganese 

operations and the 2010 stack testing did not include the only ferromanganese furnace in 

operation in the U.S. (at EMI). The commenter (0073) disagrees with the EPA’s assumption that 

that the HAP-to-PM ratio from ferromanganese manufacturing would be the same as that from 

silicomanganese manufacturing. The commenter (0073) states that ferromanganese production 

generates a fraction of the PM that silicomanganese generates, with a very different HAP profile. 

The commenter (0073) states that the MACT floor the EPA calculated based on these data does 

not represent what well-controlled ferromanganese operations “achieve” in practice. The 

commenter (0073) requests that the EPA continue the specific subcategories that were 

established as part of the original rule, evaluate all available reliable emissions data for each 

subcategory and calculate the 99% UPL based on these data. The commenter (0073) also asserts 

that the EPA should first subcategorize among the different types of ferroalloy operations, reevaluate the risk data to identify the residual risks associated with each individual subcategory, 

and then identify category-specific controls as necessary to address those risks. 

Response: Furnace #12 at EMI was tested in August 2010 while producing ferromanganese. In 

response to comments, we have compared the emission profile (PM to Mn emissions) for the two 

product types. The results are in the project docket. The analysis confirms the commenter’s 

contention that silicomanganese production has higher relative PM content and a lower relative 

Mn content. However, given that the majority of ferroalloys production occurs with fabric filters, 

which are constant PM outlet devices, we believe that outlet emissions are not a function of PM 
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loading and/or product type. We also reviewed historical data of PM emissions and found that 

the sole scrubber (typically considered an efficiency device vs. constant outlet device) emitted 

higher PM but still within the range supported by the UPL analysis. Therefore, we do not believe 

that subcategorizing the standards for PM emissions is needed. 

While we did not subcategorize, we did revise some emissions estimates. The data for Felman, 

which was modeled using information from the ICR test and was based on silicomanganese 

production, was not changed. However, in the case of EMI, we did revise emission estimates of 

manganese and mercury emissions, using a revised silicomanganese emission factor for furnace 

# 1, which was producing silicomanganese during the ICR test program. This revision was 

needed to correct the original data file assumption, which based the manganese and mercury 

emissions profile on the furnace #12 data, derived from a test during ferromanganese production. 

1.2 Method to Estimate Fugitive Emissions is Flawed

Comment: In comments on the supplemental proposal, two commenters (0270, 0276) disagree 

with the EPA’s use of emission factors to estimate fugitive emissions from furnace and tapping 

operations. Both commenters (0270, 0276) state that such factors were compiled decades ago, 

were poorly documented and are of questionable reliability. One commenter (0276) references 

an EPA evaluation report of emissions factor development in support of these concerns.1The 

commenter (0276) is concerned that use of these factors introduces significant uncertainties into

the EPA's assessment and likely leads to underestimation of fugitive emissions and risk. The 

commenter (0276) states that the uncertainty in the fugitive emissions supports the need for the 

EPA to find risk unacceptable and assure a stronger margin of safety to protect public health.

Commenter 0270 and 0276 state that to reduce the uncertainty in the fugitive emissions 

estimates, the EPA should have used the methodology it used in other instances, where fugitive 

emissions are based on measured stack emissions, estimated control device efficiency and 

estimated capture efficiency. While this methodology depends upon two uncertain estimates, the 

commenters (0270, 0276) believe it provides a better estimate than the emission factors the EPA 

used. The commenter (0270) states that based on the emissions test data provided to the EPA, 

control efficiencies can be determined for Felman and estimated for Eramet, which are greater 

than the AP-42 default estimates for control device efficiencies, and the commenter suggests the 

EPA collect the full test reports from Eramet to determine the correct control efficiency for all 

the pollutants measured. According to the commenter (0270), with this information, only the 

 

1

See, e.g., U.S. Environmental Protection Agency, Evaluation Report: EPA Can Improve Emissions Factors 

Development and Management , 2006-P-00017, Office of Inspector General, U.S. Environmental Protection 

Agency, Washington, DC, Mar. 22, 2006. Available at http://www.epa.gov/oig/reports/2006/20060322-2006-P00017.pdf (accessed November 2011); Emissions Factor Uncertainty Assessment – Review Draft Feb. 2007, 

http://www.epa.gov/ttn/chief/efpac/documents/ef_uncertainty_assess_draft0207s.pdf. 
14

capture efficiency would be estimated in determining the fugitive emissions of particulate matter, 

metals and PAH emissions. 

Commenter 0276 states that the EPA has not shown that the emission factors it used represent 

real-world impacts, and the EPA should have used the measured concentrations of metals at 

nearby schools in the EPA’s receptor models to assess of the veracity of the emission factors. 

The commenter (0276) also states that the EPA should have evaluated the EPA-collected data on 

manganese in Marietta, Ohio (Warren Elementary School).

Response: The commenter points out the uncertainty in using emissions factors to estimate 

fugitive emissions but fails to consider that uncertainty in emissions factors is a two-tailed factor, 

the uncertainty may either over estimate or underestimate emissions. The commenter is assuming 

the factor underestimates fugitive emissions when, in fact, that specificity is unknown to EPA. 

Using ambient measurement data collected at Warren Elementary School to back calculate 

fugitive emissions from a source would result in an estimate with greater uncertainty than the 

emissions factors that EPA used.

Comment: In comments on the supplemental proposal, commenter 0276 states that the EPA has 

not adequately supported its assumptions about the capture efficiency of several of the 

ventilation systems considered. The commenter (0276) states that unless the EPA can show that 

the partial capture method works to remove unacceptable risk, it must require total enclosure to 

remove unacceptable risk and assure the requisite “ample margin of safety to protect public 

health.”

Two commenters (0270, 0276) disagree with the EPA’s “unsupported” assumption that a 

ventilation system designed to meet the guidelines of the ACGIH Ventilation Manual can 

achieve 95% capture. According to the commenters (0270, 0276), this assumption is speculative,

and it is unlikely that the EPA can obtain verification of this level of capture from the authors of 

the manual.

Both commenters (0270, 0276) state that the EPA can use an alternative approach to evaluate 

capture efficiency by varying the capture efficiency and using the estimated measured captured 

particulate emissions to arrive at estimated capture efficiencies. They provided the results of this 

analysis and conclude that it shows resulting capture efficiencies that yield roughly comparable 

uncontrolled melting and tapping emissions. According to commenters (0270, 0276), the existing 

capture would be approximately 80% for combined melting and tapping at furnace 12, a capture 

efficiency of 80% for melting emissions for furnace 1 and a 20% capture of Furnace 1 tapping 

emissions. The commenters (0270, 0276) add that this analysis assumes that the ratio of PAH to 

particulate matter is consistent between the outlet and inlet, which is uncertain.

The commenters (0270, 0276) also state that the resulting estimates of fugitive emissions that are 

based upon measured data from the facilities are orders of magnitude greater that the EPA’s 

fugitive emission estimates. One commenter (0276) adds that if the EPA were to estimate 
15

fugitives based on these data, risk could be as high as 2,000 in 1 million, which is much higher 

than the EPA found in its analysis. Both commenters (0270, 0276) state that the EPA should 

improve the fugitive emissions estimates and require alternative measurement of the building 

roof monitors using a revised Method 14 (for use at facilities other than aluminum smelters) and 

require the installation of safe access and means for sampling emissions from roof monitors. The 

commenters (0270, 0276) also recommend that the EPA require a Professional Engineer 

certification that the desired capture efficiency is achieved.

Response: We have discussed various approaches for reducing fugitive emissions, and hence 

unacceptable risk, with ventilation experts and determined that a ventilation system designed 

using American Conference of Governmental Industrial Hygienists (ACGIH) principles can 

achieve 95% capture of these emissions. We would characterize our view of ventilation and 

capture performance as based on our technical judgment informed by expert opinion rather than 

mere speculation. Based on information from ventilation experts and the proposed ventilation 

plans submitted by the facilities, we believe that 95% of the overall fugitive emissions emitted 

from the various processes can be captured and controlled.

We reviewed various methodologies to estimate fugitive emissions from the various processes, 

including the methodology provided by the commenters, and determined that the emission factor 

approach provided the best estimate for these emissions. We determined that using a mass 

balance approach does not account for particles that are not emitted from the building, therefore 

overestimating fugitive emissions for the purposes of modeling, and hence overestimating the 

risk associated with these fugitive emissions. The mass balance approach also relies on other 

assumptions regarding the precise control efficiencies of each of the control devices.

We have also reviewed the installation of roof monitoring equipment to measure fugitive 

emissions from the building and determined that the cost of installing this equipment was cost 

prohibitive. The buildings that house the furnaces are old and would require much infrastructure 

to install a monitoring system. In addition, there were a number of safety issues associated with 

the installation of a roof monitoring system. For these reasons, we determined that the 

installation of a DOCS system and weekly opacity monitoring (and/or eventually monthly 

monitoring), along with parametric monitoring and the requirement to develop a capture and 

control design plan, will provide the assurance that the overall 95% capture of fugitive emissions 

is met.

Comment: Two commenters (0270, 0276) describe issues associated with relying on an estimate 

of capture efficiency based on visual observation of the plume. The commenters (0270, 0276) 

describe the limits of observation below 5 to 10 percent opacity and note that the lack of visible 

emissions does not indicate that there are no emissions. One commenter (0270) states that 

particulate matter can be over 40 mg/m3and not produce a visible plume. One commenter (0276) 

adds that past studies have shown that at opacities of about 5 percent, trained observers would 

likely assign a value of zero.
16

The commenters (0270, 0276) also note that the visibility of emissions under ideal conditions is 

highly dependent on the particulate size and other characteristics, such as lighting conditions.

They concluded that the only reliable basis of determining capture efficiency is to measure the 

emissions captured by the ventilation system and the emissions which have escaped capture, as is 

done in the Primary Aluminum Production rule.

Response: The EPA does not require opacity monitoring as a means of complying with a PM 

emissions limit, and we recognize that there are unique and substantial differences between 

percent opacity and PM emissions concentration in any given plume. The EPA does recognize 

opacity as a visible means to ensure that emissions controls are being operated appropriately to 

control emissions and when such controls are not being operated appropriately an opacity 

measurement will demonstrate that fact in a manner that is quicker, less expensive, and nearly as 

reliable as an emissions test. We conclude that the opacity limits being promulgated in this rule, 

along with the other requirements in the rule, will ensure that the process fugitives are effectively 

captured and controlled. 

1.3 Stack Testing Data Used in Estimating Emissions

Comment: In comments on the supplemental proposal, two commenters (0270, 0276) describe 

concerns about the overall quality of the test reports and the lack of recognition by the EPA of 

particular deficiencies. The commenters (0270, 0276) state that the EPA had sufficient time to

identify deficiencies, require their correction (or repeat tests), explain how the EPA would 

reconcile the deficiencies and explain how the EPA would use the data in spite of the 

deficiencies, but the record is silent on this. The commenters provide examples where there was 

apparently inadequate QA for testing of PAH and mercury compounds. They believe that the 

EPA did not establish clear primary and secondary Data Quality Objectives, otherwise several 

ICR tests would have been returned to the industry for correction or retesting. They provide 

several files that include their comments on source test reports that were in the docket. 

To assure data quality for information the EPA uses in this rulemaking, the commenters (0270, 

0276) state that the EPA should (1) require the submission of the documentation for all tests; (2) 

review the documentation for compliance with the published test methods; and (3) use only the 

test data which includes the complete documentation for the target pollutants and meets specified 

data quality criteria. If necessary, the commenters (0270, 0276) state that the EPA should require 

industry to retest or resubmit data, without delay, to correct their errors and ensure the EPA has 

sufficient data to perform its regulatory duties in this rulemaking. 

The commenters (0270, 0276) add that these quality issues are the basis for their 

recommendation that performance tests to demonstrate compliance with any emission limit the 

EPA establishes must be performed by a crew with a field crew lead that is a Qualified 

Individual according to the ASTM D7036-04 and that this individual be employed by a company 

which is accredited by an authoritative body per these same ASTM criteria. They believe that the 
17

errors shown here illustrate that having a facility implement these tests without the appropriate 

qualified supervision will not produce data EPA or the public can rely on. 

Response: The test data provided by the facilities used to calculate emissions used for risk 

modeling and for determining emission limits have gone through an extensive review and have 

met the QA/QC requirements for this RTR. We believe that the current data set provides a solid 

basis for estimating emissions for risk modeling and for calculating emission limits. The majority 

of the comments on the test reports submitted by the commenter were already noted and 

addressed in the test data database before the data were used in the development of the emissions 

estimates used for modeling or for the emission limit calculations. The data sets we used for our 

analyses include multiple valid test runs from the furnaces for the HAP pollutants and account 

for changes in production and seasonal variations.

Comment: Two commenters (0270, 0276) describe data quality concerns with test run averaging. 

They said that it is difficult to determine if any data were excluded from averaging, which data 

were averaged and how the EPA averaged the data to arrive at the emissions used for the residual 

risk assessment and the enhanced capture and control estimates. The commenters (0270, 0276) 

state that it appears the data are averaged on a test run basis, but the EPA has not shown that 

averaging in this manner is appropriate or scientifically valid. They suggest that the EPA 

consider a more representative methodology based on averaging the test runs for each test series 

and then averaging the test series. According to the commenters (0270, 0276), with this 

methodology, the within-source variation of emissions receive equal weighting so that a test 

series that includes a higher number of test runs is not over-represented and a single test run test 

is not under-represented. 

The commenters (0270, 0276) believe that variations in the emissions are due primarily to 

process variations, which have not been fully documented in the test reports, and may not be 

documented in other records available to the company. For example, the commenters (0270, 

0276) suggest that the high variations in the measured PAH emissions may be the result of 

variations in the coal tar pitch in the Soderberg paste, the destructive distillation of the coal 

added to the molten metal and the mass of Soderberg paste used for the specific metal being 

produced. They state that excluding a single run test or averaging on a run-by-run basis would 

cause this normal process variation to be under-represented in the residual risk assessment. They 

conclude that the potential causes of the variation must be investigated and those variables which 

the company can control and which result in higher emissions should be excluded from use in

establishing emission limits.

Response: The emissions estimates used for modeling for each of the facilities were calculated 

using the average of each test for the specific pollutant. Therefore, if we had 4 tests for a specific 

pollutant with each test consisting of 3 runs, the average of the 4 tests were used to determine the 

emissions and not the average of all of the individual runs. If one or more of the test runs were 
18

determined to not meet the QA/QC requirements of this RTR, the test point(s) were removed and 

the test average would be calculated using the valid runs.

For calculating the emissions limits, the UPL uses the individual test run data to determine the 

variability within the data set to determine an emission limit that can statistically be achieved 

99% of the time. For purposes of calculating this UPL value, we only used test data that 

consisted of 2, 3 or 4 runs. The approach to calculate MACT limits and the data sets used to 

calculate the UPL are described in more detail in the MACT Floor memorandum which is 

available in the docket.

1.3.1 Nickel Speciation of Emissions

Comment: In their comments on the 2011 proposal, commenter 0073 states that the EPA 

assumed that 100 percent of the nickel was the most cancerous form (nickel subsulfide). The 

commenter (0073) reports that, based on a laboratory analysis, they determined that their dust 

contains virtually no nickel subsulfide, with most nickel in the form of nickel oxide – which 

presents a significantly lower cancer risk than nickel subsulfide. The commenter (0073) asserts 

that changing this assumption will lower Felman’s risk results to within acceptable levels.

Commenter 0066 adds that that there is no basis to expect that nickel subsulfide is more than a 

minor component of total nickel emissions from Ferroalloys Production facilities, if it is present 

at all. The commenter (0066) references examples from oil-fired steam generating units and from 

Texas CEQ.

In their comments on the supplemental proposal, commenter 0269 supports EPA’s decision to 

reverse its 2011 decision to treat all nickel compounds as having equal toxicity and/or 

carcinogenic potential. The commenter states that nickel emissions from ferromanganese 

operations involve mixtures of nickel compounds. The commenter (0269) further states that, as 

the Agency has noted, current science recognizes these different nickel compounds have 

different potential toxicity and carcinogenic hazards, and that a mixture of different nickel 

compounds poses significantly lower health risks than nickel subsulfide.

Response: The commenter is incorrect in saying that the EPA assumed that 100 percent of the 

nickel emissions from the ferroalloys facilities were nickel subsulfide. What the EPA does 

assume, as described in more detail in the risk assessment report for the supplemental proposal 

available in the docket and in our response below (see the Nickel URE section), is that all nickel 

compounds have the potential to be carcinogenic. Therefore, without additional information, we 

make health protective assumptions, and for the 2011 proposal, we applied the current IRIS 

cancer unit risk estimate (URE) for nickel subsulfide to all nickel compounds in this data set.

The commenter did provide additional information during the 2011 proposal comment period, in 

the form of a laboratory test report. We have reviewed the information and we agree that it is 

unlikely that 100 percent of the nickel from the commenter’s furnace is in the form of nickel 
19

subsulfide. The commenter provided the results of Energy dispersive X-Ray Spectroscopy (EDS) 

that was used to determine the species of nickel in the baghouse dust sample. EDS is a form of 

X-ray Fluorescence Spectroscopy. The assumption in the report is that the proximity of nickel to 

sulfur elements would indicate nickel sulfur species, the absence of sulfur near the nickel would 

indicate a different form of nickel was present in the sample. This is an indirect way to determine 

if nickel-sulfur compounds are present in the particle samples. The report seems also to show 

there is not enough sulfur in the sample to combine with the nickel so nickel-sulfur compounds 

could not predominate. This is another indirect way of making the point about the form of nickel 

in the samples. We also believe that the most likely reaction occurring in the furnace would be 

oxidation, leading the formation of compounds such as nickel oxide and sulfur dioxide rather 

than nickel subsulfide. Taken together, we recognize that it is likely that the majority of 

emissions are probably nickel oxide and not nickel subsulfide. Given the new information, and 

our current knowledge of the carcinogenic potential of all nickel compounds, and the potential 

differences in carcinogenic potential across nickel compounds, we consider it reasonable to use a 

value that is 50 percent of the IRIS URE for nickel subsulfide for providing an estimate of the 

cancer potency for different mixtures of nickel compounds in the revised dataset for the 2014 

supplemental proposal and 2015 final rule. Please see section 2.1.1 for further discussion 

regarding the nickel cancer dose-response value used in the risk modeling.

1.3.2 Treatment of Non-detects

Comment: Commenters 0073 and 0269 note that the EPA assumes HAPs not detected in stack 

tests are actually present and have a concentration of one-half of the test method’s detection 

limit. Commenter 0269 adds that the acute risk is driven by hydrogen fluoride, a compound 

never actually detected in the emission tests. The commenter further states that this policy 

assumption could have a significant impact on the cumulative estimated MIR lifetime excess 

cancer risk. 

Response: For the purposes of estimating emissions from the ferroalloy process emission 

sources, we used the guidelines2for addressing analytical test results that are measured below the 

detection limit (BDL) to determine emissions from the test data. These procedures specify that 

for BDL tests results, one half of the method detection limit (MDL) be used to estimate the 

emission value. The MDL is the smallest amount of a substance that an analytical method can 

reliably distinguish from zero, at a specified confidence level, from the instrument signal 

produced by a blank sample. This means that even though a test results is reported as BDL, it 

does not mean that the compound is not present, but means that it is unable to be measured by 

the method and analytical equipment. Therefore, the EPA uses one half of the MDL to estimate 

the compound emissions that may be present in the test sample.

 

2 Recommended Procedures for Development of Emissions Factors and Use of the WebFIRE Database, August 

2013 (EPA-453/D-13-001)
20

We explained our approach to use non-detect data in our analyses at proposal. Our approach is 

consistent with the EPA’s policy on handling such data. As a point of clarification, acute risks do 

not contribute to the cumulative estimated MIR lifetime excess cancer risk. Cancer risk is 

estimated for carcinogens and only for chronic exposures. Acute risks, which may also be 

estimated for carcinogens if they have both a URE and an acute dose-response value, are 

estimated using acute non-cancer dose-response values, for an hour exposure duration, and is not 

aggregated with cancer risks.

1.4 Use of Allowable vs. Actual Emissions

Comment: Three commenters (0075, 0106, 0271) assert that the EPA cannot lawfully use 

MACT allowable emissions in the proposed risk assessments and residual risk determinations 

because the Agency has failed to provide an explanation for why risk assessments based on 

actual emissions estimates are inadequate. One commenter (0075) asserts that lack of an 

explanation as to why this approach is justified or any record evidence supporting the use of 

MACT allowable emissions renders the proposal insupportable under the law. Commenters

(0075 and 0271) note that section 112(f)(1)(B) requires the EPA also to report on “the actual 

health effects with respect to persons living in the vicinity of” affected sources, and that the 

Agency’s risk assessment methodology already reflects numerous conservative assumptions. 

They believe that these requirements clearly provide for the reporting of real risk based on 

reliable actual emissions data, not hypothetical risk based on less reliable data. Commenters 

(0075, 0106) state that the EPA has provided no data demonstrating that affected sources 

actually emit at levels significantly higher than the actual data show for any significant period of 

time. 

One commenter (0106) states that Section 112(f)(2) only provides for risk based standards "if 

promulgation of such standards is required in order to provide an ample margin of safety...." 

(emphasis added) and notes that in Natural Resources Defense Council v. EPA, 824 F.2d 1146, 

1164-65 (D.C. Cir. 1987), the court noted that “safe” does not mean “risk-free” and the Act 

should be interpreted and applied in a reasonable manner, reflecting the fact that risks are an 

accepted part of life and that the Act does not seek to proscribe risk levels that are otherwise 

“acceptable in the world in which we live.” The commenter (0106) asserts that considering all of 

the conservative assumptions the EPA independently builds into its risk assessment 

methodology, simply assuming that a facility will emit far more than it actually does (possibly 

more than it ever has) without some reasoned explanation is unreasonable.

Commenter 0107 states that the agency's analysis of risk using only the “allowable” emissions 

number is incomplete because facilities may violate that standard and emit HAPs at a level 

beyond what is “allowable” under the rule. The commenter (0107) states that ignoring the 

potential for non-compliance is equivalent to treating additional health risk caused by 

exceedances as zero when the EPA knows that there is additional risk from malfunctions and 

violations. The commenter (0107) adds that the EPA must consult data regarding the use of the 
21

malfunction (or “SSM”) exemption and enforcement actions in the past and other information it 

has regarding the history or likelihood of malfunctions or other violations. The commenter 

(0107) states that the factor approach that the EPA has used to address acute health risk shows 

that the EPA can create a more appropriate factor that would account for the potential for 

malfunctions and violations of the standard. It should do so and then assess health risk 

accordingly for acute, cancer and non-cancer risk when emissions spike above the “allowable” 

level under the existing standard.

Commenter 0065 recommends the EPA consider potential or allowable emissions, rather than 

actual emissions, as much as possible in evaluating residual risk, especially in conducting the 

post-control risk assessment and in assessing acute health risks. Since facility emissions could 

increase over time for a variety of reasons, and with them the associated impacts, the use of 

potential or allowable emissions is more appropriate. The commenter (0065) adds that the major 

source HAP thresholds are based on maximum potential to-emit, as opposed to actual emissions, 

and air agencies issue permits based on potential emissions. The commenter (0065) contends that 

limiting the scope of a risk evaluation to actual emissions would be inconsistent with the 

applicability section of Part 63 rules. 

In their comments on the supplemental proposal, commenter 0272 asserts that the EPA has no 

authority to base risk acceptability decisions on a hypothetical worst-case emission scenario that 

simply assumes without a factual basis that EMI is capable of emitting every HAP at its 

maximum permitted rate continuously for a sustained basis, including 30 to 70 years in the case 

of cancer risk assessments. The commenter (0272) believes that the EPA incorporated even 

greater unreasonableness into its “allowable” scenario by ignoring the technology-based 

standards it has proposed under Section 112(d), which the EPA intends to impose regardless of 

the results of the risk assessment.

The commenter (0272) believes that these scenarios allow an assessment of the impact of EPA’s 

unreasonable assumption that future worst-case emissions could be at the rates allowed by the 

1999 NESHAP rather than the 2014 NESHAP, along with its use of emission factors that 

produce modeled emission estimates six times higher than measured results (e.g., EPA’s fugitive 

emissions factors). The scenarios also remove the hypothetical emissions from EMI’s inoperable 

Furnace 18. In addition, the scenarios assessed the impact of EPA’s failure to account for 

respirable particulates and its use of implausible exposure assumptions.

The commenter (0272) also provided alternative enhanced capture scenario emissions by 

applying their “corrected actual” emissions scenario, even though the commenter believes that 

the EPA has no basis for requiring additional particulate controls.

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) for the 

ferroalloys source category (see e.g., the National Emission Standards for Coke Oven Batteries 
22

(70 FR 19998-19999, April 15, 2005) and in the proposed and final National Emission Standard 

for Organic Hazardous Air Pollutants from the Synthetic Organic Chemical Manufacturing 

Industry, or HON (71 FR 34428, June 14, 2006, and 71 FR 76603, December 21, 2006)). In 

those previous actions, we noted that modeling the allowable levels of emissions (i.e., the highest 

emission levels that could be emitted while still complying with the NESHAP requirements) is 

inherently reasonable since they reflect the maximum level sources could emit and still comply 

with national emission standards. This is in accord with the statutory requirement that the EPA 

evaluate “standards promulgated pursuant to subsection (d)” and if those standards “do not 

reduce lifetime excess cancer risk to the individual most exposed” the EPA must promulgate 

standards under section 112(f). This language most naturally refers to allowable emissions, since 

those are what the standards allow. Quite simply, in determining whether unacceptable residual 

risk remains after promulgation of section 112(d) technology-based standards, it is reasonable to 

consider the emissions allowed by those standards. In addition, the Benzene NESHAP looked to 

allowable emissions in assessing residual risk, and section 112(f) specifically preserves the 

Benzene NESHAP decision framework. But we also explained that it is reasonable to consider 

actual emissions, where such data are available, in both steps of the risk analysis, in accordance 

with the Benzene NESHAP. Sources could be emitting lower than MACT allowable levels and, 

if so, overall risk incidence is probably less than the maximum estimated levels. Failure to 

consider available data on actual emissions in risk estimates could unrealistically inflate risk 

levels. (See National Emission Standards for Coke Oven Batteries, 70 FR 19992, 19998, April 

15, 2005.) 

We disagree with the commenter that emissions that exceed standards should be part of the risk 

analysis. We further disagree with the commenter that we have ignored the risk associated with 

malfunctions. The final rule is designed to require sources to comply during all periods of 

operation. As explained in the preamble to the proposed rule, it is not possible to model 

malfunctions in the risk assessment, because by nature they are infrequent and unpredictable. 

The main purpose of the risk review is to evaluate whether the emission standards should be 

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

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

the emission standard under the residual risk rule will avoid or mitigate such violations. In other 

words, a source that is violating the MACT emissions standard promulgated under section 112(d) 

would not be any more likely to be able to avoid such violations and comply with a different 

presumably more stringent standard promulgated under section 112(f). Such events are violations 

and subject to enforcement by the EPA, the States, or citizens, and an action for injunctive relief 

is the most effective means to address violations whether or not they are caused by malfunctions 

if an emissions event poses a significant health or environmental risk.

Comment: In their comments on the supplemental proposal, commenter 0272 states that the EPA 

has assumed in its allowable emissions scenario that EMI’s idle Furnace 18 will be used in the 

future and included the estimated emissions from that source when estimating the risk associated 
23

with “allowable” emissions. This appears to be based on the fact that Furnace 18 is still covered 

by EMI’s current operating permit and on statements from EMI that it is conceivable Furnace 18 

might operate again sometime in the future. However, Furnace 18 is idle due to extensive 

damage that occurred to the unit in 2010 due to a furnace blow and EMI has no provision for 

reactivating the furnace in its current five-year operational plan. Extensive repairs would be 

necessary before any future use would be possible. The commenter (0272) notes that the EPA 

addressed an analogous scenario in the Benzene NESHAP and deleted from its assessment coke 

batteries on cold-idle that would require substantial construction or a pad-up rebuild before they 

could be restarted. The commenter (0272) believes that Furnace 18 fits this characterization and 

should be treated consistently in this rulemaking.

Response: We disagree with the commenter and believe that the inclusion of potential emissions 

from Furnace 18 is appropriate. The furnace is currently permitted to operate and is therefore an 

allowable emission source. With respect to including Furnace 18 emissions in the allowable 

scenario, it is still covered by EMI’s operating permit and could operate in the future, so to be 

consistent with estimating “allowable” emissions, we included Furnace 18 in the allowable 

scenario. However, since it is damaged and would need extensive repairs, to calculate allowable 

emissions for this source, we assumed it would be subject to the standards in the 1999 NESHAP 

for new or major reconstructed sources if it was repaired and operating again. With respect to the 

scenario described in the Benzene NESHAP, the text before the referenced comment response 

states that commenters supplied specific information regarding permanent plant or battery

closure and changes in plant processes. EMI has not provided such information.

2.0 EPA RISK ASSESSMENT

2.1 Dose-Response Values

2.1.1 Chronic Dose-Response Values

Comment: Commenter 0107 states that the EPA must account for the increased susceptibility of 

children and pregnant women to HAP emissions from this source category in the risk assessment 

based on findings of the NAS review and CalEPA studies. The commenter (0107) is concerned 

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

HAP emissions systematically underestimates risk from the Ferroalloys source category for 

several HAP (POM, formaldehyde, arsenic, manganese, hexavalent chromium) and provides 

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

on the guidelines and other materials that the EPA should use to conduct such analyses. To 

satisfy its duty to protect children, the EPA must follow the best available science, at minimum, 

the EPA must adopt the following: 

1. OEHHA Cancer Guidelines (Age-Dependent Adjustment Factors) for all carcinogens and 

include pre-natal susceptibility, and 
24

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

3. Children’s Default Safety Factor of At Least Ten (for Non-Cancer Chronic & Acute Impacts), 

where specific information on children’s vulnerability is unavailable.

Commenter (0276) adds that the EPA ignores the scientific recommendations to account for 

early life exposure and lead exposure from its own Children’s Health Advisory Committee. 

Response: We disagree with the commenter’s claim that the risk assessment for this source 

category does not consider the groups that may be most at-risk (e.g., children and pregnant 

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

hazardous air pollutants, including metal HAP, it also considers the most sensitive populations 

identified in the available literature, and importantly, these are the values used in our risk 

assessments.3The EPA has an approach for selecting appropriate health benchmark values and in 

general, this approach places greater weight on the EPA derived health benchmarks than those 

from other agencies.4 Additionally, the approach of favoring EPA benchmarks (when they exist) 

has been endorsed by the SAB and ensures the use of values most consistent with wellestablished and scientifically-based EPA science policy. The EPA is currently evaluating the 

most appropriate use for the Cal OEHHA child- specific reference doses. We note that there are 

currently no such values for HAP inhalation, therefore their current utility would be limited to 

persistent and bioaccumulative HAP, which may be associated with non-negligible ingestion 

exposures. The evaluation of the appropriateness of these values in the context of the RTR 

Program and EPA science policy is necessary prior to using these child-specific reference doses 

(RfDs)

With respect to exposure, we use a health-protective assumption of a 70-year exposure duration, 

in which populations are conservatively presumed to be exposed to airborne concentrations at 

their residence continuously, 24 hours per day for a full lifetime, including childhood. 

With respect to cancer, the EPA uses the age-dependent adjustment factor approach referred to 

by the commenter, but limits the use of those factors only to carcinogenic pollutants that are 

known to act via mutagenic mode of action, in contrast to the OEHHA approach, which uses 

them across the board for all carcinogens regardless of mode of action (MOA). In lieu of 

chemical-specific data on which age or life-stage specific risk estimates or potencies can be 

determined, default age dependent adjustment factors can be applied when assessing cancer risk 

for early-life exposures to chemicals which cause cancer through a mutagenic MOA. With regard 

to other carcinogenic pollutants for which early-life susceptibility data are lacking, it is the 

Agency’s long-standing science policy position that use of the linear low-dose extrapolation 

 

3 US EPA. (2002). A review of the reference dose and reference concentration processes. EPA/630/P-02/002F. Risk 

Assessment Forum, Washington, DC. Available online at http://www.epa.gov/raf/publications/pdfs/rfd-final.pdf

4

http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf
25

approach (without further adjustment) provides adequate public health conservatism in the 

absence of chemical-specific data indicating differential early-life susceptibility or when the 

mode of action is not mutagenicity.5 The basis for this methodology is provided in the 2005 

Supplemental Guidance.6

The EPA also disagrees with the commenter that a children’s default safety factor of 10 or more 

should be added to EPA’s reference values in response to the 10X factor enacted by Congress in 

the Food Quality Protection Act (1996).

7

In response to the EPA non-cancer reference value 

derivation, the Agency evaluated the methods for considering children’s risk in the development 

of reference values. As part of the response, the U.S. EPA (i.e. the Science Policy Council and 

Risk Assessment Forum) established the RfD/RfC Technical Panel to develop a strategy for 

implementing the Food Quality Protection Act (FQPA) and examine the issues relative to 

protecting children’s health and application of the 10X safety factor. One of the outcomes of the 

Technical Panel’s efforts was an in depth review of a number of issues related to the RfD/RfC 

process (U.S. EPA 2002). The most critical aspect in the derivation of a reference value 

pertaining to the FQPA has to do with variation between individual humans and is accounted for 

by a default uncertainty factor (UF-H) when no chemical-specific data are available. EPA 

reviewed the default UF for inter-human variability and found the EPA’s default value of 10 

adequate for all susceptible populations, including children and infants. The EPA also 

recommended the use of chemical-specific data in preference to default uncertainty factors when 

available (US EPA, 1994, 2011)8, and is developing Agency guidance to facilitate consistency in 

the development and use of data-derived extrapolation factors for RfCs and RfDs (U.S EPA, 

2011).9 Additionally, the EPA also applies a database uncertainty factor (UF-D) which is 

intended to account for the potential for deriving an under protective RfD/RfC as a result of an 

incomplete characterization of the chemical’s toxicity. In addition to the identification of toxicity 

information that is lacking, review of existing data may also suggest that a lower reference value 

might result if additional data were available.

 

5 U.S. EPA. A Review of the Reference Dose and Reference Concentration Processes. U.S. Environmental 

Protection Agency, Risk Assessment Forum, Washington, DC, EPA/630/P-02/002F, 2002

6 U.S. EPA. (2005), Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens. 

EPA/630/R-03/003F. Washington, DC. Available online at: http://www.epa.gov/cancerguidelines/guidelinescarcinogen-supplement.htm. 

7 US Environmental Protection Agency, Pesticide: Regulating Pesticides. The Food Quality Protection Act (FQPA). 

1996. Available at http://www.epa.gov/pesticides/regulating/laws/fqpa/backgrnd.htm.

8 U.S. EPA (1994). Methods for derivation of inhalation reference concentrations and application of inhalation 

dosimetry. (EPA/600/8-90/066F). Research Triangle Park, NC. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=71993

9 U.S. EPA (2011) External Review Draft of Guidance for Applying Quantitative Data to Develop Data-Derived 

Extrapolation Factors for Interspecies and Intraspecies Extrapolation http://www.epa.gov/raf/DDEF/index.htm
26

In conclusion, the estimated risks must also be considered in the context of the full set of 

assumptions used for this risk assessment. Our unit risk estimates for HAP are considered a 

plausible upper-bound estimate with an appropriate age dependent adjustment factor; actual 

potency is likely to be lower and some of which could be as low as zero. Our chronic noncancer 

reference values have been derived considering the potential susceptibility of different 

subgroups, with specific consideration of children. In addition, an extra 10X uncertainty factor 

is not needed in the RfC/RfD methodology because the currently available factors are considered 

sufficient to account for uncertainties in the database from which the reference values are 

derived. After considering these and other factors, we continue to consider the risks from 

emissions after application of the revisions to the NESHAP for this source category to provide an 

ample margin of safety (consistent with the Benzene NESHAP framework).

Comment: Commenter 0107 notes that for the Ferroalloys source category, it is unclear whether 

there are HAPs missing from the EPA’s risk assessment and that the EPA should confirm that it 

has assessed the health risk for all emitted HAPs. The commenter (0107) adds that it is not clear 

from the record whether the EPA’s health risk assessment includes the currently uncontrolled 

emission points for which the EPA proposes to set standards. The commenter (0107) states that 

the EPA must assess health risk from all pollutants, even where it has no current reference value, 

or must use an uncertainty factor to make up for the lack of a reference value. The commenter 

(0107) states that in the absence of an available reference dose, the EPA must, at minimum, add 

an uncertainty factor to account for the additional risk that a HAP likely causes, until such time 

as the EPA does have a reference value to use.

Furthermore, the commenter (0107) notes that the EPA’s risk assessment acknowledges other 

HAP emissions for which it has no reference values, but states that the EPA has failed to assess 

risk at all for these pollutants. The commenter (0107) adds that the EPA states that it performed 

no risk assessment for some hazardous air pollutants emitted by this source. The commenter

(0107) is concerned that the EPA appears to have failed to account in any way for the acute 

health risks posed by manganese because of the lack of a reference value. The commenter states 

(0107) that this is irrational and unlawful. The commenter (0107) states that the EPA did not 

even carry out a qualitative assessment of these HAPs, in effect assuming that risk from the 

HAPs is zero, which is not justified. The commenter (0107) notes that the EPA recognizes that 

its approach creates a potential understatement of health risk, but the EPA has not adequately 

explained how it has attempted to remove that understatement.

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

10, 2010, (EPA-SAB-10-007) response to the EPA Administrator.10 In that response, the SAB 

 

10 The SAB peer review of RTR Risk Assessment Methodologies is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-

unsigned.pdf.
27

Panel recommended that, for HAP that do not have dose-response values from the EPA’s list, the 

EPA should consider and utilize, as appropriate, additional sources for such values that have 

undergone adequate and rigorous scientific peer review. The SAB panel further recommended 

that the inclusion of additional sources of dose-response values into the EPA’s list should be 

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

agree with this approach and have considered other sources of dose-response data when 

conducting our risk determinations under RTR. However, in some instances no sources of 

information beyond those included in the EPA’s list are available. 

The EPA agrees that we should ultimately develop toxicity values for all HAP 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 HAP lacking dose-response 

assessments further increases the importance of Agency activities to streamline and fully utilize 

the EPA’s already overloaded 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. As a result of this prioritization, while not all HAP have scientifically 

accepted dose-response values that can be used in residual risk assessments, it is clear that the 

vast majority of HAP which carry the potential to significantly impact the results of residual risk 

assessments do, in fact, have credible dose-response values. Thus, while we are not yet at the 

point where all HAP have dose-response values, we are capable of deriving reasonable risk 

estimates for those HAP which dominate the risks from any one source category. In the course of 

each residual risk assessment, should we encounter HAP without dose-response values which 

carry the potential to create significant risks, we shall clearly point those out as uncertainties and 

target them for future IRIS assessments. Moreover, as additional dose-response values become 

available, the EPA will incorporate these dose-response values into future risk assessments.

The EPA notes that we did state which HAP currently have no reference value. In the risk 

assessment document, Table 3.1-1 lists all the HAP emitted by the source category, and indicates 

whether there is an available cancer, chronic noncancer, and/or acute dose-response value. 

We disagree with the commenter’s claim that it is not clear from the record whether the EPA’s 

health risk assessment includes the currently uncontrolled emission points for which the EPA 

proposes to set standards. Appendix 1 to the health risk assessment contains a full discussion of 

the testing conducted for the ICR, how emissions estimates were developed from those test 

results, and how the modeling file (which is the basis for the risk assessment) was populated with 

the emissions estimates.

Comment: Commenter 0107 notes that an IRIS review is currently in process to update the 

EPA’s toxicity information for formaldehyde, hexavalent chromium, naphthalene, and PAH, 

which are pollutants emitted by this source category. The commenter (0107) adds that for these 

and any other pollutants currently under IRIS reassessment, the EPA must use the best available 

scientific information from the IRIS review during the current rulemaking. The commenter 
28

(0107) concludes that if the EPA determines that it must wait until these reassessments are 

complete to use the newly available scientific information, then the EPA must take a more 

protective approach due to the outdated health risk reference information that it is using. The 

commenter (0107) adds that, to account for the delay and lack of reference values for some 

pollutants, and the fact that it is still updating the toxicity information for other pollutants, the 

EPA must set a regulatory deadline no later than 8 years from the finalization of these rules, to 

review the current residual risk analysis and again perform a residual risk rulemaking once 

additional data on reference values become available.

Commenter 0075 asserts that the EPA’s data evaluation scheme which prioritizes the use of IRIS 

data as the highest ranking information is not reasonable or justifiable given the systemic failures 

identified by NAS. 

Response: The EPA has a tiered prioritized list of appropriate health benchmark values and in 

general this hierarchy places greater weight on the EPA derived health benchmarks than those 

from other agencies.11 We have a prioritization process aimed at incorporating into our 

assessments the best available science with respect to dose-response information. This 

information is obtained from various sources and prioritized according to 1) conceptual 

consistency with the EPA risk assessment guidelines and 2) level of peer review received. Where 

we are lacking dose-response information with higher priority (e.g., IRIS), we use other 

information sources, such as CalEPA. Notably, this priority list favoring the EPA benchmarks 

(when they exist) over all others has been endorsed by the SAB.12 “The Panel found the EPA’s 

approach to selecting dose-response chronic toxicity values to be generally sound... The Panel 

supports the use of the Integrated Risk Information System (IRIS) as the preferred database for 

chronic dose-response data. The Panel also strongly recommends that the EPA develop toxicity 

values for all HAP insofar as the data permit, and that it updates IRIS in a timelier manner.” 

“The preferred database for chronic dose-response data is and should be the IRIS database. 

(p.17)”

The cancer dose-response values that were used in the 2014 supplemental proposal risk 

assessment for formaldehyde and hexavalent chromium are the current peer reviewed IRIS 

values, while naphthalene and PAH dose-response values are from Cal EPA. The chronic 

noncancer dose-response values that were used in the 2014 supplemental proposal risk 

assessment for hexavalent chromium and naphthalene are the current peer reviewed IRIS values, 

while the formaldehyde value is from ATSDR. The sources for all values used in the risk 

assessment are presented in tables in Section 2.6.1 of the risk assessment document. At the time 

this analysis was performed these values were deemed to represent the best science. Revised 

 

11 http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf

12 http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-

unsigned.pdf
29

IRIS values for these or other pollutants were not available at the time the analysis was 

performed. We cannot pick and choose newly available values that have not gone through the 

IRIS (or other similarly accepted) review process. We cannot delay rules for new IRIS values 

that may be developed in the future, however we can re-examine rules as new health information 

becomes available. Also, the commenter falsely assumes that all new IRIS dose-response values 

will be more stringent than the existing values. The new IRIS dose-response values could be less 

or more stringent, or equal to the existing values depending on what the scientific data support.

2.1.1.1 Manganese RfC

Comment: In their comments on the 2011 proposal, several commenters (0070, 0072, 0073, 

0075, 0106) state that the EPA’s residual risk assessment significantly overstates the risks 

associated with manganese by relying on an RfC that overstates risk. The commenters state that 

the EPA should re-evaluate its risk assessment using a manganese inhalation reference supported 

by the full body of available data. These commenters state that the EPA used an outdated RfC for 

manganese, and the use of the current IRIS RfC of 0.05 μg/m3 for manganese does not constitute 

the best available science. Commenter 0075 notes that since this RfC was last updated in 1993, 

substantial research has been done to characterize the potential risk of inhaled manganese, 

including a 2009 publication by Bailey et al. which proposed an alternative RfC for manganese 

of 0.002 mg/m3 (based on 12 more-recent occupational studies), which is over two orders of 

magnitude lower than the EPA’s RfC. The commenter (0075) states that the manganese HI value 

and the number of people exposed to high HI values would be much lower if this RfC was used. 

Commenter 0106 notes that the manganese RfC is based on particle inhalation, so the emissions 

and the concentration should only represent the toxicologically relevant fraction (i.e., PM2.5). 

The commenter (0106) also notes that the EPA established the current manganese RfC 

incorporating an “uncertainty factor” of 1000 to provide conservative layers of safety based on 

gaps in the science that existed in 1993 and states that the more recent peer-reviewed studies 

(Bailey et al.) have addressed and eliminated the data gaps that necessitated this 

conservative1000-fold uncertainty factor. The commenter (0106) asserts that the EPA’s 

explanation in the preamble to the proposed rule for use of the 1993 RfC does not address the 

large body of relevant peer-reviewed science that has eliminated the justification for a 1000-fold 

“uncertainty factor.” 

Also in comments on the 2011 proposal, two commenters (0070, 0073) note the EPA has 

previously acknowledged that the manganese RfC is based on incomplete data and of 

questionable reliability. In particular, the commenters (0070, 0073) note the failure to employ the 

preferred benchmark dose (BMD) statistical analysis in the development of the 1993 RfC. Three 

commenters (0070, 0073, 0106) state that the EPA’s reliance on an outdated manganese RfC 

without the requisite assessment of the best available data does not meet the EPA’s obligations 

under the Agency’s information quality (IQ) guidelines. These commenters (0070, 0073, 0106), 

along with commenter 0072 state that the EPA should defer the final rule pending a 

comprehensive reassessment of the IRIS manganese RfC, correct the information related to the 
30

IRIS manganese RfC to make it conform to the IQ guidelines in this rule, or decline to rely on 

the outdated manganese RfC and use available information to develop the risk assessment. One 

commenter (0073) also states that if a new RfC isn’t used, they want an explanation as to why 

and a chance to comment on that explanation.

In contrast, commenter (0107) cites several studies that are attached to the main comment letter 

that document neurological, developmental, and reproductive health threats associated with 

manganese exposure, including neurotoxicity and impaired motor function. They also state that 

there is no known safe level of children’s exposure to manganese and the EPA must address the 

potential increased vulnerability to children from manganese exposure. The commenter (0107) 

concludes that the EPA should consider all of this information as part of this rulemaking.

In their comments on the supplemental proposal, three commenters (0266, 0269, 0271) state that 

they further support the EPA’s decision to use the ATSDR for manganese instead of the existing 

IRIS RfC. One commenter (0269) noted that in their comments to the original proposal the 

existing IRIS RfC is more than twenty years out of date and significantly overstates the risks 

associated with manganese exposure. They believe the manganese ATSDR incorporates more 

recent scientific information and updated scientific analysis. However, they note that the ATSDR 

value still does not represent the best available science. The commenter (0269) supports the 

comments of the Manganese Interest Group (0266) and recommends that EPA follow MIG’s 

recommendations in the final rule.

One commenter (0266) believes that the ATSDR took into account the existence of 

physiologically-based pharmacokinetic (PBPK) models in its manganese risk assessment, but 

ATSDR did not formally apply the models, nor did ATSDR consider application of the PBPK 

models by a variety of researchers who published important scientific papers after ATSDR’s 

assessment of the available science effectively ended. The commenter (0266) believes that 

application of the new science would result in an RfC or MRL for manganese no lower than 1.3 

μg/m3 or potentially an order of magnitude higher. Commenter 0272 believes the ATSDR MRL 

is overly conservative by a factor of 10 because the EPA did not take into account that the 

manganese emissions from ferroalloys production consist predominately of manganese oxides. 

Another commenter (0271) believes that the data clearly indicate that the risk value that should 

be used for manganese is no lower than 1.3 μg Mn/m3 and believes that the EPA should use the 

1.3 μg Mn/m3 value in its risk analysis. Commenter 0266 requests that the EPA correct its 

residual risk assessment for the ferroalloy NESHAP by deferring issuance of a final rule pending 

a reassessment of the ATSDR manganese MRL based on the best available science. The 

commenter (0266) provided a study (see Attachment B) entitled, “Physiologically Based 

Pharmacokinetic Modeling for Comparative Exposure Assessment of Essential Elements: An 

Example of Manganese.” The study concluded that continuous exposure to manganese 

concentrations ranging from 50 μg/m3 to greater than 200 μg Mn/m3 would be needed to exceed 

the NOAEL concentration, and potentially cause adverse effects, for the brain.
31

In contrast, commenter 0276 disagrees with the EPA’s use of the ATSDR MRL and states that 

the EPA has not provided sufficient rationale to justify use of this less protective value. The 

commenter (0276) states that there is significant new information suggesting that the value 

should be more protective, not less. The commenter (0276) describes several recent studies, 

which show that the 1993 study that was the basis for the original IRIS value likely 

underestimates the neurological harm caused by manganese exposure, particularly to children. 

The commenter (0276) adds that it is inconsistent with the EPA’s own child-protection focused 

policies to use the ATSDR number instead of the more protective IRIS number. 

The commenter (0276) states that waiting for “future” reviews to assess the implications of these 

2014 studies ignores the harm to health risks now that are being addressed by the ferroalloys risk 

assessment. The commenter (0276) adds that at a minimum, the EPA should apply an additional 

factor to account for the risk not addressed in the current analysis. The commenter notes that the 

most current research also provides further support the EPA’s finding of unacceptability and the 

need for strong health risk-based standards that assure an “ample margin of safety to protect the 

public health.”

Response: In response to the comments pertaining to use of the IRIS RfC in the 2011 proposal, 

we agree that there is newer information available since the development of the RfC for 

manganese, and the preferred approach for developing reference values (i.e., the benchmark dose 

approach) has since been widely adopted in the IRIS Program. However, we would note that 

statistical modeling, as was done in 1993, is consistent with the benchmark dose approach. We 

also agree that use of another value could change the risk results and presumably the 

acceptability decision. The ensuing paragraphs explain the approach taken by EPA in choosing 

reference values for use in the RTR Program.

The EPA has developed a tiered list of reference values; IRIS as is our preferred source for 

reference values. The remainder of reference values on the preferred list give priority to values 

from sources that are conceptually consistent with the EPA’s risk assessment guidelines and 

have undergone rigorous peer review. This prioritization scheme has been through a Scientific 

Advisory Board (SAB) review and was favorably received. 

In response to public comments on the 2011 proposal, the EPA considered the existing peerreviewed health effect reference values for chronic inhalation exposure to manganese from other 

federal, state and international agencies and organizations, and notes the following details on the 

derivation of each:13 

 

13 U.S. EPA. Mn and BTEX Reference Value Arrays (Final Reports). U.S. Environmental Protection Agency, 

Washington, DC, EPA/600.R-12/047F, 2013.
32

• The current IRIS RfC (U.S. EPA, 1993) of 0.05 μg/m3 was based on the lowest 

observed adverse effect level (LOAEL) from the study by Roels et al. (1992) on 

neurobehavioral effects in exposed workers. The LOAEL was used as the point of 

departure (POD) and then adjusted for dosimetry (ventilation rate from occupational 

to ambient, assuming systemic effects) and to account for duration of exposure (from 

occupational to continuous); and applying a total uncertainty factor (UF) of 1000 to 

account for these extrapolations. 

• In 2012, the Agency for Toxic Substances and Disease Registry (ATSDR) developed 

a chronic Minimal Risk Level (MRL) of 0.3 μg/m3based on neurobehavioral effects 

in exposed workers reported by Roels et al. (1992). The MRL used a BMCL10 (a 

higher benchmark response level than used for the two values below) as the POD. It 

was adjusted for duration of exposure (from occupational to continuous) and a total 

UF of 100 was used (ATSDR, 2010). This value is six times the existing IRIS value.

• The Office of Environmental Health Hazard Assessment (OEHHA) for the State of 

California (OEHHA, 2008) developed a chronic Reference Exposure Level (CAREL) for Mn, based on neurobehavioral effects in exposed workers reported by Roels 

et al. (1992). The CAL-REL was calculated using a BMCL05 as the POD, which was 

adjusted for duration of exposure (from occupational to continuous), and application 

of a total UF of 300. The resulting value is 0.09 μg/m3, which is about a factor of 2 

greater than the current IRIS RfC.

• Health Canada (2010) developed an RfC for Mn based on a study conducted by 

Lucchini et al. (1999) on neurobehavioral effects in exposed workers. The value was 

derived using a benchmark concentration analysis (BMCL05) as the POD, which was 

adjusted for duration of exposure (from occupational to continuous) and application 

of a total uncertainty factor (UF) of 100. The resulting value is the same as the current 

IRIS RfC of 0.05 μg/m3(U.S. EPA, 1993).

• The World Health Organization (WHO, 2000) developed a Health Guideline value 

for exposure to Mn based on a study of Roels et al. (1992). The value was derived 

using a BMCL05 as the POD with adjustments to account for duration, and a total UF 

of 50. The resulting value is 0.15 μg/m3, which is a factor of 3 higher than the current 

IRIS RfC.

The current IRIS RfC for manganese is within a factor of three of the chronic inhalation 

reference values above, including those which use the benchmark analysis. 

We note that the size of the manganese-containing particle has a bearing on the toxicity and 

some of the organizations listed above and others (especially those for occupational exposures) 
33

have developed reference values based on different size fractions.14 The range of size fractions 

on which reference values have been developed include PM2.5, PM3.5, PM5, PM10, and TSP. The 

current and historical monitoring information is limited to measurements of PM2.5 or PM10, 

leaving these two fractions as the only ones available for any exposure analysis. The American 

Conference of Governmental Industrial Hygienists (ACGIH), the International Standards 

Organization (ISO), and the European Standardization Committee have all adopted 4 μm as the 

50 percent cut point and indicator of respirable particles;

15 in essence, this means 50 percent of 

respirable particles will be captured with a 4 μm impact separator and the other 50 percent will 

be larger particles with increasingly smaller proportions being captured as the size goes up. 

Adoption of a PM2.5 cut point would therefore ignore a large portion of the mass which is defined 

as respirable by a number of authoritative bodies, and making the choice of PM10 as being the 

most appropriate for RTR regulatory decisions. All of the preferred reference values previously 

discussed are based on the same 1992 study by Roels et al., who also used 4 μm as the 

50 percent cut point. Given all of these considerations, in addition to the EPA policy to be health 

protective in the face of uncertainty, PM10 has been and will continue to be used to characterize 

these exposures to manganese. 

In our consideration of available reference values, the EPA did not include some values 

specifically noted in public comments. The level of peer review and publication purpose for nongovernmental scientific publications (e.g., Bailey et al 2009) is qualitatively different than the 

processes used to derive the reference values described in detail above. The EPA did not include 

the Ontario Ministry of the Environment (MOE) standard on manganese-containing particles 

because it is a regulatory limit, similar to a National Ambient Air Quality Standard (NAAQS), 

rather than a value developed for risk assessment purposes. The information provided by these 

additional references, however, may prove useful in the IRIS reassessment for manganese. A 

direct application of any of these values instead of an established reference value in our tiered list 

of prioritized dose-response values would be inconsistent with the EPA policy as implemented in 

the RTR Program, and with recommendations from the SAB. 

In 1994, the EPA conducted an analysis in the context of evaluating the risks of exposure to 

manganese in the fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT); this was 

not intended to be a replacement for the 1993 IRIS RfC and did not follow the established review 

procedures for an IRIS assessment. The publication explicitly stated that “the RfC estimates 

developed for the purpose of this risk assessment do not represent a revision of the current 

verified RfC for manganese (EPA, 1994, pg. 10).” As a result of the EPA’s MMT evaluation, 

 

14

 U.S. EPA. Mn and BTEX Reference Value Arrays (Final Reports). U.S. Environmental Protection Agency, 

Washington, DC, EPA/600.R-12/047F, 2013.

15 U.S. EPA, 2009. Integrated science assessment for particulate matter. EPA/600/R-08/139F. Research Triangle 

Park, NC. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546.
34

the EPA required the former Ethyl Corporation (now Afton Chemical) to conduct several studies 

under a test rule agreement.

16

 These studies produced a body of data used to develop 

physiologically based pharmacokinetic (PBPK) models for laboratory animals and humans, 

which several commenters suggest the EPA consider in its RfC. The EPA agrees that the PBPK 

models, along with all other relevant available peer-reviewed literature, will be considered in an 

IRIS reassessment for manganese, and EPA notes the use of these PBPK models to inform the 

derivation of other reference values (e.g., the MRL developed by ATSDR). 

The EPA is aware that new scientific data have become available since the 1993 IRIS assessment 

for manganese was completed, including both experimental studies and epidemiological 

evaluations of exposed human populations. However, it is premature to estimate what, if any, 

revisions to the IRIS assessment for manganese may be needed until a comprehensive evaluation 

is conducted and such an evaluation cannot be completed by the court-ordered deadline for this 

final rule. The EPA IRIS Program has placed manganese on its agenda for a revised assessment, 

which will begin with a scientific literature search and problem formulation meeting, where the 

public will be invited to participate and submit additional scientific information. Following 

problem formulation, a draft toxicological review is developed and subjected to internal Agency 

review, science consultation and discussion with other Federal Agencies and White House 

offices; a public review and comment period; and an independent external peer review. More 

detailed information on the IRIS assessment development process is available on the IRIS 

website.17

After consideration of reference values in our tiered list of prioritized dose-response values, and 

consistent with Agency policy which was supported by the SAB, we chose to rely on the 2012 

ATSDR MRL for manganese in the supplemental proposal and final rule risk assessments. Both 

the 1993 IRIS RfC and the 2012 ATSDR MRL were based on the same study (Roels et al., 

1992). In developing their assessment, ATSDR used updated dose-response modeling methods 

(benchmark dose approach) and considered recent pharmacokinetic findings to support their 

selection of an uncertainty factor in the derivation of the MRL. 

With respect to the use of the ATSDR MRL in the 2014 supplemental proposal, we disagree with 

the comment that the ATSDR value is “less protective.” Although there are other values which 

arrive at a lower final value for manganese, the ATSDR used analytical approaches such as the 

benchmark dose implementing technical guidelines most consistent with EPA practices. Further, 

 

16 More information on the MMT health effects testing can be found at: 

http://www.epa.gov/otaq/regs/fuels/additive/mmt_cmts.htm. Final test reports can be found at www.regulations.gov, 

docket number EPA-HQ-OAR-2004-0074.

17 Further explanation of the IRIS Assessment Development Process can be found at: 

http://www.epa.gov/iris/process.htm
35

the actual issue is which derivation procedure best affords accuracy – what value best 

characterizes the ambient exposures under consideration? ATSDR used the most up-to-date 

information on the kinetics (absorption, distribution, metabolism and excretion) of manganese to 

ensure the derived MRL value did not approach exposure levels which would lead to toxicity.18 

EPA intends to explore application of the PBPK model in its revisions to the IRIS assessment.

We also disagree that an uncertainty factor should be removed due to the speciation of 

manganese emissions. The available reference values were designed to be applicable to 

manganese and manganese compounds; reference values for individual manganese species are 

not available. Exploration of the PBPK model applied to specific species of manganese may be 

possible provided the exposures are characterized with respect to particle size and distribution. 

2.1.1.2 Nickel URE

Comment: In their comments on the 2011 proposal, commenters (0066, 0072, 0106) assert that 

treating all nickel compounds as having the same carcinogenic potency (URE) value as the URE 

the EPA assigned to nickel subsulfide in 1986 is deeply flawed and demonstrably illogical, and 

they urge the EPA to correct the cancer risk estimate for nickel-containing emissions. The 

commenters (0066, 0072, 0106) add the EPA has not classified nickel species other than nickel 

subsulfide and nickel refinery dust as known human carcinogens and that even if the EPA 

decides to treat all nickel species as human carcinogens, there would be no basis to apply the 

URE for nickel subsulfide to total nickel emissions, as the EPA recognizes that different nickel 

species have different carcinogenic potential. Commenter 0066 also states that studies have 

shown elevated respiratory cancer risks only in certain types of nickel refineries but not in those

where nickel is present in oxide form. Commenter (0066) further states that if the EPA chooses 

to assume that all nickel compounds are carcinogenic and that a single URE can be applied to 

“nickel compounds” as a group, it would be illogical to use the URE for nickel subsulfide 

because the IRIS URE for nickel subsulfide is an artificial value that was calculated by doubling 

a calculated URE for nickel refinery dust, based on the assumption that nickel subsulfide 

constituted 50% of the nickel species to which the refinery workers were exposed but was 

responsible for 100% of the cancer risk. Further, the commenter notes there is very little nickel 

subsulfide in emissions from ferroalloys facilities. The commenter (0066) asserts that 

epidemiological and animal studies indicate that nickel-related carcinogenicity has an actual or 

practical threshold that makes application of any linearized URE value to predict cancer risks at 

low ambient levels of exposure problematic and highly conservative.

 

18 Manganese is an essential mineral nutrient, especially for fetal and neonate neurological development. There are 

homeostatic mechanisms within the body to help regulate the level of manganese in cells to ensure proper levels are 

maintained (not too much or too little); only after these homeostatic mechanisms are overwhelmed does manganese 

exert its toxic effects.
36

Commenters 0066 and 0264 state that the EPA should use the TCEQ-developed URE of 1.7 x 

10-4 per μg/m3 for nickel compounds. The commenters (0066 and 0264) note that TCEQ has 

corrected certain methodology/calculation errors that the EPA had made, performed more refined 

modeling, and used additional data that were not available to the EPA in 1986 and asserts that 

this is the best currently available value for the EPA to use in estimating lung cancer risks 

associated with emissions of nickel-containing particulate from Ferroalloys Production facilities.

Commenter (0264) notes that the TCEQ URE value would not change the EPA’s determination 

that residual risks in ferroalloys production is unacceptable, however they believe that this URE 

provides a sound scientific foundation and used in future rulemakings.

Response: As discussed above, in Section 1.2.1.1, the EPA has a tiered prioritization list of 

appropriate health benchmark values and in general this list places greater weight on the EPAderived health benchmarks than those from other agencies.19 We have a prioritization process 

aimed at incorporating into our risk assessments the best available science with respect to doseresponse information. This information is obtained from various sources and prioritized 

according to 1) conceptual consistency with the EPA risk assessment guidelines and 2) level of 

peer review received.

In the inhalation risk assessment for the 2011 proposal, to take a conservative approach, we 

considered all nickel compounds to have the same carcinogenic potential as nickel subsulfide 

and used the IRIS URE for nickel subsulfide to estimate risks due to all nickel emissions from 

the source category. In the public comments provided in response to the proposal and available 

data in the docket, one facility provided additional data in the form of a laboratory test report that 

indicated it would be unlikely that 100 percent of the nickel from the furnace would be in the 

form of nickel subsulfide. 

Based on consistent views of major scientific bodies (e.g., IARC, NTP, WHO) that consider all 

nickel compounds to have carcinogenic potential, we currently consider all nickel compounds to 

have the potential of being carcinogenic to humans. Although the precise nickel compound (or 

compounds) responsible for carcinogenic effects in humans is not always clear, studies indicate 

that nickel sulfate and the combinations of nickel sulfides and oxides encountered in the nickel 

refining industries cause cancer in humans. The major scientific bodies mentioned above has also 

recognized that there are differences in toxicity and/or carcinogenic potential across the different 

nickel compounds. There are two additional URE values20 derived for exposures to mixtures of 

nickel compounds, as a group, that are 2-3 fold lower than the IRIS URE for nickel subsulfide 

for providing an estimate of the lower end of the plausible range of cancer potency values for 

 

19 http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf

20 Two UREs (other than the current IRIS value) have been derived for nickel compounds as a group: one developed 

by the California Department of Health Services (http://www.arb.ca.gov/toxics/id/summary/nickel_tech_b.pdf) and 

the other by the Texas Commission on Environmental Quality 

(http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf).
37

different mixtures of nickel compounds. Given our current knowledge of the carcinogenic 

potential of all nickel compounds and the potential differences in carcinogenic potential across 

nickel compounds, we consider it reasonable to use a value that is 50 percent of the IRIs URE for 

nickel subsulfide for providing an estimate of the cancer potency for different mixtures of nickel 

compounds in the revised dataset for the 2014 supplemental proposal and 2015 final rule. Fifty 

percent of the IRIS URE for nickel subsulfide is the same numeric value as the IRIS URE for 

nickel refinery dust, but we did not use “nickel refinery dust” to classify nickel emissions from 

this source category.

2.1.1.3 Arsenic Risk URE

Comment: Commenter 0106 asserts that although the estimated arsenic cancer risk (20 in a 

million) is already well below the MIR target of 100 in a million (1 x 10-4), the EPA's cancer 

risk assessment is still overestimated. The commenter asserts that: arsenic URE has not been 

updated since 1984, and the use of this value ignores recent scientific studies which showed that 

a more scientifically supported arsenic URE (based on revisions to the exposure assessment in 

the original smelter cohort used by US EPA in 1984) is about 3-fold lower than the current 

arsenic URE. 

Commenter 0107 states that the EPA must account for early exposure to this pollutant and that 

California has listed this pollutant as being known to cause developmental toxicity. Therefore, 

the assessment of risks due to arsenic exposure must be adjusted to account for increased early 

life susceptibility to non-mutagenic carcinogens.

Response: The use of IRIS values has been discussed above (in Section 2.1.1). The explanation 

of how the EPA accounts for early childhood exposure has also been discussed above (in Section 

2.1.1).

2.1.1.4 Formaldehyde URE

Comment: Commenter 0076 states that the EPA’s reliance on an outdated formaldehyde 

inhalation exposure risk without the requisite assessment of the best available data does not meet 

the EPA’s obligations under the Agency’s information quality (IQ) guidelines. The commenter 

(0076) describes the IQ guidelines and explains why the formaldehyde dose-response value is 

not in compliance. The commenter (0076) cites the history of the formaldehyde dose-response 

value and concludes that the 2011 NAS report should be used in determining what constitutes the 

best available science. The commenter (0076) asserts that the deference given to the 1991 IRIS 

Assessment is directly at odds with the EPA’s mandate to consider all credible and relevant 

information in a rulemaking proceeding. The commenter (0076) asserts that the proposed rule 

should be based on the best available science at the time of the rulemaking, and follow the EPA’s 

mandate to “consider all credible and relevant information” in the rulemaking. The commenter 

(0076) states that the EPA should reject the 1991 IRIS model and its corresponding doseresponse value and employ the CIIT biologically-based dose-response (BBDR) model, as 
38

recommended by the National Academy of Sciences in their 2011 Review of the Environmental 

Protection Agency's Draft IRIS Assessment of Formaldehyde.

Response: In 2004, the EPA determined that the Chemical Industry Institute of Toxicology 

(CIIT) cancer dose-response value for formaldehyde (5.5 x 10-9 per ug/m3) was based on better 

science than the IRIS dose-response value (1.2 x 10-5 per ug/m3), and we switched from using 

the IRIS value to the CIIT value in risk assessments supporting regulatory actions. Subsequent 

research published by the EPA suggested that the CIIT model was not appropriate and, in 2010, 

the EPA returned to using the 1991 IRIS value. The EPA has been working on revising the 

formaldehyde IRIS assessment and The National Academy of Sciences (NAS) completed its 

review of the EPA’s draft assessment in April of 2011 

(http://www.nap.edu/catalog/php?record_id=13142). The EPA will follow the NAS Report 

recommendations and will present results obtained by implementing the biologically based dose 

response (BBDR) model for formaldehyde. The EPA will compare these estimates with those 

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

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

uncertainty analyses will be an integral component of implementing the BBDR model. In the 

interim, we will present findings using the 1991 IRIS value as a primary estimate and the EPA 

may also consider other information as the science evolves. The EPA notes that formaldehyde 

was not a driver of the risks attributable to the emissions from this source category.

Comment: Commenter 0107 states that studies have found increased sensitivity of children to 

respiratory toxicity of formaldehyde and as a result “CalEPA has prioritized it as a toxic air 

contaminant of particular concern for children.” The EPA’s “residual risk assessment should 

have adjusted the dose-response values for both the cancer and non-cancer effects of 

formaldehyde exposure” to account for this increased early life susceptibility.

Response: The use of IRIS values has been discussed above (in Section 2.1.1). The explanation 

of how the EPA accounts for early childhood exposure has also been discussed above (in Section 

2.1.1).

2.1.1.5 Chromium RfC

Comment: Commenter 0075 states that the EPA relies on an outdated scientific assessment for 

chromium, one of the chemicals indicated as a driver for the unacceptable cancer risks. The 

commenter (0075) notes that this conclusion relies on data from a 13-year-old chromium IRIS 

RfC value for which the EPA noted it had low confidence. The commenter (0075) states that it is 

crucial to ensure that the residual risk assessment conclusions are based on the current scientific 

knowledge, and adds that newer scientific information is available, as evidenced by a 2003 

publication by Crump et al. which evaluated the dose-response relationship for inhalation 

exposure to hexavalent chromium and provided estimates of the carcinogenic potency. The 

commenter (0075) asserts that failure to consider this study renders the EPA’s proposed risk 

conclusions arbitrary.
39

Commenter 0107 refers to the EPA and CalEPA toxicological reviews21,22 of hexavalent 

chromium which indicate that hexavalent chromium has a mutagenic mode of action. The 

commenter states that the EPA’s risk assessment should therefore include an early life exposure 

adjustment.

Response: The use of IRIS values has been discussed above (in Section 2.1.1). The explanation 

of how the EPA accounts for early exposure has also been discussed above (in Section 2.1.1).

2.1.1.6 Lead Dose-Response Values

Comment: Commenter 0107 is concerned with EPA’s reliance on the 2008 National Ambient 

Air Quality Standards (NAAQS) for Lead in assessing noncancer hazards for lead. The 

commenter (0107) states that this is relevant information but does not address all that is needed 

for a section 112(f)(2) assessment of health risk from lead. The commenter (0107) goes on to 

claim that the NAAQS was created to protect the average exposed member of the population 

from an IQ point loss above 2 points, and states that the NAAQS is not to protect the “most 

exposed” and most vulnerable member of that population implying that is necessary under 

section 112(f)(2). The commenter (0107) also states that the NAAQS was also designed to 

address only a single pollutant (elemental lead), while section 112(f)(2) requires the EPA to 

assess and address health risk from the combined effect of a source category on the most exposed 

person. 

According to the commenter (0107), there is new information since 2008 that EPA must consider 

in assessing the risks of lead under section 112(f)(2). In comments on the supplemental proposal, 

commenter 0276 cites several recent studies as showing that harm to children can occur at levels 

below the lead NAAQS. Commenters 0107 and 0276 also state that lead can cause greater harm 

when in the presence of arsenic and manganese than lead exposure alone. 

Commenter 0276 states that the EPA must address and incorporate the best available information 

on children’s exposure, including the EPA’s Children’s Health Protection Advisory Committee 

(CHPAC) recommendation of protecting children from an ambient concentration of lead of 

0.02μg/m3 rather than assuming that the 2008 NAAQS level of 0.15 μg/m3 is protective enough. 

Finally, the commenters (0107, 0276) note that section 112(f)(2) requires the EPA to create an 

“ample margin of safety to protect public health,” while the NAAQS only must satisfy the test to 

provide an “adequate margin of safety.” Commenter (0276) adds that the residual risk standards 

are designed to do more than just replicate other statutory protections, such as those provided by 

the NAAQS. If Congress had intended the EPA simply to replicate the NAAQS , or some other 

different Clean Air Act requirement, commenter 0276 states that the section 7412(f)(2) 

 

21 EPA 2010. Toxicological Review of Hexavalent Chromium (CAS No. 18540-29-9): In Support of Summary 

Information on the Integrated Risk Information System (IRIS) at 238.

22 Cal. EPA, OEHHA 2010. Draft Public Health Goal for Hexavalent Chromium in Drinking Water.
40

requirement would become redundant for any HAP that also has any relationship to any other 

regulated pollutant. According to the commenter (0276), if there were any ambiguity on this 

question, statutory construction requires a reading of section 7412(f)(2) that preserves its 

independent value and meaning. 

Commenter 0107 concludes that rather than only relying on the NAAQS to assess health risk 

from lead, the EPA should use all of the best available, most current information, including 

California’s lead health benchmark.

Response: While recognizing that lead has been demonstrated to exert “a broad array of 

deleterious effects on multiple organ systems,” the lead NAAQS targets the effects associated 

with relatively lower exposures and associated blood lead levels, specifically nervous system 

effects in children including cognitive and neurobehavioral effects (73 FR 66976). The 2008 

decision on the lead NAAQS was informed by an evidence-based framework for neurocognitive 

effects in young children. In applying the evidence-based framework, we focused on a 

subpopulation of U.S. children, those living near air sources and more likely to be exposed at the 

level of the standard; to the same effect see 73 FR 67000/3--“The framework in effect focuses on 

the sensitive subpopulation that is the group of children living near sources and more likely to be 

exposed at the level of the standard. The evidence-based framework estimates a mean air-related 

IQ loss for this subpopulation of children; it does not estimate a mean for all U.S. children”; 73 

FR 67005/1--“the air-related IQ loss framework provides estimates for the mean air-related IQ 

loss of a subset of the population of U.S. children, and there are uncertainties associated with 

those estimates. It provides estimates for that subset of children likely to be exposed to the level 

of the standard, which is generally expected to be the subpopulation of children living near 

sources who are likely to be most highly exposed.” In addition, in reviewing and sustaining the 

lead primary NAAQS, we note that the D.C. Circuit specifically noted that the rule was targeted 

to protect children living near lead sources: “EPA explained that the scientific evidence showing 

the impact of lead exposure in young children in the United States led it ‘to give greater 

prominence to children as the sensitive subpopulation in this review’ and to focus its revision of 

the lead NAAQS on the ‘sensitive subpopulation that is the group of children living near [lead 

emission] sources and more likely to be exposed at the level of the standard.’ Given the 

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

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

was not arbitrary or capricious.” Coalition of Battery Recyclers, 604 F. 3d at 618.

As noted in the risk assessment document, there is no RfD or other comparable chronic health 

benchmark value for lead compounds. In 1988, the EPA’s IRIS program reviewed the health 

effects data regarding lead and its inorganic compounds and determined that it would be 

inappropriate to develop an RfD for these compounds, stating,

“A great deal of information on the health effects of lead has been obtained through 

decades of medical observation and scientific research. This information has been 
41

assessed in the development of air and water quality criteria by the Agency’s Office of 

Health and Environmental Assessment (OHEA) in support of regulatory decision-making 

by the Office of Air Quality Planning and Standards (OAQPS) and by the Office of 

Drinking Water (ODW). By comparison to most other environmental toxicants, the 

degree of uncertainty about the health effects of lead is quite low. It appears that some of 

these effects, particularly changes in the levels of certain blood enzymes and in aspects of 

children’s neurobehavioral development may occur at blood lead levels so low that a 

threshold has yet to be determined. The Agency’s RfD Work Group discussed inorganic 

lead (and lead compounds) at two meetings (07/08/1985 and 07/22/1985) and considered 

it inappropriate to develop an RfD for inorganic lead.”

The EPA’s IRIS assessment for Lead and compounds (inorganic) (CASRN 7439-92-1) can be 

found here: http://www.epa.gov/iris/subst/0277.htm.

With regard to the information identified by the commenters, much of this information was 

similar to information available at the time of the 2008 NAAQS decision. For example, in 2005, 

the CDC recognized the evidence of adverse health effects in children with blood lead levels 

below 10 μg/dL, and that there is no safe level of blood lead in young children (CDC, 2005). 

The commenter also cites a benchmark analysis by California OEHHA that was completed 

during the time of the last review (Carlisle and Dowling, 2007). The quantitative relationship 

from this analysis of a correlation of 1 IQ point change with a 1.0 μg /dL change in blood lead is 

actually a substantially smaller change in IQ per μg /dL blood lead than the slope of 1.75 IQ 

points per μg /dL blood lead used in the evidence-based framework that the Administrator relied 

upon in his 2008 decision on a revised level for the lead NAAQS in 2008 (73 FR 66964). 

Regarding the CHPAC recommendation on level and averaging time referenced by the 

commenter, this was made to EPA in January of this year (2015) in the context of the current 

NAAQS review and the same comment was made and considered in the 2008 review, that 

concluded with the current lead NAAQS.

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

pollutants from a source category on the most exposed person, we agree and consider our 

analysis to have done this. The approach used to calculate chronic non-cancer risks, developing 

the target-organ specific hazard index, specifically considers the combined effect of multiple 

pollutants on the same target organ. For this particular source category, lead and manganese were 

both considered to have an effect on the neurological system (lead is also considered to have a 

developmental effect). Any new scientific information concerning lead will be reviewed in 

accordance with the NAAQS review process. 

The commenter also makes the legal argument that EPA cannot simply replicate the primary 

NAAQS in its proposed residual risk rule because The Clean Air Act sets different tests for these 

rules to meet and EPA cannot substitute one for the other. We do not accept the commenter’s 

argument. The EPA considered the primary NAAQS for lead --which incorporates an adequate 
42

margin of safety -- in determining whether lead risks (taken together with cancer and other noncancer health risks) from air-borne lead from ferroalloys facilities are acceptable or 

unacceptable. Thus, to the extent the commenter’s argument rests on the difference between 

‘adequate’ and ‘ample’ margin of safety, the argument is misplaced.23 Margin-of-safety 

determinations for this rule are conducted separately, in accord with the two-step framework set 

forth in the Benzene NESHAP and the en banc opinion in Vinyl Chloride. See not only Vinyl 

Chloride, 824 F. 2d at 1165, 1166 but NRDC v. EPA, 902 F. 2d 962, 973-74 (D.C. Cir. 1990) 

(distinguishing the NAAQS process, whereby the margin of safety analysis is incorporated as 

part of the standard without a two-step analysis, from residual risk determinations).24 Using that 

framework, with its consideration of costs, cost-effectiveness, technological feasibility, and other 

factors set out in the Benzene NESHAP, at proposal we did not identify any additional controls 

beyond those that would need to be implemented to ensure an acceptable level of risk with an 

ample margin of safety. The EPA thus disagrees with the commenter that section 112 (f)(2) 

standards would become redundant for any hazardous air pollutant that also has a relationship to 

any other regulated pollutant.

2.1.2 Acute Dose-response Values

Comment: Commenter 0065 states that the use of AEGLs or ERPGs does not include adequate 

safety and uncertainty factors and cannot be relied upon to protect the public from the adverse 

effects of exposure to toxic air pollutants. The commenter (0065) describes that these limits were 

developed for accident release emergency planning and are not appropriate for assessing daily 

human exposure scenarios. The commenter (0065) notes that in the December 2002 EPA 

document, "A Review of the Reference Dose and Reference Concentration Processes," The EPA 

stated that the primary purpose of the AEGL program is to develop guidelines for once-in-alifetime short-term exposures to airborne concentrations of acutely toxic chemicals. The 

commenter (0065) states that they are not meant to evaluate the acute impacts from routine 

emissions that occur over the life of a facility. Unlike the reference concentrations (RfCs) for 

chronic exposures, the AEGLs and ERPGs do not include adequate safety and uncertainty factors 

and cannot be relied upon to protect the public from the adverse effects of exposure to toxic air 

pollutants. The commenter (0065) states that their use is not appropriate in risk assessments and 

urges the EPA to increase its reliance on the California Reference Exposure Levels (RELs) to 

address acute exposures in the residual risk assessments.

Response: The EPA does not rely exclusively upon AEGL values for assessment of acute 

exposures. Rather, the EPA’s approach is to consider various acute health effect reference values 

 

23

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

acceptability of risk is an added conservative (i.e. protective) element in its approach here. 

24

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

applicable to the revised provision. 
43

(see 76 FR 52772), including the California REL, in assessing the potential for risks from acute 

exposures. To better characterize the potential health risks associated with estimated acute 

exposures to HAP, and in response to a key recommendation from the SAB’s peer review of the 

EPA’s RTR risk assessment methodologies,25 we generally examine a wider range of available 

acute health metrics (e.g., RELs, AEGLs) than we do for our chronic risk assessments. This is in 

response to the SAB’s acknowledgement that there are generally more data gaps and 

inconsistencies in acute reference values than there are in chronic reference values. In some 

cases, when Reference Value Arrays26 for HAP have been developed, we consider additional 

acute values (i.e., occupational and international values) to provide a more complete risk 

characterization. As discussed in the preamble to the proposed rule, the exposure guidelines EPA 

considers depends on which exposure guidelines are available for the various HAP emitted. The 

EPA uses AEGL and ERPG values (when available) in conjunction with REL values (again, 

when available) to characterize potential acute health risks. However, it is often the case that 

HAP do not have all of these acute reference benchmark values. In these instances, the EPA can 

only describe the potential acute health risk in relation to the acute health values that are 

available. Importantly, when interpreting the results, we are careful to identify the benchmark 

being used and the health implications associated with any specific benchmark being exceeded.

2.1.2.1 Nickel

Comment: In response to the 2011 proposal, commenter 0106 states that the acute reference 

exposure level (REL) for nickel is based on the toxicity of nickel sulfate, which is more toxic 

than nickel oxide, the primary nickel species expected in the EMI emissions, and resultantly the 

acute inhalation risk from nickel emissions near the EMI facility is likely overestimated. The 

commenter (0106) asserts that there is evidence that nickel oxide could be 10-fold less toxic than 

nickel sulfate, suggesting the nickel screening HQ could be closer to 1 (or no risk).

Response: Although the commenter states that there is evidence that nickel oxide is 10-fold less 

toxic than nickel sulfate, the commenter does not provide quantitative evidence characterizing 

the 10-fold differential toxic potential between nickel oxide and nickel sulfate (the latter being 

the form of nickel used to derive the acute REL value from Cal EPA). Because there are great 

uncertainties associated with various aspects of the assessments of risks from acute exposures to 

HAP (uncertainties related to the acute health effects assessments, characterization of exposure 

concentrations, etc.) and given the fact that these analyses represent worst-case scenarios, the 

 

25 The SAB peer review of RTR Risk Assessment Methodologies is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-

unsigned.pdf.

26 U.S. EPA. (2009) Chapter 2.9 Chemical Specific Reference Values for Formaldehyde in Graphical Arrays of 

Chemical-Specific Health Effect Reference Values for Inhalation Exposures (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R–09/061, and available on-line at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
44

estimated health acute impacts of nickel did not weigh heavily in the regulatory decision. Before 

the supplemental proposal, we evaluated the Cal EPA REL value for nickel and determined that 

it was not appropriate to use in this instance. Therefore, for the supplemental proposal and final 

rule we did not use the Cal EPA REL value to assess acute exposures to nickel (discussed further 

below).

Comment: In comments on the supplemental proposal, commenter 0276 states a concern that the 

EPA is not using the California REL (Cal. REL) for nickel. The commenter (0276) notes that the 

EPA states that it is not using the more protective Cal. REL for a 1-hour period of exposure 

partly because it is the same as the ATSDR intermediate MRL, which supposedly provides 

protection for 364 days. The commenter (0276) states that the REL could therefore be 364*24 

(8736) times more protective, and such a difference in magnitude of protection should cast doubt 

on the protective nature of the MRL, not the REL. The commenter (0276) also states that the 

EPA’s justification for not using the Cal. REL is that it “departs” from its guidelines, and this

justification is insufficient. The commenter (0276) also disputes the EPA’s rationale that 

California does not apply an inhalation dosimetric adjustment factor without explaining why this 

difference undermines the REL. In addition, the commenter states that the EPA should address 

potential harm to the immune system in addition to inhalation risk, and the REL is based on 

research showing harm to the immune system.

Response: As described in the Risk Assessment document (section 2.6.2), we have concluded 

that the California EPA 1-hour acute REL value is not appropriate to use to support EPA’s risk 

and technology review rules. This conclusion, based on details provided in the risk assessment 

document, takes into account: the effect on which the acute REL is based; aspects of the 

methodology used in its derivation; and how this assessment stands in comparison to the ATSDR 

toxicological assessment, which considered the broader nickel health effects database.

The broad nickel noncancer health effects database strongly suggests that the respiratory tract is 

the primary target of nickel toxicity following inhalation exposure. The available database on 

acute noncancer respiratory effects is limited and was considered unsuitable for quantitative 

analysis of nickel toxicity by both California EPA27 and ATSDR.28 The California EPA’s acute 

(1-hour) REL is based on an alternative endpoint, immunotoxicity in mice, specifically depressed 

antibody response measured in an antibody plaque assay. 

In addition, the California acute (1-hour) REL for nickel includes the application of methods that 

are different from those described in EPA guidelines. Specifically, the (1-hour) REL applies 

uncertainty factors that depart from the defaults in EPA guidelines and does not apply an 

inhalation dosimetric adjustment factor. 

 

27 http://oehha.ca.gov/air/allrels.html

28 http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=44
45

Further, the ATSDR’s intermediate MRL (relevant to nickel exposures for a time frame between 

14 and 364 days), was established at the same concentration as the California EPA (1-hour) 

REL, indicating that exposure to this concentration “is likely to be without appreciable risk of 

adverse noncancer effects” (MRL definition29) for up to 364 days. We have high confidence in 

the nickel ATSDR intermediate MRL. Our analysis of the broad toxicity database for nickel 

indicates that this value is based on the most biologically-relevant endpoint. That is, the 

intermediate MRL is based on a scientifically sound study of acute respiratory toxicity. 

Furthermore, this value is supported by a robust subchronic nickel toxicity database and was 

derived following guidelines that are consistent with EPA guidelines.30 Finally, there are no 

AEGL-1/ERPG-1 or AEGL-2/ERPG-2 values available for nickel. Thus, for all the above 

mentioned reasons, we will not include nickel in our acute analysis for this source category or in 

future assessments unless and until an appropriate value becomes available.

2.1.2.2 Arsenic

Comment: In their comments on the 2011 proposal, commenter 0106 notes that the acute REL 

for arsenic of 0.2 μg/m3 was developed by the California Office of Environmental Health Hazard 

Assessment, using assumptions inconsistent with standard US EPA risk assessment methodology 

(e.g., interpretation of the significance of a small decrease in fetal body weight). The commenter 

(0106) suggests that use of more appropriate methodology would yield a more scientifically 

valid value of 2 μg/m3, and would eliminate the screening exceedance for acute exposures to 

arsenic.

Response: We acknowledge the comment, however it is not relevant to the final rule. Due to 

emissions estimate changes between the 2011 proposal and the 2014 supplemental proposal (and 

2015 final rule), there are no longer exceedances of the acute REL for arsenic. In other words, 

for the supplemental proposal and for the final rule, the acute hazard quotient for arsenic was 1.

2.2 Chronic Risk Assessment Issues

2.2.1 Census Block Centroids

Comment: Commenter 0107 states that the EPA did not assess chronic or cancer risk at the

closest or maximum point of exposure, even in those instances where local residents live nearer 

to a facility than the geographic centroid of the census block. The commenter (0107) explains 

that this approach underestimates exposure and could easily be remedied because HEMAERMOD allows the system to make such an adjustment. The commenter (0107) notes that this 

conflicts with the recommendation of the SAB, which has urged the EPA to consider “specific 

 

29 Agency for Toxic Substances and Disease Registry (ATSDR), Toxic Substances Portal, Minimal Risk Levels 

(MRLs) http://www.atsdr.cdc.gov/mrls/index.asp

30 US EPA 2002. Review of the reference dose and reference concentration processes (EPA/630/P-02/002F) 

December 2002, http://www.epa.gov/raf/publications/pdfs/rfd-final.pdf
46

locations of residences.” The commenter (0107) adds that the EPA has regularly received 

comments on this issue from state air pollution control agencies in past rulemakings. The 

commenter (0107) recommends that in this and future rulemakings, the EPA should follow the 

advice of these state regulators and start assessing risk at the edge or fence-line of the facility –

i.e., the point of maximum exposure – not just at the centroid of a census block. The commenter 

(0107) concludes that failing to do so would be unlawful, arbitrary and capricious, as this 

approach fails to assess risk for the person “most exposed” to the source category‘s emissions. 

Commenter 0065 made a similar comment that use of the most highly exposed census block 

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 (0065) states that census blocks are not homogeneous and even if the area near the 

property line is not developed, over time homes and businesses could locate closer to the facility. 

The commenter (0065) states that by using HEM-3, the 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. 

Response: 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. In determining 

chronic risks, it is appropriate to use census block information on where people actually reside, 

rather than points at the property line, to locate the estimation of exposures and risks to 

individuals living near such facilities. 

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

developed by the U.S. Census Bureau); on average, a census block is comprised of 

approximately 50 people or about 20 households. In the 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 systematic bias. 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 fence lines do not typically represent locations where chronic exposures are likely 

(i.e., people do not typically live at the fence line of facilities) and 3) there is no bias introduced 

into the estimate of the MIR by using census block centroid locations. In its peer review of the 
47

methodologies used to estimate risks as part of the RTR rulemaking efforts, the EPA’s Science 

Advisory Board (SAB) endorsed this approach.31

In addition to the approach described above, the EPA recognizes that where a census block 

centroid is located on industrial property or is large and the centroid is less likely to be 

representative of the block’s residential locations, the block centroid may not be the appropriate 

surrogate. For this source category, as described in the risk assessment document available in the 

docket (and in more detail in Appendix 8 of that document), in cases where a census block 

centroid was within 300 meters of any emission source (and therefore possibly on facility 

property), we viewed aerial images of the facility to determine whether the block centroid was 

likely located on facility property. Likewise, we examined aerial images of all large census 

blocks within one kilometer of any emission source. If the block centroid did not represent the 

residential locations within that block, we relocated it to better represent them and/or we added 

additional receptors for residences nearer to the facility than the centroid. For this source 

category, we relocated three census blocks that appeared to be on facility property (ferroalloys or 

other industry) or were otherwise not representative of the surrounding population. In addition, 

we added six user receptors to represent the surrounding population. Appendix 8 of the risk 

assessment, titled Residual Risk Assessment for the Ferroalloys Source Category in Support of 

the September Supplemental Proposal (September 2014) provides additional information about 

these changes. 

2.2.2 Activity Patterns and Exposure

Comment: Two commenters (0073, 0106) state that the exposure analysis employed by the EPA 

does not make use of widely accepted activity patterns, which results in an overestimation of 

potential risks. 

Commenter 0075 states that, in its estimation of chronic human inhalation exposure, the EPA did 

not consider short-term or long-term mobility of the exposed populations and its potential 

influence on their exposure. The commenter (0075) adds that several methodologies are 

currently available to address the mobility of the population, including a 2011 report by Felter et 

al., which proposed guidance for cancer risk assessments for less-than-lifetime exposures based 

on current knowledge of mode of action and dose-response. 

 

31 U.S. Environmental Protection Agency, Office of the Administrator Science Advisory Board. Review of EPA’s 

draft entitled, “Risk and Technology Review (RTR) Risk Assessment Methodologies: For Review by the EPA’s 

Science Advisory Board with Case Studies – MACT I Petroleum Refining Sources and Portland Cement 

Manufacturing.” EPA-SAB-10-007. May 7, 2010. 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-

unsigned.pdf.
48

Three commenters (0122, 0123, 0272) disagreed with the use of a 24-hour per day exposure over 

a 70-year lifetime to estimate individual and population cancer risks for refined risk assessments. 

According to commenter (0122), this exposure assumption is inconsistent with the 

recommendations by the National Research Council and the Commission on Risk Assessment 

and Risk Management. In their Reports to Congress, these organizations support development of 

distributional approaches to exposure characterization based on knowledge of the characteristics 

of a population's variability. The commenter (0122) asks EPA to develop a refined exposure 

methodology that incorporates information available on population residency times that will 

more accurately reflect population risk estimates. The development of this exposure 

methodology should also include a probabilistic analysis of estimated exposures. The commenter 

(0122) states that the use of such an unrealistic assumption makes the results overly conservative 

and will lead to additional and unnecessarily stringent standards more frequently than necessary. 

The commenter (0123) states that the EPA has developed the risk assessment guidance necessary 

to apply more accurate exposure and believes that the EPA’s failure to apply such assumptions in 

the proposed ferroalloys NESHAP rulemaking is arbitrary and capricious.

The commenter 0272 states that the EPA failed to apply the best available scientific knowledge 

on public exposure patterns, which results in overstating the risks. As an example, the 

commenter (0272) notes that the EPA’s assumption that a hypothetical person would spend their 

entire life outdoors at one precise location is contrary to common sense and to the risk 

assessment improvements developed by the EPA since the Benzene NESHAP rulemaking in 

1989. The commenter (0272) believes that the EPA possesses well-supported alternatives that 

produce a very conservative high end assessment of maximum plausible exposures. Therefore, 

the commenter (0272) believes that the EPA’s use of an implausibly high exposure assumption 

produced a 40 percent overstatement of the maximum individual non-cancer risk (see Appendix 

A at Section 3.1.1).

The commenter (0272) further adds that in its statutorily required report to Congress on its 

approach to estimating residual risks under Section 112(f) of the Act, the EPA indicated that they 

estimate human health exposures in accordance with its 1992 guidelines.32 The guidelines 

discuss the concept of a “maximum exposed individual” and explicitly distinguish such a 

receptor from a “worst case exposure.” The Guidelines, at 27 n.20, make clear that the 

“maximum exposed individual” should reflect the upper end of actual exposures in the relevant 

population:

The term “worst case exposure” has historically meant the maximum possible exposure, 

or where everything that can plausibly happen to maximize exposure, happens. While in 

actuality, this worst case exposure may fall on the uppermost point of the population 

 

32 Guidelines for Exposure Assessment, EPA/600/Z-92/001
49

distribution, in most cases, it will be somewhat higher than the individual in the 

population with the highest exposure. The worst case represents a hypothetical individual 

and an extreme set of conditions; this will usually not be observed in an actual 

population. The worst case and the so-called maximum exposed individual are therefore 

not synonymous, the former describing a statistical possibility that may or may not occur 

in the population, and the latter ostensibly describing an individual that does, or is 

thought to, exist in the population.

The Guidelines further provide that the high end exposure scenario should be “plausible” and 

should “fall within the actual distribution, rather than above it.” Id. The commenter (0272) 

believes that the “70-year continuous maximum exposure” assumption relied upon by the EPA to 

define the “maximum individual risk” for the proposed ferroalloys NESHAP is not plausible and 

is above, rather than within, the range of exposures that would ever be experienced by anyone in 

Marietta.

The commenter (0272) believes that the EPA’s “70-year continuous exposure” assumption more 

closely reflects, in the terms of the Guidelines, a “theoretical upper bounding estimate” that 

reflects the mathematical limit of potential exposure calculated by assuming the maximum 

values of each exposure factor (see the Guidelines at 77). Therefore, the commenter (0272) 

believes that this assumption is best suited for screening-level use and not for residual risk

determinations regarding the need for emissions controls. The commenter (0272) provided 

proposed exposure scenarios (see Appendix A) based on conservative high-end assumptions 

from the EPA’s own Exposure Factors Handbook and other literature values, and believes that it 

is representative of the approach suggested in both the Guidelines and the EPA’s 1999 Residual 

Risk Report to Congress.

The commenter (0272) adds that the EPA’s reliance on a factually impossible exposure scenario 

is also inconsistent with EPA’s own acknowledgement years ago that use of a more reasonable 

exposure scenario is appropriate. The commenter (0272) notes that in the preamble to its final 

residual risk NESHAP for coke oven batteries, 70 Fed. Reg. 19991, 19999 (Apr. 15, 2005) that 

the EPA acknowledged that the 70-year maximum exposure assumption does not reflect actual 

exposures, and that the EPA intended in the future to use a more refined methodology that would 

incorporate more realistic exposure considerations.

The commenter (0272) states that the EPA’s assumption that “the individual most exposed to 

emissions from a source” will be the same individual for a full 70-year life is no longer 

consistent with the EPA’s own cancer risk assessment policies and practices. The commenter 

(0272) notes that the most current EPA guidance should have been used in this risk assessment, 

which applies a 30-year exposure duration in high-end risk calculations involving Superfund 

sites, and more recently has recommended a 26-year exposure duration. The commenter (0272) 

believes that the EPA’s inconsistent application of its guidance for high-end residential exposure 
50

frequency and duration resulted in more than a 70 percent overstatement of the maximum 

individual cancer risk.

The commenter (0272) also notes that the regulatory criteria for determining whether a particular 

risk is unacceptable are unique to Section 112, but the best available science is not. They believe 

that the EPA’s accepted methodology for quantifying a specific risk should not vary by

regulatory program. They also believe that the cancer risk associated with inhalation exposure to 

a given concentration of a given pollutant is the same, regardless of whether that exposure results 

from an emission source regulated under the Clean Air Act or a source regulated under the 

Superfund statute. Nothing in the statutory language suggests that Congress intended otherwise.

The commenter (0272) states that the EPA has previously acknowledged the limitations of its 

conservative exposure assumptions in the context of assessing acceptable risk under Section 

112(f)(2) and found estimated cancer risks substantially greater than those estimated in this 

rulemaking to be acceptable in light of the conservatism of the 70-year continuous exposure 

assumption. The commenter (0272) notes that in the residual risk NESHAP for coke oven 

batteries, EPA’s risk assessment estimated the cancer MIR at 300 in 1 million (versus 20 to 100 

in 1 million here), 70 persons exposed to a risk greater than 100 in 1 million (versus none here), 

500,000 persons with a risk greater than 1 in 1 million (versus 31,000 here) and an excess cancer 

incidence of 0.6 cases per year (versus an incidence of 0.002 here). See 70 Fed. Reg. 19992, 

19994 (Apr. 15, 2005).

The commenter (0272) also states that the EPA found such risks to be acceptable in the Coke 

Batteries residual risk NESHAP, in part because the “health protective assumption of a 70-year 

exposure duration” produced risk estimates six times higher than if EPA had instead used the 

national average residency time of 12 years. Id. The commenter (0272) notes that while no two 

risk assessments are identical, the conservatism of EPA’s outdated 70-year exposure assumptions 

is a constant and there is no principled basis for EPA to acknowledge and explicitly “temper” its 

risk conclusions on that basis in one rulemaking, while rigidly applying is in another.

Response: The commenters have commented on specific aspects of our exposure assessments 

from the 70-year exposure duration to incorporating short-term mobility into our assessments. 

Several specific points are addressed below. However, in general, we strive to strike a balance in 

our assessments, meaning that while some factors likely lead to overestimates of risk (e.g., 70-

year exposure duration), others likely lead to underestimates of risk (e.g., average annual 

emissions). We conclude that the risk assessment for this source category is sufficient to support 

a decision on the acceptability of the risk and ample margin of safety. 

The commenter is correct that the EPA did not consider short-term or long-term mobility in the 

assessment. Mobility was not considered because we do not believe that assumption, in 

combination with other modeling assumptions, lead to a significant bias in the risk results in any 

one direction. For example, the EPA does not consider that homes and businesses may locate 
51

closer to facilities over time, which could lead to an underestimation of risk. Additionally, 

estimates of the maximum individual risk (MIR) contain uncertainty, because they are derived at 

census block centroid locations rather than actual residences. This uncertainty is known to create 

potential underestimates and overestimates of the actual MIR values for individual facilities, but 

overall, it is not thought to have a significant impact on the estimated MIR for a source category. 

Processes like deposition, plume depletion, and atmospheric degradation are not considered, 

which may introduce bias to the population exposure estimates. Finally, we did not factor in the 

possibility of a source closure occurring during the 70-year chronic exposure period, leading to a 

potential upward bias in both the MIR and population risk estimates; nor did we factor in the 

possibility of population growth during the 70-year chronic exposure period, leading to a 

potential downward bias in both the MIR and population risk estimates. These uncertainties are 

described in section 4.1 of the risk assessment document.

In assessing risk, we estimate the MIR or the maximum HI, which are defined as the risk (or 

hazard) associated with a lifetime of exposure at the highest concentration where we determine 

people may actually reside. For this assessment, we used the annual average ambient air 

concentration of each HAP at each census block centroid as a surrogate for the lifetime 

inhalation exposure concentration of all the people who reside in the census block. Basing 

exposure estimates at census block centroids may underestimate or overestimate actual exposure 

concentrations at some residences. Further reducing exposure estimates for the most highly 

exposed residents by modeling their short-term behavior could add a systematic low bias to these 

results and is not expected to affect the MIR result. Thus, this risk analysis did not consider the 

short-term human activity patterns and their potential influence on exposure. Our experience 

with the 1996 and 1999 National-Scale Air Toxics Assessments (which modeled daily activity 

using the EPA’s HAPEM model) suggests that, given our current understanding of 

microenvironment concentrations and daily activities, modeling short-term activity would, on 

average, reduce risk estimates about 25 percent for particulate HAP; it will also reduce risk 

estimates for gaseous HAP, but typically by much less.

We agree that our assumption that people may be present at their homes for 24 hours per day 

over a 70-year lifetime represents a scenario that likely overestimates the actual exposures 

received by people living near the facilities. Most people have daily activities that take them to 

areas where exposure concentrations are different and people may move to new residences 

periodically. Both of these behaviors will likely tend to lower lifetime exposures and, therefore, 

risk if they are no longer in the vicinity of sources in the source category. 

In our risk assessments, we estimate risk for the “maximum individual risk” (MIR) which is 

different than the “maximum exposed individual (MEI).” The MEI could be equal to or greater 

than the MIR as the MEI is the highest estimated risk to a hypothetical exposed individual, 

regardless of whether people are expected to occupy that area. The MIR, on the other hand, is the 

highest estimated risk to an exposed individual in areas people may actually occupy. We are 

using the MIR to be considered equivalent to the “individual most exposed” phrase from the 
52

CAA section 112(f)(2). This approach is consistent with the Commission on Risk Assessment 

and Risk Management report recommendation that exposure assessments should not be based on 

a hypothetical MEI.

2.2.3 Respirable Emissions

Comment: One commenter (0106) states that consideration of more plausible exposure 

assumptions to account for time spent indoors, and the reduction in ambient PM2.5 concentrations 

indoors would reduce exposures to respirable manganese and hence, associated risk, by 40 

percent. The commenter (0106) adds that correcting the modeled manganese particulate 

concentration for the fraction of PM2.5 identified by US EPA would result in a further reduction 

in exposure and, hence, associated risk, by 59 percent. One commenter (0106) provides a 

detailed review of the EPA’s modeling and risk assessment, including the following points for 

the 2011 proposal:

 The EPA failed to account for the fact that only those particles of “respirable” size 

(particles 2.5 micrometers in diameter or smaller) are toxicologically relevant when 

assessing potential manganese inhalation risks.

 The EPA assumed 100 percent of the air emissions were in a gaseous state, which is 

overly conservative since particle deposition decreases ambient manganese 

concentration. If the EPA has correctly applied the correct PM2.5 fraction, then assuming 

100 percent gaseous emissions is acceptable because PM2.5 does not significantly deposit 

over distances less than 10 km.

In their comments on the supplemental proposal, commenter 0272 reiterates that EPA assumed 

that all manganese particles emitted in ferroalloys production are capable of entering the blood 

stream and causing adverse health effects, however scientific research shows that only inhalation 

of “respirable” manganese particles leads to adverse health effects (see Section 3.1.2 of 

Appendix A). They note that the EPA’s air program has adopted the position that “respirable” 

generally means particles with an aerodynamic diameter of 2.5 microns or less (“PM2.5”). As an 

example, the commenter (0272) points out in the EPA’s December 2009 “Integrated Science 

Assessment of Particulate Matter,” EPA/600/R-08/139F, at 3-3, the Agency acknowledged that a 

PM10 cut point is commonly understood to define the “thoracic” fraction of inhaled particulates 

(small enough to reach the lung airways, but not the gas-exchange region of the lungs), while a 

PM2.5 cut point is generally considered the measure of the “respirable” fraction.

In their comments on the supplemental proposal, two commenters (0266, 0271) believe that 

when modeling inhalation risk for any HAP, it is critical that only the respirable fraction (PM2.5) 

of particulate be used. One commenter (0271) notes that toxicity values for HAPs are often based 

on respirable fractions like the manganese RfC used for this modeling was developed and based 

upon respirable manganese (Roels et al.,1992). They also note that the EPA’s own guidance 
53

states that risk modelers should use the same particulate fraction that the reference value is based 

on.

The commenter 0271 states that the EPA has particle size emission data in AP-42, from multiple 

sources in multiple industries, including Section 12.5., which indicate that only a fraction of 

emissions from various processes and control devices are respirable. They note that in the 2011 

Regulatory Impact Analysis for Manganese Ferroalloys RTR report, EPA estimated the PM2.5 

percentage of total particulate emissions from the facilities covered by this rule was 41 percent. 

They believe that the EPA must conduct the risk assessment by modelling only the respirable 

fraction of total PM emissions.

Response: The point about time spent indoors was addressed in Section 2.2.2. As discussed in 

Section 2.1.1.1, we do note that the size of the manganese-containing particle has a bearing on 

the toxicity and some of the organizations listed in Section 2.1.1.1 have developed their 

reference values based on different size fractions.33 The size fractions include PM2.5, PM3.5, PM5, 

PM10, and TSP. Given that some of these other agency values are based on size fractions greater 

than PM2.5, it remains reasonable to include larger size particles in this analysis. The use of PM2.5

over PM10 would necessitate a lower reference value to adjust for particles larger than PM2.5 as 

done by other groups, e.g., American Conference of Governmental Industrial Hygienists 

(ACGIH) and Ontario Ministry of the Environment. This is especially important given that 

ACGIH, the International Standards Organization, and the European Standardization Committee 

have adopted a 50 percent cut point of 4 μm as an indicator of respirable particles.34

2.2.4 Cumulative Risk

Comment: Commenter 0107 states that the EPA has failed to satisfy section 112(f)(2) or to 

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

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

recent report on the subject, “Concepts, Methods and Data Sources for Cumulative Health Risk 

Assessment of Multiple Chemicals, Exposures and Effects: A Resource Document” developed

by the SAB. The commenter (0107) states that for both its inhalation risk assessment and its 

multipathway risk assessment, the EPA fails to account for the impact of adding new air 

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

experienced from this source category. As a result, according the commenter (0107), the EPA 

fails to adequately assess the cumulative impact of exposure to this source category’s emissions. 

The commenter (0107) asserts that in many instances people living near these facilities already 

have background levels of past exposure and past pollution that increase their current health risk. 

 

33 U.S. EPA. Mn and BTEX Reference Value Arrays (Final Reports). U.S. Environmental Protection Agency, 

Washington, DC, EPA/600/R-12/047F, 2013.

34 U.S. EPA, 2009. Integrated science assessment for particulate matter. EPA/600/R-08/139F. Research Triangle 

Park, NC. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546.
54

The commenter (0107) adds that for areas like these, where there are multiple sources of air 

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

address background as well as new health risk. 

The commenter (0107) states that the EPA’s refusal to assess cumulative impacts or risk here 

from multiple types or source categories of HAP emissions conflicts with its own recognition 

that considering the most-exposed person’s full health risk is an important part of the section 

112(f)(2) analysis. The commenter (0107) adds that this decision also conflicts with the 

recommendation from the SAB that in May 2010 urged the EPA to incorporate cumulative risks 

into its residual risk analysis. The commenter (0107) states that uncertainty is not a rational 

explanation for failing to address this important element of health risk and describes ways that 

the EPA can manage uncertainty. NEPA and ESA both consider context of all other impacts.

Response: For the ferroalloys source category, the EPA conducted an assessment of the 

cumulative cancer risks from emitted carcinogens and the cumulative noncancer hazard indices 

from all emitted non-carcinogens affecting the same target organ system for the source category 

emissions. While the incorporation of additional background concentrations from the 

environment in our risk assessments (including those from mobile sources and other industrial 

and area sources) could be technically challenging, they are neither mandated nor barred from 

our analysis. In developing the decision framework in the Benzene NESHAP currently used for 

making residual risk decisions, the EPA rejected approaches that would have mandated 

consideration of background levels of pollution in assessing the acceptability of risk, concluding 

that comparison of acceptable risk should not be associated with levels in polluted urban air‘‘ (54 

FR 38044, 38061, September 14, 1989). Background levels (including natural background) are 

not barred from the EPA’s ample margin of safety analysis, but the EPA may consider them, as 

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

the second step of its section 112(f) analysis. This assessment excludes background contributions 

because the available data are of insufficient quality upon which to base a meaningful analysis.

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

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

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

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

quotients. 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. All TOSHI calculations presented here were based exclusively on effects 

occurring at the “critical dose” (i.e., the lowest dose that produces adverse health effects). We 

also disagree with the commenter’s assertion that additional assessment of risks from sources 

outside the source category is required under the statute. The statute requires the EPA to provide 

the risk information necessary to inform RTR regulatory decisions and, to this end, the EPA 

conducts a comprehensive assessment of the risks associated with exposure to the HAP emitted 
55

by the source category and supplements that with additional information that is available about 

other possible concurrent and relevant risks.

Further, the risk assessment modeling accounts for the effects of multiple facilities that may be in 

close proximity when estimating concentration and risk impacts at each block centroid. When 

evaluating the risks associated with a particular source category we combined the impacts of all 

facilities within the same source category, and assessed chronic exposure and risk for all census 

blocks with at least one resident (i.e., locations where people may reasonably be assumed to 

reside rather than receptor points at the fenceline of a facility). The maximum individual risk 

considers the combined impacts of all sources in the category that may be in close proximity. 

Comment: Commenter 0107 states that after assessing each type of risk, the EPA fails to 

combine all health risks. According to the commenter (0107), leaving these risks segmented in 

its analysis prevents the EPA and the affected public from being able to perform a full 

assessment of the total health risk of the most-exposed person. The commenter (0107) notes that 

while the EPA did appropriately combine some risks (e.g., the risk from each individual 

carcinogen to create a total lifetime cancer risk), the EPA needs not only to sum this risk but also 

ensure that it assesses the synergistic, carcinogenic (and other) effects of different pollutants. The 

commenter (0107) describes specific deficiencies including the fact that the EPA does not create 

a combined acute risk number that would represent the total acute risk for all pollutants that act 

in a similar way on the same organ system or systems, similarly to the chronic TOSHI. The 

commenter (0107) adds that the EPA has failed to perform a cumulative risk assessment that 

combines inhalation and multipathway risk for each pollutant, such as POM, that causes both 

risks and that the EPA also fails to combine the multipathway risks created by POM and other 

persistent pollutants, such as arsenic and manganese. The commenter (0107) is also concerned 

that the EPA does not create any metric to assess the total, combined health risk that could be 

used to assess the cumulative impact of all of the types of risks. The commenter (0107) states 

that even though the EPA found a combination of cancer and noncancer risk to create 

“unacceptable” risk, the EPA also must create a cumulative burden metric to assess and consider 

the total, cumulative burden of the most-exposed person. The commenter (0107) asserts that this 

is needed to assess the way different individual health risks (even if potentially “acceptable” on 

their own) combine to cause the full amount of “unacceptable” health risk for this source 

category. The commenter (0107) supports the EPA’s conclusion that cancer and chronic 

noncancer risks each contribute to create “unacceptable” risk and urges the EPA to finalize that 

determination and also to complete a full analysis of the cumulative burden that this source 

category creates.

The commenter (0107) states that to perform a cumulative impact analysis, the EPA should 

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

specific source category the EPA is reviewing. The commenter (0107) states that 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 
56

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

commenter (0107) states that the EPA must also draw on the OEHHA community assessment 

approach.

Response: We have combined risk assessment results to the extent that it is appropriate to do so

and as described in the previous response. We consider the effect of mixtures of carcinogens and 

use a target organ-specific hazard index (TOSHI) approach for our chronic noncancer 

assessments. We do not use a TOSHI approach for acute analyses nor do we combine the results 

of our inhalation and multipathway assessments.

Regarding the comment that the EPA should assess the synergistic and carcinogenic effects of 

pollutants, we do follow the EPA’s guidelines for mixtures because most of the receptors in these 

assessments receive exposure to multiple pollutants rather than a single pollutant. As described 

in the risk assessment report provided in the docket at proposal, we estimated the aggregate 

health risks associated with all the exposures from a particular source category combined. To 

combine risks across multiple carcinogens, our assessments use the mixtures guidelines35, 36

default assumption of additivity of effects, and combined risks by summing them using the 

independence formula in the mixture guidelines. 

As described in the risk assessment report (available in the docket for this action), we do not sum 

results of the acute noncancer inhalation assessment to create a combined acute risk number that 

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

system or systems (similar to the chronic TOSHI). The worst-case acute screen is already a 

conservative scenario. That is, the acute screening scenario assumes worst-case meteorology, 

peak emissions for all emission points occurring concurrently and an individual being located at 

the site of maximum concentration for an hour. Thus, as noted in section 2.7.2 of the Draft 

Residual Risk Assessment for the Ferroalloys Source Category, “because of the conservative 

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

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

approach.”

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

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

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

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

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

and due to the theoretical construct of the screening model, exceedances of the thresholds are not 

 

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

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

36 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.
57

directly translatable into estimates of risk or hazard quotients for these facilities. Rather, it 

represents a high-end estimate of what the risk or hazard may be. For example, an exceedance of 

2 for a non-carcinogen can be interpreted to mean that we have high confidence that the hazard 

would be less than 2. Similarly, an exceedance of 30 for a carcinogen means that we have high 

confidence that the risk is lower than 30-in-1 million. Our confidence comes from the 

conservative, or health-protective, assumptions that are in the screens: we choose inputs from the 

upper end of the range of possible values for the influential parameters used in the screens; and 

we assume that the exposed individual exhibits ingestion behavior that would lead to a high total 

multipathway exposure. For this category, we were able to conduct a more refined screeninglevel assessment that included some site-specific information (i.e., Tier 2). This allowed us to 

remove some of the default information and replace it with actual conditions around these 

facilities (e.g., distance to a lake). While we were able to refine the assessment somewhat, it 

remains a screening-level assessment. 

For the 2014 supplemental proposal and the 2015 final rule, we also conducted the Tier I and 

Tier II screens, but in addition, we conducted a refined multipathway assessment. For the refined 

assessments, risk or hazard values are estimated, not exceedances of a screening threshold. Those 

estimated results can be added to the inhalation results, where appropriate, but the total number

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

same receptor has the maximum results in both assessments. In other words, it is unlikely that the 

person with the highest chronic inhalation cancer risk is also the same person with the highest 

individual multipathway cancer risk. More information can be found in the risk assessment 

document or in the multipathway section of this response-to-comment document (Section 2.5).

In the Air Toxics Risk Assessment Reference Library, we developed the current persistent and 

bioaccumulative HAP (PB-HAP) list considering all of the available information on persistence 

and bioaccumulation (see http://www.epa.gov/ttn/fera/risk_atra_main.html, specifically 

Volume 1 Appendix D). (The Air Toxics Risk Assessment Reference Library provides 

information on the fundamental principles of risk-based assessment for air toxics and how to 

apply those principles in different settings (e.g., facility-specific) as well as strategies for 

reducing risk at the local level.) This list reviewed HAP identified as PB-HAP by other EPA 

Program Offices (e.g., the Great Waters Program) and also used information from the PBT 

profiler (see http://www.pbtprofiler.net/). This list was peer-reviewed by the SAB, and it is 

reasonable to use it in the RTR program. Based on these sources and the limited available 

information on the persistence and bioaccumulation of arsenic and manganese, we do not believe 

that the potential for multipathway risk rises to the level of the PB-HAP currently on the list. 

These HAP are not included as PB-HAP on any of the lists referenced in the Air Toxics 

Assessment Library.
58

2.2.5 Chronic risk assessment results

Comment: Commenter 0106 states that, due to the limited time provided to evaluate the basis for 

the 2011 proposed rule, they were unable to model relevant exposure concentrations for 

compounds other than manganese and instead relied upon the EPA's predicted exposure 

concentrations in the analysis of such non-manganese compounds. Based on the commenter’s 

finding that errors in the EPA's model overstated exposure concentrations of respirable 

manganese by a factor of eight, the commenter (0106) concludes that it is likely that exposure 

concentrations for other relevant compounds (including nickel and arsenic) are also overstated.

Response: As described elsewhere in this document, we disagree that errors in the EPA’s model 

overstated exposure concentrations of respirable manganese by a factor of eight. The time to 

provide public comment was extended for the 2011 proposed rule, and industry came in several 

times to meet with EPA staff. Furthermore, after publication of the supplemental proposal, the 

public had an additional opportunity to comment. 

2.3 Acute Risk Assessment Issues

Comment: Commenter 0106 states that the EPA’s finding of acute offsite screening risks to 

exceed a hazard quotient of 1 for nickel and arsenic in the 2011 proposal significantly 

overestimate actual risks. The commenter (0106) adds that because the EPA only conducted a 

screening assessment of acute inhalation risks, screening results do not provide evidence that 

unacceptable risks for the population are present, only that a refined risk assessment is needed to 

evaluate population risks. The commenter (0106) states that the EPA has not established a basis 

upon which to reach conclusions regarding such risks.

Response: The commenter is correct that the acute risk assessment is a screening-level 

assessment designed to identify facilities and pollutants that need further analysis. The 

commenter is not correct, however, that the screen cannot provide information about the risks 

that can feed into a decision. The screen provides us information that for those facilities where 

the hazard quotients are less than 1, we do not expect acute effects, and for those situations 

where the hazard quotients are greater than 1, the potential for acute effects exists. For those 

situations where the acute hazard quotients are greater than 1 based on our screening assessment, 

the fact that it is a screening-level assessment is taken into consideration in the decision. The 

finding of unacceptable risks is not based on any one risk metric (e.g., acute hazard quotients), 

but rather considering all of the health information available and the degree of uncertainty 

associated with that information. In addition, the commenter does not provide additional 

information as to how the EPA’s finding of acute offsite screening risks are overestimated in the 

2011 proposal.

Comment: Commenter 0107 states that the EPA fails to calculate the maximum acute health risk 

based on a true “worst case” scenario. The commenter (0107) states that in addition to failing to 

address malfunctions, the EPA also did not address or account for higher amounts of emissions 
59

that routinely occur during periods of tapping, casting, maintenance, and other similar activities 

due to the inclusion of an excursion limit of 60 percent opacity for one 6-minute period during 

the performance test. The commenter (0107) adds that “blowing taps, poling and oxygen lancing 

of the tap hole; burndowns associated with electrode measurements; and maintenance activities 

associated with submerged arc furnaces and casting operations are exempt from the opacity 

standards specified in §63.1653, but the EPA has failed to account for higher emissions that 

occur during these activities. The commenter (0107) also notes that this source category has a 

history of unusual incidents that are likely associated with acute health risks, for example the 

May 2008 fugitive emission incident at the Eramet facility in Marietta, Ohio. The commenter 

(0107) states that this incident and other similar information attached show the need for the EPA 

to calculate a higher level of acute health risk to assess a “worst-case” scenario under the existing 

standard. 

The commenter (0107) notes that the EPA has estimated that the current NESHAP standard 

allows a range of 4.9 to 81.1 times the “actual” emissions to occur, and in view of this, the EPA 

cannot justify using a factor less than 81 to perform its acute risk assessment. The commenter 

(0107) adds because the reporting capture and control efficiencies are up to 99% for the 23 

control devices in place, if the control equipment fails, emissions would be at least 100 times 

greater. The commenter (0107) concludes that a 10x margin simply does not make sense, and the 

EPA cannot rationally justify using only a factor of ten to assess the acute risk to the mostexposed individual and community.

Response: Sections 63.1650 through 63.1661 are being retained only until they are superseded

by the RTR MACT requirements in §§ 63.1620 – 63.1630 upon the effective date of the new 

provisions. We believe that the final standard will address the concerns of the commenter related 

to excursions.

When screening for potentially significant acute exposures, we used an estimate of the highest 

hourly ambient concentration at any off-site location as the surrogate for the maximum potential

acute exposure concentration for any individual. These hourly concentrations are based on 

hourly emissions. Since information is not usually available on short-term emission rates, we 

generally apply the assumption that the maximum one-hour emission rate from any source is ten 

times the average annually hourly emission rate for that source. (The average hourly emissions 

rate is defined as the total emissions for a year divided by the total number of operating hours in 

the year.) This choice of a factor of ten for acute screening was originally based on engineering 

judgement and is used if no additional information is available. 

For the ferroalloys source category assessment, however, we did have additional information. In 

the ferroalloys risk assessment, we incorporated additional information and process knowledge 

in order to better characterize acute emissions. Using emissions data obtained from the ICR, 

knowledge from site visits, and the operating characteristics of ferroalloys emissions sources we 

developed and used process-specific factors ranging from 1 to 4, not 10 as the commenter states. 
60

A default factor of 10 is used in situations where we do not have additional information 

available. For the ferroalloys source category, we had information about the operating hours for 

each process. Some processes operate continuously, so their maximum hourly emissions equal

the average hourly emissions. For other processes, they have specific cycles, with peak emissions 

occurring for a part of the cycle (e.g., 30 minutes during a 2-hour period). Additional 

conservative assumptions are made for emission rates, meteorology, and exposure location (as 

described in the Risk Assessment document):

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

occur at all emissions points at the same time.

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

assumed to be the sum of the maximum concentrations due to each emission point, 

regardless of whether those maximum concentrations occurred during the same hour.

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

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

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

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

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

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

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

2.4 Facility-wide Risk Assessment

Comment: Commenter 0075 asserts that the EPA does not have authority to consider “total 

facility” emissions in conducting the residual risk assessments for a given source category (even 

if the EPA did not conduct one in this case). The commenter (0075) states that the CAA requires 

residual risk determinations to be conducted on a category-by-category basis. 

Commenter 0107 objects that the EPA has not considered facility-wide risk in this rulemaking 

and states that the EPA has failed to justify this. The commenter (0107) describes substantial 

sources of toxic air emissions located at the same site as the Eramet facility (an existing 

chromium-emitting operation under its own control at the same site and similarly collocated 

sources at the Felman facility). The commenter (0107) states that the EPA must perform a 

facility-wide risk assessment for this source category. The commenter (0107) adds that a facilitywide risk assessment will only provide only part of the picture.

Response: As explained below, EPA has the discretion to conduct a facility-wide risk assessment 

factoring emissions outside the source category, but in the context of this rulemaking, it was 

reasonable not to do so. We disagree that examining facility-wide risk in a risk assessment 

conducted under section 112(f) exceeds the EPA’s authority. While we did not conduct a 

facility-wide risk assessment for this source category, we typically examine facility-wide risks to 

provide additional context to the source category risks. The development of facility-wide risk 
61

estimates provides additional information about the potential cumulative risks in the vicinity of 

the RTR sources, as one means of informing potential risk-based decisions about the RTR source 

category in question. We recognize that, because these risk estimates were derived from facilitywide emissions estimates which have not generally been subjected to the same level of 

engineering review as the source category emission estimates, they may be less certain than our 

risk estimates for the source category in question, but they remain important for providing 

context as long as their uncertainty is taken into consideration in the process. 

We note, however, 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 (54 FR 38044, September 14, 

1989). In the Benzene NESHAP, the EPA rejected approaches that would have mandated 

consideration of background levels of pollution in assessing the acceptability of risk, concluding 

that “...comparison of acceptable risks 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 considered this inappropriate because 

only the risk associated with the emissions under consideration are relevant to the regulation 

being established and, consequently, the decisions being made.” (54 FR 38044, September 14, 

1989). Our authority to use the two-step process laid out in the Benzene NESHAP, and to 

consider a variety of measures of risk to public health, is discussed more thoroughly in the 

preamble to the proposed rule. Nothing in the CAA or the Benzene NESHAP in any way 

forecloses us from considering facility-wide risks in making a determination under section 

112(f)(2), as such information can constitute relevant health information. 

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

background risks or contributions to risk from sources outside the source category under review 

could be one of the relevant factors considered in the ample margin of safety determination, 

along with cost and economic factors, technological feasibility and other factors. Background 

risks and contributions to risk from sources outside the facilities under review were not 

considered in the ample margin of safety determination for this source category, mainly because 

of the significant uncertainties associated with emissions estimates for such sources. Our 

approach here is consistent with the approach we took regarding this issue in the Hazardous 

Organic NESHAP (HON) RTR (71 FR 76603, December 21, 2006), which the court upheld in 

the face of claims that the EPA had not adequately considered background (NRDC v. EPA, 529 

F.3d 1077 (D.D. Cir. 2008)).

With respect to the ferroalloys source category, a facility-wide risk assessment was not 

performed because we do not have emissions data for any other operations at these facilities. In 

addition, the other operations described at Eramet have either been permanently shut down 

(Simplex/Vacuum Furnace) or have been idle for some time (electrolytic manganese and 

chromium processes). We received no indication from the facility that these processes will ever 

operate again. We also did not observe any sources of toxic emissions from sources collocated at 
62

the ferroalloy production facilities during our site visits to these facilities. Therefore, it was 

assumed that the source category risks equaled the facility-wide risks. The finding of 

unacceptable risks from the ferroalloys source category was based on source category risk 

estimates and emissions from the ferroalloys source category alone. An evaluation of facilitywide risks would not change our decisions about acceptability and ample margin of safety of the 

risks associated with the source category. Therefore, comments on how facility-wide risks were 

used by the EPA in determining acceptable risks and ample margin of safety are not germane to 

the final rule. 

2.5 Multipathway and Environmental Effects

2.5.1 Multipathway

Comment: According to commenter 0107 the EPA’s multipathway risk assessment falls short 

because the EPA did not complete this analysis for all persistent or bioaccumulative pollutants, it 

did not use “allowable” emissions for this assessment, and it did not assess all exposure routes –

particularly for children. The commenter (0107) states that it is also problematic that the EPA 

failed to use the information it found from the multipathway analysis in its overall risk analysis, 

because it did not add the multipathway risk found to the inhalation risk. 

Commenter 0107 states that the multipathway risk screening assessment for Ferroalloys was 

restricted to only those contaminants identified in the 2003 Risk Assessment Guidance as being 

both persistent and bioaccumulative in the environment (i.e., PB-HAPs). They state that this list 

of 14 PB-HAPs is incomplete as it ignores other HAPs which present a multipathway risk. 

Two commenters (0107, 0276) describe why they believe the 2003 Guidance is deficient and 

conclude that the EPA must perform a full multipathway risk assessment for all metals emitted 

by this source category, including arsenic, chromium, nickel, and manganese. The commenters 

(0107, 0276) note that California OEHHA has recommended multipathway assessment for these 

metals based on scientific research and developed a method to conduct this assessment, and the 

EPA should follow its lead. The commenters (0107, 0276) provide additional information for 

each of these pollutants for the EPA’s consideration, including information from recent studies 

showing the impacts of manganese ingestion (see pp. 21-22 of the commenter 0276 letter). The 

commenters (0107, 0276) conclude that the EPA simply may not assume that the ingestion and 

other multipathway risks are zero for these pollutants because doing so when science shows 

otherwise is arbitrary and capricious. The commenters (0107, 0276) add that the failure to assess 

multipathway risk from exposure to these HAPs, both individually and cumulatively, results in 

an underestimate of the health risks of HAP emissions from this source category. Commenter 

0276 adds that this provides further support for the finding of unacceptability and the need for 

strong health risk-based standards that assure an “ample margin of safety to protect public 

health” under section 7412(f)(2).
63

The commenter (0107) further describes those deficiencies in the multipathway screening 

analysis conducted for the 2011 proposal:

 It is irrational and unjustified that the EPA relied on a NAAQS comparison for lead to 

assess multipathway risks from lead. The EPA should have performed a full, 

multipathway risk assessment for lead that looks at the full exposure from ingestion and 

dermal pathways, including through soil and breast-milk exposure.

 The EPA‘s “refined” screening analysis accounted only for exposure due to farming and 

fishing scenarios, which assessed the “layout of the modeling domain (specifically, 

location of lakes and farms), and meteorological characteristics.” The EPA must conduct 

a full multipathway risk assessment for this source category that includes consideration of 

a child‘s multipathway exposure, in urban and rural residential scenarios. Of particular 

concern is the need to assess impacts on children of soil contamination using updated 

exposure values.

 The EPA must use the multipathway assessment appropriately, by adding the risk found 

there to the inhalation risks found, and then proceeding with the required section 

112(f)(2) analysis to determine whether or not that total level of risk is acceptable, and 

what standards are needed to reach an acceptable level and also to provide an ample 

margin of safety. The commenter (0107) adds that because the EPA treated multipathway 

risk separately from inhalation risk in its analysis, listing each of them, but not adding 

them together in an appropriate manner to recognize their combined impact on the mostexposed people, the EPA thus failed to adequately assess or address the full risk to the 

most-exposed person from the combined impact of both inhalation and other routes of 

exposure, such as ingestion, breast-milk exposure, and other pathways.

Response: We acknowledge we do not have screening values for some of the PB-HAP but we 

disagree that the multipathway assessment is inadequate. In the Air Toxics Assessment Library, 

we developed the current persistent and bioaccumulative HAP (PB-HAP) list considering all of 

the available information on persistence and bioaccumulation (see 

http://www.epa.gov/ttn/fera/risk_atra_main.html). This list reviewed HAP identified as PB-HAP 

by other EPA Program Offices (e.g., the Great Waters Program), as well as information from the 

PBT profiler (see http://www.pbtprofiler.net/). This list was peer-reviewed by the SAB and 

found to be acceptable and, therefore, we consider it to be reasonable for use in the RTR 

program. Based on these sources and the limited available information on the persistence and 

bioaccumulation of other HAP, we do not think that the potential for multipathway risk from 

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

With respect to conducting a multipathway assessment with the allowable emissions, the results 

from an allowable emissions-based multipathway assessment would not have changed our risk 

acceptability decision. The baseline risks from the category were determined to be unacceptable, 
64

and that decision included risk results using actual emissions in the multipathway assessment. 

Using allowable emissions in the multipathway assessment, where available, would result in the 

same or higher risks than using actual emissions. For some pollutants, we did not have detailed 

enough information to perform a multipathway risk assessment with allowable emissions. For 

example, for POM there is not a MACT standard in the 1999 NESHAP and thus, we were unable 

to calculate MACT-allowable emissions for POM. In this instance, we set allowable emissions 

equivalent to actual emissions and as stated, actual emissions were included in the multipathway 

assessments for all rule stages. Further, we evaluated post-control risks and determined them to 

be acceptable. The post-control risks were based on emission limits that will lower “baseline” 

allowable emissions, including for those pollutants that were not estimated in the baseline 

allowable levels. 

We disagree with the commenter that a separate multipathway risk assessment should have been 

performed for lead. As noted in previous responses, the NAAQS for lead was used as a health 

based standard in this review. It was not simply adopted mechanically, but rather is justified 

under the independent decision framework in section 112(f)(2). We note that the NAAQS for 

lead was set to protect, with an adequate margin of safety, the health of the most susceptible 

children and other potentially at-risk populations against an array of adverse health effects, most 

notably including neurological effects, particularly neurobehavioral and neurocognitive effects 

(which are the most effects to which children are most sensitive) (73 FR at 67007). We further 

note that in developing the NAAQS for lead, air-related multipathway effects were already taken 

into account. That is, as noted at 73 FR at 66971: “As was true in the setting of the current 

standard, multimedia distribution of and multipathway exposure to Pb that has been emitted into 

the ambient air play a key role in the Agency’s consideration of the Pb NAAQS.” More 

discussion on the use of the lead NAAQS in RTR can be found in Section 2.1.1.6.

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

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

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

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

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

source category. 

The commenter is incorrect in saying that the “‘refined’ screening analysis (conducted for the 

2011 proposal) accounted only for exposure due to farming and fishing scenarios.” The 

intermediate screen (or Tier 2 screen) used the full multipathway assessment conducted to 

develop the Tier 1 screening thresholds, but incorporated some site-specific information to 

replace some default parameters, such as distance to the lake and local meteorological data. The 

scope of the assessment did not change from Tier 1 to Tier 2. The use of the Tier 1 screen and 

the development of the screening thresholds are described in the risk assessment document (and 

related appendices) available in the docket for the proposed action. The description of the sitespecific information used in the Tier 2 screen is also described in these same documents. For the 
65

2014 supplemental proposal and the 2015 final rule, we conducted Tier I and Tier II screens and 

we also conducted a refined multipathway assessment.

The 2011 Exposure Factors Handbook was not available at the time the multipathway screen was 

conducted for proposal. Since that time, however, it has been made available and the Tier 1 

multipathway screening scenario has been updated to include the updated factors. As stated in 

the risk assessment document (see Appendix 4), “The screening scenario is intended to represent 

a high-end exposure for children via incidental soil ingestion. The 2011 Exposure Factors 

Handbook recommended “upper-percentile” soil ingestion rate (numeric percentile not specified) 

for children aged 3 to <6 years is 200 mg/d. This is half of the value used in the previous [i.e., at 

proposal] scenario setup (i.e., 400 mg/d), which was set based on recommendations by the EPA 

in the 1997 Exposure Factors Handbook. The EPA also recently published the Child-Specific 

Exposure Factors Handbook (2008). No additional data or recommendations for child soil 

ingestion are presented in this source, and in fact an “upper percentile” value for this parameter 

is not provided. Based on these sources, a value of 200 mg/d is used in the current RTR 

multipathway screening scenario for the child incidental soil ingestion rate.” 

As discussed previously, we have combined risk assessment results to the extent that it is 

appropriate to do so. The individual cancer risks for the category were aggregated for all 

carcinogens. We consider the effect of mixtures of carcinogens and use a target organ-specific 

hazard index (TOSHI) approach for our chronic noncancer assessments. We do not use a TOSHI 

approach for our acute analyses nor do we combine the results of our inhalation and 

multipathway assessments. The multipathway risk assessment conducted for proposal was a 

screening-level assessment (i.e., Tier 1). It used highly conservative assumptions designed to 

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

for multipathway impacts of concern. The screening scenario is a hypothetical scenario and, due 

to the theoretical construct of the screening model, exceedances of the thresholds are not directly 

translatable into estimates of risk or hazard quotients for these facilities. Rather, it represents a 

high-end estimate of what the risk or hazard may be. For this category, we were able to conduct a 

more refined screening-level assessment that included some site-specific information (i.e., Tier 

2). This allowed us to remove some of the default information and replace it with actual 

conditions around these facilities (e.g., distance to a lake). While we were able to refine the 

assessment somewhat, it remains a screening-level assessment. For this category we were also 

able to develop a slightly more refined screening-level scenario to characterize multipathway 

risks for those facilities that exceeded the Tier 1 screening thresholds by using some site-specific 

information (i.e., Tier 2). This allowed us to remove some of the default information and replace 

it with actual conditions around these facilities (e.g., distance to a lake, size of lake, etc.). 

Comment: In comments on the supplemental proposal, commenter 0276 said that rather than 

ignoring the health risks created by PCB emissions, the EPA should have used a default factor to 

account for these risks, based on chemical structure, available toxicological tests and model or 

experimental data, and data on similar chemicals that have been well-studied as recommended by 
66

the NAS. The commenter (0276) added that the EPA has likely underestimated PCB emissions 

and that the EPA’s justification that emissions are low is invalid. Also, the commenter (0276) 

states that PCBs are extremely dangerous and persist and bioaccumulate in the environment so 

that small amounts add up, get worse and do not go away over time.

Response: We acknowledge we do not have screening values for some of the PB-HAP but we 

disagree that the multipathway assessment is inadequate. As we explained in the emissions 

methodology memorandum,

37 over half of the PCB compounds were reported as non-detect.

These emissions are unlikely to impact health risks. In the Air Toxics Risk Assessment 

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

information on persistence and bioaccumulation (see http://www2.epa.gov/fera/air-toxics-riskassessment-reference-library-volumes-1-3), specifically Volume 1 Appendix D). (The Air Toxics 

Risk Assessment Reference Library provides information on the fundamental principles of riskbased assessment for air toxics and how to apply those principles in different settings (e.g., 

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

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

well as information from the persistent, bioaccumulative and toxic (PBT) profiler (see 

http://www.pbtprofiler.net/). This list was peer-reviewed by the SAB and found to be acceptable, 

and therefore we consider it to be reasonable for use in the RTR program. Based on these sources 

and the limited available information on the persistence and bioaccumulation of other HAP, we 

do not believe that the potential for multipathway risk from other HAP rises to the level of the 

PB-HAP currently on the list.

Comment: Commenter 0107 states that by failing to account for multipathway risk due to 

allowable emissions (and for higher risk due to malfunctions), the EPA has not assessed the full 

potential for non-inhalation health risk due to persistent and bioaccumulative emissions. The 

commenter (0107) notes that intermittent or short spikes of PB-HAPs, can represent a significant 

health risk because the contaminants stay in the environment and small amounts can accumulate 

into larger amounts over time. The commenter (0107) states that failing to account for the full 

multipathway risk that the EPA’s existing standard allows, or for risk due to violations from that 

standard, violates the section 112(f)(2) requirement to protect the individuals “most exposed” to 

this source category.

Response: The point about using allowable emissions in multipathway assessments was 

discussed earlier in this section. We disagree with the commenter that emissions that are 

violations of the standards 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 

 

37 Memorandum from Bradley Nelson, EC/R Inc., to Phil Mulrine, EPA OAQPS/SPPD/MMG, Revised 

Development of the Risk and Technology Review (RTR) Emissions Dataset for the Ferroalloys Production Source 

Category for the 2014 Supplemental Proposal, August 26, 2014.
67

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

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

residual risk rule will avoid or mitigate against such violations. In other words, a source that is 

violating the MACT emissions standard promulgated under section 112(d) would not be any 

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

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

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

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

emissions event poses a significant health or environmental risk.

Comment: In their comments on the 2011 proposal, commenter 0106 asserts that the EPA 

improperly used Section 112(d) to impose risk-based standards in the absence of justification 

under Section 112(f). The commenter (0106) states that the EPA’s reliance on “potential” risks 

from a screening assessment to justify mercury controls is a misuse of the relevant screening 

tool, which should only be used to determine when a site-specific risk assessment is called for to 

determine whether further emission controls are justified. The commenter (0106) states that there 

is no reason to expect that EMI’s very small mercury emissions (the maximum off-site 

concentration predicted by the EPA is about one-third of the average ambient concentration in 

the United States) would fail a multi-pathway assessment based on more accurate air modeling 

and other risk assessment parameters. 

Response: For the 2011 proposal, the multipathway screen was conducted to assess risks under 

112(f). The results of that assessment, and the fact that it is a screening-level assessment, were 

considered in the acceptability decision under 112(f). However, the emission controls proposed 

to reduce mercury emissions (e.g., activated carbon injection, or ACI) were proposed under 

112(d), the technology review section, not 112(f). Regardless of the risk assessment results, we 

had an obligation to address mercury emissions because all HAP from a major source category 

must be addressed by MACT under Sierra Club v. EPA, 479 F. 3d 875 (D.C. Cir. March 13, 

2007). The limits in the rule are technology based, not risk based. The mercury emissions 

estimated by the EPA are based on test data provided by the facility, in addition to information 

related to the type of ferroalloy being produced in each of the furnaces. Therefore, we disagree 

with the commenter’s assertion that their modeling and parameters are more accurate. The basis 

for our selection of models and parameters is explained in emissions methodology 

memorandum38 in the record for today’s rule. Further, as described earlier, a refined assessment 

was conducted (under 112(f)) for the 2014 supplemental proposal and the 2015 final rule.

 

38 Memorandum from Bradley Nelson, EC/R Inc., to Phil Mulrine, EPA OAQPS/SPPD/MMG, Revised 

Development of the Risk and Technology Review (RTR) Emissions Dataset for the Ferroalloys Production Source 

Category for the 2014 Supplemental Proposal, August 26, 2014.
68

Comment: In their comments on the 2011 proposal, commenter 0106 states that as a result of 

their finding that errors in US EPA's model overstated ambient concentrations of manganese by a 

factor of three, it is likely that ambient concentrations for mercury and POM used as the basis of 

the non-inhalation pathway screening analysis are also overstated, but they were unable to 

quantify the degree of such overstatement. The commenter (0106) states that the POM and 

mercury intermediate screening threshold exceedances in US EPA's multipathway screening risk 

assessment are not evidence of unacceptable risks, noting that because of the conservative nature 

of screening assessments, only a refined risk assessment in accordance with US EPA guidance 

can provide a reliable conclusion that risk thresholds are exceeded. The commenter (0106) notes 

that the EPA did not conduct such an assessment of the multipathway exposures and risks. The 

commenter (0106) also notes that the POM emission threshold used in the multipathway screen 

uses an uncertain toxicity value and it is inappropriate to apply that value to PAH that are not 

carcinogens. The commenter (0106) states that assuming five percent of the POM emissions are 

as toxic as benzo(a)pyrene is not applicable to ferroalloy emissions because “emissions are 

different.” 

In their comments on the 2011 proposal, commenter 0107 states that the EPA did not refine its 

analysis further for mercury or POM (or any other PB-HAPs) and it has no rational justification 

for finding a dramatically high multipathway risk and then discounting that analysis due to data 

limitation and failing to explain why it has not collected additional data and to describe what data 

it needs to complete its multipathway risk assessment. 

Response: During the comment period after the publication of the 2011 proposal, the commenter 

did not provide any additional information about the basis of the statement that mercury and 

POM concentrations are overstated (e.g., revised emissions information for mercury or POM). 

However, additional emissions were provided in the intervening years and those revised 

emissions estimates were used in the assessments for the supplemental proposal and/or final, 

depending on when it was provided. As described in the risk assessment report available in the 

docket for this proposed action, the mutlipathway screen does not use the ambient concentrations 

obtained from the inhalation modeling, so the statement that the concentrations are overestimated 

is irrelevant. The multipathway screen compares facility-level emissions to a screening level of 

emissions below which we do not expect there to be multipathway effects. 

The commenter is correct that the multipathway screen is a screening-level assessment designed 

to identify facilities and pollutants that need further analysis. The commenter is not correct 

however that the screen cannot provide information about the risks that can feed into a decision. 

The screen provides us information that for those facilities whose emissions do not exceed the 

screening thresholds, we do not expect multipathway effects, and for those situations where the 

facility emissions are greater than the screening thresholds, the potential for multipathway effects 

exists. For those situations where the facility emissions are greater than the screening thresholds 

based on our multipathway screen, the fact that it is a screen is taken into consideration in the 

decision. The finding of unacceptable risks is not based on any one risk metric (e.g., potential 
69

multipathway risks), but rather considering all of the health information available. As stated

earlier, for the 2014 supplemental proposal and the 2015 final rule a refined multipathway 

assessment were conducted.

The commenter does not elaborate on what is meant by an “uncertain toxicity value” and does 

also not explain what is meant by the comment that ferroalloys “emissions are different.” These 

statements lacking additional information do not enable us to update our analysis in a meaningful 

way. The commenter is correct that some of the PAH are not considered carcinogens. This 

determination was made after the risk assessment was conducted for the 2011 proposed 

rulemaking and has been corrected for the supplemental proposal and final rulemaking (i.e., the 

individual PAH species that are not carcinogens have not been included in the multipathway 

screen). More information is available in the risk assessment document.

Comment: In their comments on the supplemental proposal, commenter 0272 states that the 

EPA’s assumes that the Marietta area supports subsistence fishing, however the EPA presented 

no substantial evidence in the record that such an assumption is plausible for Marietta, Ohio. The 

commenter (0272) believes that outside of indigenous populations in Alaska, there is scant 

evidence to support the existence of subsistence fishing in the United States. Therefore, the 

commenter (0272) believes that the EPA should have modeled ingestion risks based on a highend recreational angler receptor, which they believe is the most conservative and plausible 

receptor for purposes of this rulemaking (see Section 3.2.2.1 of Appendix A).

The commenter (0106) states that the EPA should have used a 95th percentile fish ingestion rate 

instead of the 99th percentile as the 99th percentile is unnecessarily conservative for assessing 

risks to the general population. In addition, the commenter (0106) notes that assuming that 100 

percent of the fish consumed is caught locally is not a reasonable assumption.

Response: The design of the multipathway screen is to reflect conservative assumptions, such 

that we are reasonably confident that at emission levels below the screening thresholds we would 

not see any multipathway effects. Given that design goal, using conservative assumptions for 

fish ingestion and local fish consumption are reasonable. The refined multipathway assessment 

includes an angler scenario, which represents an individual who regularly consumes fish caught 

in a freshwater lake in the vicinity of the source of interest over the course of a 70-year lifetime 

(see Appendix 10 of the Risk Assessment Document – Technical Support Document: Human 

Health Multipathway Residual Risk Assessment for the Ferroalloys Production Source 

Category). We reviewed the potential lakes in the area to see if they are fishable by the general 

public (e.g., not located on gated, industrial property) and are of sufficient size to contain fish of 

higher trophic levels. Data is not available on the subsistence fishing activities in the area, but the 

presence of fishable lakes means it could happen.

Comment: In their comments on the 2011 proposal, commenter 0106 states the EPA's 

"maximum off-site impact" modeling location for mercury compounds is actually on-site at EMI. 
70

The commenter (0106) states that the correct off-site location has predicted air concentrations for 

mercury compounds that are approximately one-half of the values relied on by US EPA in its 

screening assessment.

Response: In response to the 2011 proposal, the facility did not provide any additional 

information (e.g., a boundary map) to enable us to update our on-site/off-site locations. EMI has 

also not provided us any additional information about the mercury species to which they are 

referring in their comment (e.g., divalent or elemental mercury). However, the on-site/off-site 

nature of the receptor does not come into play in the multipathway screening assessment. As 

described in the risk assessment report available in the docket for this proposed action, the 

multipathway screening analysis does not use the ambient concentrations obtained from the 

inhalation modeling, so the statement that the concentrations are overestimated is irrelevant. The 

multipathway screening assessment compares facility-level emissions to a screening level of 

emissions below which we do not expect there to be multipathway effects. For our chronic and 

acute inhalation assessments, we do our best to estimate risks for off-site receptors, as described 

in the risk assessment document.

2.5.2 Environmental Effects

Comment: In their comments on the 2011 proposal, commenter 0107 states that the EPA 

provides no conclusion on whether there is an adverse environmental effect currently, or whether 

its proposed rule would prevent such an effect, as required by section 112(f)(2). The commenter 

(0107) states where there is such a high potential for multipathway risk to people, there is likely 

to be a parallel high risk due to ingestion and other non-inhalation pathways of exposure for 

wildlife and other impacts to natural resources. The commenter (0107) states that the EPA must 

perform an ecological risk assessment for this source category, and may not simply rely solely on 

the human health assessment without a reasoned explanation for doing so that is not supported 

by scientific evidence in the record. The commenter (0107) states the EPA’s health risk numbers 

are not below the threshold and, although the EPA states that the reference doses it is using are 

more protective than the EPA believes is necessary to protect laboratory animals such as rodents, 

the EPA gives no basis for why this is a sufficient way to prevent an adverse environmental 

effect for more sensitive wildlife or other environmental receptors. The commenter (0107) notes 

that the EPA says nothing at all about ESA consultation, which provides further evidence that it 

has not considered or addressed its duty to prevent adverse environmental effects, as recognized 

by the D.C. Circuit. The commenter (0107) adds that each of the significant flaws described 

above in the EPA’s human health risk assessment provides an additional reason why the EPA 

cannot rely on that alone for an environmental risk assessment.

Response: Since the time of the 2011 proposal, we have developed a more robust ecological risk 

assessment screening approach, as described in the preamble to the 2014 supplemental proposal 

and the risk assessment documents for the 2014 supplemental proposal and 2015 final rule.
71

2.6 Environmental Justice Assessment Issues

Comment: Commenter 0075 asserts that the EPA does not have authority to consider 

demographics in conducting residual risk assessments. The commenter (0075) states that it 

would not be not reasonable to construe the term “public health” as used in section 112(f) as 

allowing consideration of demographic classifications that bear no relationship to the potential 

health effects presented by the HAPs at issue for the given source category or subcategory. The 

commenter (0075) adds that the EPA’s proposal would unreasonably inject racial, ethnic, and 

other policy considerations into a program designed to provide protection for the public at large, 

thus inappropriately causing arbitrary policy and political considerations to trump objective 

scientific analysis.

Response: While we did provide a demographic analysis of the at-risk populations surrounding 

the facilities within the source category addressed by this rule making, the results of our 

demographic analysis only serve to provide information about the demographic make-up of the 

populations exposed to this source category which might benefit from the proposed rule and did 

not affect any decision in this rulemaking. 

Comment: In their comments on the 2011 proposal, commenter 0107 notes that the EPA’s draft 

socioeconomic analysis is incomplete and it should add additional elements into this analysis to 

more fully assess environmental justice impacts. The commenter (0107) states that, in addition to 

looking at demographic census data, the EPA must also assess the starting point or baseline of 

“overall health” status of the affected individuals and communities using the best available data 

at a local and national level, including the baseline cancer levels. The commenter (0107) states 

that the EPA should follow the recommendations of the EPA’s own interim guidance and 

presented in the Environmental Justice Strategic Enforcement Assessment Tool (EJSEAT), and 

include other relevant EJ factors such as an assessment of the percent of population with limited 

English proficiency, percent infant mortality, and percent low birth weight births. 

The commenter (0107), with similar comments submitted by commenter 0065 (on the behalf of 

state and local air quality agencies), adds that the EPA must also analyze the demographics of 

the people who are the most exposed, within 5 km of existing plants, and for urban areas and 

perform this assessment within a 2 km radius of each facility. The commenter (0107) states that 

the EPA analyzed the demographics within a 5 km radius for the chrome plating proposal and it

must at least do the same for this source category. The commenter (0107) is concerned that 

failing to perform the localized analysis may miss environmental justice impacts if there is a 

minority or low-income community directly next to the facility but not significantly represented 

in the broader 50-km area. 

Both commenters (0065, 0107) state that the EPA should also use the most recent census data 

from 2010, to the extent it is available, rather than just data from 2000 for this analysis. One 

commenter (0107) adds that the census data available for 2010 show the largest number of 
72

people living below the poverty level in the United States in the 52 years for which poverty 

estimates have been published. 

The commenter (0107) states that the EPA must also incorporate this environmental justice 

assessment fully into the policy decision it chooses in the final rule, by recognizing that it is not 

fair or acceptable for particular individuals or communities to have this type of disproportionate 

impact. 

Furthermore, the commenter (0107) states that, as part of providing sufficient information to 

affected local communities, the EPA should publish a plain-language statement of the health 

risks and benefits from the EPA’s final action, and in future rule proposals. The commenter 

(0107) states that providing a meaningful opportunity for comment, particularly where 

disproportionate health impacts are concerned, is an environmental justice issue. Both

commenters (0065, 0107) state that it is important that the EPA provide a statement and analysis 

in this residual risk rulemaking (and all others) on the real world impacts of the EPA’s 

rulemaking, so that the affected public has a clear understanding of what the risk is, and precisely 

what types of harm to public health EPA is determining are “acceptable” and “unacceptable.” 

One commenter (0107) notes that the EPA released the Plan EJ 2014 to direct ways the agency 

intends to address environmental justice impacts, and it includes the development of scientific 

tools on cumulative impacts. The commenter (0107) states that the EPA must not wait to employ 

the best available science now, in this rulemaking, to protect local communities that face 

disproportionate impacts from these and other sources of toxic air emissions.

Response: With respect to the EJSEAT tool, we disagree that it should be used in our 

demographic analyses. At the time of the 2011 proposal, EJSEAT was a draft tool in 

development. Thus, it had not undergone a sufficient level of peer review to be incorporated into 

our analyses. Through the EPA’s interim guidance on EJ and the Action Development Process, 

the agency is encouraging rule writers and policy makers to look at the whole range of factors 

that impact communities and population groups when crafting rules. The EPA is continuing to 

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

outlined in EO 12898.

The EPA defines “environmental justice” to mean fair treatment and meaningful involvement of 

all people, and this definition represents a commitment to ensuring that EPA works to improve 

conditions affecting the public health of all Americans so that everyone has access to clean 

water, clean air and healthy communities. In the Urban Air Toxics Strategy Report to Congress 

we acknowledge that national rules and standards can address part of the risk to communities, 

but because the assessments did not include background risks or contributions to risk from 

sources outside the facilities more needs to be done at the community level with other tools 

available within the Clean Air Act and within state, local, and other federal programs. EPA is 

committed to our efforts to make a difference in communities of concern and developing an 
73

integrated strategy focusing work in communities with the most need for EPA’s assistance. We 

have been, and will continue to work in thousands of communities across the country. Over the 

next years we will look for opportunities to enhance our partnership with communities to 

strengthen and improve their health – both environmental and economic. This effort to enhance 

coordination across our EPA programs and with other federal agencies will improve how we 

support community needs. We will focus on those communities where we think we have 

opportunities to leverage resources and actions to make a real difference. As we learn lessons on 

coordinating and focusing our efforts, we will use these lessons to help more communities in the 

future.

The EPA agrees that the estimate of the percentage of people in poverty has increased between 

the 2000 Census (13 percent) and the 2010 Census (14 percent). At the time of the 2011 

proposal, the 2010 census data was not available for us to use. Since that time, we have 

incorporated it into all of our modeling assessments, and it was used in the demographic 

assessments for the 2014 supplemental proposal and the 2015 final rule.

The commenter is correct that we performed the demographic analyses for the ferroalloys source 

category differently than we did for the October 2010 proposed RTR for the Hard and 

Decorative Chromium Electroplating and Chromium Anodizing Tanks source categories. We 

performed the demographic analyses for the chromium source categories 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 of estimated risk across the 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 chromium source categories that in future rules we planned to 

extend these analyses to cover the entire modeled domain for a facility (50 km radius) to capture 

all individuals with risks above 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 all the individuals with cancer risks above 1-in-1 million.

In the February 2012 supplemental proposal for the RTR for the chromium source categories, 

our demographic analyses included populations within 50 km of each source (including those 

very near the sources) with risks above 1-in-1 million or greater or non-cancer hazard indices of 
74

1 or greater. (77 FR 6628, Feb 8, 2012). We did not include analyses using a 5 km radius in that 

supplemental proposal nor in the RTR proposal for the ferroalloys source category. We think

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 demographic analysis to populations located within 5 km of a facility. Where a risk 

assessment has been performed, these populations are identified, and the source stack parameters 

are taken into account. 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. 

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

think we have done so as much as possible. However, as future assessments are written we will 

consider the comments provided above, and to the extent possible, incorporate those that will 

make our risk and rulemaking documents more informative. 

We are not able to determine the baseline health status of individuals or communities in a 

national rulemaking. Individual privacy issues as they relate to health records and the costs that 

would be associated with such an analysis make the analysis infeasible. Through the EPA’s 

interim guidance on Environmental Justice and the Action Development Process, the agency is 

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

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

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

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

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

exposed to the maximum pollutant concentration for 70 years and to protect the greatest number 

of persons to an individual lifetime risk of no higher than 1-in-1 million. Considerations are 

made for all people regardless of racial or socioeconomic status, and the EPA does not believe it 

is necessary to establish a default factor to account for socioeconomic and other communitybased stressors.

Comment: Commenter 0065 commends the EPA for considering environmental justice issues by 

expressing concern about the disproportionate impacts of HAP emissions on certain social, 

demographic and economic groups. In addition to making the improvements suggested in the 

above comment, the commenter (0065) adds that the EPA can improve the EJ analysis by 

working with the EPA EJ office to develop criteria and specific guidance on how to interpret and 

apply the outcome of these types of analyses in the rulemaking process.

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

effort to develop new tools for considering environmental justice in rulemakings. We also note 

that our ability to quantitatively assess EJ issues is evolving; over time we expect it to become 
75

more robust, sophisticated, and capable of ensuring that we are meeting our mission as an 

agency. 

The EPA continues to evaluate and refine environmental justice analysis, such as the proximity 

analysis performed for the Definition of Solid Waste. The draft EPA document Technical 

Guidance for Assessing Environmental Justice in Regulatory Analysis is currently undergoing 

Science Advisory Board (SAB) review. The Office of Air and Radiation is contributor to this 

draft document and cites numerous examples of EJ analysis performed in agency rulemakings. 

Environment justice considerations are a part of the rulemaking process; however, various 

factors influence the scope and complexity of an assessment. These factors may include, but are 

not limited to statutory mandates, data availability, resources and/or timeframe limitations.

Comment: Commenter 0070 asserts that the EPA’s failure to assess the substantial body of 

science concerning manganese amassed since 1994 is not consistent with the Agency’s 

environmental justice objectives (bringing “the best science to decision-making around 

environmental justice issues.”) The commenter (0070) states that continuing anxiety among 

residents of areas near Eramet are reinforced by the EPA’s reliance on outdated RfC values, 

when the latest science may confirm that such anxieties are baseless.

Response: See responses In Section 2.1 related to the EPA’s use of RfC values.

2.7 Other Modeling Methodology Issues

Comment: In their comments on the 2011 proposal, two commenters (0073, 0106) assert that the 

EPA failed to follow the Agency’s own modeling guidance and, as a direct result, the EPA’s 

residual risk assessment was based on overstated and invalid estimates of off-site manganese 

exposures. One commenter (0106) provides a detailed review of the EPA’s modeling and risk 

assessment, including the following points for the 2011 proposal:

 The EPA failed to base its model the most representative meteorological data, from the 

Parkersburg, West Virginia airport (5 miles away), and instead used meteorological data 

from the Charleston, West Virginia airport (70 miles away).

 The EPA relied on a single year of meteorological data, rather than five years of such 

data to account for year-to-year variability.

Additionally, in their comments on the 2011 proposal, the commenter (0106) states that the 

EPA’s modeling errors resulted in estimates that overstated off-site respirable manganese 

concentration by 88 percent and thus produce scientifically unreliable exposure estimates, which 

the commenter confirmed via a validation test against the EPA’s own field monitoring data. The 

commenter (0106) adds that the EPA's air modeling analysis overestimates the maximum 

manganese air concentration near the EMI facility by a factor of eight and that the EPA's air 

modeling analysis greatly overestimates the overall area and population exposed to manganese 
76

emissions from EMI. The commenter (0106) provides corrected modeling files, which predict 

significantly lower off-site exposure concentrations for use in a residual risk assessment.

Moreover, the commenter (0272) states that the EPA modeled manganese emissions from the 

EMI facility as if they behave as a gas (i.e., EPA assumed zero losses due to ground deposition), 

which is a reasonable approximation for PM2.5 emissions, but not reasonable for modeling the 

dispersion of larger, heavier particles. It is unfair and unreasonable for EPA to bias the residual 

risk assessment by simultaneously (i) maximizing estimated air dispersion by treating all 

emissions as light PM2.5 particles and (ii) maximizing predicted exposure concentrations by 

deriving them from total PM, rather than constructing a scientifically consistent model based on 

respirable PM2.5 emissions. 

The commenter (0272) also states that the EPA provides no explanation in the docket for its 

assumption that all PM emitted in ferroalloys production is small enough to be respirable. The 

commenter (0272) notes that the RIA filed with the 2011 proposal states that 41 percent of such 

total PM emissions meet the Agency’s definition of respirable (i.e., PM2.5), and EPA’s 

Ferroalloys Cost Memo for the 2014 proposal asserts that PM2.5 accounts for only 21 percent of 

the total PM emissions. 

The commenter (0272) provided modeling results for both PM2.5 and PM5 based on particle size 

distributions from existing EPA guidance on emissions from ferromanganese and 

silicomanganese production39 (see Section 3.1.2 of Appendix A). The section estimates that total 

PM from production of 80 percent ferromanganese and silicomanganese consists of particles 

ranging in size from at least as small as 0.5 microns to greater than 20 microns. The commenter 

(0272) notes that the particle size distributions provided in this section of AP-42 illustrate the 

error of assuming that 100 percent of such emissions are respirable. The commenter (0272) 

believes that by failing to model for the respirable particle size (i.e., PM2.5) overstates risk by 38 

to 48 percent, and failure to even model for PM5 overstates risk by about 30 to 36 percent. 

Response: When we began performing RTR risk assessments, we chose meteorological data 

considering the amount of data quality assurance needed and AERMOD run times. We restricted 

our meteorological data to that collected prior to the installation of the Automated Surface 

Observation System (ASOS). The ASOS had been found to omit the ceiling height for a large 

percentage of observations at a number of meteorological stations. Because installation and 

operation of ASOS equipment began in 1992, we selected the year 1991. As newer, higher 

quality ASOS data have become available, we have added newer data and additional data site 

locations to the meteorological data library we use in our risk assessments. Recently, we updated 

our meteorological data library to include data for more than 800 National Weather Service 

 

39 AP 42, Fifth Edition, Volume I, Chapter 12 (Metallurgical Industry), Table 12.4-4, 

http://www.epa.gov/ttn/chief/ap42/ch12/final/c12s04.pdf
77

(NWS) surface and upper air stations across the continental United States, Alaska, Hawaii, and 

Puerto Rico. We obtained calendar year 2011 Integrated Surface Hourly Data (ISHD) for these 

stations, as well as ASOS 1-minute data for each surface station. The Parkersburg, WV station is 

in our library of meteorological data, and it was used for both facilities in the risk assessment 

conducted for this final rulemaking. 

Although 5 years of meteorological data is preferred for assessing chronic exposures and risks, 

we use a single year of meteorological data in our risk assessments because of AERMOD model 

run times. Because we frequently run AERMOD for entire source categories with many 

individual emissions points and for many receptors, using 5 years of meteorological data would 

increase already significant model run times by a factor of five compared to a single year. In a 

sensitivity analysis of the impact of using a single year of meteorological data compared to 5 

years, we found that modeled concentrations differed by less than ten percent on average and 

thus, the use of one year of meteorological data is not likely to appreciably affect the results of 

the risk assessment.40 

We did indeed treat the manganese compounds as 100 percent gaseous when we performed risk 

modeling using the HEM model. We agree that modeling the pollutant as a particulate could 

result in lower estimated air concentrations by accounting for dry depletion. However, the impact 

of dry depletion for particulate emissions depends on multiple factors, including the distance 

from the source to the receptor, and particle properties. The impact of depletion on maximum 

estimated air concentrations and risks likely would be minimal because of the short distance 

between the sources and receptors (the locations of the MIR). At longer distances (i.e., greater 

than 10 km), 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 depletion. Also, deposited emissions 

can be re-suspended in the air, and plume depletion does not account for that process.

The modeling files provided by the commenter in response to the 2011 proposal contain the 

stack parameters and the emissions that the EPA used in that proposal. However, they used a 

shorter averaging time than in our assessment (24 hours vs 1 year) and only estimated the 

concentrations at three discrete receptors (the school monitors discussed in Section 2.8 below). It 

is unclear how these “corrected” files contain new information that can be used to update the 

EPA’s assessment. AP-42 does provide particle size information for ferroalloys production 

furnaces, however these particle size distributions are based on particulate matter and do not 

provide any information on particle sizes for the metal HAP. Therefore we modeled all metal 

HAP to provide a conservative estimate for risk. For the supplemental proposal, the commenter 

 

40 US EPA, 2009: Risk and Technology Review (RTR) – Risk Assessment Methodologies: For Review by the 

EPA’s Science Advisory Board; Case Studies – MACT I Petroleum Refining Sources and Portland Cement 

Manufacturing; U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Health and 

Environmental Impacts Division, Research Triangle Park, NC, EPA-452/R-09-009, June 2009, Page 4-6.
78

did provide model results based on different PM fractions, but not the modeling files or any 

actual particle size information from their facility. As described above (in Sections 2.1.1.1 and 

2.2.3) we disagree with the commenter that only the PM2.5 fraction should be used.

In regard to the PM2.5 percentage, no particle size testing was performed and therefore in order to 

calculate the PM2.5 benefits we had to estimate the percentage of PM2.5 based on information 

from numerous sources. For the 2011 proposal we estimated PM2.5 to be 41 percent of the total 

PM based on information from the EPA SPECIATE database. For the 2014 supplemental 

proposal, we estimated PM2.5 to be 21 percent of the total PM based on information we have on 

PM2.5 data collected in the Marietta area.

Comment: In their comments on the 2011 proposal, commenter 0106 states that US EPA's model 

validation attempt, which compares modeled vs. monitored manganese air concentrations, is 

flawed and misleading. According to the commenter (0106), the EPA compared 16 days of 

monitoring in 2009 to annual average model results from 1991. The commenter (0106) 

concludes that when you compare daily modeling outputs to these monitored values, there is 

very poor correlation and in fact the comparison shows that there is another source of manganese 

in the area other than Eramet.

Response: For the 2011 proposal, we compared risk modeling results to monitoring data that was 

collected as part of the EPA's "School Air Toxic Monitoring Study." The School Air Toxics data 

was comprised of 12-16 samples collected over a three month period during the summer and fall 

of 2009. These data are available on the EPA website at: http://www.epa.gov/schoolair. The EPA 

considers that a 3-month time period, that spans two seasons, is a sufficient length of time to give 

a rough indication as to the weather patterns that may affect the wind flow patterns near the 

subject schools. The modeling results were based on emissions collected from ICR data for 

several years prior to 2011, not 1991. While the EPA agrees with the commenter that the sample 

set is small, the comparison between the school monitor data and the model was included only to 

serve as a ground-truth exercise, not a detailed model to monitoring comparison study. Further, 

the EPA thinks that this exercise shows good agreement between the measured and modeled 

ambient levels leading us to believe that the Eramet facility is the primary contributing source of 

manganese at the schools. A model-to-monitor comparison was not conducted for the 2014 

supplemental proposal for the 2015 final rule because the time separating the emissions data used 

in those modeling assessments and the school air toxics monitoring data was too great.

Comment: One commenter (0271) stated that there are problems with applying the AERMOD 

Model to estimated fugitive emissions. They state that AERMOD has been shown to perform 

poorly at low wind speeds, with low-level sources, with intermittent sources, and in complex 

terrain. They believe that despite EPA’s recent efforts to refine modeling guidance and tools, the 

refinements, using fugitive PM air dispersion modeling without making adjustments to the 

modeling protocol overestimates potential exposure and risk and is arbitrary and punitive when 

emission limits are established based on overly conservative air dispersion modeling protocols. 
79

They state that the EPA has been presented with viable alternatives during the 10th Modeling 

Conference and should apply these protocols before arbitrarily establishing compliance 

obligations using inaccurate air dispersion tools when assessing ambient exposure risks from 

fugitive PM emission sources. 

Response: In the commenter’s letter, they specifically refer to fugitive sources such a roadways 

and material storage. It is important to note that these sources are not included in this assessment. 

With respect to the modeling approach, the risk assessment followed the current EPA modeling 

guidance as prescribed in Appendix W41 and clarification memos posted on the EPA TTN 

SCRAM website.42 With respect to AERMOD performance at low wind speeds, as discussed in 

the risk assessment document, at the time we conducted the processing of the meteorological 

data in AERMET, the public version of AERMET did not include the surface friction velocity 

adjustment (u*). Also at the time, an updated version of AERMET was under development that 

incorporated further surface friction velocity adjustments to AERMET version 12345. In 

anticipation of the update, EPA processed meteorological data using a pre-public release version 

of AERMET and incorporated the updated surface friction velocity adjustment in the output. It 

was EPA’s judgement that the pre-public release version of AERMET would generate 

AERMOD-ready meteorological data very close to that generated with the 13350 version of 

AERMET. The AERMET meteorological data posted on EPA’s FERA website under the HEM 

model page was generated with the pre-public release version of AERMET 13350.

Comment: In their comments on the 2011 proposal, commenter 0122 identified errors in the 

physical parameters associated with the area sources in the AERMOD air dispersion model used 

to estimate residual risks associated with the EMI facility’s manganese emissions. Specifically, 

the commenter (0122) states that the release height for fugitive emissions from tapping and 

casting at Furnaces 1 and 12, casting at MOR and crushing/screening should be set at the height 

of the facility’s roof monitors (100 ft), which is generally consistent with the NATA 2005 data 

set. Also, the commenter (0122) states that the dimensions of the facility roof monitors through 

which the fugitive emissions exit are generally understated and should be revised to lengths 

corresponding to 1/3 of the building roof monitor length in the end of the building where the 

relevant process is located, which is also generally consistent with the NATA 2005 dataset. 

Finally, the commenter (0122) states that the physical parameters for the Furnace 1 baghouse 

outlet used in the modeling supporting the proposed rule were based on data for the wet scrubber 

that was replaced by the baghouse in 2011 and should be updated to reflect current conditions.

 

41 EPA 2005: 40 CFR Part 51 Revision to the Guideline on Air Quality Models: Adoption of a Preferred General 

Purpose (Flat and Complex Terrain) Dispersion Model and Other Revisions; Final Rule; Federal Register/Vol. 70, 

No. 216/Wednesday, November 9, 2005. 68218-68261

42 http://www.epa.gov/ttn/scram/guidance_clarificationmemos.htm)
80

Response: The modeling files have been updated to reflect our current understanding of baseline 

conditions to assess the impacts of the final control options and have been corrected consistent 

with the changes suggested by the commenter. In addition, we checked the orientation of the area 

source fugitive emissions to the furnace buildings, and determined that these emissions should be 

oriented to be parallel to the buildings at both plants. We have made this correction as well to the 

final modeling files. See section 1.10 for more information on development of the final modeling 

files.

2.8 Community Health Impacts and Concerns

2.8.1 Community Issues

Comment: Two commenters (0085, 0107) describe a recent pilot study43 run by University of 

Cincinnati researchers that found the following:

 Estimated annual average ambient air Mn concentrations in the study area obtained from 

AERMOD varied from 0.02 to 2.61 mg/m3. 

 Mean blood and hair Mn values were 9.12 mg/L (SD 3.90) and 5.80 mg/g (SD 6.40 

mg/g), respectively and were significantly correlated (r = 0.30, p < 0.01). 

 The average blood lead value was 1.75 μg/dL. 

 The relationship between hair Mn and estimated ambient air Mn became significant when 

genes for iron metabolism were included in linear models. 

 Length of time lived at their current residence and the number of years lived in the area 

were significantly correlated with blood Mn (Table 2). 

 The preliminary ambient air and biological concentrations of Mn found in this population 

demonstrate the need for further research into potential health effects.

One commenter (0107) also referenced another local pilot study44 that concluded: “Preliminary 

findings suggest subclinical impairment in postural balance among residents chronically exposed 

to ambient Mn.” 

The commenter (0107) describes an ongoing community health study45, Communities Actively 

Researching Exposure Study (“CARES”), which is a joint project of Marietta College and the 

Department of Environmental Health at the University of Cincinnati to study neurobehavioral 

effects of manganese exposure on children living near the Eramet facility, particularly on 

 

43 E. Haynes, P. Heckel, P. Ryan, S. Roda, Y. Leung, K. Sebastian, P. Succop, Environmental manganese exposure 

in residents living near a ferromanganese refinery in Southeast Ohio: A pilot study, NEUROTOXICOLOGY 31 

(2010) 468–474

44 Standridge et al., Effect of chronic low level manganese exposure on postural balance: A pilot study of residents 

in southwest Ohio, J. Occup. Envtl. Med (Dec. 2008), 50(12): 1421–1429

45 CARES Website, http://www.eh.uc.edu/CARES/ 
81

neuromotor function. The commenter (0107) states that the EPA should communicate with the 

research team to receive more information about this research and get a summary of the 

preliminary findings and data so far for the EPA to review during this rulemaking. The 

commenter (0107) urges the EPA to consider these findings and recognize that these show the 

need for stronger emission standards from the Ferroalloys source category to protect exposed 

people in Marietta and other local communities affected.

In addition, the commenter (0107) describes that as part of the CARES study, researchers also 

surveyed air quality-related concern and risk perception in Washington County, Ohio. They 

found that the vast majority of surveyed residents (91%) were “very concerned” to “concerned” 

about the quality of the air, 75% were similarly concerned about odor, and 77% were similarly 

concerned about manganese exposure. It also found that the vast majority of respondents 

“perceived air quality to influence their health (93%) and the health of their children (94%).” 

Researchers found that the local community is especially concerned about air pollution-related 

cancer, respiratory health threats, brain development, and threats to children‘s health.

Dr. Erin Haynes from the University of Cincinnati summarizes the findings of her research and 

provides copies of manuscripts for the EPA’s consideration, as part of comment 0085. Following 

is a brief description of the relevant studies provided by Dr. Haynes:

 Standridge et al 200846 found a significant positive association between hair Mn 

concentration and sway area and sway length. Postural balance of residents in the smelter 

community was significantly larger than controls in 5 out of 8 postural balance outcomes. 

The primary sites of excessive Mn deposition within the brain are the globus pallidus and 

putamen within the basal ganglia. One important function of the basal ganglia is the 

integration of sensory feedback from the visual, proprioceptive and vestibular systems 

suggesting that Mn exposure at concentrations experienced by Marietta residents resulted 

in negative impacts on their motor control feedback mechanisms, thereby impairing their 

balance.

 Haynes et al 201047 is a full pilot study of 141 Marietta area residents who participated 

ranging from 2-81 years of age. Mean blood and hair Mn values were 9.12 μg/L (SD 

3.90) and 5.80 μg/g (SD 6.40 μg/g), respectively and were significantly correlated. Blood 

and hair Mn was significantly associated within families, respectively. Estimated annual 

average ambient air Mn concentrations in the study area obtained from AERMOD varied 

from 0.02-2.61 μg/m3. The relationship between hair Mn and estimated ambient air Mn 

 

46 Standridge et al., Effect of chronic low level manganese exposure on postural balance: A pilot study of residents 

in southwest Ohio, J. Occup. Envtl. Med (Dec. 2008), 50(12): 1421–1429

47 E. Haynes, P. Heckel, P. Ryan, S. Roda, Y. Leung, K. Sebastian, P. Succop, Environmental manganese exposure 

in residents living near a ferromanganese refinery in Southeast Ohio: A pilot study, NEUROTOXICOLOGY 31 

(2010) 468–474
82

became significant when genes for iron metabolism were included in linear models. This 

study further supports the literature that genes involved in iron metabolism play an 

important role in Mn metabolism. In our pilot study, 58% had hair Mn values >3.0 μg/g; 

the geometric mean of hair Mn in children (n=12) was 3.42 μg/g. In addition, an inverse 

association between hair Mn and IQ was found in 6th grade children living near a 

hazardous waste site in Oklahoma. The mean hair Mn levels for children in our pilot 

study were 12 times higher than the hair Mn levels found in the hair of these Oklahoma 

children living near a hazardous waste site.

 Following the pilot research, NIEHS funded a study48 assessed the neurobehavioral 

effects of manganese exposure on children living near the ferromanganese refinery. 

Currently in the 4th year of funding, the study has enrolled 322 children in the study are 

and control area, with the goal of enrolling 300 or more children from the Marietta area. 

The average concentration recorded from a stationary air sampler operating at Marietta 

College from October 2008 to September 2010 was 17.44 ng/m3. Personal air sampling 

and postural balance testing was also conducted on a small cohort of children. Although 

the data from the entire study cohort is not complete to determine the significance of Mn 

exposure through air, diet and home dust and their effects on multiple neurobehavioral 

outcomes, we have completed 2 sub-studies that do have adequate sample size to 

determine significance: personal air sampling and postural balance. The commenter 

(0085) describes these results in more detail.

Dr. Haynes concludes that overall, the findings from our studies indicate that residents of 

Marietta, Ohio are exposed to concentrations of ambient air Mn that can result in adverse 

neuromotor consequences. The commenter (0085) urges the panel to also consider genetic 

variance in iron metabolism, as this population may have the ability to absorb and retain higher 

concentrations of Mn than other populations. The commenter (0085) adds that the CARES 

research study is still generating data that can be useful to the EPA’s deliberations.

Another commenter (0106) states that, in attempting to determine whether the existing 

ferroalloys NESHAP exposed off-site residents to unacceptable residual risks, the EPA relied 

entirely on modeling and thereby failed to properly credit a peer-reviewed, site-specific 

epidemiological study49 of actual conditions that found no clinical evidence of manganeserelated health effects among Marietta, Ohio residents and concluded “Associations between midair and adverse [central nervous system] effects are thus unlikely to occur.” The EPA’s elevation 

of conservative theoretical estimates of risk over direct health studies, like its failure to account 

 

48 E. Haynes et al., Developing a Bidirectional Academic-Community Partnership with an Appalachian American 

Community for Environmental Health Research and Risk Communication, ENVIRONMENTAL HEALTH 

PERSPECTIVES, 10.1289/ehp.1003164 (available at http://dx.doi.org/), Online 16 June 2011

49 Kim, Y; Bowler, RM; Abdelouaha, N; Harris, M; Gocheva, V; Roels, HA. 2011. "Motor function in adults of an 

Ohio community with environmental manganese exposure." Neurotoxicology 32(5):606-614.
83

for actual field measurements of particulates, reflects an arbitrary process that is not designed, as 

Congress intended, to address “real world risks.” Accordingly, there is no risk-based justification 

for the EPA’s proposed requirement that EMI retrofit its process buildings to capture all fugitive 

particulate emissions at a cost up to $41 million in new capital expenditures and increased 

operating costs of over $12 million per year.

In their comments on the supplemental proposal, commenter 0272 reiterated that the EPA failed 

to incorporate results of recent health studies50 of the Marietta population, which demonstrate 

that the impacts implied by the EPA’s modeling results are not occurring. The commenter (0272) 

notes that although the EMI facility has been in operation for 60 years (and historical emissions 

were undoubtedly much higher than today), their reviewers found no clinical evidence of the 

predicted chronic health effects in Marietta, aside from higher anxiety, which could easily be 

associated with the widespread public campaigning of those that believe such effects must be 

occurring. The commenter (0272) notes that levels of manganese in blood in Marietta residents 

were no different than in the control group studied by their reviewers (see Section 3.1.3.2 of 

Appendix A). The absence of observed adverse health effects is consistent with recent studies 

that have not found elevated concentrations of manganese in the blood of children in Marietta.

The commenter (0272) continues that health effects data are reinforced by local ambient air 

monitoring data that shows such levels to be very low in comparison to the levels at which 

adverse health effects would be expected to occur. The 2012 Haynes, et al. study51, which 

published results of a personal air monitoring study of Marietta school children, found that actual 

measured exposures to respirable manganese averaged over 90 percent below the manganese 

MRL (5.45 to 10.33 ng/m3vs MRL of 300 ng/m3) among both Marietta school children and at 

the fixed monitoring station at Marietta College. The Haynes results for respirable manganese 

concentrations are themselves consistent with the very low levels of total manganese or PM10

manganese directly measured by EPA and ATSDR in Marietta over the last decade.

The commenter (0272) states that the EPA labels the estimates produced by its computer 

modeling as “facts,” while making no mention of and assigning no weight to the results of actual 

studies that directly measured manganese levels and health conditions in Marietta, Ohio. The 

commenter (0272) states that the CAA does not mention computer modeling, much less mandate 

reliance on such modeling over site-specific data, and the courts have observed that Congress 

intended for the residual risk process to address “real world risks.” However, the commenter 

(0272) notes that the EPA has acknowledged that use of directly measured data is preferable to 

reliance on modeling and that even if modeling is necessary, any directly measured data that is 

available should be considered. In this matter, manganese exposures in Marietta have been 

 

50 Kim, Y; Bowler, RM; Abdelouaha, N; Harris, M; Gocheva, V; Roels, HA. 2011. "Motor function in adults of an 

Ohio community with environmental manganese exposure." Neurotoxicology 32(5):606-614.

51 Haynes, et al., “Assessment of personal exposure to manganese in children living near a ferromanganese 

refinery,” Sci. Total Environ. (2012), doi :10.1016/ j.scitotenv.2012.03.037
84

actively investigated by multiple researchers looking for evidence of the sort of risks predicted 

by EPA’s modeling. Where the results of those studies contradict EPA’s modeling predictions, 

real world data should be given precedence over mathematical predictions. The commenter 

(0272) believes that at a minimum, the EPA should have used that information to adjust its 

modeling assumptions for maximum agreement between estimated conditions and directly 

measured conditions. The commenter (0272) believes that the model’s predicted manganese 

concentrations at the site of the Marietta College air monitor should be no more than equal to the 

measured concentration from all sources.

However, the commenter (0272) states that the EPA’s predicted manganese concentrations at the 

location of the Marietta College air monitor during the time periods when air concentrations 

were directly measured, when adjusted to include only the respirable PM2.5 size fraction are six 

times larger than the actual concentrations: 32 ng/m3 manganese PM2.5 (modeled) vs. 5.5 ng/m3

manganese PM2.5 (measured) during April-May 2009 and 67 ng/m3 manganese PM2.5 (modeled) 

vs. 10.3 ng/m3 manganese PM2.5 (measured) during March-June 2010. They believe that even if 

100 percent of the manganese actually measured in Marietta is attributed to EMI, EPA’s 

modeling has still overestimated the actual respirable manganese concentrations in the 

community by six times, and since EPA used total PM as a surrogate for respirable PM, the 

modeled manganese concentrations that EPA chose to use in reaching its risk conclusions 

actually exceeded the directly measured respirable concentration by about nine times (see 

Section 2.3 in Appendix A). The commenter (0272) states that EPA’s failure to account for real 

world data in its assessment meant the difference between a computer-estimated “risk” and a 

directly-measured “no risk.”

Commenter 0073 states that the EPA’s analysis focused on its own overly-conservative 

exposure assessment, and ignored other valid data indicating risk levels lower than the EPA’s 

estimates. The commenter (0073) specifically notes that the preamble mentions, but disregards a 

2011 EPA study of chronic adult exposure to ambient manganese near EMI, which found “no 

significant differences in blood manganese concentrations or major health outcomes between 

residents living near the facility and residents in a comparison town[.]”

In comments on the supplemental proposal, commenter 0270 states appreciation that the EPA 

acknowledged that risk to Marietta’s citizens from manganese exposure is too high. The ambient 

air monitoring in the mid-2000’s showed manganese within a 5-mile radius of the plant at levels 

2 to 60 times the existing federal health standard. The commenter (0270) suggests that air 

monitoring again be done in Marietta, Boaz and Vienna for a period of at least 2 years.
85

The commenter (0270) is disappointed that Dr. Haynes’ manganese study on area children52 is 

not being taking into account. To ignore the most recent study of the most relevant population to 

the EPA’s decision seems irresponsible and unfathomable. The commenter (0270) urges the EPA 

to take into account Dr. Haynes’ findings when finalizing the ferromanganese rules.

Response: A large number of documents were submitted for consideration in relation to this 

rulemaking, both in response to the 2011 proposal and the 2014 supplemental proposal. These 

documents included scientific studies published in the peer-reviewed literature, summaries of 

unpublished studies, government reports and other materials. The EPA appreciates receipt of 

these materials; however, a thorough evaluation of this information is not within the scope of this 

action. These studies are potentially relevant to the upcoming revision of the EPA’s doseresponse assessment for manganese. The Agency has an established process for updating its 

dose response assessments that includes a thorough review and evaluation of the scientific 

literature and peer review of the final results. Any partial review of the manganese scientific 

literature for the current action would be premature and inconsistent with the Agency standards 

of practice regarding scientific quality of assessments including thoroughness, quality control 

and peer review.

2.8.2 Local Resident Concerns Regarding Health and Air Quality

Comment: In response to the 2011 proposal, a group of commenters (0068, 0077, 0089, 0090, 

0091, 0093, 0094, 0097, 0098, 0099, 0100, 0101, 0247, 0257) described their personal 

experience with air quality problems in the Marietta, Ohio area. One commenter (0091) notes 

that she has lived in Marietta for 24 years, raising two children, and has had concerns about the 

amount of local air pollution (especially manganese) on health. Another commenter (0093) 

remembers that a number of years ago, the commenter’s parents put a brass light on their porch. 

The commenter (0093) states that the finish was guaranteed for life, but it didn't take long for it 

to become tarnished. The commenter (0093) continues that the manufacturer replaced it once but 

refused to honor any future warranty on the finish because the air quality was so bad. The 

commenter (0093) asks that if the air isn't safe for metal, how it can be safe for humans. 

One commenter (0098) states that her family has lived here (Marietta, Ohio area) for 20 years 

now, and though they love this area, many times we have considered moving away because of 

the extreme air pollution. The commenter (0098) adds that there have been many nights that she 

has been startled from a sound sleep by the toxic air rolling in through the open window. They 

ask why it is legal for a business to pollute the air but individual citizens would be arrested, 

convicted and jailed if they were to dump our trash on the lawn, our neighbor’s lawn, or a public 

 

52 Haynes, et al., “Assessment of personal exposure to manganese in children living near a ferromanganese 

refinery,” Sci. Total Environ. (2012), doi :10.1016/ j.scitotenv.2012.03.037
86

space. In addition, they ask why a large French corporation (Eramet) is able to pollute the air to 

the point where they cannot sleep at night.

One commenter (0089) states that they first became aware of the pervasive odors and particulate 

soot emitted from (then) Elkem Metals, (now) Eramet Marietta in 1995 when they purchased 

land and began building a home just north of downtown Marietta, Ohio. The commenter’s (0089) 

journey to find the source of the odors that awakened us during the night and the soot that 

covered our freshly painted porch railing, led us to the ferroalloy factory, Eramet which was 4-5 

miles away. The commenter (0089) adds that their family live every day with the breathing 

problems, headaches and constant worry about what they are being exposed to. The commenter 

(0089) adds that asthma rates are high and our small rural communities support two very busy 

and always expanding cancer centers, Strecker Cancer Center in Marietta and Camden Clark 

Comprehensive Cancer Center in Parkersburg, WV – within a 12 mile radius. 

Similarly, one commenter (0077) states that she is very concerned about the toxic air pollution 

from Ferroalloys, because of the Eramet plant in Marietta, OH. The commenter (0077) lived in 

Marietta, OH for 6 years and developed asthma and chronic sinusitis after moving to Marietta. 

Since the commenter (0077) moved away from Marietta, OH, 5 years ago, the frequent sinusitis 

has stopped and she rarely has a wheezing experience. Another commenter (0090) states that 

asthma and respiratory problems in general are rampant in this valley and are a serious and 

growing problem nationally. The commenter (0090) adds that inhalation of small particle 

pollution is directly linked to these problems. 

One commenter (0094), a physician and property owner in Washington County Ohio, writes to 

urge the EPA to move forward with a new Clean Air Act Rule providing much needed protection 

from toxic air pollution emanating from the Eramet plant in Marietta, Ohio. The commenter 

(0094) states that it is unavoidably obvious to local residents and anyone spending time in 

Marietta and environs that Eramet emits gross quantities of toxic chemicals into the atmosphere. 

The commenter (0094) adds that these emissions particularly occur during hours of the night in a 

transparent effort to conceal clearly unacceptable operations. The commenter (0094) states that it 

is well known that these emissions contain manganese and other substances known to be 

carcinogenic and deleterious to human health and that immediate action is mandatory. 

One commenter (0097) asks that the EPA not delay any longer the strengthening and 

enforcement of the Clean Air Act which will provide better air quality to this community. The 

commenter (0097) adds that the air quality has forced some residents to move elsewhere, and 

other prospective residents not to settle here. Similarly, another commenter (0101) states that had 

they known about Marietta’s pollution problems they never would have moved there 13 years 

ago. The commenter (0101) hopes to sell his house and move to a location with cleaner air. 

As a public health official, one commenter (0100) has been worried for a very long time that we 

were putting children at risk for impaired mental function and seniors at higher risk of 
87

developing Parkinson’s. The commenter (0100) is currently collaborating with the University of 

Cincinnati to study on the effects of exposure to manganese, and hopes that the question of 

health effects will be answered soon. 

One commenter (0091) states that the affected community needs the EPA to set strong emission 

standards to provide an "ample margin of safety to human health," and urges the EPA to review 

all the community health studies done in our area- especially the CARE study to be sure that 

those "margins of safety" take into consideration at risk groups such as pre-natal, pregnant 

women, children, and the elderly, as well as the general population. The commenter (0091) urges 

the EPA to require more protection than the proposed rule would provide. The commenter 

(0091) agrees that the EPA needs to look at all of the community health studies on the Marietta 

community, including the CARE study. Additionally, two other commenters (0077, 0099) agree 

that the EPA needs to look at all of the science showing the need to protect everyone, and 

especially the children, from manganese and other pollutants. 

Two commenters (0089, 0098) are concerned about long-term effects of low levels of manganese 

inhalation over time and the cumulative effect of being exposed to many sources that are 

emitting toxic substances. One commenter (0089) adds that the Marietta area is an example of a 

community overburdened with pollution from local industry. A quick drive along Ohio Route 7 

will expose you to carbon black from Degussa, manganese, chromium, etc. from Eramet, very 

heavy Styrene odors from Americas Styrenics and who knows what Marietta Industrial 

Enterprises does within its secret little world? The commenter (0089) adds that because of our 

exposure to various chemicals the children and adults of our area have become guinea pigs for 

health studies for PFOA from DuPont and are now participating in health studies for heavy metal 

exposure. The commenter (0089) states that there are reports that physicians all around the 

country ask if the patient spent any amount of time living in the mid-Ohio Valley. 

Two commenters (0077, 0099) urge the EPA to set strong standards that will protect the 

Marietta, OH community from toxic air pollution. The commenters (0077, 0099) are especially 

worried about chronic and acute health impacts from manganese, lead and other pollutants. The 

commenters (0077, 0099) understand that the EPA’s proposed rule would reduce the cancer risk 

in the community and agree that it important to set standards that will prevent a cancer risk 

above 1-in-1 million. The commenters (0077, 0099) add that the EPA should make sure that no 

child is exposed to an unacceptable level of health risk. The commenters (0077, 0099) believe 

that there is need for a real margin of safety to protect public health from the pollution and asks 

the EPA to require even more protection than the proposed rule would provide. The commenters 

(0077, 0099) add that while it is positive that the EPA is proposing to set standards for the first 

time for pollutants that have not had any limit before, like mercury, what is needed is stronger 

protection from all of the pollution from this source, including fugitive emissions. 

Commenter 0068 adds that it essential to base emission standards on health data. Several groups 

have begun to study the Marietta “laboratory” and the University of Cincinnati, University of 
88

San Francisco and the Agency on Toxic Substances and Disease Registry studies are finding is 

that Marietta’s children are likely most affected by manganese exposure. The commenter (0068) 

states that we should be setting our expectations for industry based on the needs of our weakest 

populations, instead of allowing the industry to dictate what is possible. 

In their comments on the supplemental proposal, commenter 0247, a local government 

representative, states that the EPA needs to ensure that Mn levels below 0.1 μg/m3 to protect 

vulnerable populations. The commenter (0247) noted that there are documented exposures of 

0.25 μg/m3 in the recent past in Vienna, WV approximately 5 miles away. The commenter 

(0247) believes that particulate collection at the roof and assuring levels less than 0.1 μg/m3 at 

the fenceline are important, and advocates particulate monitoring in communities surrounding 

the facilities.

One commenter (0257) stated in their comments on the supplemental proposal that that these 

standards should have been in place a long time ago.

Response: The EPA sympathizes with the concerns expressed above. This final rule seeks to 

reduce emissions from the ferroalloy production source category under the authority provided by 

the Clean Air Act. As we stated in the preamble, the RTR rules for this source category require 

that existing sources in the category achieve substantial emission reductions of both carcinogens 

and non-cancer HAP. We anticipate these rules will further reduce the emissions from 

ferroalloys production that impact the local communities.

3.0 DECISION

3.1 Finding of Unacceptable Risk is Justified

Comment: In their comments on the 2011 proposal, commenter 0107 supports the EPA’s 

determination that the current level of health risk is unacceptable and states that this 

determination is well-supported. According to the commenter (0107), in addition to a high 

cancer and chronic noncancer risk, there is a high acute health risk which is 10 times the EPA’s 

presumed safety threshold, and high multipathway risk from mercury, POM, and lead (as well as 

other pollutants that the EPA did not assess). The commenter (0107) adds that communities in 

this source category have faced unacceptable levels of toxic air pollution from this source 

category for many years. The commenter (0107) believes that immediate action is vital to protect 

the local community from extremely high and unacceptable health risk. The commenter (0107) 

adds that omissions in the EPA’s own analysis and uncertainties also weigh in favor of a finding 

that health risk is “unacceptable.” 

In comments to the supplemental proposal, commenter 0276 agrees that the EPA should finalize 

the proposed determination that health risks are unacceptable due to the combination of high 

cancer and non-cancer chronic health risks from inhalation, particularly due to manganese. The 
89

commenter (0276) adds that the EPA has likely undercounted and underestimated the health 

risks.

Response: We acknowledge your support. As mentioned previously, the emissions were revised 

for the final rule as a result of the comments received on the 2014 supplemental proposal, and the 

risk assessment has been re-done. However, we continue to conclude that baseline risks are

unacceptable.

Comment: Commenter 0122 conducted an independent evaluation of the residual risk after 

enhanced fugitive emission source control in response to the 2011 proposal. As described in a 

comment to its original comment, the commenter (0122) revised the area source and point source 

parameters in the AERMOD model to reflect (1) the fugitive source controls described by the 

commenter in their comments, (2) the corrected physical parameters described in their 

comments, and (3) the baseline and controlled emission estimates described in their comments. 

The commenter (0122) presents the resulting HQ for a range of potential manganese reference 

concentrations (RfCs) under several modeled scenarios: (1) corrected meteorological data, (2) 

corrected meteorological data and adjustment of exposure concentrations to reflect a 41 percent 

respirable manganese fraction, and (3) these two adjustments plus the use of a more “reasonable” 

MIR exposure period to reflect time indoors and time away from home. The results of this 

analysis are summarized in Table 1, below.

Table 1. Residual Risks after Additional Source Control

Exposure Scenario (EPA Model with 

Various Revisions)

Maximum Off-site Manganese HQ at Various RfC 

Values

Use of 

Parkersburg 

Meteorological 

Data

Use of 

Respirable 

Fraction 

(PM2.5)

Exposure 

Adjusted 

for Time 

Indoors 

and 

Away 

from 

Home

Highest 

Calculated 

Off-site 

Manganese 

Concentration 

(μg/m3)

0.05 

μg/m3

0.1 

μg/m3

0.5 

μg/m3

1

μg/m3

2 

μg/m3

■ 0.145 3 1 0.3 0.1 0.07

■ ■ 0.055 1 0.6 0.1 0.06 0.03

■ ■ ■ 0.033 0.6 0.3 0.06 0.03 0.02

Response: We appreciate the commenter’s attention to detail in providing their supporting 

information. As mentioned in previous sections, we have incorporated some suggestions 

provided by the commenter (e.g., meteorological data in section 2.7) and we disagree with the 

commenter on other suggestions (e.g., exposure scenarios in Section 2.2.2). As described in 

these (and other) sections, we have considered the comments related to the modeling files and 

developed final modeling files based on our analysis of the comments received. Based on this 

analysis, we conclude that the findings of unacceptable baseline risk and acceptable post-control 

risk are reasonable.
90

3.2 Finding of Unacceptable Risk is Not Justified

Comment: In their comments on the supplemental proposal, commenter 0272 does not agree 

with the EPA's conclusion that risks are unacceptable. The commenter states that the cancer risk 

and multipathway risks clearly meet the EPA’s stated “acceptable risk” criteria for those 

conditions, and therefore cannot serve as a principled justification for EPA’s finding. Commenter 

(0272) notes that the EPA’s estimate of the MIR cancer risks from EMI’s emissions are 80 

percent lower than the acceptability threshold, and they continue to meet the 100-in-1 million 

acceptability threshold even under EPA’s worst-case assumption that EMI’s emissions increase 

in the future to the maximum levels allowed by law. In their comments on the supplemental 

proposal, commenter 0269 also notes that the EPA calculated a potential maximum individual 

risk (MIR) estimate for Felman’s potential cancer emissions to be 20-in-1 million, which meets 

the applicability threshold. The commenter (0272) notes that the EPA’s unacceptable risk finding 

relies in part on predicted multipathway exposures representing an MIR noncancer HQ of 1, 

which the commenter notes, does not represent unacceptable risk by definition. 

The commenter (0272) states that although a noncancer HQ of 1 corresponds to an exposure 

concentration at which no adverse health effects will occur, the EPA has historically declined to 

define a MIR HQ of 1 to be the noncancer risk acceptability standard. The commenter (0272) 

also noted that the EPA predicted that EMI’s post-control actual emissions would present a MIR 

HQ of 2 in the 2011 proposal in this rulemaking, and the EPA concluded that such risks were 

acceptable. The commenter (0272) states that the EPA’s estimate of an MIR HQ of 4 is entirely 

dependent upon the incorporation of fugitive emission factors that overstate the level of 

ferroalloys tapping and casting fugitive emissions. They believe that the EPA’s adoption of “at 

the source” emission factors derived for basic oxygen furnaces (“BOFs”) used in steelmaking 

causes the model to over-predict directly measured concentrations of respirable manganese by a 

factor of six to nine. When ferroalloys fugitive emissions are approximated through the more 

reliable BOF “at the monitor” emission factors, the modeled MIR exposure concentration for 

manganese under EPA’s model is 0.31 ug/m3, which produces an HQ of 1 using the ATSDR 

MRL and an HQ of 0.1 using the scientifically adjusted MRL. The commenter (0272) states this 

conclusion is supported by data from health studies conducted in Marietta, which found 

exposures to be far lower than EPA has predicted and an absence of the health effects expected 

at exposure concentrations predicted by the EPA’s modeling. The commenter 0269 also believes 

the maximum risk estimates are substantially greater than any potential actual risks due to the 

EPA’s data inputs and methodologies that are biased to overestimate potential risk, such as using 

a 70-year exposure duration, using data for non-detected emissions at half the detection limit and 

using an overstated manganese RfC value.

The commenter (0272) states that the EPA’s determination of unacceptable risk is based on 

allowable emissions calculated using the 1999 emissions standards. They believe that this 

allowable scenario is not plausible and should be based on the technology-based limits that the 

EPA is proposing under Section 112(d).
91

The commenters (0269 and 0272) believe that incorporating appropriate and well-established 

modeling assumptions to reflect the best available facts and science would confirm that 

ferroalloys emissions meet EPA’s standards for acceptable risk. The commenter (0272) notes 

that Eramet’s emissions also meet the Section 112(f) “ample margin of safety” standard, which 

they believe should preclude the imposition of any additional limits or controls to further reduce 

theoretical cancer risks.

Response: In the risk assessment for the supplemental proposal and the final rule, we concluded

that the risks are unacceptable based on all the available information, including the fact that the 

noncancer hazard quotient ranges from 4 based on actual emissions to 40 based on allowable 

emissions. We have not established under section 112 of the CAA a numerical range for risk 

acceptability for noncancer effects as it has with carcinogens, nor have we determined that there 

is a bright line above which acceptability is denied. However, we have established that, as 

exposure increases above a reference level (as indicated by a HQ or TOSHI greater than 1), 

confidence that the public will not experience adverse health effects decreases and the likelihood 

that an effect will occur increases. For the ferroalloys source category, the potential for members 

of the public to be exposed to manganese at concentrations from 4 up to potentially 40 times the 

MRL reduces our confidence that the public is protected from adverse health effects and 

diminished our ability to determine that such exposures are acceptable. We also considered the 

fact that the cancer risk estimate for actual emissions is 20-in-1 million and potentially up to 100-

in-1 million for allowable emissions. While 20-in-1 million is well within the acceptable range, 

risks from allowable emissions are at the upper end of the range of acceptability. These results

combined with a refined multipathway HQ for mercury that is at the level of the RfD, leads us to 

conclude that the risk from this source category is unacceptable. All the risk results (including 

metrics not brought up by the commenter such as population exposures, incidence, and acute 

values) are considered together in the risk acceptability decision, not just one metric individually. 

These results are based on the emission estimates, both process and fugitive, using multiple test 

data from the facilities and emission factors from AP-42. Emission factors are commonly used 

by plants to estimate emissions from their processes. We reviewed the factors and determined 

that the use of the BOF tapping and hot metal transfer as surrogates for ferroalloys tapping and 

casting are appropriate, given the absence of AP-42 factors specific to ferroalloys. However, we 

disagree with the use of the “at the monitor” factors suggested by the commenters. 

First, we note that these emission factors were not based on emissions collected at the roof 

monitor, but instead collected in hoods or ductwork located above the actual emission source and 

estimates of assumed capture efficiency were applied to estimate the “uncontrolled” portion. 

This differs from a measurement of actual emissions at the roof monitor. Second, the respective 

BOF tapping and hot metal transfer tables each include a second emission factor associated with 

each operation (“at the source.”) For tapping the factor is 0.291 lb/ton and for hot metal transfer 

the factor is 0.19 lb/ton. These factors are also based on tests that sampled the air inside a hood 

or duct (assumed to be closer to the source of the emissions than the “at the monitor” collection 
92

sites) with assumptions made about capture efficiency to determine uncontrolled emissions. We 

decided to use the higher emission factors in our calculations because we believe these factors 

are likely to more accurately reflect actual emissions from these sources.

As stated throughout this document, we also disagree with the comment that we should use the 

reference value for manganese that the commenter has provided (see Section 2.1.1), that our 

exposure assumptions are incorrect (see Section 2.2.2), and that we should use their estimate of 

respirable emissions (see Section 2.2.3). Responses to these individual points are explained 

elsewhere in this document and therefore are not repeated here. 

With respect to the commenter’s point that EPA already proposed an HI of 2 to be acceptable (in 

the 2011 proposal) and that nothing else has changed since that time, we disagree. At the time of 

the proposal, we were using the IRIS RfC for manganese. A value using analytical approaches 

consistent with EPA practices is now available (the ATSDR MRL) and we have used this value 

in the 2014 supplemental proposal and the 2015 final rule. As discussed in Section 2.1.1.1, 

ATSDR used up-to-date information in the derivation of the MRL, including information on the 

kinetics of manganese to ensure the derived MRL value did not approach exposure levels which 

would lead to toxicity. Therefore we have more confidence that exceeding this value has more 

potential for adverse health effects than exceeding the IRIS value by the same magnitude. In 

addition, the following have also changed: the station used for meteorological data, the versions 

of AERMET and AERMOD used in the assessments, the input parameters to the model, the user 

receptors, and most importantly, the emissions estimates. At the time of the 2011 proposal, the 

fugitive emissions were calculated using a mass balance calculation approach, while for the 2014 

supplemental proposal, more reliable emission factors were used (as described above in this 

response). In addition, more stack tests were conducted during the intervening years and 

therefore we have more confidence in the emissions relied on for the final rule. When making a 

risk management decision, all risk assessment results are considered together along with their 

associated uncertainties. The final rule risk assessment has reduced uncertainties (e.g., for

emissions and the manganese reference value used) compared to the assessment conducted for 

the 2011 proposal and as a result we have more confidence in our assessment. Given all the 

changes described above (most notably the change in emissions and the manganese reference 

value since the 2011 proposal), it is reasonable to conclude that the health risks at baseline 

(based on consideration of all risk results and health factors along with the associated 

uncertainties) are unacceptable.

3.3 Finding of Acceptable Post-Control Risk is Deficient

Comment: In their comments on the 2011 proposal, commenter 0107 states that the EPA does 

not require enough emission reductions to achieve an “acceptable” level of health risk, and the 

EPA must provide notice of the level of cancer risk that its standard would allow, based on 

“allowable” emissions. The commenter (0107) states that the EPA must reduce cancer risk to a 

lower level and aim to achieve a cancer risk below 1-in-1 million, and the commenter discusses 
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how this is consistent with community norms and as intended by Congress. The commenter 

(0107) adds that the EPA’s proposed rule would still expose at least 1,300 people to a cancer risk 

above 1-in-1 million and states that the EPA has failed to justify not requiring additional 

emission reductions to provide stronger protection for the most-exposed people.

The commenter (0107) states that the EPA’s proposed rule will not reduce chronic non-cancer 

risk enough to achieve an “acceptable” level and argues that the EPA must reduce the TOSHI 

presumptive acceptability threshold to 0.2 or below, per the EPA’s own staff’s 2002 

recommendation, to protect the most-exposed people in local communities experiencing impacts 

from multiple sources and types of toxic air pollution. Commenter 0065 is also concerned that 

the EPA has not reduced the chronic noncancer risk to below 1, but the commenter recognizes 

that the proposed measures would provide dramatic decreases to the TOSHI. The commenter

(0107) adds that the EPA should take an especially protective approach on chronic noncancer 

risk due to manganese because of the significant evidence of harm from manganese inhalation, 

the fact that the EPA’s risk assessment for manganese is likely to underestimate the full risk, and 

because of the EPA’s own recognition that the science includes uncertainty on the full risk. The 

commenter (0107) cites the other deficiencies in the risk assessment (e.g., failure to assess 

facility-wide risk or cumulative risk) as further reason to take a more protective approach 

regarding chronic non-cancer risk.

Additionally, the commenter (0107) states that the EPA’s proposal would still allow 

multipathway risk due to POM that is 20 times the EPA’s safety threshold. The commenter 

(0107) states that the EPA has failed to justify allowing such a high level of risk, particularly 

when this is cancer risk that will occur in combination with the inhalation-based cancer risk. 

According to the commenter (0107), as a result of this high multipathway risk, the most exposed 

person will face a total cancer risk that is significantly higher than the 5-in-1 million that the 

EPA describes. The commenter (0107) concludes that the EPA must require further reductions in 

multipathway risk to achieve an acceptable level.

The commenter (0107) further states that the EPA fails to provide any reasoned explanation for 

not requiring a greater reduction in acute health risk. The commenter (0107) states that the 

EPA’s acute health risk number does not include the combined acute health risk that can occur 

due to multiple pollutant emissions simultaneously in an acute health incident. The commenter 

(0107) notes that the EPA did not consider the combined acute health risk for multiple pollutants, 

did not assess the acute health risk based on allowable emissions scenario and did not calculate 

or provide any information on facility-wide acute health risk. The commenter (0107) states that 

the EPA fails adequately to explain how an acute health risk of 0.3 could be safe or acceptable, 

when it has failed to assess what the cumulative health burden would be for this source category, 

especially when its own staff have recommended preventing exposure above 0.2.

Response: As an initial matter, we note that in 1990 Congress codified in section 112(f)(2)(B) of 

the Clean Air Act the approach we use for our residual risk analyses. Under that approach, the 
94

100-in-1 million cancer risk is not a bright line indicating that risk is “acceptable.” Conversely, 

cancer risks greater than 1-in-1 million are not automatically considered “unacceptable” as 

implied by the commenter saying we have to reduce risks to levels below 1-in-1 million. Rather,

we consider this health metric conjunction with a variety of health factors and their associated 

uncertainties 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 (e.g., cancer and chronic non-cancer risks) and their associated uncertainties in 

conjunction with the costs of controls, technical feasibility, and other relevant factors to 

determine whether further additional controls should be required to provide an ample margin of 

safety to protect public health. 

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

noncancer risks from source category HAP emissions. It is always important to consider the risk 

results along with specific uncertainties of the emissions and health effects information regarding 

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

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

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

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

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

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

uncertainty associated with emissions and health benchmark values. 

Also, the level of cancer risk that the revised standard would allow (i.e., “allowable” risks), are 

indeed provided in the preamble. Since the post-control risks were based on estimates of postcontrol emissions, which were designed to reflect the level of emissions after implementation of 

the proposed standards, we maintain that the post-control scenario is reflective of allowable risks 

of the proposed standards. While the comment specifically refers to the risks at proposal, the 

same comparison holds true for the final rule. The risks estimated for the post-control scenario 

are the risk estimates that would be “allowed” by the final standards.

The EPA disagrees with the commenter’s notion that any TOSHI value greater than 0.2 should 

be considered unacceptable. We note that pollutant-specific reference concentrations (RfCs) are 

not absolute thresholds, but estimates of chronic inhalation exposures at or below which health 

effects would not be expected to occur after a lifetime of exposure, including in sensitive 

subgroups. We further note that these RfCs are developed using a health-protective approach 

(see uncertainty discussion in risk assessment document section 4.2), that TOSHI values of 1 or 

less are generally considered to carry no appreciable risk of adverse health effects and that there 

is generally no need to compound this protection by suggesting that any source category 

maximum TOSHI value would need to be at or below 0.2 before we would consider it to be 

acceptable. Finally we note that the commenter’s source for its statement that default limits HI 
95

should or must be establish at 0.2 rest on an internal EPA staff memo (from 2002) which was 

never adopted as agency policy (and never reviewed by the public or by any peer review body) 

and consequently carries no precedential weight.

Regarding the multipathway risks in the 2011 proposal, we disagree with the commenter that 

“multipathway risk due to POM is 20 times the EPA’s safety threshold.” As described earlier, 

the emissions are used in the multipathway assessment and are compared to multipathway 

screening emissions thresholds, not risks. It is not a measure of “safety” but rather a measure of 

where more analysis may be needed considering the availability of appropriate site-specific data 

and time and resource constraints. In this case the “20” is an upper bound estimate of possible 

cancer risks, meaning the actual cancer risks will be less than 20-in-1 million, but it is 

inappropriate to say that the risk is 20. As discussed in a previous response, it is not appropriate 

to combine the results of a refined inhalation assessment with those from a screening-level 

multipathway assessment. A refined multipathway assessment was conducted for the 

supplemental proposal and the final rule, and those results are provided in the respective 

preamble and risk assessment documents.

Regarding the acute health risks, as described in the risk assessment report available in the 

docket for the proposed action and elsewhere in this document, we do not sum results of the 

acute noncancer inhalation screen because of its conservative nature and the variable nature of 

emissions and potential exposures. The use of allowable emissions is also not considered due to 

the conservative assumptions used to gauge worst-case potential acute health effects. The 

conservative estimates built in to the screen include 1) worst-case meteorology (from one year of 

local meteorology); 2) that a person is located downwind at the point of maximum impact during 

this same 1-hour period; and 3) that all emission points have their peak emission rates occur 

simultaneously. Thus, performing an acute screen based on allowable emissions would be overly 

conservative and at best, of questionable utility to decision makers. Finally, as mentioned 

previously, for the ferroalloys source category, a separate facility-wide assessment was not 

performed because there are no other operating sources present at these facilities. However, if a 

facility-wide assessment had been performed, acute risks would not have been part of that 

assessment. The emissions included in a facility-wide assessment have generally not been 

subjected to the same level of engineering review as the source category emission estimates and 

are likely to be less certain than our emissions estimates for the source category. That, combined 

with the already conservative nature of the acute assessment, would lead us to not conduct an 

acute risk assessment using facility-wide emissions. Finally we note that the commenter’s source 

for its statement that default limits HI should or must be establish at 0.2 rest on an internal EPA 

staff memo (from 2002) which was never adopted as agency policy (and never reviewed by the 

public or by any peer review body) and consequently carries no precedential weight.

Comment: Commenter 0107 states that the EPA fails to show that its proposed rule will reduce 

cumulative health risk to an “acceptable” level. The commenter (0107) states that the EPA must 

aggregate health risk for the source category and decide whether the total health risk from each 
96

pollutant, pathway, and risk, and from all combined is acceptable. The commenter (0107) states 

that in order to protect local communities, particularly children, the EPA must account for the 

history of exposure to toxic air pollution, and for ongoing exposure to the source category’s toxic 

air emissions combined with other HAP emissions from multiple sources, by applying additional 

safety factors in its acceptability determination. The commenter (0107) adds that, in addition, 

even if the risk is below the listed contribution or threshold levels, the EPA still needs to 

determine case-by-case whether stronger limits are needed (based on the types of pollutants 

emitted, and each of the scientific factors relevant to protect public health, especially for children 

and other vulnerable individuals).

The commenter (0107) states, in conclusion, that the EPA must set a standard that will achieve a 

cancer risk below 1-in-1 million (the statutory goal), a chronic non-cancer risk below 0.2 and an 

acute health risk below 0.2 (per EPA’s 2002 staff memo), a multipathway risk below 1, and a 

cumulative burden that ensures the combined health risks to this community are not as a whole 

unacceptable.

Response: We have combined risk assessment results to the extent that it is appropriate to do so. 

We do consider the effect of mixtures of carcinogens. We do not use a TOSHI approach for 

acute noncancer like we do for chronic noncancer. We also do not combine the results of our 

inhalation and multipathway assessments. The basis for each of our methodological decisions on 

which sets of results to combine is explained in the risk assessment document53. Moreover, to 

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

conducts a comprehensive assessment of the risks associated with exposure to the HAPs emitted 

by the source category (i.e., those emissions that can actually be affected by the specific 

rulemaking) and supplements that with additional available information about other possible 

concurrent and relevant risks. In some cases, we have additional information about HAP 

emissions that are outside the scope of the particular rulemaking but within the boundaries of the 

subject facilities. In other cases, we may have ambient HAP monitoring data that can be 

considered as part of the regulatory decision-making. In still other cases, we may have very little 

additional risk information that can be considered. In all cases, however, when we consider 

additional information about risks, we also consider its attendant uncertainties, and information 

which carries significant uncertainties generally carries much less weight in the overall 

regulatory decision.

All of the quantitative risk assessment information about HAP emissions from the source 

category under consideration is also considered in the manner prescribed by the decision 

framework set forth by the CAA for residual risk decision-making (i.e., the Benzene NESHAP 

decision framework), and this means that the general guidelines of risk acceptability have been 

 

53 EPA Office of Air Quality Planning and Standards, Residual Risk Assessment for the Ferroalloys Source 

Category in Support of the September Supplemental Proposal, September 2014. (EPA-HQ-OAR-0895-0136)
97

developed in a way that they already take into account the impossibility of accurately quantifying 

the health risks posed by outside forces on every individual in the population. This 

acknowledgment allows the EPA to make risk-based decisions by focusing on the risks 

associated with the emissions that are themselves the subject of regulation being considered.

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

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

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

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

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

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

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

38061, September 14, 1989). Background levels of certain HAP can be relatively high, perhaps 

even above a level that might be considered “safe.” Background levels (including natural 

background) are not barred from the EPA’s ample margin of safety analysis, but the EPA may 

consider them, as appropriate and as available, along with other factors, such as cost and 

technical feasibility, in the second step of its section 112(f) analysis.

As discussed above in response to the previous comment, the EPA disagrees with the 

commenter’s notion that any TOSHI value, or acute HQ value, greater than 0.2 should be 

considered unacceptable. We further note that we generally draw no bright lines of acceptability 

regarding cancer or noncancer risks from source category HAP emissions, and that it is always 

important to consider the specific uncertainties of the emissions and health effects information 

regarding the source category in question when deciding exactly what level of cancer and 

noncancer risk should be considered acceptable. In addition, the source category-specific 

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

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

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

source category risk. Experience with source category rulemakings in the past tells us that this 

means that drawing bright lines for such decision-making is impossible. The Benzene NESHAP 

decision framework of 1989 acknowledged this; in today’s world, such flexibility is even more 

imperative, because new information relevant to the question of risk acceptability is being 

developed all the time, and the accuracy and uncertainty of each piece of information must be 

considered in a weight-of-evidence approach for each decision. This relevant body of 

information is growing fast (and it will continue to grow faster and faster), necessitating a 

flexible weight-of-evidence approach that acknowledges both complexity and uncertainty in the 

simplest and most transparent way possible. While this challenge is formidable, it is nonetheless 

the goal of the EPA’s RTR decision-making, and it is the goal of the risk assessment to provide 

the information to support the decision-making process. 
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3.4 The Rule Does Not Provide an Ample Margin of Safety

Comment: Commenter 0107 states that the EPA fails to set a residual risk standard that provides 

the requisite ample margin of safety to protect public health, pursuant to CAA section 112(f)(2)

and cites several deficiencies, including: 

 The EPA’s proposal would still expose people to a cancer risk significantly higher than 

the 1-in-1 million target of section 112(f)(2), to chronic non-cancer risk that is 2 times the 

EPA’s safety threshold, and to multipathway risks that are 60 times greater than the 

EPA’s threshold.

 The EPA fails to consider whether the uncertainty that has likely led it to underestimate 

health risk in the first place requires a greater margin of protection at this final 

rulemaking stage.

 The EPA also fails to assess what margin of safety would be ample to protect the health 

of exposed children.

 By failing to address cumulative impacts in its ample margin analysis, the EPA has failed 

to assess or address the full health risk that local communities face from these source 

categories.

 The EPA failed to assess facility wide risk and takes no account of risks from other toxic 

air emissions in the vicinity and the combined impact for nearby communities, as it must.

 The EPA needs to address environmental justice factors in deciding what margin is 

needed to provide ‘ample’ protection for public health.

 The EPA fails to consider or determine whether its proposed rule provides the maximum 

feasible protection against health risks for the greatest number of people.

The commenter (0107) further states that the EPA does not explain how it follows that because 

the EPA has been unable to identify less expensive options, the margin of safety is “ample.” The 

commenter (0107) states that the EPA may not put cost above health by failing to consider health 

at all from the perspective of the most-exposed person. The commenter (0107) adds that the EPA 

has not explained in the record how it made the cost-based decision in the ample margin 

determination. The commenter (0107) states that the EPA should have considered additional 

options for reductions, such as any controls, practices, or processes used at the Eramet's sister 

facility in Norway and set emission standards for the U.S. source category that are at least as 

protective. 

In comments submitted in response to the supplemental proposal, commenter 0276 states that to 

assure the requisite “ample margin of safety to protect public health,” the EPA should determine 

the level of emission limitation and the resulting ambient air level of pollutants that is necessary 

to assure the statutory level of protection for the pollutants driving risk, including manganese.

The commenter states that without this information, the EPA does not show how compliance 

with the requisite margin of safety is assured. The commenter (0276) believes the EPA could 

accomplish this showing partly by requiring a compliance determination on actual emissions, 
99

similar to that used for the Primary Aluminum Production standard, and by requiring ambient air 

monitoring similar to what the South Coast Air Quality Management District is requiring for 

secondary lead smelters. The commenter (0276) added that the EPA can make any modifications 

needed, such as to EPA Method 14, to measure emissions from roof ventilation. 

Response:

The “deficiencies” listed by the commenter have been addressed in previous comments and 

responses and are not repeated here. The commenter’s misuse of the chronic noncancer and 

multipathway “thresholds” warrants further explanation. The chronic noncancer RfC is not a 

safety threshold, as stated by the commenter. It is a level (or air concentration) below which, we 

do not believe there to be adverse effects given a lifetime of exposure to this concentration. This 

does not mean that concentrations above this level are unsafe. It means there is more potential to 

see an effect than at a lower concentration. Further, the multipathway screening threshold, as has 

also been described previously (Section 2.5.1), is not meant to be used to produce a quantitative 

result of multipathway risks (i.e., the multipathway risk from POM does not equal 60-in-1 

million), but rather to identify pollutants or facilities that may warrant further analysis. It is not a 

regulatory number and should not be interpreted as a safety threshold.

When making its ample margin of safety determination, the EPA does consider health risks and 

their associated uncertainties, but also considers costs, technical feasibility, and other factors. For 

the ferroalloys source category, in Step 1 of the Benzene NESHAP framework, the risks were 

determined to be unacceptable given all of the health information. Standards were proposed to 

bring the risk down to acceptable levels, not considering costs. Once the risks were determined 

to be at acceptable levels, Step 2 of the Benzene NESHAP framework requires the EPA to again 

consider health risks, but also cost, technical feasibility, and other factors, in determining if any 

additional controls should be required to achieve an ample margin of safety. For the ferroalloys 

source category, at proposal and again in the supplemental proposal, the EPA proposed that it 

was not appropriate to require additional controls (either based on costs, feasibility, or 

availability) beyond what were proposed to achieve acceptable risks, regardless of health risks, 

thus we concluded that the proposed standards to address unacceptable risks also achieved an 

ample margin of safety. The same decision framework was used for the supplemental proposal 

and the final rule. While updates were made to emissions and the risk assessment as described 

throughout this document, when considering the results available for the final rule, our decisionmaking process produced the same result as in the supplemental proposal regarding acceptability 

and ample margin of safety.

Regarding investigation of European technologies and their costs, it is very difficult to compare 

them to U.S. standards because of differences in the way emissions are reported and control 

requirements are put in place. For the stack limits, we investigated the possibility of 

promulgating even lower standards at existing sources (even lower than the PM limits being 

promulgated in the final rule, as described in the preamble to the final rule) based on the levels 
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that could be achieved by replacing the existing scrubber at Eramet with a new fabric filter. 

However, given the additional capital and annualized costs that would be imposed on the one 

facility under this option (in addition to the costs for the substantially improved fugitive emission 

controls described in the preamble), and given the relatively minor additional emissions 

reductions that would be achieved under this option, we conclude that this option is not cost 

effective (at approximately $63,000 per ton of PM reduced) for this source category. In the 

revised technology review for the 2014 supplemental proposal, we did not identify any new 

developments in practices, processes, or control technologies that have been implemented since 

the proposed rule was published, and therefore have established emission limits based on the 

current level of control.

4.0 PREVIOUSLY UNREGULATED POLLUTANTS AND EMISSION POINTS AND 

TECHNOLOGY REVIEW

4.1 Regulating Previously Unregulated Pollutants and Emission Points

Comment: Commenters 0074, 0075 and 0106 state that the EPA’s 2011 proposed rule exceeds 

the bounds of its authority by attempting to establish new MACT standards for HAPs that are not 

covered by the 1999 MACT standards for ferroalloy production (formaldehyde, hydrochloric 

acid, mercury, and PAH), and commenter 0106 states the EPA also erroneously includes 

pollutants not regulated by the current MACT standards in its residual risk assessment under 

Section 112(f) (nickel, mercury, chromium, lead and arsenic). 

The commenter (0106) states that the EPA may not regulate HAPs for the first time under 

Section 112(d)(6) of the Act, and commenters 0074 and 0075 state that 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." Commenter (0074) states 

that the EPA cannot merely change its mind about what standards are required to comply with 

CAA sections 112(d)(2) and (3), nor can it fill “gaps” in existing MACT standards or recalculate 

a MACT floor based on subsequent performance. Commenter (0075) notes that Section 

112(d)(6) expressly authorizes EPA to review existing determinations and provides specific 

criteria to guide and constrain the review. The commenter (0075) asserts that the existence of this 

express authority forecloses the Agency’s ability to directly invoke sections 112(d)(2) and (3) for 

a given source category when a MACT determination has already been issued for the source 

category. The commenter (0074) notes that challenges to MACT standards must also be raised 

within 60 days of their promulgation. Commenters (0074 and 0106) state that even if the EPA 

did have authority to go back and change the existing MACT standards, it would have to justify 

why the decisions reflected in the current standards are wrong and why the new standards meet 

the required criteria that the EPA must satisfy in issuing MACT standards under CAA sections 

112(d)(2) and (3). Commenter 0106 asserts the proposed MACT standards for pollutants other 

than manganese were not properly promulgated and are legally invalid. 
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The commenter (0106) asserts that the EPA may not address residual risk under Section 112(f) 

for HAPs without MACT standards, stating that the scope of EPA’s authority does not extend to 

an evaluation of all risks presented by all HAP emissions of a source category, but rather is 

limited to an evaluation of the residual risks from pollutants that have been subjected to 

technology-based standards. The commenter (0106) adds that the only pollutant subject to 

technology-based standards in the original 1999 rulemaking was manganese and, therefore, the 

EPA’s residual risk assessment should have been limited to residual risks attributable to those 

manganese emissions regulated under the 1999 rulemaking. The commenter (0106) asserts that 

the EPA’s imposition of a risk-driven standard for mercury (and indirectly for PAH, since the 

EPA’s justification for a 90% reduction in PAH emissions is that the technology used to reduce 

mercury emissions will also reduce PAH emissions) was unlawful. The commenter (0106) also 

asserts that the EPA should revisit its unacceptable risk determination, this time based solely on 

manganese risks. The commenter (0106) states that if such a review is based on corrected air 

modeling, reasonable exposure assumptions and an RfC that reflects current science, the EPA

will find that EMI’s manganese emissions do not present an unacceptable risk. The commenter 

(0106) adds that since the EPA’s selection of a “beyond the MACT floor standard” was 

explicitly and impermissibly based on risk, that standard should be removed and (at most) 

replaced with a technology-based standard consistent with Section 112(d)(3), with appropriate 

consideration for the product being produced and the mercury content of the ore involved.

In their comments on the supplemental proposal, commenter 0272 reiterates that EPA’s authority 

does not extend to the evaluation of all risks presented by HAP emissions from a source 

category, but is limited to an evaluation of the residual risks from pollutants after they have been 

regulated under technology-based standards. They believe that two of the three unacceptable risk 

findings are based on predicted risks (cancer and multipathway) attributed to compounds other 

than manganese, and include arsenic, cadmium, chromium, PAH and mercury, for which there 

are no technology-based standards. They believe by doing this, EPA has disregarded Congress’ 

intent and direction in Section 112 that these risks can only be considered after technology-based 

MACT limits have been applied. Therefore, the commenter (0272) believes that EPA should 

remove all risk assessments and screening assessments addressing non-manganese compounds 

and reassess its unacceptable risk determination based on manganese emissions.

In contrast to these comments, commenter 0107 states that the statute does not say: only 

promulgate section 112(f)(2) standards for the already regulated emission points within each 

such category, but instead says to promulgate section 112(f)(2) standards 8 years after 

promulgation of standards for each source category. The commenter (0107) concludes that the 

promulgation of any section 112(d) standard for a source category is what triggers the EPA’s 

obligation to conduct a complete section 112(f)(2) rulemaking for the entire source category (or 

subcategory), including all HAP emissions and emission points, including but not limited to any 

emission points that the section 112(d) standard previously covered. The commenter (0107) 

describes the legislative history supporting this interpretation.
102

Response: In Medical Waste Institute v. EPA, 645 F. 3d 420, 425-27 (D.C. Cir. 2011), the D.C. 

Circuit held that the EPA may permissibly amend improper MACT determinations, including 

amendments to improperly promulgated floor determinations, using its authority under section 

112 (d)(2) and (3). The absence of standards for 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.) The D.C. Circuit’s December 9, 2011in Portland Cement Ass’n v. EPA

(D.C. Cir. No. 10-1358) confirms that the 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 mercury, PAH, formaldehyde, and HCl emissions here. Put another way, if the EPA did 

not adopt a proper MACT standard initially, it is not amending a MACT standard but adopting 

one for the first time. That is the case here for mercury, PAH, formaldehyde, and HCl emissions. 

Here, the EPA adopted no MACT standard at all for these HAP, an approach soundly rejected by 

the D.C. Circuit in National Lime, 233 F. 3d at 633-34. Consequently, the EPA is not barred 

from making MACT floor determinations and issuing MACT standards pursuant to section 112 

(d)(2) and (3) here.

4.2 Technology Review

Comment: Commenter 0107 states that section 112(d)(6) serves as an ongoing ratchet to 

continually require EPA to update standards to keep pace with new technology in order to 

decrease emissions. The commenter (0107) further states that section 112(d)(6) requires EPA to 

recalculate the MACT floor when there have been advances in technology, practices, and 

processes, and while the court in NRDC v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008) explained 

that recalculating the floors was not necessary because “petitioners have not identified any post1994 technological innovations that the EPA has overlooked,” the MACT floors must be 

recalculated when there is information showing that greater emission reductions have been 

“actually achieved.” In fact, we conclude that it is appropriate to promulgate MACT limits for 

these previously unregulated HAP, as we have done in today’s final rule and as explained in the 

preamble to the final rule.

Response: As part of the section 112(d)(6) technology review, we reviewed the MACT limits for 

stack emissions and revised them to reflect recent test data regarding the performance of the 

control devices that are in use in the industry and reduced those limits consistent with the UPL 

process. In terms of advances in technology, practices, and processes, we consider fabric filter 

control to be the state-of-the-art. Consequently, we evaluated the impact of replacing the existing 

remaining scrubber with a baghouse. Because of the relatively low level of emissions reduction

and the substantial capital and annualized costs that would be imposed on one facility in addition 

to the costs for the required fugitive emissions controls (described in the preamble to the final 

rule), we determined that such a replacement would not be cost effective for this source category 
103

at approximately $63,000 per ton of PM reduced, and therefore not a feasible advancement in 

technology. We have, however, required enhanced monitoring of the control devices, particularly 

a requirement for sources to install and operate bagleak detections systems. This change, which 

does represent an advancement in operational technology, should result in better operation of the 

source’s baghouses. 

Comment: Commenter 0107 states that the EPA must both “look back” to recalculate the MACT 

and perform a beyond-the-floor analysis and “look around” to assess emission reduction 

“developments” in current industry “practices, processes, and technologies” in performing its 

section 112(d)(6) review. The commenter (0107) states that the EPA fails this effort by 

interpreting the term “developments” too narrowly. The commenter (0107) states that the EPA

needs to consider an increase in acceptance and utilization of a technology or process within a 

category as a development warranting consideration during a review. The commenter (0107) 

adds that the EPA needs to consider whether technology has advanced so that higher efficiency 

has been achieved in practice or that a control device, that had been considered experimental, is 

now commercially demonstrated. The commenter (0107) states that merely noting the existence 

of a technology or practice in the initial rulemaking can hardly form the basis for declining to 

evaluate it during the 8-year review. The commenter (0107) also states that the EPA’s analysis is 

deficient because it did not look to jurisdictions with the most stringent standards for HAP 

emissions or to gather data from facilities about control systems that are attaining the highest 

control efficiencies, including requirements for similar source categories.

Additionally, the commenter (0107) states that the EPA collected emission test data for this 

source category that allows it to fully recalculate the existing MACT (which was designed for 

only one source, and there is now a new source in the category). The commenter (0107) states 

that the EPA overlooks the potential lower emissions that sources are achieving by failing to use 

actual emission test data and ignores the potential HAP emissions that the control devices 

themselves emit by failing to collect such emissions data from facilities that have installed 

control devices. The commenter (0107) states that information EPA did collect suggests that it 

should require greater emission reductions for this source category, but yet according to its own 

analysis, its limits would not require any new controls to be installed (beyond the enclosure 

provision).

The commenter (0107) further states that the EPA has not considered the greater emission 

reductions achieved by Eramet’s Norway facility and that the EPA must consider what controls, 

practices, and processes that facility uses to achieve lower emissions. 

Response: We have reviewed the operating permit limits for not only the two facilities in the 

source category, but for other domestic ferroalloy producers. These permits reflect state 

requirements and none of them are more stringent than the proposed and final revised limits. We 

believe that the focus on capture and control of process fugitives in today’s final rule goes 

beyond what states currently require and will achieve substantial reductions in HAP emissions 
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from these facilities. Regarding investigation of European technologies, it is very difficult to 

compare them to U.S. standards because of differences in the way emissions are reported and 

control requirements are put in place.

In developing the emission limits for this source category, we collected numerous stack test data 

(22 PM stack tests total) and established a PM limit (used as a surrogate for metal HAP) in the 

supplemental proposal that reflects the current control technologies used in this industry. This 

established limit is much lower than the standards in the 1999 NESHAP and is based on 

available PM test data from several emissions tests conducted over the past several years. Further 

details on how the limit was derived is provided in the Technology Review memoranda which 

are available in the docket for this action. We estimate that the PM standard, in addition to the 

HAP standards for hydrogen chloride, mercury, polycyclic aromatic hydrocarbons and fugitive 

emissions capture, will reduce risk and provide HAP reductions of 76 tons per year.

Comment: Commenter 0073 reiterates the requirement that since the EPA has identified new 

technology deemed to be available based on application in a similar industry, the new 

developments must either represent a new MACT-level technology, or must be justified as a 

beyond-the-floor standard based on cost, non-air-quality health and environmental impacts, and 

energy requirements. The commenter (0073) asserts that the total building-wide negative 

pressure environment that the EPA seeks to require does not exist, and that the CCMA facility 

that the EPA relies on as the basis for its finding does not use a negative-pressure PTE at all, but 

instead relies on targeted equipment controls together with fugitives management practices. The 

commenter (0073) states that because the PTE EPA has proposed has not yet been used within 

the metals manufacturing industry as EPA presumed, it is not a “development” in “control 

technologies” under Section 112(d)(6). The commenter (0073) asserts that even if the PTE were 

an available control technology (or EPA amended the proposal to require the use of the type of 

controls used at CCMA), the Agency would still need to demonstrate that the controls qualify as 

MACT – either as MACT floor level control, or as “beyond-the-floor” controls to be required 

considering costs, other environmental impacts, and energy considerations. The commenter 

(0073) states that these controls are clearly not MACT floor level controls (no facility within the 

Ferroalloys Production source category is currently using either the full-building PTE proposed 

by the EPA or the controls used by CCMA), and thus must be evaluated as a “beyond-the-floor” 

level of control. The commenter (0073) further asserts that the proposed standards have been 

evaluated for only one of the three congressionally-mandated factors (costs).

Response: We proposed full building enclosure with negative pressure in 2011 to reduce risk 

under section 112(f)(2) and as part of technology review under section 112(d)(6). Making a 

MACT floor determination was not part of the process. We agree that we overstated the 

connection to the building ventilation system at CCMA, given the requirement to maintain 

negative pressure at building openings at proposal. Both plants provided cost and engineering 

assessments of the impacts of requiring a total building enclosure to be maintained at negative 

pressure, which is costly, as they demonstrate. As described in the preamble, we have reassessed 
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the costs and impacts of requiring total building ventilation systems (with negative pressure) and 

local capture options and have decided not to require such controls. 

We have considered costs, economic impacts, and other environmental impacts to the extent 

possible, consistent with our obligations under the Act. 

Comment: Commenter 0073 requests that the EPA take the following actions to account for its 

errors in technology review: (1) subcategorize among the various operations; (2) regardless of 

whether the Agency subcategorizes, reevaluate the controls in place at CCMA to redefine the 

scope of the “beyond-the-floor” technology the Agency seeks to impose; (3) perform a full 

analysis of these redefined controls, including their costs, their non-air-quality environmental 

and health impacts, and their energy impacts; and (4) provide Felman and other interested parties 

with the opportunity to comment on the Agency’s revised technology description and costbenefit analysis.

Response: EPA’s obligation under the Administrative Procedures Act is to propose 

requirements, take comments on those requirements, and be responsive to those comments in the 

promulgated regulations. We can make changes to the proposal to the extent that the changes are 

construed as a logical outgrowth of the original proposal. However, after reviewing the 

comments, concerns, additional data and information on the 2011 proposed amendments to 

subpart XXX (76 FR 72508), we determined that was appropriate to revise some of the analyses 

and published a supplemental proposal that addresses these issues. This included revisions to the 

particulate matter emission standards for furnaces and local ventilation control devices, 

technology review, revisions to the emission limits for mercury, polycyclic aromatic 

hydrocarbons (PAH), and hydrochloric acid (HCl) from the furnaces, and changes to the 

compliance requirements for fugitive emissions. In addition, we received additional test data that 

were used to develop the final emission standards and improve the dataset used for the risk 

assessment. 

Comment: Commenter 0107 states that the EPA should also consider requiring additional 

emission reductions based on EPA’s review of practices, processes and technologies in use at the 

Eramet Norway facility, which has substantially lower levels of dust emissions.

Response: As described earlier, it is very difficult to compare emissions between European 

requirements and U.S. requirements. In this case, we have extensive data from the two plants 

subject to the NESHAP, and we are promulgating requirements that will satisfy the risk 

reduction and technology review requirements of the Act.

Comment: In comments on the supplemental proposal, two commenters (0270, 0276) state that 

the EPA has not adequately supported its assumptions underlying the PAH limits and should 

strengthen these before finalizing the rule. First, the commenters (0270, 0276) want the EPA to 

investigate evidence that reducing the coal tar pitch allowed in the Soderberg paste may 

dramatically reduce the PAH/POM emissions. Both commenters (0270, 0276) provided studies 
106

supporting this potential for emission reduction and note that low PAH paste or petroleum-based 

asphalt is available and could be used by the sources in FeMn and SiMn production. One 

commenter (0276) states that the EPA must review the use of low PAH paste as a “development: 

under section 7412(d)(6), and as a method to assure an “ample margin of safety to protect public 

health” under section 7412(f)(2). The commenter (0276) points to the phasing out of PFOSbased fume suppressants in the Chrome Plating NESHAP as precedent to require use of a less 

toxic input or material as a reason to revise the standards.

Response: We reviewed the information provided by the commenter and obtained information 

from other vendors and studies. The commenter provided MSDS sheets for the paste, but 

provided no emissions data from the use of this paste. The studies that we located involved using 

different Soderberg paste base materials, which resulted in a lower VOC paste, however none of 

these studies measured organic HAP emissions during use of this paste. Therefore at this time, 

we are unable to make a definitive determination that reducing the coal tar pitch in the Soderberg 

paste would dramatically reduce PAH/POM emissions.

Comment: Commenter (0276) disagrees with the EPA’s basis is for concluding to distinguish 

and subcategorize the sources in terms of PAH emissions. The commenter (0276) states that the 

EPA has not met the test to show that the two existing sources fall into such different “classes, 

types, and sizes” of sources that would justify separate subcategories under the Act. 

Response: We disagree with the commenter and believe it is appropriate to subcategorize the 

furnaces for PAH emissions. We found a significant statistical difference in the furnace PAH 

emissions between SiMn production and FeMn production. Even though the furnaces are 

comparable in how they operate and they use the same Soderberg paste, the raw materials used 

to produce the different products are very different. Among other factors, the raw materials for 

FeMn production include more carbon in comparison to the raw materials used for SiMn 

production. We believe the additional carbon sources needed by the FeMn process is the reason 

for the higher PAH emissions during FeMn production. Therefore, we determined that the PAH 

emission limit should be subcategorized by the product being produced (e.g., SiMn, FeMn).

Comment: Commenter 0107 states that it is unclear why EPA's proposed rule under section 

112(f)(2) almost exactly matches EPA’s proposal under section 112(d)(6). The commenter 

(0107) states that the measures required to comply with the EPA’s proposed rule do not have 

high costs, as EPA has recognized in the record (although it is not lawfully allowed to consider 

costs at the acceptable stage). The commenter (0107) notes that by stating that no additional 

controls would be required to comply with these proposed limits, it appears that the EPA may 

have unlawfully considered cost to propose the residual risk standards. The commenter (0107) 

states that the EPA must explain why these proposed rules match, and how the proposed 

standards meet each of the legal tests under sections 112(f)(2) and (d)(6). The commenter (0107) 

notes that the EPA may not set a residual risk standard that sets limits just based on the 

(unlawfully) narrow view of its duty to assess developments under section 112(d)(6).
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Response: In conducting our technology review under section 112(d)(6), the EPA identifies all 

known control options, and those same options are considered in our residual risk evaluation if 

they have the potential to reduce risks. It is often the case that we propose (and finalize) 

requirements under both 112(f)(2) and 112(d)(6), as was the case in the Ferroalloys proposal 

(and is the case in the final rule). The commenter is correct that controls needed to bring risks to 

an acceptable level must be required regardless of cost, and we did not consider cost in our 

selection of the controls being required under our 112(f)(2) acceptability determination. The 

finding in our 112(d)(6) analysis that the controls are cost-effective did not factor into our 

selection of controls needed to reduce risks to an acceptable level. We also note that technically 

feasible, cost-effective control options beyond those that we proposed in our supplemental 

proposal were not identified.

Comment: Several commenters (0068, 0077, 0089, 0092, 0098) state that stricter air pollution 

regulations are long overdue. One commenter (0089) notes that over the last 14 years a group of 

concerned citizens, who became Neighbors for Clean Air, have worked tirelessly to get the 

attention of Eramet officials, Ohio EPA officials and US EPA officials. The commenter (0089) 

states that citizens are tired of breathing the excess emissions of an aging factory which has been 

exempt from strong enough regulations that would have protected the health and quality of life 

of generations of citizens had they been put in place years ago, when they should have been. 

Three commenters (0077, 0092, 0098) ask EPA to adopt regulations that will protect the public 

health and safety from emissions arising from ferroalloy manufacturing and then enforce those 

limits. One commenter (0092) notes that people say that we need jobs, and this is true, but not 

jobs that compromise the health of children and adults. The commenter (0092) states that there 

should not be large loopholes where many toxic substances are able to be "not counted". The 

commenter (0092) states that her organization has met with the management of Eramet many 

times and they have stated that the regulatory environment is part of the decision as to whether or 

not investment is made in a facility in terms of pollution-control upgrades. The commenter 

(0092) concludes that if the regulatory environment is lax, the investment will not be made. 

Commenter 0068 states that it is imperative that stricter standards be set for emissions from 

manganese refineries like Eramet Marietta Incorporated. The commenter (0068) has worked with 

neighbors of the Eramet facility for more than a decade, helping them to conduct a “good 

neighbor” campaign that resulted in more than 58,000 letters and petitions to company decision 

makers that prompted Eramet to announce $150 million in investments designed to improve 

efficiency and environmental performance. The commenter (0068) attached a copy of a 

documentary titled “Eramet Neighbors Speak Out,” which was produced in 2007 as part of a 

joint grassroots campaign conducted with Neighbors for Clean Air, as part of comment 0105.

Several private citizens (0078, 0079, 0080, 0081, 0082, 0083, 0084, 0086, 0087, 0088, 0093, 

0095, 0096, 0102, 0103, 0104) submitted the following identical comment regarding the need for 

strong, health-based standards: 
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Identical Comment: As a concerned Ohioan, where according to U. S. EPA, we rank #1 for 

toxic air pollution, these are my comments on the proposed new rules for ferroalloys facilities. 

Eramet Marietta Incorporated is the largest ferroalloy producer in North America. Thanks to 

them, the community of Marietta has become a perfect laboratory for studying the impact of 

airborne manganese on humans. The University of Cincinnati, University of San Francisco and 

Agency on Toxic Substances and Disease Registry have all done community health studies there 

just since 2007. I encourage U. S. EPA to look at all the science available and to set rules that 

create a real margin of safety to protect people from manganese and other pollution from 

ferroalloys plants. Specifically, people need full protection from fugitive emissions and from 

emission spikes during tapping and casting. U.S EPA should require full enclosure of furnace 

buildings and remove all exemptions for fugitive emissions from protective standards. EPA 

needs to make sure there is proper testing and reporting so that there are no more high spikes in 

emissions during tapping and casting or malfunctions. Thank you for considering my comment. 

Response: We think the final rule will provide the environmental protection the citizen 

commenters are seeking. 

Comment: Three private citizens (0077, 0089, 0099) state the need for more stringent 

requirements, including: 

 Set stronger emission limits than the EPA has proposed for all pollutants that will prevent 

us from facing cancer risk above 1-in-1 million and other unacceptable chronic health 

risks from manganese.

 Set a more stringent opacity limit that is no higher than 10%, and do not allow any 

exceedances of this for any period of time, rather than finalizing a “one 6-minute period” 

exemption as proposed.

 Provide full protection from fugitive emissions and from emission spikes during tapping 

and casting.

 Finalize a strong, numerical limit on manganese that is lower than the limit EPA has 

proposed, and require monitoring at the fenceline, so we can tell whether we are getting 

health protection we need.

 Make sure there is proper testing and reporting so that there are no more high spikes in 

emissions during tapping and casting or malfunctions.

Response: As described in the proposal notice, the EPA does not define “rigid lines[s] of 

acceptability” for MIR, but rather considers broad objectives to be weighed with a series of other 

health measures and factors. 

The final rule includes stringent requirements for the capture and control of process fugitive 

emissions. These include improved primary capture and control of process and secondary 
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capture and control of fugitive emissions for an overall capture and control of 95% of process 

fugitive emissions. 

In addition to more stringent control requirements, the final rule also contains extensive 

monitoring, reporting, recordkeeping, and testing requirements to ensure that the sources comply 

with the rule on a continuous basis. These include monitoring of control equipment to ensure 

they are operating correctly, weekly opacity measurements from the furnace and MOR building 

using DOCS, and HAP emission standards.

Comment: Two commenters (0073, 0106) assert that the EPA’s cost and feasibility assessments 

were erroneous, resulting in gross underestimates of implementation costs for the new control 

requirements in the proposed rule. 

Response: See Sections 4.3 and 4.5.1 for more details and the EPA’s response.

4.3 Stack Emission Limits

Comment: Commenter 0073 agrees with the Agency’s decision to reduce the stack emissions 

limit, but requests that this limit be phrased in terms of mass instead of concentration.

Response: EPA appreciates the support. See section 4.8.2 for our response regarding the format 

of the final standards.

Comment: Commenter 0107 states that it is legally unjustifiable that the EPA has proposed a 

weaker limit for existing furnaces than for new/reconstructed furnaces. The EPA provides no 

justification at all, much less a rational one, for setting a weaker limit for existing sources, 

particularly when those are the sources currently threatening human health. The only possible 

rationale for setting a weaker limit for existing sources could be cost. At the acceptability stage, 

the EPA may not lawfully consider cost. The EPA therefore must finalize the standards 

necessary to achieve acceptable risk for all sources, including existing sources (which would be 

no higher than the lower limit of 9.3 mg/dscm, instead of 24 mg/dscm). 

Response: We determined that the risks for this source category at baseline were unacceptable

and are finalizing tighter PM emission limits for the stacks, which significantly reduce risk due 

to allowable emissions. We are also reducing risk due to process fugitive emissions by requiring 

a system of primary hoods (that capture process fugitive emissions near the source) and/or 

secondary capture of fugitives (which would capture remaining fugitive emissions near the roofline). We estimate that the actions finalized under CAA section 112(f)(2) to address unacceptable 

risks, will reduce the MIR to 10-in-1 million. The cancer incidence will be reduced to 0.002 

cases per year and the number of people estimated to have cancer risks greater than 1-in-1 

million will be reduced to 26,000 people. The chronic noncancer inhalation TOSHI will be 

reduced to 1 and the number of people exposed to a TOSHI level greater than 1 will be reduced 

to 0. In addition, the potential multipathway impacts will be reduced. Based on these results, we 

concluded that these risks, after the implementation of proposed controls, will be acceptable. 
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Nothing in the statute compels the emission standard for new sources to be the same as the 

standard for existing sources under section 112(f), provided that both standards achieve 

acceptable risk. In the ample margin of safety analysis, where cost is among the factors to be 

reviewed, it is possible that different conclusions could be reached as to whether further emission 

reductions are needed to achieve a margin of safety that is ample.

Comment: Commenter 0107 states EPA’s proposed regulatory language does not actually match 

the proposed limit for the MOR (1.5 mg/dscm corrected to 2 percent CO2), but instead is higher 

(3.9 mg/dscm). The commenter states that the EPA must at least finalize the residual risk limit 

proposed (1.5 mg/dscm). 

Response: The 1.5 mg/dscm limit described on page 72531, column 2, of the proposal notice 

was listed in error. The correct value is 3.9 mg/dscm, which was described on page 72533, 

column 3, and is consistent with the MACT floor analysis for the proposed rule in the project 

docket. 

Comment: Commenter 0073 asserts that the UPL analysis for the MACT floor does not address 

“abnormal” operations because it is based solely on stack test data which does not reflect the full 

range of “normal” source operation. The commenter (0073) notes that the resultant MACT 

standard is set at a level that a well-operated source should be able to meet during 99% of future 

stack tests, but the limit applies at all times. The commenter (0073) points out that compliance 

determinations are not limited to stack test periods and thus if compliance is required at all times, 

the data set which MACT is based on should include the full range of operating conditions. The 

commenter (0073) adds that if the EPA intends to establish MACT based on limited stack test 

data, they could establish MACT based on 100% of the stack test data, or clarify that the credible 

evidence rule does not apply under the Ferroalloys NESHAP and that compliance with the 

MACT limits may be determined solely on the average of three stack test runs.

Response: Ideally, sources would be equipped with continuous emissions monitors and the 

resulting long-term data could be used to set MACT standards. However, typically, costs and 

other practical realities often mean that the best available data are obtained through stack 

emissions tests. We believe that the use of the UPL analysis is an appropriate approach to 

address variability in emissions between stack tests. We also note that compliance with the stack 

limits are based on periodic stack tests, not CEMS. Therefore, the stack limits should be 

achievable under these conditions.

Comment: In their comments on the supplemental proposal, commenter 0269 expressed

concerns that emissions from tapping operations are subject to two separate and inconsistent 

requirements. First, tapping emissions are directly regulated as furnace emissions under 

§63.1623(a). This section requires Felman to install, operate, and maintain an “effective” capture 

system that collects tapping emissions (along with the furnace emissions) and routes them to a 

control device meeting the applicable emissions standard. Second, tapping emissions are also 
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regulated as a “process fugitive emissions source” §63.1623(b). This requirement obligates 

Felman to install, operate, and maintain a capture system that is designed to collect at least 95% 

of emissions from process emissions sources, which are defined under §63.1622 to include 

tapping emissions, and to convey those emissions to a compliant control device.

The commenter (0269) believes that the regulation of tapping emissions as part of the furnace 

operations under § 63.1623(a) does not reflect the physical configuration of the furnace control 

design. They note that emissions from operating the furnace (e.g., charging and melting) 

originate from the same location: the top of the furnace, where the raw materials and catalyst are 

exposed to the atmosphere. However, they note that tapping emissions originate from the bottom 

of the furnace; therefore these emissions cannot be captured and managed via the same fans and 

equipment that capture emissions from the furnace.

The commenter (0269) is also concerned that as drafted, the supplemental proposal may require 

it to install a separate control system around the tapping area to provide “effective” capture of 

tapping emissions. They state that this requirement is inconsistent with the “area-wide” control 

approach that they intend to install to manage fugitive emissions from the furnace, tapping, 

casting, and raking and skimming operations. They believe that requiring this additional layer of 

controls would impose significant additional costs and would provide no additional 

environmental benefits. They state that the rule also provides no guidance on what degree of 

controls would be considered “effective,” making it impossible to even attempt to design such a 

system.

The commenter (0269) requests that the reference to “tapping operations” be removed from 

§63.1623(a). They believe that these emissions are fugitive and therefore are more appropriately 

regulated under the process fugitive provisions at §63.1623(b).

Response: We agree with the commenter and have removed the reference to tapping operations 

from §63.1623(a).

Comment: In their comments on the supplemental proposal, commenter 0269 states that 

§63.1623(b) requires that all process fugitive emissions be managed via a system that is designed 

to provide at least 95% capture; compliance with this obligation is demonstrated pursuant to 

§63.1624(a). Section 63.1624(a), in turn, requires a detailed engineering plan, “designed to 

achieve sufficient air changes to evacuate the collection area frequently enough to ensure process 

fugitive emissions are effectively collected by the ventilation system”; the plan must also 

account for “variables that affect capture efficiency such as operations that create cross-drafts[.]” 

§63.1624(a)(i).

The commenter (0269) believes that these requirements are inappropriately stringent and 

unfeasible for the operations in question. As Felman has previously documented to the EPA, its 

furnace building is both extremely large and very old, with a large number of openings and leaks. 

The controls necessary to capture and manage fugitive emissions within such a large, unique 
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space cannot simply be bought off the shelf. Instead, Felman’s entire control plan has been 

individually designed and represents a control system that has never before been applied within 

the ferroalloy industry.

Furthermore, the commenter (0269) believes that there are very few engineers who are capable 

of designing such a system, much less preparing the extensive documentation required by EPA. 

In fact, all of the consultants that Felman has contacted to generate the required plan 

documentation have insisted on conducting modeling before they will certify that the plan will 

meet all of the criteria set forth in the proposal; however, given the size and complexity of the 

building, and the novel nature of the planned controls, these consultants do not believe they have 

sufficiently concrete data on the required model input parameters to do so. To date, Felman has 

not identified a consultant that has agreed to perform the modeling required to demonstrate 

compliance with all of these criteria.

The commenter (0269) requests that these extremely detailed criteria be streamlined into a

broader requirement that the plan be designed based on the best available information and

engineering principles, and that the specific details of what that entails be left to the discretion of

the relevant permitting authority.

Response: The facility provided a fugitive capture design narrative in their supplemental 

comments to the proposed rule. The proposed design improves the existing direct exhaust system 

while providing a secondary exhaust system in order to fully capture and contain process fugitive 

emissions that are generated. The use of both a primary hood exhaust system and a general 

secondary exhaust system in conjunction was estimated to provide a total building capture rate of 

approximately 95%, including the tapping; casting; crushing/screening and skimming/slag raking 

processes. This design narrative includes ACGIH elements and design principles and we believe 

will be able to achieve the requirements in the final rule.

4.4 Object to UPL Methodology 

Comment: Two commenters (0065, 0107) support the EPA’s decision to set limits for previously 

uncontrolled sources of emissions, including mercury, PAH, HCl, and formaldehyde because this 

is consistent with section 112(d) which requires the EPA to set emission standards for all emitted 

pollutants. One commenter (0107) adds that closing loopholes and correcting problems that exist 

in the existing standard is an important part of the EPA’s job under section 112(d)(6). The 

commenter (0107 (and in its comments on the supplemental proposal - 0276)) disagrees, 

however, with the EPA’s use of such a high variability factor in setting the MACT standards for 

these pollutants as it is unsupported and results in a standard that is higher than appropriate. The 

commenter (0107) states that using an upper prediction limit to set standards reflecting the worst 

performance these sources could have in a purely statistical sense does not yield an accurate 

picture of the best sources’ actual performance, and it is especially arbitrary in the absence of 

any explanation of why the EPA thinks that the relevant best sources’ performance would ever 
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be so bad, other than the fact that it is statistically possible. The commenter (0276) also states that 

the EPA has not clearly explained its approach in the limited data sets memo or the UPL memo

The commenter (0107) adds that, even if the EPA could justify using an upper predictive limit 

(UPL) of 99% for some source category, it has failed to provide any rational explanation for 

using it for the Ferroalloys source category.

Commenter 0107 further adds that the EPA’s dataset also includes other uncontrolled HAP 

emissions, including hydrogen fluoride (HF) and naphthalene emissions, and the EPA has failed 

to propose a limit to control these emissions. The commenter (0107) states that Section 112 

requires EPA to set an emission standard to control all HAPs emitted. The EPA must do so, at 

least by setting the limit at the detection level if emissions fall below that. 

Commenter 0272 recommended using ProUCL for calculating UPLs for MACT limits. They 

note that ProUCL is a tool for statistically evaluating data for environmental decision making 

and has been supported through the EPA ORD.

Commenter (0276) objects to the EPA’s use of a representative detection level (RDL) to increase the 

limit for HCL and states that this decision is not justified based on the science, record or what has 

been achieved. The commenter 0276 also notes that the EPA appears to propose to continue to use 

the UPL to set floor standards, even after the D.C. Circuit remanded EPA’s use of that method in 

NACWA. The commenter (0276) states that the EPA appears to be attempting to evade the Court’s 

direction to follow the plain text of § 7412(d)(3) to set standards based on the “average emission 

limitation achieved.” According to commenter 0276, the EPA has failed to justify its interpretation of 

the statute’s direction for this “average,” § 7412(d)(3), and has failed to provide the necessary factual 

support to use the approach it chooses even if it could be considered to meet the statutory test. 

Response: As stated in the memorandum entitled “Use of the Upper Prediction Limit for 

Calculating MACT Floors” (Docket No. EPA-HQ-OAR-2010-0895-0179) (“UPL 

memorandum”), in “the context of development of MACT floors, the UPL is a value, calculated 

from a dataset, which identifies the average emissions level that a source or group of sources is 

meeting and would be expected to meet a specified percent of the time that the source is 

operating. That percent of time is based on the confidence level used in the UPL equation, as 

explained in more detail below. For a single best controlled emission source that serves as the 

basis for a new source MACT floor, the 99 percent UPL is the emissions level that the source 

would be predicted to be below during 99 out of 100 performance tests, including emissions tests 

conducted in the past, present, and future, based on the short term stack test data available for 

that source. It is important to note that the UPL does not represent the worst emissions 

performance of the best performing units at any time, but rather the average level expected to 

have been achieved over time, as the first element of the UPL equation is the average of the 

short-term emissions test data from the best performing units. In other words, the 99 percent 

UPL is the level of emissions that we are 99 percent confident is achieved by the average source 

represented in a dataset (in the case of MACT standards, the dataset representing the 
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performance of the best performers as specified in the CAA) over a long-term period based on its 

previous, measured performance history as reflected in short-term stack test data.” Contrary to 

the commenter’s assertion, the NACWA court did not find the UPL to be an arbitrary approach, 

but simply asked for a better explanation from the Agency. The UPL memorandum provides the 

explanation of what the UPL represents sought by the NACWA Court. It also explains why the 

UPL is representative of the level of performance achieved by the best performing unit or units. 

The court did not state that the “average emissions limitation achieved by the best performing 12 

percent” must be equal to the mean of the available data, as suggested by the commenter, and in 

past decisions the court has upheld that it is appropriate for EPA to account for variability when 

establishing numeric MACT standards. See Mossville Environmental Action Now v. EPA, 370 

F.3d 1232, 1241-42 (D.C. Cir. 2004).

We also refer the commenter to the proposal MACT floor memorandum, which is in the 

rulemaking docket. This memorandum provides a detailed discussion of the EPA’s authority to 

consider variability, especially given that MACT and other technology-based standards are 

necessarily derived from short term emissions test data and such data are not representative of 

the range of operating conditions that the best-performing facilities face on a day-to-day basis. In 

statistical terms, each test produces a limited data sample, not a complete enumeration of the 

available data for performance of the unit over a long period of time. The EPA, therefore, often 

needs to adjust the short-term data to account for these varying conditions in order to properly 

estimate these sources’ performance over time. The types of variability that the EPA accounts for 

include variability between and within tests at the same unit as well as between units in the pool 

of “best performing units.” This memo also describes the EPA’s selection of the UPL 

methodology to address such variability. 

For some HAP (e.g., dioxins and furans, PCBs, and hydrogen fluoride) the majority or even all 

of the test samples were below the limit of detection for the test method. We do not believe we 

can establish an appropriate MACT floor limit for this source category for these HAP when there 

is so much uncertainty that the pollutants are even being emitted. 

While naphthalene was modeled separately from the other PAHs in the risk assessment, with 

regard to MACT standards, naphthalene is a PAH and is one of the PAHs covered by PAH 

MACT limit (via method 429). Therefore, there is no reason to establish a separate limit for 

napthalene because it is being regulated along with the other PAH compounds by the PAH limit.

Comment: Commenter 0073 agrees that the EPA may establish limits based on what MACT can 

achieve during normal operations, and not at some higher level that would encompass all 

conceivable malfunctions, but notes that if the EPA bases standards on an emissions level that 

MACT can achieve only 99 percent of the time, they must first ensure that MACT-level 

technology can actually comply with these emissions limits during all normal operations (the 99 

percent), and then provide an adequate exemption for the other 1 percent of the time, when even 

properly maintained and operated MACT-level technology cannot comply. 
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Response: The 99 percent UPL is a standard statistical analysis to address variability between 

stack tests, and the EPA believes it is an appropriate basis on which to establish stack limits 

based on test data.

4.5 Emission Averaging Across Multiple Furnaces

Comment: Commenter 0107 states that the EPA must not allow emissions averaging under 

section 112(f)(2) or section 112(d) for the following reasons:

 When the EPA sets an emission standard for each source, it must apply to each source, 

continuously without exception, because averaging means that some sources under 

common ownership at the same location can emit above the level allowed by the standard 

if others are operating below that standard and this is unlawful. Emissions averaging is 

bad for public health and the environment because the end result is an amount of 

emissions not allowed by the standard.

 EPA has found that current health risk is unacceptable and that specific emission 

reductions are required to achieve an acceptable level of health risk. Section 112(f)(2) 

requires EPA to set a standard to ensure those reductions and achieve an acceptable level 

of risk, and the EPA may not provide an alternative compliance option under which 

sources could exceed the very emissions limits it has found necessary to achieve 

acceptable risk.

 EPA attempts to justify this proposal based on EPA’s general policy of encouraging the 

use of compliance approaches that are more flexible and less costly alternative to 

controlling certain emission points to MACT levels. This statement shows that the EPA

has improperly considered cost at the acceptability stage of the section 112(f)(2) analysis. 

The EPA may not lawfully consider cost at all at this stage.

 EPA may not justify the use of emissions averaging under section 112(d), because that 

provision requires EPA to set and ensure compliance with an emission standard that 

meets the requirements of section 112(d)(2)-(3). Allowing averaging is a way of 

circumventing the requirement that emission standards must apply at all times.

In their comments on the supplemental proposal, commenter 0276 supports the EPA’s removal 

of the emissions averaging allowance.

Response: As described in section 4.10.2, we have decided to retain a concentration format for 

the final stack standards. While we believe this is the best format for this NESHAP, we have 

determined that it is not the best format to consider under an emissions averaging option. We are 

concerned that emissions from a large furnace emitting a lower than average concentration could 

still emit more emissions than a small furnace with a higher than average concentration. This 

could result in a net increase in emissions from the two furnaces compared to their emissions if 

they were not allowed to average emissions. For this reason, we have deleted the emissions 

averaging provisions from the final rule. 
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Comment: Commenter 0073 supports EPA’s decision to allow for emissions averaging across 

multiple furnaces to demonstrate compliance with the applicable emission limits. 

Response: EPA appreciates the support; however, as noted in the previous response, we have 

removed the emissions averaging provisions from the final rule.

Comment: Commenter 0073 states that the EPA has not provided sufficient information to allow 

response to the EPA’s request for comments on “discount factors”, specifically a definition of 

what the “discount factor” means, and how it would be applied to stack emission factors. The 

commenter (0073) states that if they have interpreted the proposal correctly (e.g. if a facility 

operates two furnaces, each subject to an emissions limit of X, should the emissions averaging 

approach establish a limit of 2X, or should that combined limit be established at some lower 

value, such as 90% of 2X), then they disagree with the EPA’s proposal and reiterate their 

previous comments regarding subcategorization for different processes and the need for a massbased emission limit.

Response: As described in section 4.8.1, we have determined that it is neither desirable nor 

appropriate to subcategorize by process/product for the metal HAP/PM stack emission limits. As 

noted in the previous response, we have removed the emission averaging provisions from the 

final rule. Without the provisions for emission averaging, we do not believe that the use of 

discount factors is appropriate. Therefore, the discount factors have been removed from the final 

rule.

Comment: Commenter 0073 states that they are unable to respond to the EPA’s request for 

comment on the potential for averaging emissions from crushing and screening equipment with 

other emission groups including furnace stacks or process fugitives because the preamble is 

unclear about how EPA proposes to average such emissions when the equipment at issue is 

subject to different emission limitations and with and without CO2 standardization.

Response: As discussed in this section, we have removed the emissions averaging provisions 

from this rule. Therefore, there is no need to provide guidance for averaging equipment with 

different emissions limitations. We agree that it would be difficult to average together units, 

some of which had a CO2 standardization factor and others that did not.

4.6 Fugitive Emissions Capture

4.6.1 Total Negative Pressure Enclosure

Comment: Commenter 0261 recommended that the EPA not base the acceptance of a suitable 

system to capture fugitive emissions based on the guidelines by the American Conference of 

Governmental Industrial Hygienists (ACGIH). They note that the guidelines are intended to 

reduce worker exposure and do not provide any assurances of capture efficiency of fugitive 

emissions. They provided an article outlining techniques used by EAFs in Japan to reduce 

fugitive emissions and an EPA manual for measurement of fugitive emissions from roof 
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monitors. The commenter (0261) recommends using computational fluid dynamics or emission 

testing of the roof monitoring ventilation.

Response: In addition to our own analyses, we also consulted with ventilation experts working 

with hot process fugitives like those found in the ferroalloys industry (e.g., electric arc furnace 

steel mini-mills and secondary lead smelters) who stated that a fugitive capture system should be 

based on guidelines from the ACGIH. In addition, we have included requirements for process

fugitive emissions capture to be designed to achieve sufficient air changes to evacuate the 

collection area frequently enough to ensure process fugitive emissions are effectively collected 

by the ventilation system and ducted to the control device(s). We believe these requirements will 

achieve 95% capture of process fugitive emissions from the furnace building. 

Comment: Commenter 0073 disagrees that a total building negative-pressure environment is 

either necessary or feasible to mitigate the health risks EPA has assumed, The commenter (0073) 

states that the EPA’s selection of this control scheme is based on a significant misunderstanding 

of the scope of controls that have been used within the industry, which lead the Agency to 

overstate the benefits associated with enclosure of the building under negative pressure 

compared to the demonstrated benefits of localized control efforts. The commenter (0073) 

asserts that the total building enclosure and control system in the proposed rule is not 

representative of any sources in the ferroalloy industry. The commenter (0073) states that the 

EPA’s assertion that such a system has been successfully used at a non-manganese ferroalloy 

producer fundamentally misrepresents what that technology is and exactly what it does. The 

commenter (0073) notes that the existing furnace building ventilation system on which EPA 

bases the proposed rule (at CC Metals & Alloy, Inc.’s facility in Calvert City, Kentucky) is not 

sealed, and is not under negative pressure. The commenter (0073) states that the EPA’s residual 

risk standard under section 112(f) and its technological update under section112(d)(6) are based 

on the assumption that a negative pressure permanent total enclosure is a technology achieved in 

practice within the industry, however, no one has ever employed a negative pressure permanent 

total enclosure within the ferroalloy manufacturing industry.

Commenter 0106 asserts that the total building enclosure and control system is entirely novel to 

the ferroalloys industry, and that the referenced example - CCMA, is not a sealed, negative 

pressure system. The commenter (0106) states that the CCMA facility is far smaller than EMI’s 

furnace buildings, and the CC Metals facility does not meet the performance standards imposed 

under the proposed rule, capturing a much smaller fraction of its fugitive emissions than the 

proposed rule requires. 

Response: We re-evaluated the proposed negative pressure ventilation requirement and 

concluded that the full-building enclosure option may not be feasible and would have significant 

economic impacts on the facilities. Based on this re-evaluation, we concluded that an option 

based on enhanced local capture and control of process fugitive emissions using a combination 

of primary and secondary hoods is a feasible and cost-effective approach to achieve significant 
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reductions in fugitive HAP emissions. Therefore, in the 2014 supplemental proposal, instead of 

full building enclosure, we proposed that facilities would need to install and operate a local 

capture system using a combination of primary and/or secondary hoods that is designed to 

achieve at least 95 percent capture and control of process fugitive emissions. In the final rule we 

are promulgating requirements (based on mainly on enhanced local capture and control) that are 

very similar to the requirements we proposed in the 2014 supplemental proposal. 

Comment: Commenter 0069 states that the EPA has misrepresented the fugitive dust controls in 

place on CCMA's #15/16 furnace building, and that the control system in place at CCMA is 

nothing like the total building capture and control system mandated by the proposed rule. The 

commenter (0069) notes that the proposed rule envisions the permanent total enclosure of shop 

buildings under negative pressure, while in actuality, the building is not sealed and has “open 

area of roughly 20 percent of the exterior wall area.” The commenter (0069) describes their 

existing building ventilation system in this manner:

“In the early 1990’s, CCMA entered into an agreement with the State of Kentucky 

Division of Air Quality to augment their existing exhaust system in the #15/16 building 

with spare capacity in the #6 baghouse serving the adjacent production area referred to as 

the #6 furnace area. This was accomplished by construction of a duct from the #6 

building to the #15/16 building and splitting that duct to vent a casting operation of a 

specialty product, and secondarily, the production area roof vent. This was done to 

augment the existing system and help reduce emissions from the building roof vent.

There was no intent to evacuate a significant portion of the building. It was recognized 

that due to the fact that the particulate is entrained in hot air, it is buoyant, and therefore, 

rises to the roof vent area. It is therefore a natural location to collect hot air that at times 

was not collected by the individual vent systems associated with various processes at the 

facility.”

The commenter (0069) adds that this misrepresentation of their existing controls results in a 

gross underestimate of the cost of the proposed requirement to reduce fugitive emissions (i.e., 

putting shop buildings under a negative pressure of at least 0.007 inches of water). The 

commenter (0069) states that despite the fundamental difference in the systems, the EPA

performed their cost estimate as if the proposed rule requirement was similar to CCMA's facility. 

The commenter (0069) incorporates by reference Felman’s comments providing a more accurate 

estimation of the costs to install a building ventilation system that would comply with the 

language of the proposed rule. 

Response: We agree that the CCMA operation lacks a negative pressure component, with the 

result that use of that system as currently configured is not an accurate model for the proposed 

building ventilation system we described in the 2011 proposal.
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Comment: Commenter 0073 asserts that the Agency’s cost analyses for the “beyond-the-floor” 

level of control are critically flawed in several ways:

 The Agency relied on a single vendor, who provided a single quote on what the proposed 

technology might cost.

 The quote dramatically understates the true cost of the required controls, largely due to 

misunderstanding of the amount of air flow a PTE would require to maintain a negative 

pressure environment while ensuring that the air inside meets the acceptable OSHA PEL 

for manganese. (The commenter (0073) provides detailed cost estimates showing actual 

costs over fifteen times higher than those in the EPA’s proposal.)

 The quote provided by the EPA’s vendor assumed an airflow requirement of 150,000 

actual cubic feet per minute (“ACFM”), while data gathered by the commenter (0073) 

demonstrates that the required airflow is 1.24 million ACFM – nearly ten times higher 

than the EPA’s assumption.

The commenter (0073) estimates that the total capital investment required for Felman to comply 

with the proposed rule’s building enclosure requirement is over $45 million, more than fifteen 

times EPA’s estimate. The commenter (0073) estimates that the annual operating costs for the 

equipment are more than three times EPA’s estimate, while the amortized capital cost over 20 

years totals over $4.2 million. The commenter (0073) describes significant flaws in the EPA’s 

analysis of costs for total building ventilation and control to address fugitive emissions because 

of EPA’s assumption that the CC Metals and Alloys facility in Kentucky is a comparable 

scenario, when in fact it is not.

Commenter 0106 also provides an extensive analysis of the deficiencies in the EPA’s cost 

analysis and offers an alternative methodology based on using the costs of maintaining a 0.007 

inches of water at building openings and sufficient air changes to support industrial hygiene 

requirements, which results in significantly higher air flow requirements to the new baghouse. 

The commenter (0106) states that EMI would require new equipment to provide 2.5 million 

additional cfm of ventilation – more than 8 times the amount calculated by the EPA. The 

commenter (0106) concludes that establishing complete building ventilation and capture systems 

for EMI’s three furnace buildings would cost more than $41 million to install over the next two 

years (rather than $6.3 assumed by the EPA) and would increase annual operating costs by more 

than $9.7 million per year (rather than $1.5 million per year assumed by the EPA).

Response: We re-evaluated the option based on negative pressure and building ventilation as 

described in the 2011 proposal. This control option involves installation of full building

ventilation at negative pressure for furnace buildings instead of installing fugitive controls on 

individual tapping and casting operations. This option would require installation of ductwork

from the roof vents of furnace buildings, additional fans, structural repairs to buildings and a new 

fabric filter for each building. 
120

We thoroughly reviewed the information provided by the companies along with information 

gathered from other sources, and then revised our cost analyses accordingly for the supplemental 

proposal. We estimated that the full building enclosure option would reduce PM emissions from 

the facilities by 252 tons per year (and total HAP emissions by 83 tons per year). The total 

estimated capital cost for these fugitive controls is $61 million. Annualized capital cost and 

operational and maintenance costs are estimated at $19 million per year, which results in an 

estimated cost per ton of metal HAP removed of $226,000 per ton and a cost per ton of PM 

removed of $74,200 per ton and achieve PM2.5 emission reductions of 53 tons, resulting in a cost

per ton of PM2.5 removal of $353,000 per ton. The incremental cost effectiveness comparing the 

enhanced capture option to the building ventilation option is $501,000 per ton of PM removed, 

$2.4 million per ton of PM2.5 removed and $2.2 million per ton of HAP removed. Based on these 

analyses, we conclude that the full-building enclosure option with negative pressure may not be

feasible and would have significant economic impacts on the facilities (including potential 

closure for one or more facilities). However, we concluded that the enhanced local capture 

option is a feasible and cost-effective approach to achieve significant reductions in fugitive HAP 

emissions and will achieve almost as much reductions as the full building enclosure option (229 

vs 252 tons PM reductions) thus achieving most of the risk reductions. 

Comment: Commenter 0265 states that the capture of casting fugitive emissions should be 

reviewed to determine if additional controls can be reasonably implemented at Eramet.

Response: Based on the proposed ventilation plans submitted by the facilities and the fugitive 

capture requirements in this rule, we conclude that fugitive emissions from the casting processes

will be substantially reduced through implementation of the requirements in the final rule. We 

also conclude that no further reductions will be needed beyond those reductions that we expect 

will be achieved through this final rule.

4.6.2 Enhanced Local Capture Option

Comment: Commenter 0073 asserts that the EPA overstates the benefits of total building 

enclosure in comparison to other, more targeted control technology and emission reduction 

efforts. The commenter (0073) notes specific steps taken by CCMA to minimize fugitive 

emissions (tightening furnace doors, enclosing tapping operations) and asserts that the emissions 

reductions at CCMA are largely a result of the type of localized emission reduction and control 

efforts summarily rejected by the EPA in the proposed rule as insufficient to limit risks.

Commenter 0106 states that the local emission capture approach achieves almost half the 

predicted emission reductions of total building capture at six percent of the required capital 

investment and six percent of the annual operating cost. The commenter (0106) asserts that 

resultantly, localized capture is seven times more cost-effective for PM control and eight times 

more cost-effective for HAP control than total building capture when viewed on an aggregated 

basis for both their operating furnaces, while cost-effectiveness for their EAF No.1 is even more 
121

attractive given the absence of need for additional baghouse installation to achieve this local 

capture. 

In supplemental comments, two commenters (0122, 0123) proposed that controlling process 

fugitive sources with enhanced source control would cost significantly less than the proposed 

total building enclosure and satisfy the residual risk requirements of section 112(f). Both 

commenters (0122, 0123) based their proposed strategies on an overall assumption that 

improvements could be made to existing operations to achieve 95 percent capture for process 

fugitives. The commenters (0122, 0123) also proposed that all capture systems should have a 

minimum hood face capture velocity of 300 fpm based on acceptable engineering standards such 

as those published by the American Conference of Governmental Industrial Hygienists. Both 

commenters (0122, 0123) retained ventilation engineering firms to assess their current (baseline) 

process fugitives capture systems and prepare draft plans to improve performance to achieve the 

stated objectives of their process fugitives strategy.

Based on the engineering analysis, one commenter (0122) proposed to make improvements to 

tapping operations by installing an enhanced hood system extending over the charge ladle, 

adding hoods for the casting beds at the two furnaces and adding new retractable hoods for slag 

raking and skimming. The commenter (0122) also proposed modifying the pour/casting station 

for the MOR tapping (pouring) and casting process. The commenter (0122) proposed installation 

of additional control equipment where needed to address the additional captured emissions. The 

commenter (0122) also proposed that they could enclose a section of the MOR building roof to 

capture fugitive (secondary) emissions not captured by the close fitting primary hoods in the 

MOR building. In addition, the commenter (0122) proposed changes to facilitate close capture of 

fugitive emissions such as adding a rail car transfer system to the tapping area and to make 

structural changes to prevent the overhead crane operation from interfering with the new tapping 

and casting hoods.54

Commenter 0123 proposed to repair the existing direct exhaust system, which they determined 

was operating under capacity. According to the commenter (0123), the original ventilation 

system for the existing furnaces and casting/tapping process was not designed for the current, 

lower temperature ferroalloy process, which had resulted in a lower ventilation rate of 

approximately 180,000 CFM compared to the original rate of 250,000 CFM, a 30 percent 

decrease in capacity. The commenter (0123) proposed to add new fans and motors to bring the 

system up to the original design capacity. Similarly, the commenter (0123) proposed to install 

new fans/motors to increase the capacity of the crushing capture system and to install a curtain 

wall to reduce cross contamination between the hot metal bay and crushing/screening area. The 

 

54 For additional detail on specific proposed changes, see the QSEM Solutions, Inc. report, “Technical Comments to 

Alternative Approach).
122

commenter (0123) also proposed to install new casting “shields” to capture and direct emissions 

to the casting hood and to enclose the tapping areas.

The commenter (0123) also proposed to install a general exhaust system to collect all emissions 

above the roof rafters that are missed by the direct exhaust system, including emissions 

generated during the skimming/slag raking processes. The commenter (0123) proposed to use 

this system because source control of these emissions would not be possible because installation 

of ductwork in the area to capture emissions locally would interfere with overhead crane 

traffic.55

One commenter (0122) also proposed that the proposed design standards be supplemented with 

the visible emissions standard that would limit visible emissions from any building housing a 

ferroalloy EAF, MOR, or casting operation to 20 percent or less, measured as a 6-minute 

average, except for one 6-minute period. For more discussion of the opacity standard, see section 

4.8.

Both commenters (0122, 0123) proposed that controlling process fugitive sources with enhanced 

source control would cost significantly less than the proposed total building enclosure and satisfy 

the residual risk requirements of section 112(f). Both commenters (0122, 0123) based their 

proposed strategies on an overall assumption that improvements could be made to existing 

operations to achieve 95 percent capture for process fugitives. The commenters (0122, 0123) 

also proposed that all capture systems should have a minimum hood face capture velocity of 300 

fpm based on acceptable engineering standards such as those published by the American

Conference of Governmental Industrial Hygienists. Both commenters (0122, 0123) retained 

ventilation engineering firms to assess their current (baseline) process fugitives capture systems 

and prepare draft plans to improve performance to achieve the stated objectives of their process 

fugitives strategy.

Based on the engineering analysis, one commenter (0122) proposed to make improvements to 

tapping operations by installing an enhanced hood system extending over the charge ladle, 

adding hoods for the casting beds at the two furnaces and adding new retractable hoods for slag 

raking and skimming. The commenter (0122) also proposed modifying the pour/casting station 

for the MOR tapping (pouring) and casting process. The commenter (0122) proposed installation 

of additional control equipment where needed to address the additional captured emissions. The 

commenter (0122) also proposed that they could enclose a section of the MOR building roof to 

capture fugitive (secondary) emissions not captured by the close fitting primary hoods in the 

MOR building. In addition, the commenter (0122) proposed changes to facilitate close capture of 

fugitive emissions such as adding a rail car transfer system to the tapping area and to make 

 

55 For additional detail on the specific proposed changes, see the July 9, 2012 Chu and Gassman “Design Narrative.”
123

structural changes to prevent the overhead crane operation from interfering with the new tapping 

and casting hoods.56

One commenter (0123) proposed to repair the existing direct exhaust system, which they 

determined was operating under capacity. According to the commenter (0123), the original 

ventilation system for the existing furnaces and casting/tapping process was not designed for the 

current, lower temperature ferroalloy process, which had resulted in a lower ventilation rate of 

approximately 180,000 CFM compared to the original rate of 250,000 CFM, a 30 percent 

decrease in capacity. The commenter (0123) proposed to add new fans and motors to bring the 

system up to the original design capacity. Similarly, the commenter (0123) proposed to install 

new fans/motors to increase the capacity of the crushing capture system and to install a curtain 

wall to reduce cross contamination between the hot metal bay and crushing/screening area. The 

commenter (0123) also proposed to install new casting “shields” to capture and direct emissions 

to the casting hood and to enclose the tapping areas.

The commenter (0123) also proposed to install a general exhaust system to collect all emissions 

above the roof rafters that are missed by the direct exhaust system, including emissions 

generated during the skimming/slag raking processes. The commenter (0123) proposed to use 

this system because source control of these emissions would not be possible because installation 

of ductwork in the area to capture emissions locally would interfere with overhead crane 

traffic.57

Response: As described above, we have significantly revised our view of the role that local 

ventilation can and should play in designing an optimized building ventilation system. Regarding 

costs, see the discussions in the preambles of the supplemental proposal and final rule.

Comment: Commenter 0270 believes that the EPA should evaluate the capability of achieving 

emissions that provide acceptable public health protection. The commenter (0270) suggests that 

by starting with an acceptable ambient concentration of the hazardous pollutants and employing 

the various EPA receptor models, the total plant emissions can be estimated. Then the EPA could 

assess whether it is reasonable to expect a well-designed ventilation system to achieve the 

percent capture combined with the emissions from add on controls to achieve emissions that pass 

the screening levels. The commenter (0270) states that this would be best implemented by 

compliance determination in a manner similar to that used for the Primary Aluminum Production 

standard, recognizing that the EPA will need to make minor modifications of EPA Method 14 for 

measuring the emissions from roof ventilation. 

 

56 For additional detail on specific proposed changes, see the QSEM Solutions, Inc. report, “Technical Comments to 

Alternative Approach).

57 For additional detail on the specific proposed changes, see the July 9, 2012 Chu and Gassman “Design Narrative.”
124

Response: We appreciate the suggestion from the commenter. However, we think we have taken 

the proper steps to evaluate acceptable health protection using the modeling risk assessment 

approach that we used. There were a number of issues with trying to install a roof top 

measurement system because of the age of the building and other factors. We think the proposed

tight opacity limits (which would be measured at the emissions sources), along with the proposed 

requirements to install, operate and maintain effective fugitive capture and control systems,

emissions limits for the stacks and various parametric monitoring requirements, are appropriate 

control requirements to ensure effective capture and control of emissions.

4.7 Ambient Air Monitoring Option

Comment: Commenter 0107 states that the EPA should strengthen the ambient concentration 

limit to require reductions so that the most exposed person, at the fenceline, is not exposed to 

manganese emissions at two times the safety level but instead require emission reductions to 

ensure no one is exposed above the child-specific reference level that California OEHHA has 

created, which is 0.03 mg/kg/day. The commenter (0107) adds that the EPA should require 

ambient air monitoring for manganese to assure compliance with the emission standards and 

allow EPA to assess the ongoing status of public health in the affected communities. The 

commenter (0107) notes, however, that this limit alone could not satisfy section 112(f)(2), which 

must include specific numerical emission limits on all emitted HAPs. The commenter (0107) 

adds that the EPA may not use manganese as a surrogate for all HAP metals, including the 

cancer-risk drivers which may be emitted at a lower level and still cause a substantial cancer risk.

In comments on the supplemental proposal, commenter 0276 is disappointed that the EPA is 

proposing not to finalize the alternative approach on ambient air fenceline monitoring. The 

commenter (0276) states that the EPA should at least require monitoring in addition to the 

emissions standards like the requirements the SCAQMD has established for secondary lead 

smelting. The SCAQMD existing rules require that:

 Minimum of four monitors at facility locations approved by the Executive Officer;

 Samples collected once every 3 days;

 Results reported monthly;

 Daily sampling if 0.120 μg/m3is exceeded after January 1, 2015.

 Curtailment of operations if lead and arsenic exceed certain monitored levels.

The commenter (0276) adds that SCAQMD is proposing to strengthen the requirements to 

include daily sampling for lead and arsenic, provisions for monitor failure and 1-year sample 

retention. The commenter (0276) states that the EPA should consider requiring similar

provisions for at least manganese, lead, arsenic and cadmium and other toxic metals the EPA 

recognizes are significant and driving risk.

Response: In reviewing the information received on fenceline monitoring, we determined there 

were various issues associated with fenceline monitoring at facilities within this source category, 
125

including highly variable wind patterns, uncertainties as to how to account for background 

concentrations and road dust and the large difference between emissions release heights (from 

the high roof vents and stacks) compared to heights where fenceline monitors would be located 

(near ground level). Therefore, we are not including fenceline monitoring in the final rule as an 

alternative method to demonstrate compliance with a specific ambient level as was described in 

the 2011 proposal. We believe the proposed tight opacity limit (which would be measured at the 

emissions sources), along with the proposed requirements to install, operate and maintain 

effective fugitive capture and control systems, emissions limits for the stacks and various 

parametric monitoring requirements, are appropriate control requirements to ensure effective 

capture and control of emissions.

Also, as discussed earlier, the RfC or MRL is not a “safety level” so being exposed to an air 

concentration above the RfC does not necessarily indicate an “unsafe” situation. Second, the 

child-specific reference level of 0.03 mg/kg/day that the commenter mentions is an oral reference 

dose, not an inhalation value. It would be inappropriate to use an oral value to develop an 

ambient air standard. Third, also discussed earlier, this value was developed for a specific school 

siting program in California. It was not developed for use in their Hot Spots program, and it was 

not developed by the EPA-approved methods. 

Comment: Commenter 0073 supports the inclusion of a fenceline monitoring compliance option, 

but objects to a limit based on the Mn RfC in its current form. The commenter (0073) asserts that 

the EPA should set the ambient air concentration limit on the latest analyses of leading health 

authorities and the recent pharmacokinetic modeling data and exposure studies. The commenter 

(0073) notes that the health risks associated with manganese arise from chronic, not acute 

exposure, and that the monitoring frequency should be commensurate with the risk. The 

commenter (0073) requests that the EPA revise the monitoring provisions to require monthly 

monitoring and a 6-month rolling average.

Commenter 0106 supports flexibility in compliance options, but an alternative “fenceline” 

standard is not warranted in this case because additional manganese controls are not warranted. 

The commenter (0106) adds that, if such a standard were established, it should be established as 

part of a work practice standard under Section 112(h), reflecting the fact that uncontrolled 

fugitive emissions are not reliably measurable. The commenter (0106) states that consequently, 

exceedance of the fenceline standard would not constitute a violation of the Act, but rather would 

be a trigger for follow-up to evaluate the causes of the exceedance and the potential need to 

modify fugitive practices within the facility. The commenter (0106) adds that since the fenceline 

standard is based on ambient monitoring, such an evaluation might also determine that a 

fenceline exceedance resulted from non-regulated sources and no modifications were required. 

The commenter (0106) further states that the monitoring frequency and fenceline threshold 

should also be adjusted to reflect the facts that (1) the relevant manganese risks are based on 

chronic exposures, so short-term exposures to slightly elevated levels would not warrant 
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significant modifications, and (2) ambient concentrations at the fenceline would not represent 

exposure concentrations, because receptors do not live along EMI’s fenceline. The commenter

(0106) adds that a 60-day rolling average is unjustified to address chronic exposures, which are 

typically evaluated on the basis of annual exposures. The commenter (0106) suggests that a more 

reasonable standard would be based on a rolling average of at least six months of data, with 

samples collected no more frequently than monthly. The commenter (0106) asserts that to 

calculate a scientifically defensible fenceline standard, the analysis should be based on a range of 

4 ug/m3 manganese PM2.5 to 14 ug/m3 manganese PM2.5, which corresponds to an HQ of 2 at the 

range of manganese RfCs identified in Bailey et al., and then be adjusted to a total manganese 

concentration of 9.8 ug/m3to 34 ug/m3based on the 41 percent fraction used by the EPA in this 

rulemaking.

In their comments on the supplemental proposal, commenter 0269 strongly supports the EPA’s 

proposed decision in the supplemental proposal to reject fenceline monitoring for manganese 

emissions this alternative. As discussed in their previous comments, ferroalloy facilities may be 

located in industrialized areas; Felman, for example, is located adjacent to two power plants, one 

of which is being decommissioned, and the other of which continues to operate. Given the 

variability in topography, wind patterns, and release heights, it would be infeasible to attempt to 

identify which portion of any monitored concentrations are due to Felman’s operations and 

which are due to those of its neighbors.

Response: As we explained in the preamble to the supplemental proposal, the final preamble and 

elsewhere in this document, we have decided not to require fenceline monitoring in the final rule. 

The rationale for such decision is also explained in the preambles of the supplemental and/or 

final rules and elsewhere in this RTC document. So, we are not repeating that information here.

Comments on how to structure a fenceline monitoring requirement including the issues of 

frequency and authority, are mooted by the decision not to require fenceline monitoring. 

Comment: The commenter 0271 states that fenceline monitoring is not an accurate measure of 

source-specific emissions nor is an indicator of PM effects from those sources on a community. 

They note that these monitors would capture emissions from stationary and mobile sources not 

covered by this rulemaking and not owned or controlled by the affected facilities. In addition the 

commenter (0271) believes that the background contributions from other sources would not be 

able to be accurately distinguished from the affected facility sources.

Commenter (0272) stated in their comments on the supplemental proposal states that the EPA’s 

fenceline monitoring proposal is not adequately described and is not capable of producing 

relevant emissions information. The commenter notes that the supplemental proposal does not 

discuss how the location or height of the monitors would be determined, and the EPA should not 

take further action on this proposed research project before issuing a specific, adequately defined 

project for public notice and comment.
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The commenter notes that EPA admits that fenceline monitoring does not measure emissions, but 

instead it measures ambient conditions that may contain emissions as well as any number of 

additional, indistinguishable sources of particulates and/or manganese. The commenter disagrees 

that such monitoring, even with “meteorological data and modeling tools” would be capable of 

quantifying emissions entering or leaving EMI’s property, and there is no way to attribute such 

emissions to particular EMI sources. The commenter also states that while such monitoring may 

be technically feasible, collecting legally relevant data from such monitoring is infeasible, and 

EPA’s curiosity about “trends in ambient concentrations” does not fall within the statutory 

objectives of Section 112. 

Response: We agree with the commenter and have not included any requirements for fenceline 

monitoring in the final rule.

4.7.1 Activated Carbon Injection

Comment: In comments on the supplemental proposal, commenter 0276 states that the EPA 

should evaluate address the use of activated carbon injection to reduce the mercury and dioxin 

emissions and strength the mercury and dioxin limits accordingly. 

Response: We reviewed information on the reduction of mercury and organic HAP using ACI 

from many different sources. For mercury, we determined that ACI was not cost effective for 

existing sources producing SiMn or FeMn. We were unable to quantify the reductions of organic 

using ACI from the information, and therefore no changes to the emission limits were developed. 

Comment: Commenter 0106 states that the EPA overstated the technical ability of ACI to reduce 

emissions, specifically EPA’s assumption that ACI would capture 90% of mercury and PAH 

emissions from EMI’s two furnaces using wet scrubbers, even though the addition of ACI to 

other wet scrubbers has almost never reduced mercury emissions by more than 30%, and is 

typically closer to 20 percent.

Response: See pollutant specific responses for mercury and formaldehyde, below. In the case of 

PAH, there have been a few studies that have shown significant PAH reductions with the 

installation of ACI. Albemarle, a company that provides mercury control equipment to 

industries, noted in a presentation58 that 9 out of 10 conventional boilers equipped with ACI 

reported PAH analytical results below the detection limit. The other boiler reported PAH results 

that were only 10 percent above the detection limit. Another study59 found that ACI can achieve 

74-91 percent reduction in PAH emissions depending on the concentration of activated carbon in 

 

58 Presentation by Dr. Ronald R. Landreth, Albemarle, Alternative Method of Hg and THC Control Using Existing 

Cement Kiln Particulate Control Equipment, February 9, 2010.

59 Hong-Cang Zhou, Zhao-Ping Zhong, Bao-Sheng Jin, Ya-Ji Huang, and Rui Xiao, Experimental study on the 

removal of PAHs using in-duct activated carbon injection, Chemosphere, November 17, 2004.
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the flue gas. Based on this information, we think that an activated carbon system that is designed 

to achieve up to 90 percent reduction in mercury emissions, should also achieve significant 

reductions in PAH. Nevertheless, as explained in the supplemental proposal preamble, final rule 

preamble, and elsewhere, we decided not to require ACI controls on these sources because of 

costs and economic factors.

4.7.2 Mercury Control

Comment: The commenter 0271 states that, in the preamble to the supplemental proposal, the 

EPA suggests that trials using brominated ACI at a taconite facility in Minnesota resulted in 75 

percent mercury removal. The commenter (0271) notes that the study was done in two phases, 

and the second phase of testing provided total mercury removal rates ranging from 25-61 

percent.

Commenter 0265, in their comments on the supplemental proposal believes that beyond the floor 

requirement of ACI for new facilities is too burdensome and can cause closure of the affected 

facilities.

Response: The referenced study was based on ACI in conjunction with a wet scrubber and was 

used to estimate the mercury reduction of a furnace equipped with a wet scrubber. We are not 

requiring beyond the floor mercury control for existing sources, and therefore determination of 

the actual mercury reduction from this study is not necessary. However, we believe that new 

furnaces would be equipped with baghouses and can install and operate an ACI system and 

achieve 90% reduction of mercury emissions. 

4.7.3 Formaldehyde Control

Comment: Commenter 0106 states that formaldehyde is a polar molecule, while activated carbon 

is composed of largely neutral carbon atoms with no electrical gradients between molecules, and 

thus, carbon does not attract polar molecules. The commenter (0106) asserts that polar 

compounds like formaldehyde therefore have a poor affinity for carbon compared to non-polar 

compounds, and further, it is difficult to retain formaldehyde on carbon due to its high volatility. 

The commenter (0106) states that no data supporting removal of formaldehyde to the very low 

concentrations equivalent to the proposed standard (201 ug/dscm or approximately160 parts per 

billion) were found. The commenter (0106) asserts that based on these considerations, the EPA’s 

assumption of 90 percent formaldehyde removal by ACI in EAF#1 and EAF #12 has no 

scientific basis.

Response: The proposal preamble correctly states our conclusions regarding formaldehyde 

control efficiency using ACI: We recognize the potential for some co-control of formaldehyde 

emissions that would be achieved by using activated carbon injection to control mercury 

emissions, but we were unable to quantify those reductions. (p.72528, column 1) The proposed 

(and final) formaldehyde limit is based on the MACT floor determination and should not result 

in the need to install controls specifically to reduce formaldehyde emissions. We have revised 
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our post-control modeling scenario to remove the assumption that 90 percent of formaldehyde 

would be reduced to an assumption that none would be because we lack information to support a 

specific reduction capability at this time.

4.8 Opacity Standards

Comment: Commenter 0073 states that, given EPA’s new residual risk standard incorporating 

total building negative pressure enclosure proposed in the 2011 proposal, there is no legal basis 

for retaining any opacity standard, much less adopting a more stringent one. The commenter 

(0073) adds that if the EPA modified its proposal to require more targeted controls, the EPA still 

has not identified any “improvements” in fugitive control technology or practices that would 

support tightening the standard. The commenter (0073) notes that the EPA’s evaluation of 

opacity performance within the industry identified several incidents that would have exceeded 

the new proposed 10 percent standard, which suggests this limit does not reflect the 99 percent

UPL. 

Response: The opacity standard is a main piece of the compliance strategy for the process 

fugitive emissions standards. A key aspect of the opacity limit is that it can be used by the source 

to establish a correlation between successful operation of capture system parameter values 

(capture system fan motor amperes and all capture system damper positions or volumetric flow 

rate through each separately ducted hood that comprises the capture system) and opacity levels, 

and then the source can continuously monitor the parameters to help ensure the opacity limits are 

achieved continuously and that the capture and control system is effectively capturing fugitives 

on a continuous basis. This combination yields an enforceable parameter limit that is designed to 

ensure continuing operation of the capture system at a level consistent with operation during the 

performance test.

Theoretically, a perfectly designed building ventilation system should always exhibit 0 percent 

opacity. However, we conclude this scenario would not be feasible for these facilities. Given that 

these are retrofit situations and there may be short-term process fluctuations, we felt that it was 

important to allow for the presence of at least minimal fugitive emissions in setting the standards. 

We note that the historical opacity data observations that were above 10 percent obviously do not 

reflect the addition of improved local capture. We believe that the installation and operation of a 

well-designed local capture system can meet the opacity standards in the final rule.

We note that the historical opacity data observations that were above 10 percent obviously do not 

reflect the addition of improved ventilation systems. In addition, we note that we are no longer 

requiring total building negative pressure enclosure.

Comment: In their supplemental comments, commenter 0122 suggests that their proposal for 

enhanced fugitive control would include a 20 percent opacity limit for visible emissions, 

measured as a 6-minute average, from any building housing a ferroalloy EAF, MOR or casting 

operation, except for one 6-minute period per hour.
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Response: We believe that the robust local ventilation systems, combined with rooftop capture, 

suggested by the plants will result in a high degree of control for reducing process fugitive 

emissions of approximately 80 percent. Furthermore, both plants have suggested controls on 

ladle raking and slag skimming operations, which are not represented in the emission modeling 

files because we lack information (emission factors) to estimate emissions from these operations. 

The control of these additional, previously uncontrolled, process fugitive sources should address 

the remaining sources of rooftop emissions that could result in elevated opacity readings. In fact, 

we believe these additional capture devices and controls will be able to keep the opacity at or 

below an 8% average for each furnace cycle. Thus, as described in the preamble to the final rule, 

we are promulgating an average opacity limit of 8%.

We believe that an 8-percent opacity limit is consistent with stringent capture and control of 

process fugitive emissions. Furthermore, to accommodate potential short-term higher emissions, 

as described in the preamble to the final rule, we are allowing opacity to be as high as 20% for 

any 2 consecutive 6-minute readings. We do not believe there is justification for including a 6-

minute exemption, because the capture equipment should be operating at all times the processes 

in question are being operated.

Comment: In their comments on the supplemental proposal, commenter 0269 supports the 

EPA’s conclusion that compliance with the limits on process fugitive emissions should be 

demonstrated through opacity observations because other alternatives are not feasible and would 

not generate reliable data. One possible alternative, direct monitoring of fugitive emissions, is 

technologically infeasible; given the number and size of the openings in the Felman building, 

and the variations in airflow through the buildings and across the openings, it would not be 

possible to accurately capture both concentration and flow across each of these openings over the 

course of a test period.

The commenter (0269) believes that the 8 percent opacity standard required by the proposal is 

unnecessarily stringent and not supported by the record. The commenter (0269) notes that 

opacity observations are the judgment of individual observers under varying atmospheric 

conditions. Hence, compliance requirements were historically drafted in 20 percent increments. 

More recent standards have reduced some of these requirements to 10 percent increments (e.g., 

an hourly average of 10 percent opacity, with a not-to-exceed limit of 20 percent). The 

commenter (0269) believes that reducing the allowed opacity limit to 8 percent implies a degree 

of precision that the observation methodology was simply not designed to meet.

The commenter (0269) notes that the 2011 proposal included a 10 percent opacity standard, 

which was based on total building enclosure. The new approach, of providing partial primary and 

secondary-level controls, is designed to achieve a 95 percent reduction with an 8 percent opacity, 

which is lower than that assumed by the original proposal. The commenter (0269) states that the 

supplemental proposal identifies no basis for this illogical conclusion.
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Response: The commenter is correct that individual opacity readings are read in increments of 

5%, however the 6-minute reading is an average of multiple individual readings (24 readings 

total). These 6-minute readings are then averaged over the entire furnace cycle. Because the 

opacity standard is based on multiple readings, the determination of the opacity average over the 

furnace cycle does not need to be in 10 percent or 20 percent increments. The commenter is 

correct that the proposed rule did include a proposed 10 percent opacity requirement. However, 

as explained in the supplemental proposal preamble, after further evaluation, we decided that an 

average opacity limit of 8% for the entire furnace cycle was more appropriate to reflect effective 

capture and control of process fugitive emissions. The determination of the 8 percent opacity 

standard was based on averaging opacity data provided by the facilities and includes opacity data 

for the various process cycles in the production of ferroalloys and also based on consideration of 

the emissions reductions that would be achieved through the enhanced local capture and control 

systems described in the supplemental proposal. After reviewing these data and after considering 

the significant improvements that are expected regarding the capture and control of process 

fugitive emissions, we believe that the average opacity can be reduced to 8 percent or lower 

using the enhanced capture systems that will be required to comply with the final rule.

Comment: In their supplemental proposal comments, commenter 0269 believes that the EPA has 

provided no basis for replacing the existing provisions allowing higher short-term opacity levels 

as a result of specific operating conditions (e.g., oxygen lancing) with a much more limited 20

percent opacity limit. While these events are infrequent, they are unavoidable and necessary in 

certain situations. Furthermore, the quantity of emissions during these short-term events may 

temporarily overwhelm even the best-designed fugitive control system. During the development 

of the prior NESHAP, the EPA agreed that these kinds of events merited a higher short-term 

opacity limit. The Agency has identified no basis for reversing its position in the current 

proposal.

Response: The EPA recognizes that longer term averaging periods allows facilities to 

incorporate greater operational variability within a compliance regimen. Without an appropriate 

averaging time, high emissions events may quickly force a non-compliant situation that is 

unavoidable, as the commenter points out, where a longer term average allows for such an event 

to not trigger an enforcement action where operations are generally stable and emissions are well 

controlled. We believe the final opacity limits accommodate these concerns by providing a 

sufficient averaging time for both the average opacity limit of 8% (averaged over an entire 

furnace cycle) and for the maximum opacity limit of 20% (for any 2 consecutive 6-minute 

readings, or 12 minutes).

Comment: Two commenters (0265, 0272) in their comments on the supplemental proposal state 

that the opacity requirements in the supplemental proposal require a tap to tap opacity reading 

from each of the furnace buildings. They note that the building that house the MOR and Furnace 

18 would considered by the definition in the rule as a shop building. However, the commenter 
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notes that only the MOR is in operation in that building and that operation does not include any 

tapping.

Response: The EPA thanks the commenter for the additional information and will modify the 

final rule to require opacity observations on emissions from the MOR building to a better suited 

time period for that operation.

Comment: In their comments on the supplemental proposal, commenter (0272) states that the 

process fugitive emissions provision in §63.1623(b)(3), is ambiguous regarding the link between 

the proposed 8 percent average opacity requirement and §63.1623(b)(3)(ii), which requires that, 

if an opacity test finds the average to exceed 8 percent over one process cycle, two additional 

furnace cycles must be observed over a seven-day period and the average opacity over the entire 

three-cycle period must be 8 percent opacity or less. The commenter believes that the EPA 

should have added the following words, “Unless you meet the criteria of §63.1623(b)(3)(ii),” to 

the beginning of §63.1623(b)(3), which will then read: “Unless you meet the criteria of 

§63.1623(b)(3)(ii), you must not cause emissions exiting from a shop building, to exceed an 

average of 8 percent opacity during furnace process cycles at all times.”

Response: The EPA agrees with the commenter and has included the change in the rule text.

Comment: In comments on the supplemental proposal, two commenters (0270, 0276) state that 

the EPA should establish an opacity limit with a form that limits the duration of the required 

observation to a period that spans the operation with the highest potential for visible emissions 

rather than a full heat. For example, the commenters (0270, 0276) note, pouring and tapping 

operations would be expected to provide the greatest challenge in capturing fumes from the 

operation. The commenters (0270, 0276) state that the proposed form is significantly less 

stringent than opacity standards that were established in the 1980’s for basic oxygen furnaces, 

electric arc furnaces at Steel Production plants, Steel Foundries and Gary Iron Foundries. The 

commenters (0270, 0276) also state that these processes are very similar to the operations at 

Ferroalloys plants and there is no reason why the visible emissions from the facility cannot be 

maintained at least as stringently as with these sources. The commenters (0270, 0276) add that 

this approach would allow the facility and other observers to more easily identify when 

adjustments are required to maintain good emissions control performance. It would also decrease 

the burden to comply with the monitoring component of the rule by limiting the observation 

period to the time associated with these higher potential emissions.

Response: The EPA disagrees with the commenter in that where batch processes are involved 

(such as a furnace heat cycle) emissions should be averaged throughout the entire batch to 

adequately understand the emissions potential of all periods of normal operation in discrete sets.

Comment: In comments on the supplemental proposal, two commenters (0270, 0276) state that 

the EPA should require the use of the best available testing method, digital opacity monitoring. 

The commenters (0270, 0276) describe the benefits of the DCOT compared to Method 9 and 
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provide supporting documentation. In particular, one commenter (0276) supports the DCOT 

because it is EPA certified as a valid test method for opacity and approved for its use, the use of 

a camera creates a good electronic record of the observations, conditions, location, etc. and a 

number of regulated entities are using this method to assess opacity. The commenter (0276) adds 

that using cameras can save resources, citing a Department of Defense project to reduce Method 

9 certification costs. The commenter (0276) adds that the EPA should also require opacity 

determinations to be documented on an electronic form and proved on the Internet in real time 

for public review.

The commenter (0276) adds that the EPA should not allow Method 9 to be used, unless there is a 

power outage requiring the facility to go to the use of Method 9 to assure opacity standard 

compliance. They also add that instead of Method 9, the EPA should require a source to use 

either continuous opacity monitor or DCOT.

Response: We appreciate the information from the commenters and moved forward with 

requiring the DOCS for measuring opacity from the furnace and MOR buildings. We also agree 

with the commenter that the DOCS creates a record of the opacity observation and conditions, 

and also provides an objective record supporting the determination of the opacity. The EPA does 

not believe that Method 9 observations would be useful in a compliance determination if there 

were there to be a power loss at the facility as the source and associated controls would 

malfunction immediately. 

Comment: In comments on the supplemental proposal, two commenters (0270, 0276) provide 

additional comments on the proposed §63.1625(d), compliance demonstration with the shop 

building opacity standards. First, one commenter (0276) states that the EPA has not shown how a 

facility could develop a correlation or benchmark for a parameter during a compliance test of 

three runs. In a laboratory assessment, it requires a minimum of seven tests to statistically 

evaluate a parameter. Even with a statistically valid assessment, it is unclear that knowledge of 

the fan’s operation would detect excess opacity due to atypical furnace operation. The 

commenter (0276) adds that the alternative use of an engineering assessment to establish 

operating parameters could be even further removed from actual data on opacity than a 

compliance demonstration. Nor has the EPA shown how that such an assessment could be 

adequate to determine compliance according to the commenter.

Both commenters (0270, 0276) suggest that instead, testing should be required and compliance 

determined as required for Primary Aluminum, e.g., use of Method 14 (or modified Method 14), 

with the target analytes would be PAH, PM, extractable organic matter and metals (manganese, 

arsenic and chromium). The commenters (0270, 0276) suggest that annual testing should be 

required to assure compliance and allow action to be taken to reduce emissions and risks if 

estimates and assumptions do not match on-the-ground results. One commenter (0270) adds that 

if the results of 3 years of annual testing substantially below the emission level associated with a 

unit risk index would allow a reduction in the frequency of emission testing to once every 30 
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months or once every 5 years. Both commenters (0270, 0276) reference EPA technical 

documents that would support development of a method appropriate to ferroalloys (see p, 37 of 

comment letter 0276). 

Commenter 0276 adds that should the EPA decide that a total emission rate is impossible to 

establish and continue with the 95 percent capture efficiency alone, then in addition to the 

building monitor testing, the emissions captured by the ventilation system should also be 

measured in order to determine the percentage of PM, PAH, Mn and other key risk-driver 

pollutants are actually captured.

The commenter (0276) states that, between performance tests the opacity during one furnace 

cycle should be determined by COMS or COCS, not just Method 9. The commenter (0276) adds 

that it should also be required that the facility post the results of the opacity or COMs reading to 

the Internet within 1 week of the test, at the latest. If the DOCS system is used, the images taken 

at 15-second intervals should be available on the Internet for public view in real time. The 

facility should review the images each day and select the top three 12-minute periods which 

appear to contain the greatest opacity and submit the 24 minutes bracketing the center of those 

12 minutes of which the maximum 12-minute opacity will be determined. This opacity should be 

posted to the web for public review. The EPA should determine a procedure for the facility to 

retain the complete record of the 24-minuete images and require retention of a least one image 

per minute.

As an indicator of continuing capture and control, both commenters (0270, 0276) said that the 

EPA should require daily monitoring of parameters indicative of continued operation as 

demonstrated during the compliance test. For the air pollution control device, the EPA should 

consider requiring the installation of a bag leak detector (Triboflow, nefelometer, particle 

counter) which is more sensitive than opacity monitoring. The commenters (0270, 0276) add that 

the EPA should require daily opacity monitoring as the primary indicator of performance 

between compliance tests, even if the compliance tests includes no periods of opacity over 5

percent. Also, as described above, the opacity limit should be in a form that limits the duration of 

the required observation to a period that spans the operation with the highest potential for visible 

emissions rather than a full heat.

Both commenters (0270, 0276) state that the EPA should obtain opacity data from a 

representative number of well operating electric arc furnaces in Steel Mills, Steel Foundries, 

Gray Iron Foundries and Basic Oxygen Furnaces to establish the performance of well-designed 

ventilation systems. Alternatively, the commenters (0270, 0276) suggest, the EPA should 

establish the opacity limit during the performance test based upon the observations during the six 

or twelve minutes with the greatest average opacity. One commenter (0276) suggested that in 

addition to using the three tapping and pouring periods during the performance test, the EPA 

could allow the addition of the tapping and pouring periods just before or after the performance 

tests.
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Response: The EPA disagrees with the commenter in that we have a long history of using three 

test runs to establish operating parameter limits that function as compliance assurance 

monitoring between compliance tests. In lieu of requiring Method 14 tests, we are requiring 

weekly opacity monitoring at each of the ferroalloy process building using digital opacity camera 

technique (DCOT), where a record of the visual emissions will be taken and analyzed by a 

computer to determine the opacity. We think this will provide assurance that the fugitive 

emission requirements are being met by the facilities. In addition, facilities will be required to do 

daily checks of control equipment to ensure that they are operating in a manner consistent with 

the manufacturer’s specifications. 

Comment: One commenter (0272) in their comments on the supplemental proposal states that 

they do not object to the inclusion of opacity standards to reflect proper operation of control 

equipment. However, the commenter states that the technology review provides no factual basis 

for the selection of an opacity standard or the conclusion that the limit is achievable through 

implementation of enhanced local fugitive capture. In addition, the commenter states that an 

opacity standard cannot be justified based on risk reduction, because opacity measurements 

cannot be equated to a mass emissions rate. If the EPA intends to require additional fugitive 

controls, the commenter recommends that the existing opacity standard be applied until the 

additional controls are put in place and performance testing can be performed to establish a limit 

based on the actual operation of such controls. The commenter also requests original opacity 

standard be maintained until additional data can be collected to measure opacity during nonroutine operating conditions (e.g., blowing tap, oxygen lancing, electrode burndowns and some 

furnace blows). 

Response: The EPA disagrees in that we have been provided with visible emissions data from 

the facilities that demonstrates they are capable of meeting the proposed opacity limits 

throughout a substantial portion of their operations even before additional controls are in place. 

We expect that with the additional capture and control systems envisioned with this rule, that 

facilities will be able to maintain opacity levels at or below the limits being finalized in today’s 

final rule. Furthermore, we believe the opacity limit will provide a benchmark to indicate 

whether or not the controls are operating as designed.

4.9 Fugitive Dust

Comment: Commenter 0107 states that the EPA has proposed no requirements to address 

fugitive dust emissions outside of the facility, but EPA should do so. The commenter (0107) 

states that the EPA should require material control and handling requirements that it has required 

for other source categories, such as enclosure, and that the EPA should also require a numerical 

limit as a direct restriction on emissions that applies to fugitive dust as section 112 requires.

Response: The revised subpart retains the same requirements for outdoor fugitive dust sources as 

does the existing subpart. See new §63.1625(b) and existing §63.1654(a). Enclosures are 

generally not appropriate for these types of fugitive dust enclosures and information on 
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emissions and effectiveness of work practices are largely limited to use of AP-42 emission 

factors. In the absence of more detailed information, we determined that retaining the current 

requirements to develop and implement a fugitive dust control plan is reasonable.

Comment: Commenter 0271 in their comments on the supplemental proposal, states that the 

inclusion of outdoor fugitive emission sources such as roadways, yard areas and outdoor material 

storage and transfer operations in the RTR air dispersion modeling risk assessment has the 

potential to significantly over predict PM concentrations and their associated impacts. The 

commenter states the CAA directs the EPA to make revisions as may be necessary to eliminate 

any significant over-predicting of air quality effects of fugitive particulate emissions.

Response: Outdoor fugitive emission sources were not included in the air dispersion modeling 

for this source category.

4.10 Format of the Regulation

4.10.1 Need to Retain Subcategories

Comment: Commenter 0073 states that the EPA should subcategorize the industry to account for 

varying emissions of different processes, and notes the effect this might have on cost-benefit 

calculations. The commenter (0073) notes that if most of the risks are attributable to a certain 

type of product or furnace, then controlling only those operations (for example, through 

enhanced localized controls) would allow EPA to maximize the emissions reductions and health 

benefits, without requiring unaffordable generalized controls on equipment that does not pose 

such risks. The commenter (0073) requests that the EPA reassess its beyond-the-floor analysis 

under Section 112(d)(6) taking subcategorization into account.

Response: Regarding subcategorization, we believe there is no reason to do so for PM or HAP 

metals emissions based on the available data and based on the capture and control technologies 

in use. The commenter’s issue also relates to their contention that the EPA should focus on 

manganese content (because silicomanganese production emits less than ferromanganese in 

terms of tons of emissions per ton of product produced). Our final rule is based on the revised 

risk analysis, including taking into account that EMI sometimes produces silicomanganese 

instead of ferromanganese at one or more furnaces. In any case, we conclude the baseline risks

due to HAP emissions are still unacceptable for the source category (which includes both 

products/companies). Therefore, we conclude that it is appropriate that the standards for process 

fugitive emissions should apply to both plants and that both plants will need to improve controls 

to reduce fugitive emissions.

4.10.2 Concentration Format is Not Appropriate

Comment: Commenter 0073 asserts that the EPA’s switch from a mass emission limit to a 

concentration-based standard is inappropriate and that the EPA has not provided a reasoned 

justification for the change. The commenter (0073) notes that both the furnace and building 
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enclosure systems capture large volumes of ambient air, which dilutes pollutant concentrations 

and makes a standard based on concentration impractical. The commenter (0073) suggests that a 

standard based on the overall mass of pollutant per ton of alloy produced would avoid this 

problem. The commenter (0073) adds that mass-based limits create incentives for pollution 

prevention, encourage improvements allowing for multi-pollutant reductions, avoid concerns 

about dilution, and limit total pollutant emissions rather than allowing potentially unlimited 

quantities of pollutants to be emitted, so long as other materials in the stack exhaust provide 

sufficient dilution to remain below the concentration limit. The commenter (0073) requests that 

the EPA change the format of the proposed MACT standards for PM, mercury, PAH, HCl, and 

formaldehyde to units of mass of pollutant per ton of ferroalloy produced or, if the EPA rejects 

their comment, explain the basis for changing the format of the standard and provide opportunity 

for review and comment. 

Response: We recognize that there are many advantages to a production-based format for an 

emissions standard. However, neither the data from the ICR test program nor the historical 

compliance data were collected is such a way to provide consistent information of production 

during the emissions tests. Even where data were provided on amount of product tapped, we 

have no assurance that the tapping periods were consistent from test to test. The current rule 

states that the furnace stack test must be conducted such that at least one tapping period, or at 

least 20 minutes of a tapping period, whichever is less, in included in at least two of the three test 

runs. This means that a third tapping period could be included in the third test run, or that only 

partial tapping periods are included at the beginning or end of the test run. 

Comment: Commenter 0106 states that load-based limits are more appropriate for this category, 

because the emission standards at issue in this rulemaking address chronic, rather than acute, 

risks. The commenter (0106) states that the principle focus of the emission standards in this 

matter should be mass loading, rather than simple concentrations. The commenter (0106) adds 

that concentration-based limits discriminate against sources, such as EMI’s MOR unit, that 

produce very low levels of emissions and, as a consequence, present less practical significance. 

The commenter (0106) requests that the final rule should continue to express limits in terms of 

pounds per hour, as EPA elected to more appropriately address the types of HAPs emitted by this 

category in the original MACT.

The commenter (0106) adds that a concentration-based limit requiring correction to 2% CO2 is 

not rational for building emissions that consist almost entirely of ambient air. The commenter 

provides (01060 additional analysis in Appendix B of this topic. The commenter (0106) states 

that both the building ventilation option and the existing configuration of EMI’s furnace #1, 

draw significant ambient air, such that the concentration of CO2 is very low and equivalent to 

background levels, i.e., at 390 ppm (0.039%), consistent with the general atmosphere, without 

applying any correction factor. The commenter (0106) notes that correcting to 2% CO2 

notwithstanding the ambient air makeup of the exhaust, would require corrections that render the 

proposed limit for building ventilation baghouse emissions (including Furnace #1) far more 
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stringent than the EPA has suggested. The commenter (0106) explains that, to achieve 24 

mg/dscm expressed at 2% CO2, the exhaust gases would actually need to contain less than 0.48 

mg/dscm particulates [24*(0.039/2)], which is an unrealistically stringent limit that is not 

supported by the EPA’s residual risk assessment or any other aspect of the proposed rule. 

Response: We continue to believe that a concentration format is preferable to a pounds per hour 

format in this rule. This is because the majority of the control devices are fabric filters, which are 

constant outlet devices. We recognize there may be some concern about excess dilution air being 

used as a technique to ensure compliance, but feel that this is unlikely as control devices are 

designed for specified flow rates taking into account the cost of achieving those flow rates. 

We agree with the commenter that the CO2 concentration correction poses a problem in both the 

building ventilation option and the Furnace #1 configuration. While such a concentration 

correction is appropriate for combustion sources such as boilers, we agree that its use in the 

context of ferroalloys production is not helpful. The final limits in the rule have been 

recalculated to remove the correction factor.

4.10.3 PM Cannot be Used as a Surrogate

Comment: Three commenters (0107, 0270, 0276) state that the EPA has failed to justify using 

PM as a surrogate for all HAP metals under section 112(d). Two commenters (0107, 0276) 

explain 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). These commenters (0107, 0276) state that the EPA has not shown that this 

source meets factor three, in view of the potential variety in raw materials used for Ferroalloys, 

and the agency must investigate whether these may lead to specific metal emissions that are not 

always proportional to PM. The commenters (0107, 0276) conclude that the EPA must fully 

analyze the reduction methods for manganese and other metals, and should set a HAP-specific, 

numerical emission standard that limits each of these pollutants, and allows both the EPA and the 

public to assess compliance.

In their comments on the 2011 proposal, commenter 0107 states that under section 112(f)(2), the 

EPA may not use PM as a surrogate for all HAP metals. The commenter (0107) adds that 

although courts have allowed EPA to use this to meet the MACT requirements of section 112(d) 

in certain instances, the EPA has no legal basis to use a surrogate in the context of public health 

under section 112(f)(2). The commenter (0107) states that the EPA instead must finalize 

emission limits for all regulated HAPs which will ensure an acceptable level of health risk and 

provide an ample margin of safety to protect public health. The commenter (0107) continues 

that, even if the EPA could use PM as a surrogate in any circumstance under section 112(f)(2), 

the EPA has not shown that using PM as a surrogate satisfies the three-part test. The commenter 

(0107) states that the EPA must address whether different raw materials going into the 
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Ferroalloys source category may significantly affect the specific emission of different HAP 

metals, without having a proportional relationship to PM.

Two commenters (0270, 0276) note that one would expect that a good surrogate would have a 

high correlation with the target pollutant at concentrations near the regulated limits, especially in 

the case of manganese. However, the commenters (0270, 0276) present analysis showing that 

when all tests containing filterable particulate and manganese analysis were evaluated, the 

correlation between the two was less than 15%. When the test data is limited to fabric filter 

controls, the best correlation was 0.208 using a power equation. The commenters (0270, 0276) 

presented correlation data for arsenic, chromium, nickel, cadmium and lead (see pp. 30-33 in 

comment letter 0276) and conclude that the data do not adequately demonstrate a surrogacy 

relationship for PM and the HAP metals of concern. 

Both commenters (0270, 0276) suggest that the EPA should consider using EPA Method 29 to 

quantify metal emissions at a small incremental cost to the overall collection of PM emissions.

One commenter (0270) recommends that the EPA should base the emission limitation for the 

facilities on the measurement of emissions of the pollutant with the greatest risk (minimum of 

PAH and manganese) and any use of a surrogate pollutant with a poor relationship to the target 

pollutant producing the greatest potential risk should accommodate the correlation uncertainties. 

The commenter (0270) believes that any surrogate that has a correlation lower than 70% at levels 

near compliance concentration levels is less than acceptable for use in assessing compliance 

without significant adjustment due to correlation uncertainties.

Response: The rule does meet the tests for using PM as a surrogate. First, metal HAP emissions 

were measured during the stack tests and in fabric filter dust. Second, the particulate matter 

control devices used in the industry (fabric filters and scrubbers) achieve broad spectrum control 

of PM emissions and the associated metal HAP. In a similar fashion, the EPA identified PM as a 

surrogate for metal HAP emissions in establishing MACT standards for Iron and Steel Foundries 

(Foundry MACT). When promulgating the Foundry MACT standard, the EPA explained that 

PM is a reasonable surrogate in this context because the ‘technologies currently used by 

foundries that reduce metal HAP emissions are those specifically designed to control PM.’ 

Foundry metal HAP emissions, particularly those associated with melting processes, include PM 

emissions in the exhaust stream. Thus, the use of control devices (e.g., fabric filters and wet 

scrubbers) to reduce metal HAP emissions to comply with the Foundry MACT will also result in 

the control of PM. 

The commenter is correct that theoretically there could be variations in metal HAP content over 

time due to variations in the raw materials used at different plants and variations in raw materials 

from the same source. We are not aware that any source in the category treats the raw material 

input prior to use in a manner that would reduce HAP. We also lack information to establish the 

exact nature of the variability. However, even if we had such information, the record reflects that 
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PM controls are the only approach sources use to reduce metal HAP, and we know of no way to 

selectively control specific metal HAP. Furthermore, the small number of units in each 

subcategory limits the impact of raw material variability on the metal HAP emissions. All the 

sources in each subcategory are included in the MACT floor calculation so all the raw material 

input variability for the sources is reflected in the data and by extension considered in the MACT

floor analysis. For example, ferromanganese production occurs only at the Eramet plant and only 

from two furnaces that share common ore sources. The performance of these two furnaces does 

not depend on a lower HAP source of ore. While silicomanganese is produced at two plants with 

separate sources of ore, having only five furnaces in total in operation at these plants requires the 

ore sources of both plants be reflected in the MACT floor. See CAA 112(d)(3)(B) (existing 

source floors for categories and subcategories with less than 30 sources are based on the average 

of the best 5 performing sources). Because all the sources were considered, the input variability 

of all the sources is reflected in the data for the different sources. In addition, the end of stack 

PM control devices are the only methods, practices, or processes that we are aware of that 

reduce metal HAP at these sources. Therefore, the use of PM as a surrogate ensures that metal 

HAP is indiscriminately controlled along with non-metal HAP PM.

For HAP metals, the manganese emissions dominate all other HAP metal emissions at both 

plants (approximately 27 tons per year under the estimated final controls). All other HAP metals 

emissions are estimated to be less than 4 tons per year from both plants under the final controls. 

We do not have sufficient data to determine the proportional relationship of each metal HAP to 

PM, but note that the PM control device should be capable of addressing any variation in 

emissions to the same high degree of reduction as for PM in general. Thus, we believe that 

setting limits for individual HAP would only add unnecessary complexity to the rule, without 

changing the overall level of HAP reduction that is obtainable.

4.11 Compliance Testing Requirements

Comment: In comments on the supplemental proposal, commenter 0276 states that the EPA 

should strengthen performance test requirements in several areas. First, the commenter (0276) 

states that the EPA should require that every run include a tapping period and that the facility 

should test a full cycle (i.e., the test duration is equal to the time between taps.) The commenter 

(0276) states that the EPA has not given a reasoned explanation for limiting test to just 20 

minutes of a tapping period and that the proposed method would underestimate emissions.

The commenter (0276) adds that only Method 3A should be allowed if the test is of a positive 

pressure baghouse. The commenter (0276) states that the Fyrite and Orsat analyses are likely to 

be too imprecise and will undermine accurately determining dilution of the flue gas.

Response: Where test results require correction to diluent concentrations, such as 7% O2, the 

EPA requires the use of Method 3B (Orsat) or Method 3A (Instrumental) measurements. Orsat 

measurements are the reference method for oxygen and carbon dioxide and are no less accurate 

than Method 3A when done appropriately. Fyrite analysis is only allowed if oxygen and carbon 
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dioxide measurements are being taken solely for the purpose of calculating the molecular weight 

of the emissions gas stream and, in that role, are adequate for measurement purposes. 

Comment: Commenter 0276 provides several comments of use of EPA test methods.

For Method 30B, the commenter states that the EPA should add a requirement that if any test run 

exceed the acceptability limits of Method 30B, then a repeat test should be conducted within 90 

days, at the latest. The commenter (0276) states that three consecutive tests with at least one run 

excluded due to QA criteria should be considered to be non-compliance with the standard.

For Method 14, the commenter (0276) states that the EPA should revise provisions for 

quantifying PAH, metals and PM. For PAHs, the EPA should require a facility to retest any time 

that the QA criteria of CARB Method 429 is not met. The commenter (0276) states that this 

includes the need for the laboratory to dilute the sample such that the surrogate spikes are no 

longer within the calibration range of the analysis. The commenter (0276) adds that submitting a 

noncompliance test should not allow a source to show compliance.

The commenter (0276) states that since one group of HAP compounds are semivolatile 

compounds, the EPA Method 5 is an inappropriate surrogate for PAH compounds. The 

commenter (0276) recommends that compliance by test methods which measure the pollutants 

that are intended to be controlled. The commenter (0276) suggests that Method 5 in combination 

with Method 202 could be used following periodic tests using both the methods which measure 

the target pollutants and which measure total PM.

The commenter (0276) adds that any testing of the building ventilation should cover at least 6 

hours per test run to assure accuracy and complete data.

Response: Method 30B is a self-validating method whereby each measurement set provides 

enough QA/QC to validate the results. The test method allows for the discard of a test run where 

these criteria are not met, however we recognize that a valid Method 30B test consists of three 

valid test runs. As such, testers are wise to bring analytical equipment with them on site to make 

such determinations while they are still able to collect additional data if need be. The General 

Provisions (60.8 and 63.7) allow for a regulatory authority to base a compliance decision on two 

test runs if a sample is lost enroute to a lab, or other extenuating circumstance. 

With PAH testing, the EPA believes that a source would be unable to demonstrate compliance 

with a test where a lab had to dilute a sample so many times that they lost the isotope trace. 

Where this potential exists we allow for sources with high PAH emissions to also resolve their 

sample concentrations using low resolution mass spectrometry internal standard recovery. 

Comment: Commenter 0276 said that the EPA should require at least annual testing for the 

building monitors and the control devices. The commenter (0276) is concerned that the proposed 

5-year testing schedule would allow a source to be noncompliant for 5 years without any 
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knowing and would dramatically weaken the data available to any seeking to assure compliance. 

The commenter (0276) states that the EPA has provided no valid justification for delaying testing 

by more than 1 year, particularly for sources for which the health risks are severe and which the 

EPA has recognized as unacceptable under section 7412(f)(2).

Commenter 0270 states that the EPA should require that compliance determinations be based 

upon annual tests if the measured total facility emissions are expected to result in an estimated 

risk greater than a risk index of 0.5 with a reduction to every 3 years if the measured total facility 

emissions are expected to result in estimated risk that is above 0.3 and a reduction to every 5 

years if the estimated risk is below 0.3. The commenter (0270) adds that as is done in part 75, the 

use of a test company that uses a filed team lead that is a Qualified Source Test Individual in the 

test methods used for determining compliance and be employed by an accredited test company.

Response: The EPA disagrees with the commenter in that we employ parametric monitoring 

between compliance tests to demonstrate continuous compliance with emissions limitations. The 

commenters input disregards the value of those monitoring approaches wherein we see great 

value and have a long history of such.

4.12 Monitoring, Reporting and Recordkeeping Requirements

Comment: Commenter 0107 states that the EPA should fully investigate the past compliance, 

malfunction, and May 2008 cloud-like incidents that have occurred from this source category in 

the past. The commenter (0107) states that the EPA should fully review the monitoring 

requirements it has proposed and ensure that they are stringent enough to ensure that the EPA, 

states, and citizens can easily assess whether a facility is in full compliance with the standards 

within a short period of time of any violation. The commenter (0107) presents the following 

suggested changes:

 Because of the history of non-compliance incidents for this source category, the EPA

should require performance tests every year instead of every 5 years. 

 The commenter (0107) supports EPA‘s proposal for electronic reporting because fast, 

accurate, electronic reporting will help strengthen EPA, state, and citizen enforcement, 

and provide prompt information transparency for local communities near facilities in this 

source category. However, it is important that the EPA ensure immediate disclosure of 

these reports to the public on the Internet within 7 days of receipt of a report, without the 

need for any person to submit a FOIA request. 

 In comments to the supplemental proposal, commenter 0276 reiterates support for 

electronic reporting and the importance of ensuring that the information is promptly made 

available online to the public in an accessible format.

 EPA must require continuous monitoring of emissions from this source category using 

available technology to perform CEMS for Hg, HCl, HF, PM, and opacity. The EPA

should require the use of this technology for this source category, particularly due to the 
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problematic compliance and exceedance history. The EPA should require immediate 

reporting on the Internet of all monitoring reports. 

Response: Both EPA Region V and the Ohio EPA are fully aware of the compliance issues 

described by the commenter. Regarding the performance test requirements, we believe that an 

annual frequency is not required for all HAP given that the rule now requires sources that operate 

fabric filters (the predominant control device) to install and operate bag leak detection systems. 

We consider these systems to be a form of continuous monitoring. The rules also requires 

continuous parameter monitoring of elements associated with the other control devices (wet 

scrubber) as well as elements related to the capture system. Given the already high capital costs 

of complying with the final rule, we believe these monitoring technologies are both reliable and 

appropriate. We note that it is not physically possible to install CEMS on the positive pressure 

baghouses in use in this industry without substantial retrofit costs. Similarly, there is not a 

current technology of conducting continuous opacity monitoring at building roof monitors.

Comment: In their comments on the supplemental proposal, commenter 0269 states that the 

existing baghouse and baghouse monitoring system at the Felman site constrain the kinds of 

monitoring and monitoring systems that Felman can use. They note that an automatic leak 

detection system has never been demonstrated on a positive-pressure baghouse. In addition, they 

state that the facility uses a computerized system that automatically adjusts the damper position 

based on the fan amperage, which means that these two variables are interdependent, not 

independent as the rule assumes.

To reflect these physical constraints, the facility requested flexibility in the monitoring

requirements for the baghouse itself and its associated capture system. Specifically, that the

baghouse leak detection system requirement be removed, and that Felman be allowed to conduct

an engineering assessment that would (i) identify the appropriate parameters and limits necessary

to ensure ongoing compliance with the capture system requirements, and (ii) set forth a schedule

for monitoring these parameters with appropriate frequency.

The commenter (0269) states that the proposed regulation adopts these changes for baghouses 

used to control process fugitive emissions, see §§63.1625(d)(2), 63.1626(g)(2), but still appears 

to retain the original requirements for baghouses used to control furnace emissions, see 

§§63.1625(c)(iii), 63.1626(d). However, the baghouse used to control process fugitives is the 

same baghouse that is used to control furnace emissions. Therefore, the commenter (0269) 

requests that EPA revise the requirements for baghouses used to comply with §63.1623(a) to be 

consistent with the requirements for baghouses used to comply with §63.1623(b).

Any other alternative would effectively require Felman to replace its existing control system 

with a negative-pressure baghouse, simply to meet the baghouse monitoring requirement. This 

requirement would impose very significant additional costs – costs that would likely force the 

plant out of business – for no additional environmental benefit; indeed, Felman is not aware of 
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any situations where EPA required the replacement of emissions controls that were fully capable 

of meeting the substantive MACT emissions standards, solely because a different design allows 

for improved monitoring. That is the tail wagging the dog. Commenter 0269 does not believe 

that EPA intended such a draconian result here and therefore requests that the proposed 

regulations be revised to require only that monitoring that the current positive-pressure baghouse 

can feasibly and reasonably accommodate.

Response: The EPA has knowledge of BLDs being used on positive pressure baghouse systems 

including those baghouses with large area roof emissions points. A change to a negative pressure 

baghouse would not be necessary. Manufacturers of BLDs would have information on how best 

to deploy their instruments on the outlet of a positive pressure baghouse.

Comment: The commenter 0271 believes that using a portable filter to quantify process fugitive 

emissions leaving a furnace building through a roof vent is not a reliable measure of emissions

and only should be done using approved isokinetic sampling techniques. They also note that 

portable filters may capture PM that may normally settle in the building and do not measure a 

specific emission source; but all sources in the building.

The commenter (0271) also states that automated opacity monitoring cameras do not accurately 

interpret visible emissions from roof vents. Issues that may affect performance include; 

variability in meteorological conditions (e.g., rain, snow and fog) and interference from steam 

leaving the roof vents. In addition, the commenter (0271) states that opacity camera do not have 

the ability to discern the difference between visible emission plumes and steam plumes. They 

note that ASTM D7520-13 states that steam plumes cause significant errors in measuring 

opacity. Another issue with opacity monitoring cameras is the images must be sent to a thirdparty for analysis. Therefore, there is a long lag time before results are obtained, which puts the 

source at a disadvantage as it will not be able quickly investigate and take corrective actions.

Response: The EPA does not believe that there are significant sources of water in a melt shop 

that would cause a substantial steam plume to develop from these processes without such an 

event causing a substantial malfunction of equipment and controls. 

The DCOT camera provides an image that the facility could access immediately, with QA/QC 

done within 45 minutes (according to comments received) to validate the image and initial 

readings. Consider that it takes (beyond the act of reading visible emissions manually) about 30 

minutes for an observer to return from the field and average their manually assembled data such 

that they can report the average that they recorded over the previous ninety minutes of 

observations. We view the initial visible recording as sufficient evidence to provide a facility 

enough reason to initiate, investigate and correct concerns that may create elevated visual 

emissions observations and the 45 minute turnaround time on actual opacity values to be quick 

enough to provide a facility the confirmation they would need to be assured that they have taken 

appropriate action.
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Comment: Commenter 0255 provided information on laser based and LED based opacity 

monitors which could be used to measure opacity on partially covered roofs, and asked if these 

could be viable options for measuring opacity in the rule.

Another commenter (0260) provided their experience with the Virtual Technology, LLC Digital 

Opacity Compliance System (DOCS II) which measures opacity using ASTM D7520/EPA 

Alternative Method 082. The commenter (0260) stated that this system never failed any 

certification and was better than average in comparison with human VE readers. They believe 

this system would provide a cost savings to the industry in comparison to certifying staff to 

perform the opacity readings. The commenter (0260) also added that the system can be 

configured to capture opacity at different times during the day.

Commenter 0262 states that digital cameras or recorders can be used in conjunction with ASTM 

D7520/EPA Alternative Method 082 to provide near continuous monitoring of VE. They

provided an example of an opacity monitoring setup at Felman Production using a two camera 

system.

Response: Opacity monitors that meet the requirements of PS-1 and its associated Procedure 3 

QA/QC document will satisfy opacity monitoring requirements of this rule for point source 

emissions. We thank the commenters for sharing their information and experience with the 

DOCSII system.

Comment: The commenter (0272) states in their comments on the supplemental proposal that the 

EPA proposes to further expand EMI’s monitoring and reporting obligations, but does not 

identify the legal authority under which such obligations might be imposed. They believe that the 

requirements are only put in place to collect various types of data that the EPA believes would be 

interesting to see. Considering the substantial increase in opacity monitoring costs that the 2014 

proposal already entails, the commenter strongly objects to these proposed requirements as 

unnecessary, unreliable and unlawful.

They commenter (0272) believes that the EPA’s rooftop monitoring proposal is too vague, 

infeasible and would not provide relevant data for purposes of Section 112. The commenter is 

unaware of any commercially deployed systems of this type and EPA does not adequately 

describe the type of equipment that it would seek to adapt for this research project. They note 

that the supplemental proposal states that it would involve “no less than 3” systems, but does not 

specify whether this means three per facility, three per shop building or three per furnace. This 

detail impacts cost, feasibility and the nature of the data that would be collected. In addition, the 

commenter states that it is impossible to comment on sampling duration and frequency without a 

better understanding of what equipment would be deployed and where. The commenter believes 

that the EPA should provide a specific monitoring proposal, not just a couple of conceptual 

sentences, for public review and comment.
146

The commenter (0272) believes that this research project would be far more expensive and 

provide far less useful information than periodic Method 9 opacity measurements. The 

commenter also notes that the proposed rooftop monitoring is infeasible at EMI because the

fugitive roof emissions occur through long, rectangular roof monitors and the location of such 

emissions from the roof monitors varies constantly depending upon a range of process and 

meteorological variables that are constantly changing. In addition, the commenter notes that the 

roofs of EMI’s furnace buildings are not designed or equipped to bear the loads that would be 

associated with installing and maintaining test equipment. The commenter states that there is no 

statutory need or justification for the proposal.

Response: The EPA has a long history of establishing and enforcing opacity monitoring 

requirements from building vents, including long rectangular roof openings such as those 

described by the commenter. We specifically requested public comment on various approaches 

for these facilities as we recognize there are expenses and shortcomings involved in requiring 

certified Method 9 observers to conduct visible emissions surveys over extended periods on a 

frequent basis. Where superior, less expensive or more reliable monitoring approaches can be 

found we find it prudent to seek input from public and private industry and construct rules that 

we feel are at once workable and appropriate to an emissions standard that is protective of the 

environment.

Comment: In their comments on the supplemental proposal, commenter 0272 states that the 

EPA’s fixed digital camera monitoring requirement is not adequately explained and has not been 

shown to be a demonstrated alternative to Method 9 for purposes of assessing compliance with 

the opacity standards. The note that the supplemental proposal does not describe in sufficient 

detail how many fixed digital cameras would be required or specify a methodology for 

determining that number. The commenter believes that the open continuous roof monitors would 

make this approach infeasible or would require too many fixed cameras that it would be 

unreasonably costly. The commenter believes that the EPA should provide a specific proposed 

requirement and allow public review and comment before finalizing any such requirement.

The commenter states that pictures for digital cameras are an unproven substitute for Method 9 

measurements. The commenter views the technology as less reliable than Method 9 

measurements by a trained and certified reader, because a fixed, automated camera is incapable 

of taking into account all of the potential confounding factors, such as sun position, 

meteorological variables, and visible non-regulated emissions such as steam plumes.

While the 2014 proposal includes an unreasonable frequency of opacity measurements, the 

commenter is open to considering less labor-intensive options that are capable of providing valid 

data. However, the commenter believes that the provision in the 2014 proposal that permits 

voluntary use of digital camera technology is not the appropriate approach. 
147

Response: The EPA has codified digital camera technology as a validated and accepted approach 

for continuous visible emissions analysis. Additionally we are aware of ASTM standards that 

also define and support appropriate use of this technology. We specifically requested public 

comment on various approaches of reading visible emissions for these facilities as we recognize 

there are expenses and shortcomings involved in requiring certified Method 9 observers to 

conduct visible emissions surveys over extended periods on a frequent basis.

4.13 Compliance Date

Comment: Commenter 0107 states that the 2-year compliance delay is unlawful and arbitrary, 

and it cannot be reconciled with the EPA’s own recognition that HAP emissions from this source 

category are unacceptable. The commenter (0107) adds that Eramet emits persistent and 

bioaccumulative pollutants that have already built up in the air, soil, and people’s bodies, 

including those recognized by the EPA – lead, mercury, and POM – and those not recognized by 

the EPA – manganese, nickel, arsenic, and naphthalene. The commenter (0107) states that 

because of the history of exposure in the affected communities, there is an even greater health 

risk from each additional day of exposure than there would be if none of the pollutants were PBHAPs. The commenter (0107) states that there is evidence of manganese in the hair of children 

living near the Marietta facility and the Ohio Health Department has placed Marietta, OH on the 

list of “high risk” zip codes for lead poisoning. The commenter (0107) also notes that some of 

the individual pollutants emitted by this source category, such as lead, are pollutants for which 

there is no safe level of inhalation exposure, and yet people in this area are being exposed both to 

this and to all other emitted pollutants combined. The commenter (0107) adds that the EPA is 

already several years behind in its obligation to conduct the RTR, which was required in 1999. 

The commenter (0107) adds that the EPA must not waive critical emission reduction 

requirements for 2 years when local communities immediately need these protections. 

The commenter (0107) concludes that because the EPA has also delayed the compliance date of 

the MACT update under section 112(d)(6) based on the section 112(f)(2) compliance delay, the 

proposed 2-year MACT compliance delay is also unlawful for reasons similar to those described 

above. The commenter (0107) adds that, the EPA also has not met the standard under section 

112(i)(3) to demonstrate that a MACT compliance date for existing sources ―shall provide for 

compliance as expeditiously as practicable.

Moreover, the commenter (0107) provides an extensive analysis of the Clean Air Act waiver 

provisions.

Response: EPA is of course aware of the requirements of section 112 (f)(3) and (4). See 76 FR at 

72508, November 23, 2011. The EPA is not ignoring the requirements of this provision. Rather, 

as documented in the memorandum “Estimated Time Needed to Achieve Compliance with the 

Proposed Revision to the MACT standard for Ferroalloys Production”, the EPA has made caseby-case findings for each existing source as to the amount of time required to comply with the 

risk based stack and fugitive emission standards for HAP. The EPA does not interpret §63.6 
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(i)(4)(ii) of its regulations to mandate individual applications when all of the necessary 

information is already before the EPA, and the EPA applies that information in an 

individualized, case-by-case manner, as done here. Moreover, section 112 (f)(4)(B) is a direct 

grant of authority which can be implemented not just by regulation but by other EPA action, as 

done here. As documented in the memorandum cited above, the existing sources discussed in the 

memorandum will need to undertake such improvements to the capture system, and addition of 

control devices for fugitive control (with such attendant interim steps as obtaining capital, 

purchase and delivery of equipment, installation of equipment, and shakedown operation). These 

activities simply cannot be accomplished in 90 days, and 2 years is a reasonable amount of time 

to carry them out. 

The statute likewise contains the requirement that the EPA must find that “steps will be taken 

during the period of the waiver to assure that the health of persons will be protected from 

imminent endangerment” in order to extend the compliance date. We note first that the EPA does 

not believe that any unacceptable risk under section 112 (f) automatically equates to an 

“imminent endangerment”, given that Congress authorized extensions of the compliance date. 

We note further that existing ferroalloys production sources are already controlled to some 

degree, and will necessarily make further reductions of their emissions as they implement steps 

toward full compliance. For example, we note that the sources have been making improvements 

since the ICR test program (including development of improved fugitive emissions capture of 

tapping and casting operations at Felman and installation of a new baghouse to control Furnace 1 

at EMI (the largest furnace at the plant). We anticipate that the sources will begin making 

changes in an incremental fashion to ensure they are in compliance by the specified date, 

resulting in additional pre-compliance emission reductions. Under these circumstances, the EPA 

believes that steps will indeed be taken in the period before full compliance to reduce emissions 

and prevent an imminent endangerment. 

Comment: Three private citizens (0077, 0091, 0099) believe that the final rule should require 

compliance within a short time frame, e.g., within 90 days. OCA encourages the EPA to approve 

and enact these rules as swiftly as possible, before the proposed implementation date of 2014. 

The commenters (0077, 0091, 0099) add that the people of Marietta have suffered for 

generations from emissions from this facility and everything possible must be done to hasten 

their relief.

Commenter 0106 states that the EPA should not finalize the ACI and building ventilation 

requirements in the 2011 proposal, but, if the EPA decides to finalize those requirements, and 

even if EMI could somehow afford to implement the proposed ACI and building ventilation 

controls required under the proposed rule, 2 years is not a sufficient period for budgeting, 

designing, permitting, procuring, installing, and testing those complex, overlapping emission 

controls. The commenter (0106) states that the EPA should exercise its authority under the Clean 

Air Act to set a 3-year compliance schedule for standards established under Section 112. The 

commenter (0106) provides several instances justifying a longer time frame:
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 EMI’s analysis of building ventilation shows that EMI actually would need to install a 

total of eight to ten, 250,000-cfm systems and the amount of work involved in installing 

so many systems is not reflected in the memorandum from the EPA’s consultant on 

which EPA bases its compliance period.

 The EPA incorrectly assumes that obtaining funding for the projects would take just 2 to 

3 months in today’s conservative lending atmosphere. Even if projects are funded using 

internal cash flow, EMI’s budget allocation process takes a year to implement.

 Also, the consultant memorandum does not allow sufficient time for engineering of the 

fugitive emission controls.

 There is no evidence that the EPA accounted for the time needed to apply for and obtain 

state and local authorizations, such as air permits for control devices or local building 

permits that may be required for aspects like large elevated ductwork.

 Concerns regarding expected availability of necessary engineering contractors, 

equipment, and supplies in the current market, which has experienced a significant 

increase in demand from the overlapping impacts of so many recent EPA initiatives.

According to the commenter (0106), under a proper reading of the statute, the EPA can allow up 

to 3 years under Section 112(i)(3)(A), while Section 112(f)(4) prohibits it from requiring 

compliance in less than 90 days and also allows case-by-case waivers of up to 2 years in cases 

where EPA decides to allow less than 2 years on a category-wide basis under Section 

112(i)(3)(A). The commenter (0106) concludes that, regardless of EPA’s views regarding 

residual risk standards, there is no reason to doubt EPA’s authority under Section 112(i)(3)(A) to 

allow 3 years for compliance with MACT standards promulgated pursuant to Section 112(d)(6).

One commenter (0272) stated in their comments on the supplemental proposal that the EPA 

should exercise its authority under the Act to set a three-year compliance schedule for standards 

established under Section 112. The commenter notes that the EPA’s two-year proposal is based 

on several unrealistic assumptions which include: obtaining funding for the projects would take 

just two to three months, sufficient time for engineering of the fugitive emission controls, time 

needed to apply for and obtain state and local authorizations, such as air permits for control 

devices or local building permits, and obtaining the necessary engineering contractors, 

equipment, and supplies in the current market, which has experienced a significant increase in 

demand from the overlapping impacts of so many recent EPA initiatives.

In proposing a two-year compliance period, the EPA refers to its authority under Section 

112(f)(4)(B) of the Act to grant a facility-specific waiver from compliance with residual risk 

standards for a period of no more than two years. This ignores EPA’s broader authority under 

Section 112(i)(3)(A) to allow up to three years for achieving compliance on a category-wide 

basis with standards issued under any provision of Section 112. Under a proper reading of the 
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statute, the EPA can allow up to three years under Section 112(i)(3)(A), while Section 112(f)(4) 

prohibits it from requiring compliance in less than 90 days and also allows case-by-case waivers 

of up to two years in cases where EPA decides to allow less than two years on a category-wide 

basis under Section 112(i)(3)(A).

Under Section 112(i)(3)(A), EPA must require compliance with any standard issued under 

Section 112 as expeditiously as practicable, but in no event later than three years after the 

effective date of the standard. The language in Section 112(i)(3)(A) allowing for a three-year 

compliance period covers “any emission standard, limitation, or regulation promulgated under 

this section.”. “Section,” by definition, refers to all of Section 112, including subsections (d)(2)-

(3), (d)(6), and (f)(2).

Section 112(f)(4)(A) further specifies that EPA may not set a compliance deadline of less than 

90 days for a residual risk rule, and EPA may grant a waiver of up to two years for such rules 

under Section 112(f)(4)(B) in cases where it has decided under Section 112(i)(3)(A) to allow less 

than three years on a category-wide basis. For example, if EPA establishes a general categorywide compliance schedule of one year under Section 112(i)(3)(A), a facility could still be 

granted up to one additional year to comply under Section 112(f)(4)(B) if it faces unique 

circumstances. This reading of the statute gives meaning to the plain language of both Section 

112(f)(4) and Section 112(i)(3)(A).

As an example, the commenter notes that the EPA previously acknowledged this when 

developing standards for halogenated solvent cleaning. In the proposed rule, EPA said that 

“CAA section 112(i)(3)(A) by its terms applies to ‘any’ standard promulgated under CAA 

section 112, which includes those under CAA section 112(f), in allowing up to a three year 

compliance period for existing sources.” 71 Fed. Reg. 47670, 47686 (Aug. 17, 2006). In the final 

rule, EPA allowed three years for achieving compliance on the grounds that “CAA section 112(i) 

was the controlling provision that addresses compliance deadlines for existing sources with 

regard to standards promulgated under CAA sections 112(d)(6) and 112(f)(2).” 72 Fed. Reg. 

25138, 25146 (May 3, 2007). 

The commenter believes at a minimum that the EPA should allow three years for compliance 

with any standards imposed under Section 112(d). They note that several recently issued risk and 

technology review rules allow three years for compliance with such standards. For example, in 

the final rule for wood furniture manufacturing, EPA allowed three years for existing facilities to 

comply with formaldehyde coating/contact adhesive limits and other requirements promulgated 

under Section 112(d)(6). 76 Fed. Reg. 72050, 72055 (Nov. 21, 2011). They also note that the 

facilities need time to develop a fundamental understanding of the factors that influence the 

variability in such emissions and to develop cost-effective approaches to manage those factors 

and reduce variability.
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Response: We disagree with commenters who state that a 90-day compliance period is possible 

for implementing these new, more stringent requirements. We agree that the time required to 

design, purchase, and install large control devices and new or enhanced ventilation systems will 

take a matter of many months, not days. Once installed, the new equipment must be tested and 

compliance demonstrated. Therefore, we believe that the practical requirements of the steps 

required to demonstrate compliance with the promulgated standards indicate that we should 

allow the full 2-year compliance period as proposed. We note that the sources have been making 

improvements since the ICR test program (including development of improved fugitive 

emissions capture of tapping and casting operations at Felman and installation of a new baghouse 

to control furnace #1 at EMI (the largest furnace at the plant). We anticipate that the sources will 

begin making changes in an incremental fashion to ensure they are in compliance by the 

specified date, resulting in additional pre-compliance emission reductions.

We disagree with the commenter’s claim that we can allow up to 3 years under section 

112(i)(3)(A) for requirements developed under the Section 112(f) residual risk process. We note 

that Section 112(i)(3) establishes the compliance timeframe for any standard issued under section 

112 for existing sources and provides that the compliance date shall be as expeditious as 

practicable but no later than 3 years following the effective date of the standard. Section 

112(f)(4), however, expressly provides more specific requirements for standards issued under 

section 112(f) and thus for section 112(f) standards those more specific requirements (i.e. a 

specific requirement for section 112 (f) standards) govern in place of the more general 

compliance date requirements in section 112(i)(3). Specifically, section 112(f)(4) provides that a 

source cannot emit an air pollutant in violation of a standard issued under subsection (f) except 

that the standard will not apply until 90 days after its effective date. It also provides that the 

Administrator may grant a waiver for a period of up to 2 years from the effective date if 

necessary for the installation of controls and if measures will be taken in the interim to ensure 

public health is protected from imminent endangerment.

5.0 ECONOMIC IMPACTS OF PROPOSED RULE

5.1 Impacts on Economy and National Interests

Comment: Two commenters (0073, 0106) note that ferroalloys producers operate in an 

extremely difficult competitive environment - EMI operates the only remaining ferromanganese

production furnaces in the U.S., and they are the only two domestic silicomanganese production 

facilities. The commenters (0073, 0106) state that their primary competitors are foreign 

companies not subject to U.S. environmental regulations. One commenter (0106) notes that 

foreign competition from China and other countries that control 80% of the U.S. ferroalloys 

market effectively prevent them from recovering environmental control costs through higher 

prices. Both commenters (0073, 0106) state that up-front capital costs are critical, because 

equipment must be paid for when installed, not over 20 years, and states that if their corporate 

parent no longer profits from its investment in their operations or concludes they could earn a 
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greater return elsewhere, it would close the company. The commenter (0269) adds that the EPA 

seems to believe the ultimate ownership of the companies is a relevant question to its EIA, which 

they believe is not. The commenter (0269) asserts that any owner will invest in a business 

venture only if there is a reasonable likelihood to earn a rate of return comparable to other 

investment options. Owners of the ferroalloy facilities will not continue to invest in emission 

control devices for their facilities in the United States unless these operations can produce a 

product at a competitive price and provide a competitive rate of return. The commenter (0269) 

notes that the EPA has acknowledged this business reality in other rulemakings such as its recent 

Underground Storage Tank rulemaking’s economic impact assessment. 

Commenters (0073, 0106) note the potential effects of this rule if it forces the U.S. ferroalloys 

industry to go out of business, including effects on local power prices, increased unemployment, 

and national security (because the facilities are the only two remaining U.S. suppliers of 

silicomanganese, an ingredient in military grade armor plate steel.)

One commenter (0073) states that because of the competitive, low-margin nature of the 

silicomanganese business, the up-front capital investments required by the proposed rule could 

put them out of business. The commenter (0073) notes that the true costs they have estimated for 

the building-wide negative pressure PTE are more than fifteen times their annual capital 

expenditures for 2011 and more than double the company’s current net worth. 

One commenter (0106) states that the new emission controls proposed by the EPA are 

economically unsustainable by EMI. The commenter (0106) provides detailed economic and 

engineering analyses showing that the actual costs of the regulation may be up to $71 million in 

capital expenditures over the next two years with increased annual operating costs of $11.6 

million. The commenter (0106) states that these costs are far greater than the EPA’s flawed 

analyses project and are greater than the commenter’s ability to pay. 

Furthermore, the commenter (0106) states that since, due to foreign competition, they cannot 

raise prices to recover additional production costs, those costs must be absorbed through lower 

profit margins. The commenter (0106) provides economic analyses showing that when their 

projected costs of compliance with the proposed rule are converted to cost per ton of product 

sold, they far exceed EMI’s average net margin per ton over the past three years, and would 

consume more than 70% of its net profit margin during its most profitable recent years. In their 

comments on the supplemental proposal, commenter 0272 states that the EPA’s economic 

analysis does not provide any basis for the assumption that Eramet could afford to implement 

either the 2011 or the 2014 proposal. The commenter notes that their analysis shows Eramet is 

unable to pass cost for fugitive controls on to customers through higher prices or absorb these 

costs out of profits.

The commenter (0106) agrees with the EPA that that the proposed rule should not affect 

ferroalloy prices, but notes that this is because ferroalloys are a commodity product where price 
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is largely controlled by the lowest cost producers, primarily foreign competitors who will not be 

subject to the costs of proposed rule. Commenter (0106, 0269) note that the International Trade 

Commission (ITC) has found their foreign competitors sometimes use their competitive 

advantages to “dump” ferroalloys on the U.S. market at below-market pricing. Commenter 0269

notes that their decision in 2013-2014 to curtail production due to lower demand and higher 

operating costs demonstrates the intense, international competition in the industry. The 

commenter (0106) also states that when new compliance costs must be absorbed without price 

increases, affected businesses will experience reduced profits, which may turn negative and 

result in plant closure, and that even if profits have a chance of remaining positive, the affected 

businesses may not be able to obtain the financing necessary for compliance, and would thereby 

also be forced to close. The commenter (0269) believes that the EPA’s regulation must be 

tailored to the actual potential hazards and must be as cost-effective as possible to preserve 

manufacturing jobs in the United States.

In their comments on the supplemental proposal, commenter 0271 states that EPA’s proposed 

rule affects the steel industry’s ability to compete in a global market and to procure resources 

from reliable domestic producers. They state that the ferroalloys production industry is critical to 

the steel industry, which is critical to national security. They believe that if this rulemaking were 

adopted as proposed, it could have devastating effects on the ferroalloys production industry in 

the U.S. in the form of lost jobs to overseas markets. They also note that the loss of the 

ferroalloys industry in the U.S. would cause reliance on foreign-produced ferroalloy products, 

which do not necessarily have U.S. interests in mind.

Commenter 0265 believes that the companies may be in jeopardy of closure due to the 

significant capital and operating costs in the rule.

Response: The statements on economic impacts provided by each commenter are sensitive to a 

major degree on their position that the EPA has underestimated the 2011 proposal’s compliance 

costs by a large margin. 

While ferroalloys are a commodity whose price is set on a worldwide market as mentioned by 

the commenters, and that EMI and Feldman are therefore price takers, this has not kept these 

companies from being profitable currently. For example, the report by NERA that constitutes 

much of EMI’s comments on the economic impact analysis for the proposal indicates indirectly 

that EMI has been profitable in 2010 and 2011, though not profitable in 2009. We note that EMI 

was not profitable in 2009, an entire year, but the Marietta, OH plant continued to operate and 

was not closed by EMI or its parent, Eramet Group. This reality is in contradiction to the 

commenter’s statement that if the corporate parent no longer profits from its investment in a 

facility, as was the case in 2009 based on the commenter’s own report, then the plant will simply 

close. Clearly, this did not take place at the Marietta, OH plant. 
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The use of a 3-year period by the commenter for establishing a baseline for impact calculation is 

inconsistent with the EPA’s use of a single year baseline (2011, roughly – generally the latest 

calendar or fiscal year) for estimating costs and other impacts in the RIA for the 2011 proposal. 

The use of a 3-year period includes 2009 as part of an argument to show that the costs of 

compliance will be more than the commenter can afford, yet this was a year in which the 

commenter was not profitable but did not close. Use of a latest year for a baseline would 

undoubtedly lead to different conclusions regarding the affordability of the capital investment in 

pollution control for compliance with the rule. 

While a 20-year investment in pollution control technology may be problematic to incorporate 

into economic forecasting at the firm level, it should be noted that there are deductions allowed 

in both the U.S. Tax Code and various states’ tax codes to reduce the tax burden associated with 

pollution control investment. Section 169 of the U.S. Tax Code allows for deductions, and Ohio 

allows firms to exempt pollution control investments from property taxes as noted at 

http://codes.ohio.gov/orc/5709.25. 

The U.S. Department of Defense (DOD) in 1982 established a Stockpile Upgrade program to 

have an inventory of key materials available for use in U.S. military applications. Ferroalloys 

was one material whose domestic production was encouraged by this program. The Stockpile 

Upgrade program was disbanded in the mid-1990s, however, as a result of changing U.S. 

military priorities emerging from the end of the Cold War, and was never resumed despite the 

continued decline of ferroalloys production capacity since that time in the U.S. In addition, the 

U.S. DOD has not been a participant in the Work Group for this proposal, nor has it been a 

commenter on the proposed rule. Thus, the U.S. DOD does not appear to regard the contribution 

of domestic ferroalloy production to the national security to the degree it once did, and therefore 

may not perceive this rule to increase risk to national security by its implementation. 

Comment: Commenter 0106 disagrees with the EPA’s assertion that economic impacts on EMI 

will be “low,” because the EPA’s estimate of the increased annual operating costs required by 

the proposal are small compared to EMI’s annual sales and small compared to the annual 

revenues of EMI’s parent company. The commenter (0106) states that this analysis is incorrect 

because it is net profits, not sales revenue, which determine the resources a company has 

available to support increased production costs. The commenter (0106) asserts that the EPA’s 

comparison to parent company sales is also unreasonable because it implies that companies will 

operate unprofitable businesses so long as the company has other businesses that generate 

enough profits of their own to cover the losses of the unprofitable businesses. 

Commenter 0073 adds that the EPA has compounded the error of vastly underestimating 

compliance costs by assuming that Felman’s parent company will invest more than Felman’s 

current net worth to comply, because it represents “only” 0.1% of the parent company’s global 

sales. The commenter (0073) suggests that the likely result of these costs will be the end of 

ferroalloys manufacturing in the United States. The commenter (0073) provides a study 
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“Economic Impact of Felman Production, Inc. on West Virginia 2011,” which details the number 

of employees at their facility, the percentage it represents of manufacturing works in their 

county, and the significant effects which closing the plant could have on the economy of West 

Virginia. 

Response: While net profits are more useful in calculating impacts to firms than sales data, it is 

noted that reported profits often reflect legally available deductions for tax purposes at both the 

Federal and state level, and thus official reported profits are often not a true indicator of the 

economic profits to the firm. This is a key reason why metrics for small business impact analysis 

as done by the EPA include sales rather than profits. The RIA’s economic impact chapter 

explains why this is so. Felman’s presumption that its parent company will not invest funds for 

compliance equipment at its facility are predicated on the presumption that the EPA’s 

compliance costs are vastly underestimated. Thus, the statement of the costs being more than 

Felman’s net worth is only true if Felman’s estimate of the costs is accurate or close to being 

accurate. 

Comment: Commenter 0101 states that the "Toxic Soup" (air quality in Marietta, Ohio) affects 

the economy as well as the health of the residents of Marietta. 

Response: We performed analyses that show that this action will reduce health-based risk in 

addition to providing monetary benefits for the areas where the plants are located. These 

monetary benefits include; reduced exposure to HAPs, including arsenic, chromium, nickel, 

manganese, mercury and polycyclic aromatic hydrocarbons, and improvements to both 

ecosystems and visibility. This action is also expected to reduce the cancer incidence, target 

organ-specific hazard index (TOSHI) and the maximum individual risk (MIR) associated with 

these HAP compounds. More details on the risk assessment and the economic benefits can be 

found in the preamble for this action.

Comment: Commenter 0263 states that the EPA failed to consider the social benefits and social 

costs of additional energy usage as a result of this rulemaking. The commenter (0263) states that 

the proposed rule proposes limits and controls on fugitive emissions which increase energy 

consumption, but the economic impacts do not provide an estimate of the energy consumption or 

the impact on GHG emissions. They note that this exclusion is inconsistent with the EPA’s 

approach in other rulemakings which provide the social cost of carbon (SCC). The commenter 

(0263) recommends that the EPA include SCC costs for this rulemaking consistent with OMB 

Circular A-4 and include the total energy implications across the economy.

Response: OMB Circular A-4 requires agencies to prepare and submit to OMB a Statement of 

Energy Effects for significant energy actions, to the extent permitted by law. This Statement is to 

include a detailed statement of “any adverse effects on energy supply, distribution, or use 

(including a shortfall in supply, price increases, and increased use of foreign supplies)” for the 

action and reasonable alternatives and their effects. 
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It was determined that the proposed rule was not a significant energy action as designated by the 

Administrator of the Office of Information and Regulatory Affairs because it is not likely to have 

a significant adverse impact on the supply, distribution or use of energy. In addition, this action 

will not create any new requirements, and, therefore, no additional costs for sources in the energy 

supply, distribution or use sectors.

5.2 Benefits Analysis

5.2.1 Regulatory Comments

Comment: Commenter 0073 states that the benefits analysis is flawed because it focuses on 

benefits from additional PM controls, while the NESHAP is a HAP standard, and PM is not a 

HAP. The commenter (0073) asserts that the EPA has overreached by stating that the health risks 

it seeks to prevent are largely caused by manganese, while ignoring significant variations in 

manganese emissions between the different products covered by the proposed rule. The 

commenter (0073) states that through their adoption of overly broad PM controls, the EPA uses 

the façade of a HAP focused regulation to maximize the reduction of non-HAP emissions, which 

is not what the CAA envisioned. The commenter (0073) adds that the courts have specifically 

limited EPA’s ability to rely on non-HAP surrogates to specific, limited circumstances and that 

the EPA’s reliance on PM2.5 benefits subverts the purpose of Section 112.

Response: The commenter is confusing quantifiable benefits with total benefits. While the EPA

is only able to quantify the co-benefits from reductions in ambient PM2.5, the rule itself results in 

substantial reductions in the HAP that are the focus of the rule. Specifically, the controls 

expected to be adopted as a result of this rule will reduce emissions of metal HAP by 78 percent. 

While we cannot quantify the effects of these reductions, they are indeed a benefit of this rule 

and in fact are the goal of the rule. In addition, the EPA disagrees with commenter that the 

benefits of the rule do not focus on the benefits from reducing the pollutants regulated under this 

rule. The monetized benefits of this rule reflect the co-benefits to health achieved via PM2.5 

reductions due to HAPs control in particular manganese. While the benefits of reducing 

manganese emissions are not monetized, the co-benefits from PM2.5 largely outweigh the cost of 

implementation. Other HAPs controlled by the ferroalloys rule were likewise not quantified due 

to data, resource and methodological limitations. Even if we were able to fully monetize the 

public health benefits of reducing exposure to all HAPs, it is likely that the PM benefits would 

continue to dominate the total monetized benefits due to the size of the exposed population and 

the severity of the associated health effects. In line with EPA and OMB guidance, the EPA

estimates all of the anticipated costs and benefits associated with a regulatory action, to the 

extent feasible. We further note that if we were able to fully monetize all of the benefit 

categories, the benefits would exceed the costs by an even greater amount than we currently 

estimate.

Comment: Commenter 0106 states that in the absence of any identifiable benefits from reducing 

HAP emissions, the EPA instead claims that by coincidentally reducing PM2.5 emissions, the 
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proposed rule will deliver huge benefits, more than offsetting the tens of millions of dollars of 

added compliance costs that the rule imposes. The commenter (0106) states that such a 

justification is not a valid basis for this rulemaking, because (1) Congress intended Section 109 

of the Act, not Section 112, to inform regulatory decisions on whether regulations are warranted 

to achieve such benefits (to the extent they exist), and (2) the non-scientific “hand waving” used 

to generate EPA’s massive “co-benefits” is unworthy of judicial deference.

The commenter (0106) adds that the net effect of all of the deficiencies in the EPA’s analysis, 

described in further detail in section 6.2.2, is that the EPA’s attempt to establish a simple 

conversion factor (to assign a dollar value to PM2.5) through which it can effortlessly convert 

pounds of particulate reductions into tens of millions of dollars of rulemaking “benefits” comes 

at the expense of far too many requirements of basic scientific inquiry. The commenter (0106) 

states that while the EPA is entitled to deference when forced to make difficult judgment calls, 

the EPA was not obligated by Section 112 to develop such a conversion factor and deference to 

judgment does not extend to allowing EPA to simply ignore the scientific realities that render 

that conversion factor impossible to calculate.

Response: Consideration of PM2.5 health co-benefits is expected as a result of direct PM2.5 

reductions as directed by OMB Circular A-4 (p. 26, available at: 

http://www.whitehouse.gov/omb/circulars_a004_a-4/):

“Your analysis should look beyond the direct benefits and direct costs of 

your rulemaking and consider any important ancillary benefits and 

countervailing risks. An ancillary benefit is a favorable impact of the rule 

that is typically unrelated or secondary to the statutory purpose of the 

rulemaking (e.g., reduced refinery emissions due to more stringent fuel 

economy standards for light trucks) while a countervailing risk is an adverse 

economic, health, safety, or environmental consequence that occurs due to a 

rule and is not already accounted for in the direct cost of the rule (e.g., 

adverse safety impacts from more stringent fuel-economy standards for 

light trucks).”

It is also directed by the EPA’s Guidelines for Preparation of Economic Analyses (p. 11-2, 

available at: http://yosemite.epa.gov/ee/epa/eed.nsf/pages/Guidelines.html):

“An economic analysis of regulatory or policy options should present all 

identifiable costs and benefits that are incremental to the regulation or 

policy under consideration. These should include directly intended effects 

and associated costs, as well as ancillary (or co-) benefits and costs.”

In line with this guidance, the EPA estimates all of the anticipated costs and benefits associated 

with a regulatory action, to the extent feasible. We further note that if we were able to fully 
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monetize all of the benefit categories, the benefits would exceed the costs by an even greater 

amount than we currently estimate.

EPA also notes that while the PM co-benefits are appropriately included in the benefit-cost 

analysis accompanying the rule, the benefit-cost analysis is not the justification for the rule. The 

rule is justified based on the requirements of the CAA, which requires EPA to issue standards to 

reduce HAPs for listed source categories.

5.2.2 Methodology Comments

5.2.2.1 Double counting of PM benefits in NESHAP, a pollutant 

regulated under NAAQS

Comment: Commenter 0106 states that the EPA includes no discussion of the extent to which 

those PM2.5 emissions eliminated by the proposed rule would otherwise meet or exceed the 

NAAQS, under which EPA has already determined the level of PM2.5 emissions that will protect 

public health with an adequate margin of safety. According to the commenter (0106), to the 

extent the eliminated PM2.5 emissions would have caused an exceedance of the NAAQS, the 

proposed rule is unnecessary and the claimed benefits “double-count” benefits that would be 

provided by the NAAQS. The commenter (0106) states that, to the extent the eliminated 

emissions would not have caused an exceedance of the NAAQS, the benefits claimed do not 

justify the proposed rule because they arise from more stringent reduction of PM2.5 than the 

Administrator has determined is necessary to protect public health under Section 109, which 

Congress intended to be the statutory basis for such determinations. The commenter (0106) 

concludes that the EPA’s complete reliance on PM2.5 emissions reductions to justify the 

proposed rule is contrary to the plain purposes of both Section 109 and Section 112 of the Act.

Furthermore, the commenter (0106) states that the EPA is double-counting the PM2.5 co-benefits 

reported in this RIA if the PM2.5 emissions that would be reduced under the Proposed Rule are 

likely to be subject to control under a forthcoming PM2.5 NAAQS SIP.

Response: The EPA disagrees with the commenter that the quantified PM2.5 health benefits are 

double-counted with the health benefits achieved by other regulations. The EPA’s standard 

practice for its rules is to estimate, to the extent data and time allow, all benefits of the emissions 

reductions achieved by a rule beyond control requirements for other rules. If this rule was 

duplicative with other rules, then there would be no additional costs or benefits attributable to 

this rule. 

When the EPA estimates the benefits for rules like this one, the EPA includes other rules in the 

“baseline”. Any emission changes expected as a result of this rule are additional emission 

reductions beyond those regulations that were considered to be part of the baseline. Therefore, 

the benefits from particle reductions are not double counting – they are real health benefits from 

emissions reductions achieved by this rule alone. 
159

Further, the PM2.5 health benefits expected from this rule are not double-counted with benefits 

estimated in the NAAQS Regulatory Impact Assessments. The NAAQS RIAs illustrate the 

potential costs and benefits of attaining a new air quality standard nationwide based on an array 

of emission control strategies for different sources. In short, NAAQS RIAs hypothesize, but do 

not predict, the control strategies that States may choose to enact when implementing a NAAQS. 

The setting of a NAAQS does not directly result in costs or benefits, and as such, the NAAQS 

RIAs are merely illustrative and are not intended to be added to the costs and benefits of other 

regulations that result in specific costs of control and emission reductions. However, some costs 

and benefits estimated in this RIA account for the same air quality improvements as estimated in 

the illustrative PM2.5 NAAQS RIA.

In implementing these rules, emission controls may lead to reductions in ambient PM2.5 below 

the PM NAAQS in some areas. It is important to emphasize that NAAQS are not set at a level of 

zero risk. Instead, the NAAQS reflect the level determined by the Administrator to be protective 

of public health within an adequate margin of safety, taking into consideration effects on 

susceptible populations based on the scientific literature available at the time the standard is set. 

While benefits occurring below the standard may be less certain than those occurring above the 

standard, the EPA considers them to be legitimate components of the total benefits estimate.

5.2.2.2 Use of a “benefits per ton” rather than location-specific air 

quality modeling

Comment: Commenter 0106 states that the EPA’s co-benefit estimates in the RIA are based on a 

generic analysis of PM2.5 concentrations resulting from emissions from the “ferroalloys sector” 

of the U.S. as a whole, and subsequent derivation of a “benefits per ton” (BPT) that might be 

reduced by the sector. The commenter (0106) states that the emissions patterns, and hence the 

BPT estimates used to produce the RIA’s co-benefits estimates are clearly not relevant to the 

changes in PM2.5 emissions that will result from this Proposed Rule. According to the commenter

(0106), the EPA’s technical document implies that there are four areas of the U.S. that the EPA’s 

BPT analysis assumes are affected by this sector’s emissions: two in south-central Alabama, one 

in south-central West Virginia, and one on the Ohio River in Ohio, but the Proposed Rule would 

only affect emissions from two production facilities, both of which are situated on the Ohio 

River. 

The commenter (0106) states that an important aspect of having the emissions be correctly 

located in a BPT analysis is that the predicted impacts to public health per ton emitted are highly 

dependent on the number of people living in the areas that are projected to have increased 

ambient concentrations as a result of the tons emitted. The commenter (0106) speculates that at 

least one of the Alabama areas appears to be in or near Montgomery County, with a population 

density of about 283 people per square mile, and the West Virginia area appears to be close to 

Kanawha County, with a population density of about 222 people per square mile. In contrast, the 

commenter (0106) states, the Felman plant is in Mason County, West Virginia, which has a 
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population density of about 60 people per square mile, and the EMI plant is in Washington 

County, Ohio which has a population density of about 100 people per square mile. The 

commenter (0106) concludes that a more correct location-specific modeling of the PM2.5 impacts 

from the EMI and Felman facilities would likely indicate EPA’s predicted co-benefits would be 

less than half what EPA’s RIA reports. The commenter (0106) describes inconsistencies in the 

tons of PM2.5 models vs. the proposed emissions reductions to be achieved by the rule. The 

commenter (0106) states that either the sector-specific BPT analysis is completely unreliable for 

assessing the co-benefits from this particular rule, or the RIA’s estimate of total tons of PM2.5 

that the Proposed Rule will reduce at these two facilities is far overstated. The commenter (0106) 

concludes that either of these possibilities implies that the EPA’s estimates of co-benefits in the 

RIA are invalid and should be disregarded.

Response: As discussed in the Fann, Fulcher and Hubbell (2009) article describing the benefit 

per ton methodology, the EPA is aware that differences between the source modeling used to 

derive the benefit per ton estimates and the policy context in which these coefficients are applied 

can introduce analytical uncertainty. Such differences can include the characteristics of the 

emitting source, the population density proximate to sources and meteorology, among others. 

While a similar limitations section does not currently appear in the “Estimating the Benefit per 

Ton of Reducing PM2.5 Precursors from the Ferroalloy Sector” Technical Support Document 

(TSD), the EPA will be adding such a section to future versions of the TSD. Modeling 

limitations typically preclude the development of localized benefit per ton estimates, though 

efforts are underway to develop regional benefit per ton estimates from the sector-based source 

apportionment modeling. At this time, however, only national level estimates are available for 

each sector. The Felman and Eramet plants are located in rural areas, suggesting that the benefit 

per ton estimates for directly emitted particles could be much lower than the national average. 

However, it is important to note that the benefits from HAP reductions (that we are currently 

unable to quantify) and not the co-benefits from PM reductions are used to determine the merits 

of the regulation.

5.2.3 Uncertainties in the Benefits Analysis

Comment: Commenter 0106 states that US EPA's use of PM2.5 as a surrogate for HAPs in the 

cost benefit analysis is highly uncertain because ferroalloy-associated PM2.5 is likely to be 

toxicologically very different from ambient PM2.5. The commenter (0106) adds that the 

uncertainty in using the concentration response functions (CRFs) for ambient PM2.5 to estimate 

benefits associated with reducing ferroalloy emissions is so significant as to render this approach 

too speculative to form a reliable basis for decision making.

The commenter (0106) discusses the impacts of regional differences in PM2.5 health effects and 

concludes that extrapolating a CRF for ambient PM2.5 to PM2.5 associated with fugitive emissions 

from the EMI facility is highly uncertain, as the chemical composition of ferroalloy-associated 

PM2.5 may be very different from that of ambient PM2.5. The commenter (0106) states that US 
161

EPA should either provide documentation that ferroalloy-associated PM2.5 is sufficiently similar 

to ambient PM2.5, or at a minimum discuss uncertainties with using ambient PM2.5 as a surrogate 

for ferroalloy-associated PM2.5.

Response: Ambient PM is comprised of a wide variety of different chemical species, including 

metals such as those emitted by ferroalloy plants. The air quality modeling used in estimating the 

benefit-per ton took into account emissions’ contribution from ferroalloy plants to ambient levels 

of PM2.5. Current advice from both the Clean Air Scientific Advisory Committee and the 

Advisory Council on Clean Air Compliance, which is to assume equal toxicity between all PM 

species because the science is not yet sufficient to allow differentiation of effect estimates by 

particle type. The commenter has not provided any support to the claim that particles directly 

emitted from ferroalloy plants are any less toxic than the ambient mix. In fact, several studies in 

the PM ISA indicate that metals could be more toxic than the ambient mixture. To the extent that 

these metals are more toxic, the benefits would be underestimated.

Comment: Commenter 0106 states that a key source of uncertainty in the ambient PM2.5

concentration response functions (CRF) relates to whether there is a threshold for adverse 

effects. Specifically, exposure measurement error, which is inherent in air pollution studies 

(including those by Pope et al., 2002 and Laden et al., 2006) due to use of measurements from 

centrally located monitors that can differ substantially from individual exposures, can cause a 

nonlinear CRF to appear linear. There is also uncertainty in the studies by Laden et al. (2006) 

and Pope et al. (2002), and the commenter describes some inconsistent/unexplained findings, 

such as:

 Statistically significant associations between PM2.5 and mortality observed only for 

people with high school education or less;

 Cardiopulmonary and lung cancer mortality paradoxically greater (although not 

significant) in never vs. current smokers;

 Protective effect of carbon monoxide on cardiopulmonary mortality and lung cancer; and

 Protective effect of total suspended particles on lung cancer.

The commenter (0106) states that another source of uncertainty in CRFs for PM2.5 is US EPA's 

reliance solely on the studies by Pope et al. (2002) and Laden et al. (2006).

Response: The EPA notes that we use concentration-response factors from the broadest time 

periods available to take advantage of the available data most comprehensively. The choice of 

relative risk estimates from Pope et al. (2002) and Laden et al. (2006) is supported by the EPA 

Advisory Council on Clean Air Compliance Analysis (Hammitt et al. 2010, available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/9288428b8eeea4c885257242006935a3/59e06b6c5ca

66597852575e7006c5d09!OpenDocument&TableRow=2.3#2.):
162

“Overall, the HES finds the EPA analyses, data choices, and methodologies 

to be sound. The EPA bases its estimates of the mortality benefits of 

reducing fine particulate matter (PM2.5) on data analyzed from two large, 

long-running landmark studies on the health effects of air pollution, the 

Harvard Six Cities Study and the American Cancer Society (ACS) Cancer 

Prevention Study (CPS). The HES finds the selection of these cohort studies 

as the underlying basis for PM mortality benefit estimates to be a good 

choice” (p. 1).

We further note that we also estimate mortality using functions derived by 12 experts in an EPAsponsored expert elicitation (Roman et al. 2008). The Pope et al. (2002) and Laden et al. (2006) 

studies were found to be near the 25th and 75th percentiles of the mortality effect estimates 

garnered from the expert elicitation. Our use of the expert elicitation functions provides one 

estimate of the range of possible impacts.

5.2.4 Limits of Statistical Analysis

Comment: Commenter 0106 notes that in 2009, the EPA decided to extrapolate the PM2.5 -

mortality association to assume risks from PM2.5 exposures at levels of PM2.5 that are far below 

the lowest level of ambient PM2.5 for which any statistical association has ever been observed. 

The lowest measured level (LML) in any of the long-term PM2.5 exposure studies represents the 

lowest possible bound for which there is any scientific evidence at all about shape of 

relationship. The commenter (0106) asserts that any assumptions about the shape of the doseresponse relationship below the LML is unsupported scientifically because there is a strong 

presumption that the degree of risk per incremental unit of PM2.5 exposure is likely to decline as 

PM2.5 concentrations fall to levels nearing zero. The commenter (0106) states that, to the extent 

that this presumption is valid for PM2.5 as it is for most other compounds, the risk estimates 

resulting from the EPA’s extrapolation are biased upwards and there is very little chance that the 

uncertainty would include a higher risk estimate.

The commenter (0106) states that the types of statistical analyses being used may be able to 

detect the existence of an association between mortality risk and long-term PM2.5 exposure, but 

those methods are very limited in their ability to define the shape of that function, even within 

the range of observed data (i.e., above the LML). The commenter (0106) adds that the problem 

becomes more pronounced at the lower concentrations and is concerned about the extent to 

which it has driven baseline estimates of PM2.5 mortality risks upward.

Furthermore, the commenter (0106) states that the EPA has never been able to identify the 

particular types of causes of death that account for its PM2.5 -mortality associations, but usually 

argues that cardiovascular deaths are the most likely candidate. According to the commenter, in 

2005, 35% of deaths in the U.S. were due to major cardiovascular diseases. The commenter 

(0106) states that if the predicted PM2.5 -related deaths are indeed cardiovascular in nature, 22% 

of all deaths being “due to PM2.5” would mean that nearly two-thirds of all cardiovascular deaths 
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in 2005 were “due to” PM2.5. The commenter (0106) states that, given all of the other risk factors 

that are considered major contributors to cardiovascular mortality, such as smoking and weight, 

it is not credible to have a PM2.5 co-benefit estimate that is implicitly assuming almost two-thirds 

of those types of deaths are due to PM2.5. The commenter (0106) concludes that the EPA’s cobenefits estimates should be viewed as highly overstated just from these statistical implications. 

Response: The EPA disagrees with the commenter that the EPA has never been able to identify 

association of exposure to PM with cardiovascular diseases. While the EPA’s risk assessment did 

not quantify cardiovascular-related premature deaths, several recent studies have found 

consistently strong relationships between long-term PM2.5 exposure and cardiovascular-related 

mortality risk. In its recent synthesis scientific statement, the American Heart Association (AHA) 

observed that “the overall evidence is consistent with a causal relationship between PM2.5

exposure and cardiovascular morbidity and mortality, stating:

“Many credible pathological mechanisms...lend biological plausibility to 

[the] findings” and that PM2.5 exposure increases the risk of premature 

death. It also concludes that: “PM2.5 exposure is deemed a modifiable factor 

that contributes to cardiovascular morbidity and mortality.”

Another most recent extended analysis of the American Cancer Society Cohort by the Health 

Effects Institute, HEI reported the greatest PM2.5 risk estimates for ischemic heart disease-related 

death.

The EPA adopted a no-threshold approach for benefits analyses, and updated its method for 

characterizing the uncertainty in its benefits estimates. This updated method is based on the 

number of estimated premature deaths at different PM2.5 concentrations including the lowest 

measured levels (LML) from the underlying epidemiology studies. Based on the science on 

PM2.5 and health, the EPA is confident that health effects occur below the levels in the 

considered studies – 10 μg/m3in one study, and 7.5 μg/m3in the other. We do however have 

somewhat less confidence in estimating the magnitude of those health effects at low levels. 

Actual benefits at those low levels could be higher or lower than we estimate, so we use the best 

estimate. More recent studies, including the new extended reanalysis of the American Cancer 

Society cohort, suggested that we should have confidence in our mortality estimates down to at 

least 5.8 μg/m3, the LML in this new study, and somewhat less confidence in estimates below 5.8 

μg/m3. In addition, when we have sufficient air quality modeling data for a rule, LML analyses 

estimate the percentage of PM2.5 -related premature deaths avoided at or above the LML. The 

number of premature deaths at different concentrations is a good approximation of the 

monetized, PM2.5 -related benefits at those concentrations.
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6.0 STARTUP, SHUTDOWN AND MALFUNCTION (SSM) PERIODS AND 

AFFIRMATIVE DEFENSE

6.1 SSM

Comment: Commenter 0074 states that the EPA does not have authority to amend existing 

MACT standards to make them more stringent. The commenter (0074) asserts that the EPA’s 

authority under CAA section 112(d)(6) is to “review and revise as necessary (taking into account 

developments in practices, processes, and control technologies), emissions standards 

promulgated under this section no less often than every 8 years.” According to the commenter

(0074), the EPA did not invoke its section 112(d)(6) authority to support the proposed SSM 

provisions, 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, the commenter (0074) concludes, the EPA cannot 

simply revisit and redo a MACT determination long after it has been issued, as the EPA attempts 

to do with the proposed SSM provisions. 

Response: As discussed elsewhere in this document, the EPA retains significant discretion in 

balancing relevant factors in determining whether it is “necessary” to revise the existing 

technology-based MACT standards. Sierra Club v. EPA, 325 F. 3d 374, 378 (D.C. Cir. 2003). In 

reviewing section 112 (d)(2) standards, and determining whether to revise them is “necessary” 

under section 112 (d)(6), the EPA may take into consideration cost and feasibility when 

evaluating developments in practices, processes, and control technologies. Indeed, it is 

reasonable that any such “review” consider the same factors which the EPA is required to 

consider under section 112 (d)(2) – cost, non-air environmental impacts, potential impacts on 

energy usage among them.

Additionally, the EPA relies on the Sierra Club decision for the elimination of the SSM 

exemption, not for its determination to require that during periods of startup and shutdown and

during periods of malfunction, sources must meet the standards that apply during normal 

operations. The EPA’s rationale for the standards that it set was discussed in the preamble for the 

proposed rule and elsewhere in this section.

Comment: Commenter 0074 states the proposed SSM provisions are not required in order to be 

consistent with Sierra Club v. EPA. The commenter (0074) states that the Sierra Club decision 

does not prevent the EPA from adopting emission standards for SSM periods that are different 

from those required during periods of normal operation. The commenter (0074) adds that the 

Sierra Club decision does not mean that the EPA is barred from using a “requirement relating to 

the operation or maintenance of a source to assure continuous emission reduction” as the 

emission standard that applies during such events. The commenter (0074) asserts that the Sierra 

Club decision only rejected the EPA’s assertion that it had discretion to decide not to impose any 

emission standard covering SSM periods. Thus, according to the commenter (0074), despite the 
165

EPA’s implications to the contrary, the Sierra Club decision expressly recognized that different 

standards, including non-numerical standards, may (and in some cases must) apply during nonstandard operating conditions, such SSM.

First, the commenter (0074) explains that the Sierra Club decision interpreted the NESHAPs 

General Provisions. The commenter adds that it did not by its terms address what the EPA may 

or may not include in category-specific MACT standards. Second, the commenter (0074) states 

that the Sierra Club decision did not say that the same emission limitations that the EPA has 

derived for normal operations must also apply during SSM events. The commenter (0074) states 

that Sierra Club does not preclude the EPA from applying different standards during SSM events 

than apply during normal operations. The commenter (0074) concludes that there is ample 

precedent for the EPA applying a different standard during SSM events. 

Third, the commenter (0074) states that the Sierra Club decision did not address whether the 

EPA could use a “design, equipment, work practice or operational standard,” as authorized under 

CAA section 112(h) and included in the definition of “emission limitation” and “emission 

standard” in CAA section 302(k), in lieu of a numerical emission limitation during SSM events. 

The commenter adds that the EPA cannot hide behind the Sierra Club decision as a justification 

for ignoring an inability of even the “best performers” to achieve during SSM events the 

emission limitations the EPA has established for normal operations. Moreover, the commenter 

concludes (0074) that the approach the EPA is proposing would not establish “continuous 

section 112-compliant standards” that the Sierra Club decision concluded are required.

Commenter 0073 states that the EPA has interpreted the Sierra Club decision regarding SSM too 

broadly, that the decision focused on the manner in which the EPA had implemented the SSM 

exemption under section 112 – not the validity of the exemption itself. The commenter (0073) 

asserts that the Sierra Club decision requires the EPA to establish standards under section 112 

that apply during all facets of a facility’s operation – whether an emission standard under section 

112(d) or a work-practice standard under section 112(h), but that it did not overrule significant 

pre-existing case law controlling how these standards must be developed. Thus, the commenter 

(0073) reasons, because a MACT standard is technology-based, it must be based on what 

technology can achieve, with the only difference being how the EPA must treat the 1% of 

operational periods when the EPA’s 99% UPL predicts even MACT cannot achieve the emission 

standards. The commenter (0073) states that these periods must be included within the MACT 

standard itself, regulated through an independent standard, such as a work practice standard 

where a specific emissions limit is impracticable, or excused through the mechanism of an 

affirmative defense. The commenter (0073) agrees with the EPA’s decision that an affirmative 

defense is the appropriate mechanism to implement the Sierra Club decision but it must remain 

in compliance with established case law regarding development of MACT standards.

Response: The EPA does not claim that the Sierra Club case constrains its authority to prescribe 

different standards for periods of start and shutdown or for periods of malfunction. However, as 
166

explained in the preamble to the proposed rules, the EPA has determined that CAA section 112 

does not require that emissions that occur during periods of malfunction be factored into 

development of CAA section 112 standards. 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). We have set the MACT standard at a 

level that a well-operated source should be able to meet during 99% of all stack tests, which we 

believe sufficiently accounts for variability. 

The EPA disagrees with the commenters’ contention that the Sierra Club decision addresses in 

any way the EPA‘s current approach to setting standards under 112(d). As explained in the 

preamble of the proposed rule, the EPA has determined that CAA section 112 does not require 

that emissions that occur during periods of malfunction be factored into development of CAA 

section 112 standards. While the EPA accounts for variability in setting emissions standards, a

malfunction is a failure of the source to perform in a ‘‘normal or usual manner’’ and no statutory 

language compels the EPA to consider such events in setting section 112 standards. Further, 

accounting for malfunctions in setting emission standards 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, in the event that a source fails to

comply with the applicable CAA section 112 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

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).

Comment: Commenter 0074 states that the EPA must fully justify applying the same emission 

limitations during startup and shutdown as during normal operations. The commenter (0074) 

states that there are numerous reasons why a source might not be able to comply, during periods 

of startup or shutdown, with emission limitations established based on performance during 

steady-state operation, even if the control devices used are started up before the process units and 

are operational during the shutdown phase of a process. The commenter (0074) believes the EPA 

must conduct a thorough analysis and determine whether it is representative of the performance 

of best-performing sources (the MACT floor) to require ferroalloys plants to achieve the same 

emission limitation during startup and shutdown as during normal operations. The commenter 

(0074) states that the EPA cannot conclude that special provisions for emissions during startup 
167

and shutdown are not needed based on “mere speculation.” The commenter (0074) believes that 

the default assumption must be that they are needed. The EPA previously determined, in 

establishing the existing subpart XXX standards, that the best performers on which the MACT 

standards were based may not achieve those standards during startup and shutdown. The 

commenter (0074) is skeptical that the EPA has conducted a sufficient analysis to demonstrate 

the achievability of the MACT emission limits established for normal operations during startup 

and shutdown events, because of likely limitations in the available data.

The commenter (0074) notes there are several reasons why adequate data often do not exist to 

allow the EPA to conclude that an emission limitation established for normal operations also 

represents the performance of the best demonstrated control technology during startups and 

shutdowns. The commenter (0074) adds that these factors would cause the EPA to understate 

emissions occurring during startup and shutdown. 

The commenter (0074) adds that an additional problem is that it can be unclear whether a 

condition that leads to excess emissions should be characterized as a startup or shutdown event 

or a malfunction event. The commenter (0074) believes that without a clear demarcation (both in 

the EPA regulations and in practice), the EPA may be analyzing data sets that exclude events

that were treated as malfunctions but that the EPA would say should be included in calculating 

average performance as startup or shutdown conditions.

Response: As noted in the proposal preamble, we considered startup and shutdown periods. 

Information on periods of startup and shutdown received from the industry in the ICR indicate 

that emissions during these periods do not increase. Control devices such as baghouses for metal 

HAP particulate control and activated carbon controls for mercury are started up before the 

process units, and are operational during the shutdown phase of a process. No increase in 

emissions is expected during these periods. Building or localized ventilation systems for process 

fugitive emissions will be in place at all times. Therefore, separate standards for periods of 

startup and shutdown were not proposed. Periods of startup, normal operations, and shutdown 

are all predictable and routine aspects of a source’s operations and not exempting emissions from 

compliance during these periods does not increase the stringency of the standard. 

Additionally, as part of the ICR data collection for this rule, the EPA requested that sources 

provide available data on whether the emission profile of the process units differs during startup 

and shutdown than during normal operating conditions and whether there is a temporary change 

to the emission profile of the furnace when starting a new furnace, one with a cleaned-out hearth, 

or one with a cold hearth after a long shutdown. One company simply responded “no.” The other 

company responded that they do not have any test data to indicate that the emissions profile is 

different during startup and shutdown events. The EPA notes that the control device must be 

operating during startup and shutdown events, which would ensure that the source (i.e., the 

furnace) would continue to meet the emission standards throughout these events. 
168

In response to treatment of test data that might include malfunctions, if any occurred, they should 

have been identified in the test report.

Comment: Commenter 0074 believes the EPA is required to take malfunctions into account 

when adopting emission standards. The commenter (0074) states that the EPA offers very little 

support for their assertion that “EPA’s approach to malfunctions” in setting emissions standards 

“is consistent with CAA section 112 and is a reasonable interpretation of the statute.” The 

commenter (0074) states that there is nothing in CAA section 112 that allows the EPA to ignore 

malfunctions and set MACT standards based on a level of emissions that even best-performing 

sources only achieve part of the time.

The commenter (0074) believes the EPA offers a backwards, results-driven rationale for ignoring 

malfunctions, which directly contravenes congressional intent that MACT floor standards be 

based on what the best sources actually achieve: “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 commenter (0074) states that the EPA cannot ignore the 

requirement that MACT floor standards reflect performance actually achieved just because the 

EPA would like the standards to be more stringent than that actual performance reflects. 

The commenter (0074) believes that by proposing MACT standards that the EPA recognizes 

even the best performing existing sources cannot achieve part of the time, the EPA is going 

beyond the MACT floor, yet without making the demonstrations that the statute and case law 

require the Agency to make in order to impose beyond-the-floor MACT standards. The 

commenter (0074) disagrees that the EPA acknowledges that malfunctions are inevitable, even 

for the best performing sources, and yet refuse to include emissions data representing 

malfunctions in calculating the MACT floor, and then require that those MACT floor limitations 

be met even during malfunctions. The commenter (0074) asserts that if it is possible to gather 

sufficient representative data reflecting emissions during malfunctions, then the EPA is obligated 

to consider those data in its MACT floor calculations for steady-state operating conditions.

The commenter (0074) suggests several options the EPA could use for setting MACT standards 

under CAA section 112 that would apply during malfunction events. The commenter (0074) 

states that the EPA might be able to establish an emission limitation that applies at all times, but 

that has an averaging time of sufficient duration that short, infrequent spikes in emissions due to 

malfunctions would not cause the source to exceed the emission limitation (while at the same 

time ensuring that the source does not operate in a way that causes frequent, lengthy excursions 

above the normal controlled emission rate). As an alternative, the commenter (0074) suggests 

that the EPA also could use the flexibility accorded by CAA section 302(k) (defining “emission 

limitation” and “emission standard” to include “any requirement relating to the operation or 

maintenance of a source to ensure continuous emission reduction, and any design, equipment, 

work practice or operational standard promulgated under” the CAA) to address emissions during 

malfunction events through operational requirements rather than by applying the same limits on 
169

pollutant concentrations in exhaust gases that apply during normal operations. The commenter 

(0074) adds that the EPA could have concluded that it has grounds to exercise its authority under 

CAA section 112(h) to promulgate a design, equipment, work practice, or operational standard, 

or combination thereof, because it is not feasible to prescribe or enforce an emission standard.

The commenter (0074) states that the proposed affirmative defense is not a substitute for 

addressing malfunction events in the emission standards themselves. The commenter (0074) 

asserts that the Proposed Standards, incorporating the affirmative defense, still do not represent 

emission limitations “achieved” by best-performing existing sources under CAA section 

112(d)(3), nor do they meet the criteria for establishing beyond-the-floor emission standards 

under CAA section 112(d)(2).

Response: 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, we are required to ensure that section 112 

emissions limitations are continuous. 

With respect to periods of startup and shutdown, the EPA agrees that in some circumstances 

separate standards for such periods may be appropriate. However as explained in the preamble to 

the final rule, we considered startup and shutdown periods. Information on periods of startup and 

shutdown received from the industry in the ICR indicate that emissions during these periods do 

not increase. Control devices such as baghouses for metal HAP particulate control and activated 

carbon controls for mercury are started up before the process units, and are operational during 

the shutdown phase of a process. Therefore, no increase in emissions is expected during these 

periods. Building or localized ventilation systems for process fugitive emissions will be in place 

at all times. Therefore, separate standards for periods of startup and shutdown were not 

proposed. Periods of startup, normal operations, and shutdown are all predictable and routine 

aspects of a source’s operations and not exempting emissions from compliance during these 

periods does not increase the stringency of the standard. 

As the EPA further explained in the preamble to the proposed rule, the EPA has determined that 

CAA section 112 does not require that emissions that occur during periods of malfunction be 

factored into development of CAA section 112 standards. A malfunction is a failure of the source 

to perform in a ‘‘normal or usual manner.’’ 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. Setting work practice standards for malfunction periods under 

section 112 presents the same issues as setting numerical emission limits given the varied nature 
170

of malfunctions. Thus the EPA does not agree with commenter’s suggestion that the EPA apply 

work practices for malfunction events. Regarding the suggestion to establish very short 

averaging times, we believe that this suggestion is more relevant to standards that rely on 

continuous emissions monitoring systems (CEMS). In this case, sources demonstrate compliance 

with emissions tests or opacity observations, which are by their nature, based on discrete periods 

of observation. In the case of fenceline monitoring, a relatively long averaging period is required 

to account for fluctuations in emissions and site conditions. 

Additionally, the EPA does not agree that it is possible to gather representative data reflecting 

emissions during malfunctions, in order to consider malfunctions in its MACT floor calculations. 

The EPA asserts that data collected during an event that meets the definition of malfunction is 

only representative of that malfunction, and the EPA could not assert that the event would be 

representative of the same kind of malfunctions that might happen in the future, even at the same 

source. The EPA further disagrees that the EPA could characterize any specific malfunction 

event or events as representative for a source category. 

Comment: Commenter 0074 states that the EPA has not justified changing the conditions that 

apply to performance testing. The commenter (0074) notes that the Proposed Rule would 

eliminate previously applicable portions of the NESHAPs General Provisions that (a) require that 

performance tests be conducted under “representative performance” conditions “(i.e., 

performance based on normal operating conditions) of the affected source” and (b) specify that 

“[o]perations during periods of startup, shutdown, and malfunction shall not constitute 

representative conditions for the purpose of a performance test.” The commenter (0074) refutes 

the EPA’s explanation for adding proposed §63.1625(a)(5) and eliminating reference to the 

NESHAPs General Provision on representative performance testing, that the former “eliminates 

the reference to SSM exemptions applicable to performance tests,” stating that the preamble does 

not even mention the similar provisions in proposed §63.1656(a)(6). The commenter (0074) 

states that the D.C. Circuit did not vacate the provision the EPA proposes to replace, in Sierra 

Club v. EPA. The commenter (0074) believes that decision in no way authorizes the EPA to (a) 

change existing MACT standards so that (b) the EPA could direct a source to conduct 

performance testing during abnormal operations, such as startups, shutdowns or malfunctions.

The commenter (0074) states that requiring sources now to demonstrate compliance with 

numerical emission limitations in the existing MACT standards, using performance tests or 

continuous monitoring, even while the source is in startup or shutdown mode or is experiencing a 

malfunction, definitely has the effect of making those existing MACT standards more stringent. 

The commenter (0074) asserts that the EPA cannot simply “amend” existing MACT standards in 

a way that can make those standards more stringent without first, providing an adequate 

justification for departing from the EPA’s previous judgment about the appropriate level of the 

standards and the appropriate conditions for performance testing, and, secondly, demonstrating 

that the revised standards would still meet the criteria of CAA section 112(d).
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Response: The EPA inadvertently omitted specific references to changes made to §63.1656(a)(6)

in the proposal preamble. However, as noted, we did discuss the comparable changes made to 

§1625(a)(5). The EPA does not find it necessary to change or supplement the rule, which 

specifies the conditions under which performance testing is to be conducted. The conditions for 

performance tests are contained in §§63.1625(a)(3) and 63.1656(a)(3), which specify that testing 

must be conducted under conditions that are representative of normal process conditions. We 

received no additional information from commenters to the proposed rule indicating that 

conditions during startup and shutdown warrant different emissions limitations. As explained 

above, this finding was confirmed by two individual company’s responses to the ICR. 

Comment: Commenter 0074 states that the EPA has not justified adding new “general duty” 

language to the existing subpart XXX MACT standards and recommends deleting proposed 

§§63.1623(h) and 63.1652(f) from the final rule. The EPA proposes to replace the NESHAPs 

General Provisions section that establishes a “general duty” to operate a source consistent with 

safety and good air pollution control practices for minimizing emissions, with somewhat

different “general duty” language in proposed §§63.1623(h) and 63.1652(f). The commenter 

(0074) states that since this change is not being proposed under CAA sections 112(d)(6) or 

112(f), the EPA therefore lacks authority to make this change to the existing MACT standards 

for Ferroalloys Production. The commenter (0074) refutes the EPA’s only explanation for 

proposed §63.1623(h) that the new general duty provisions are “to replace General Provisions 

requirements that reference vacated SSM provisions,” pointing out that the preamble does not 

even mention proposed new 63.1652(f).

The commenter (0074) states that even if the EPA had authority to make changes to the existing 

MACT standards not required to address residual risk or new technology, the EPA would have to 

provide a cogent explanation of why the old rule was unacceptable and the new rule is necessary, 

which the EPA has not done so. The commenter (0074) states that the EPA would need to repropose the provision with some explanation of the basis and purpose for the provision, to allow 

the public an opportunity to provide meaningful comments, as required by CAA section 

307(d)(3).

Response: The EPA disagrees with the commenter, in that the EPA does not lack authority to 

make the changes proposed. The EPA explained in the proposal that we were adding language to 

this regulation to replace General Provision requirements that reference vacated SSM provisions. 

(See Federal Register /Vol. 76, No. 226 /Wednesday, November 23, 2011 / Proposed Rules 

72523, 72534 and 72536). The EPA, to be consistent with the Sierra Club decision, has modified 

the general duty requirements that were contained in §63.6(e) and placed them, modified, in 

§§63.1623(h) and 63.1652(f). The general duty requirement language was modified to remove 

references to startup, shutdown, and malfunction plans that are no longer required and no longer 

apply in the absence of SSM exemptions, and references to SSM periods which are no longer 

exempt from applicable standards, but periods during which the general duty still applies. 
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6.2 Affirmative Defense

Comment: Commenter 0107 states that the affirmative defense allows facilities to escape 

penalties due to malfunctions if they meet factors that the EPA defines, which reduces the 

deterrent value of the MACT standard and undermines the ability of people living near facilities 

that violate the standard to receive effective relief from unlawful emissions. The commenter 

(0107) adds that this new loophole reinforces the need to recognize the additional risk that would 

occur from malfunctions. The commenter (0107) states that the new affirmative defense may 

make it more likely that malfunctions happen, by giving industry a way to evade penalties if 

facilities can show a violation was due to a malfunction. The commenter (0107) describes how 

they believe that affirmative defense that the EPA proposes goes against Congressional intent. In 

addition, according to the commenter (0107), the EPA has failed to demonstrate any need or 

rational justification for an affirmative defense to penalties to be written into the regulations and 

cause the harm that will result. The commenter (0107) concludes that even if the EPA had the 

authority to promulgate any type of affirmative defense, the EPA should make the following 

changes to promulgate strong reporting, monitoring, and other compliance requirements:

 A specific amount of compensatory penalties should apply to each reported malfunction 

(consistent with the Act). These funds should be dedicated to enforcement, inspections, 

and monitoring in the local community around the specific facility, to create greater 

assurance that malfunctions will not happen again. 

 The EPA must modify the regulations so that the affirmative defense cannot be used by a 

specific facility or company more than once within a set period of time, such as 10 years. 

The affirmative defense should become automatically unavailable to a facility that has 

previously had a malfunction within the last 10 years, to ensure that this defense does not 

swallow the value of the standards.

The commenter (0107) urges the EPA not to adopt an affirmative defense that undermines 

citizen rights and remedies under the Clean Air Act because people living near Ferroalloys 

Production Plants are exposed to unacceptably high levels of hazardous air pollution that no one 

should have to face simply because of where they live. The commenter (0107) concludes that the 

EPA must not retract or weaken citizen rights and remedies by making it more difficult for 

people to win meaningful relief from facilities that have released toxic air pollution into their 

communities for years.

In comments on the supplemental proposal, commenter 0276 supports the EPA’s removal of the 

proposed affirmative defense for civil penalties in the event of a malfunction. The commenter 

(0276) states that such provisions are unlawful, as the D.C. Circuit has held and the EPA 

appropriately determined it should be withdrawn.

Response: This comment is related to the affirmative defense provisions that were include in the 

2011 proposed rule (76 FR 72508). The affirmative defense provision was struck down in NRDC 

v. EPA, 749 F.3d 1055, 1063 (D.C. Cir. 2014). For this reason, the EPA has removed the 
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affirmative defense provisions in the 2014 supplemental proposal (79 FR 60238). Therefore, this 

comment on the provisions to affirmative defense is no longer applicable.

Comment: Commenter 0074 states that the EPA has not addressed apparent limitations and 

shortcomings of the affirmative defense, which make it an entirely inadequate substitute for 

setting MACT standards that include provisions for SSM events. The commenter (0074) states 

that the EPA has provided no analysis that would supersede its long-standing determination that 

it is not desirable to rely on enforcement, rather than regulatory language, to address the inability 

to comply with technology-based standards during SSM events.

The commenter (0074) also states that if the 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. 

First, 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 the 

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: While the EPA accounts for variability in setting emissions standards, a malfunction 

is a failure of the source to perform in a ‘‘normal or usual manner’’ and no statutory language 

compels the EPA to consider such events in setting section 112 standards. Further, accounting 

for malfunctions in setting emission standards 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. Based on the test data received from the facilities, we 

determined that no separate standards are needed to address emissions during these periods.

Comment: Commenter 0074 states that the EPA offers no defensible rationale for excluding 

startup and shutdown events from the proposed affirmative defense. The commenter (0074)

believes that there is no rational basis for the EPA not to provide the same kind of affirmative 

defense that it proposes to provide for malfunctions if in fact excess emissions from those units 

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.

Response: We determined that facilities in this source category can meet the applicable emission 

standards in the Ferroalloys Production NESHAP at all times, including periods of startup and 

shutdown; therefore, the EPA determined that no separate standards are needed to address 

emissions during these periods.

Comment: Commenter 0073 states that, in general, the affirmative defense language should be 

replaced with the language used at 40 CFR 122.41(n), the upset defense provided under the 

Clean Water Act. The commenter (0073) adds that the language is generally too narrow and 
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restrictive, noting that the proposed rules would excuse only events that do not “stem from any 

activity or event that could have been foreseen and avoided, or planned for”, while it is possible 

that events such as power failure or natural disasters may be “foreseen” and “planned for,” but 

still interfere with a facility’s ability to comply with the standards. The commenter (0073) states 

that these types of foreseeable yet unpreventable events must either be reflected in the overall 

MACT requirements, or excused as a malfunction. The commenter (0073) also states that the 

EPA should expand the proposed defense to address foreseeable yet unpreventable events.

Response: This comment is related to the affirmative defense provisions that were include in the 

2011 proposed rule (76 FR 72508). The affirmative defense provision was struck down in NRDC 

v. EPA, 749 F.3d 1055, 1063 (D.C. Cir. 2014). For this reason, the EPA has removed the 

affirmative defense provisions in the 2014 supplemental proposal (79 FR 60238). Therefore, this 

comment on the provisions to affirmative defense is no longer applicable.

Comment: Commenter 0074 believes that many aspects of the affirmative defense would make it 

unavailable as a practical matter for many, if not most, malfunctions. The commenter (0074) 

states 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. The commenter (0074) adds that several of the conditions for establishing an 

affirmative defense in proposed §63.1627(a) list numerous items which may be appropriate 

considerations in determining whether excess emissions during a malfunction should be 

considered a violation, but should not to be listed as mandatory criteria. The commenter (0074) 

states that a number 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 cost-effectiveness. The commenter (0074) believes that the affirmative 

defense, as proposed, leaves open the possibility that a source will be considered to be in 

violation because the enforcement authority decides subjectively that in one or more respects it 

would have been “proper” or “possible” for the source to take further steps to prevent or 

minimize the malfunction.

Three commenters (0071, 0073, 0074) suggest modifying the affirmative defense language if it is 

to be retained. Two commenters (0071, 0074) suggest specific language to remove ambiguity 

and contradictory language, and allow for notification via electronic communication methods. 

Specific comments regarding the affirmative defense criteria follow:

 Notification Requirements: One commenter (0073) states that availability of the 

affirmative defense should not be negated by a failure to notify, especially for events with 

small emissions. The commenter (0073) adds that the immediate notification 

requirements are duplicative of notification requirements under other rules, but do not 

include emission threshold triggers which reduce the burden of the other requirements. 

 Infrequent Events: One commenter (0073) states that restricting the malfunction defense 

to “infrequent” events is legally acceptable only if more “frequent” events are either 
175

included within the 99% UPL or excepted under some version of the startup/shutdown 

defense. The commenter (0073) adds that determining whether the event is sufficiently 

“infrequent” to merit application of the defense is highly subjective and vague and does 

not put Felman on notice of the type of behavior that is necessary to comply with the law.

 Off-Shift and Overtime Labor: One commenter (0073) requests that the EPA delete the 

requirement to use off-shift and overtime labor because it impairs the ability to respond in 

a manner that is most appropriate to the circumstances.

 Severe Property Damage: According to one commenter (0073), the word “severe” should 

be removed from the requirement for measure of property damage due to its ambiguity.

 Signed Operating Logs: One commenter (0073) states that the requirement for “signed” 

operating logs should be removed because it conflicts with the common practice of using 

electronic logs.

 Control Systems Were Kept In Operation “If at All Possible”: One commenter (0074)

states that the proposed §63.1627(a)(6) requires, as a condition for the affirmative 

defense, that all emissions “control systems were kept in operation if at all possible.” The 

commenter (0074) believes that the phrase “if at all possible” should not be used because 

it is an extreme term that bears no relation to good air pollution control practices. 

Additionally, the commenter (0074) believes that this provision should be qualified, as 

the EPA has qualified similar provisions in the NESHAP General Provisions in §63.6.

 By Passing Control Equipment: One commenter (0074) is also against the proposed 

§63.1627(a)(4) that would preclude a facility from taking advantage of the affirmative 

defense if the malfunction involved bypassing control equipment or a process and the 

bypass was not “unavoidable to prevent loss of life, severe personal injury, or severe 

property damage.” The commenter (0074) states that this language is stated in such 

strong terms that it may be difficult or impossible for a source to demonstrate that it 

meets this criterion, even though bypassing the control equipment or the process was an 

appropriate exercise of good air pollution control practices. The commenter (0074) adds 

that there is nothing inherent to standards under CAA section 112 that requires a source 

to avoid bypassing control equipment to such a degree. Lastly, the commenter (0074) 

states that it is not apparent, and the EPA has not attempted to explain, why the CAA 

would disfavor bypassing “a process” in this way.

 Excess Emissions: One commenter (0074) believes the paragraph in proposed 

§63.1627(a)(5) should be eliminated: “All possible steps were taken to minimize the 

impact of the excess emissions on ambient air quality, the environment and human 

health.” In addition to the subjective term “all possible steps,” the commenter (0074) 

believes this provision again presents a disconnect between the absolute and extreme 

requirement of the affirmative defense and the provisions of the CAA designed to attain 

ambient air quality standards and protect human health and the environment. The 

commenter (0074) states that the CAA does not require sources to take “all possible 

steps” to control emissions, even to minimize the impact of hazardous air pollutant 
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emissions on human health under CAA section 112(f). In addition, the commenter (0074) 

finds it is unclear how this criterion for qualifying for the affirmative defense differs from 

proposed §63.1627(a)(3) which requires that the frequency, amount, and duration of 

excess emissions “were minimized to the maximum extent practicable.” 

 Malfunction Report: Commenter 0074 requests that malfunction reporting be required on 

a semi-annual basis, for malfunctions that occurred during the preceding 6 months, which 

is the same frequency as similar reports pursuant to NESHAPs and Title V requirements. 

The commenter (0074) states that this change would enable the EPA to review the 

source’s compliance history and the measures being taken to address malfunctions, 

without imposing unworkable reporting deadlines, or potentially encouraging sources to 

bombard the Agency with reports for malfunctions that may not ultimately result in the 

source exceeding the 30-day average emission limitation. The commenter (0074) adds 

that the EPA has not justified departing from its conclusion, reflected in the current 

subpart XXX standards, that semi-annual reporting of malfunctions is sufficient.

Response: This comment is related to the affirmative defense provisions that were include in the 

2011 proposed rule (76 FR 72508). The affirmative defense provision was struck down in NRDC 

v. EPA, 749 F.3d 1055, 1063 (D.C. Cir. 2014). For this reason, the EPA has removed the 

affirmative defense provisions in the 2014 supplemental proposal (79 FR 60238). Therefore, this 

comment on the provisions to affirmative defense is no longer applicable.

Comment: Commenter 0074 states that the requirement in proposed §63.1627(a)(9) that the 

source “have prepared a written root cause analysis to determine, correct and eliminate the 

primary causes of the malfunction and the excess emissions resulting from the malfunction event 

at issue” again does not implement the statutory criteria for standard-setting under section 112. 

The commenter (0074) is concerned that read literally it would mean that a source could never 

take advantage of the affirmative defense if the source was unable to determine the primary 

cause of the malfunction or was unable to correct that cause. The EPA has defined a malfunction 

as an event that is “unavoidable” and unforeseeable, and “not reasonably preventable.” It 

therefore should be expected that in many cases the primary cause(s) of the malfunction will not 

be ascertainable, or it will not be possible to identify a way to ensure the malfunction will not 

recur. In addition, the commenter (0074) is concerned that requiring the facility to eliminate the 

primary causes of the malfunction, without regard to “taking into consideration the cost of 

achieving such” elimination and the “non-air quality health and environmental impacts and 

energy requirements” associated with its elimination is unreasonable and entirely inconsistent 

with the criteria for standards established under CAA section 112(d). 

Commenter 0073 states that the requirement to perform a root cause analysis is vague and does 

not put Felman on notice of the type of analysis that the EPA will deem sufficient, or the time in 

which such an analysis must be performed. According to the commenter (0073), such an analysis 
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is also unnecessarily burdensome and serves no environmental protection purpose for many 

malfunction events where the “root cause” is clearly identifiable (e.g., power outage, hurricane).

Commenter 0071 asserts that the EPA’s use of the term “root cause analysis” implies a specific 

formal process. The commenter (0071) notes that for many malfunctions, the cause is 

immediately obvious and a formal process for determining the cause is not needed. The 

commenter (0071) adds that a formal root cause analysis is typically limited to very significant 

events or repeat events (e.g., the first time a thermocouple fails, the most likely cause is a bad 

thermocouple, but if a second one fails within a short period of time, then something else may be 

causing that event to happen and a more detailed analysis may be needed.) The commenter 

(0071) adds that the proposed language assumes that all malfunctions are equally significant and 

need an identical degree of investigation (e.g., a missing data point due to a malfunction of the 

data acquisition system is not as significant as a power failure or a catastrophic event such as fire 

or explosion). The commenter (0071) believes that a formal root cause analysis should only be 

used when other reasonable methods fail to show what caused the malfunction or when the 

serious nature of an event might make such an analysis necessary. The commenter (0071) states 

that other tools may be more appropriate (e.g., failure mode and effect, fault tree, etc.) or more 

powerful tools may be introduced in the future. The commenter (0071) concludes that the facility 

is the only one that can and should decide what tool to use to determine the cause of the 

malfunction. 

The commenter (0071) states that if the EPA intends for the facility to investigate and fix the 

source of the malfunction so that it is less likely to recur, they support that concept but suggests 

that the Agency use an alternative term that does not carry a specific meaning. However, if the 

Agency envisions a formal process for determining the root cause for every malfunction, no 

matter how simple, the commenter (0071) believes this is unnecessary and would result in excess 

efforts with no environmental gains. 

Response: This comment is related to the affirmative defense provisions that were include in the 

2011 proposed rule (76 FR 72508). The affirmative defense provision was struck down in NRDC 

v. EPA, 749 F.3d 1055, 1063 (D.C. Cir. 2014). For this reason, the EPA has removed the 

affirmative defense provisions in the 2014 supplemental proposal (79 FR 60238). Therefore, this 

comment on the provisions to affirmative defense is no longer applicable.

Comment: Commenter 0071 expresses concern that labeling malfunctions as an affirmative 

defense before it has been established to be a deviation improperly shifts the burden to the 

facility. The commenter (0071) suggests that the EPA should establish a rebuttable presumption 

where it is presumed that the facility did everything in their power to minimize emissions during 

malfunctions, unless the Agency proves certain facts that are enumerated in the rules, allowing 

the Agency to challenge the alleged deviation without compromising the legal rights of either 

party. 
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Commenter 0074 states that even if the proposed affirmative defense were not unreasonably 

restrictive, being able to assert a defense obviously is not the same as complying with emission 

limitations that are properly set in accordance with CAA section 112. The commenter (0074) 

believes that the affirmative defense places the source in the position of proving its innocence, 

rather than the EPA or another enforcement authority having to prove that the source violated the 

CAA. 

The commenter (0074) also finds it unclear where the EPA finds the 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 (0074) states that the EPA has not provided any statutory 

authority for requiring a source to prove its innocence, including fully demonstrating its 

innocence within 45 days of the event, without even being charged. 

Response: This comment is related to the affirmative defense provisions that were include in the 

2011 proposed rule (76 FR 72508). The affirmative defense provision was struck down in NRDC 

v. EPA, 749 F.3d 1055, 1063 (D.C. Cir. 2014). For this reason, the EPA has removed the 

affirmative defense provisions in the 2014 supplemental proposal (79 FR 60238). Therefore, this 

comment on the provisions to affirmative defense is no longer applicable.

Comment: Commenter 0074 believes it is not clear what the affirmative defense covers. 

According to the commenter, where the EPA states that the affirmative defense is “to a claim for 

civil penalties for exceedances of such standards that are caused by malfunction, as defined in 

§63.2,” the term “civil penalties,” is ambiguous. The commenter (0074) states that it is also 

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 (0074) also states 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 

(0074) states, as a matter of law, injunctive relief may not be available in cases where a civil 

penalty cannot be imposed. The commenter (0074) adds that maintaining liability for injunctive 

relief renders the affirmative defense particularly ineffective with respect to citizen suits. 

According to the commenter (0074), 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 the 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.

The commenter (0074) believes, at a minimum, the EPA should state that the affirmative defense 

applies to civil penalties, civil administrative penalties, noncompliance penalties, and injunctive 

relief, in an action brought by the EPA, a state, or a citizen-suit plaintiff. The commenter (0074) 

adds that the EPA also should reword the “affirmative defense,” so that it states that a source 
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“will not be deemed in violation of” the MACT standards for excess emissions or other 

deviations from the standards, associated with a startup, shutdown, or malfunction event, unless 

the event, and the source’s response to the event, do not meet the criteria spelled out in the 

regulations. The commenter (0074) suggests this provision for malfunction should be called 

something other than an “affirmative defense,” such as an “alternative standard for SSM events.”

Response: This comment is related to the affirmative defense provisions that were include in the 

2011 proposed rule (76 FR 72508). The affirmative defense provision was struck down in NRDC 

v. EPA, 749 F.3d 1055, 1063 (D.C. Cir. 2014). For this reason, the EPA has removed the 

affirmative defense provisions in the 2014 supplemental proposal (79 FR 60238). Therefore, this 

comment on the provisions to affirmative defense is no longer applicable.

7.0 OTHER COMMENTS

7.1 Overall Support

Comment: According to commenter 0107 even though EPA’s proposed rule needs improvement, 

the commenter appreciates that the EPA is proposing standards that the EPA believes will reduce 

health risk. The commenter (0107) also commends EPA for collecting emission test data from 

existing facilities using section 114 of the Clean Air Act. The commenter (0107) agrees that this 

is an important starting point for the EPA’s rulemaking. The commenter (0107) adds that, as the 

agency has recognized, in explaining the need for electronic reporting: “EPA and other 

authorities such as state, local and tribal agencies must have performance test data to conduct 

effective reviews of CAA sections 112 and 129 standards, as well as for many other purposes 

including compliance determinations.”

Response: The EPA appreciates the commenter’s support.

Comment: Because of the adverse health effects associated with exposure to the substances 

emitted by Ferroalloys Production facilities, commenter 0065 is pleased that the EPA is 

proposing additional control requirements in this action. The commenter (0065) commends EPA 

for identifying additional HAP for control (HCl, mercury, PAH and formaldehyde) and for 

proposing new limits that reflect technological advances and the reduced emissions of which 

sources are capable.

Response: The EPA appreciates the commenter’s support.

Comment: One commenter (0268) supports the supplemental proposal.

Response: The EPA appreciates the commenter’s support.

7.2 Request for Extension/Additional Review

Comment: Prior to the end of the original public comment period deadline (January 9, 2012), 

three commenters (0051, 0053, 0055) requested that the EPA extend the original comment 
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period on the proposed rule by 45 days, to a total of 90 days. The commenters (0051, 0053, 

0055) noted the complexity of the rule, the lack of a ferroalloys trade association to provide 

assistance in developing comments, the short duration of the original comment period, the 

federal holidays included in the comment period, and the EPA’s initial failure to provide certain 

necessary information. After receiving tentative notice from the EPA that the comment period 

would be extended by 22 days, one commenter (0051) entered another comment (0059) 

repeating their original request for a total of 90 days.

Response: The EPA formally extended the comment period by 22 days to January 31, 2012 in a 

Federal Register announcement published on December 29, 2011 (76 FR 81903). The length of 

the comment period was balanced against the time needed for the EPA to evaluate the public 

comments and prepare the promulgation package to meet the required court settlement date of 

June 29, 2012. The EPA believes that the 45-day comment period and the additional 22-day 

extension provides sufficient time to comment on the proposed rule.

Comment: Prior to the end of the supplemental proposal public comment period deadline 

(November 20, 2014), two commenters (0051, 0053) requested that the EPA extend the comment 

period on the supplemental proposal by 75 days, to a total of 120 days. The commenters (0051, 

0053) noted the complexity of the rule requires a multidisciplinary technical review, a 120-day 

public comment period would allow EMI to submit additional emissions data, the lack of a 

ferroalloys trade association to provide assistance in developing comments, the short duration of 

the original comment period, the federal holidays included in the comment period, and the EPA’s 

initial failure to provide certain necessary information. After receiving tentative notice from the 

EPA that the comment period would be extended by 18 days to December 8, 2014, one 

commenter (0051) entered another comment (0059) requesting an additional extension of 11 

days to December 19, 2014.

Response: The EPA formally extended the comment period for the supplemental proposal by 18

days to December 6, 2014 in a Federal Register announcement published on November 14, 2014

(79 FR 68152). Based on the additional request, the EPA further extended the comment period 

for the supplemental proposal by an additional 11 days in a Federal Register announcement on 

December 5, 2014 (79 FR 72160). EPA believes that the 45-day comment period and the 

additional 29-day extension provides sufficient time to comment on the supplemental proposal.

Comment: In their comments on the supplemental proposal, commenter 0272 states that the 74-

day public comment period did not provide a meaningful opportunity to participate in the 

complex rulemaking. They noted that the 1999 NESHAP only addressed a single HAP (e.g., 

manganese), whereas the supplemental proposal regulates 5 HAPs under a broad range of 

regulatory rationales under Section 112 of the CAA and include a MACT Floor under Section 

112(d)(3), technology review under Section 112(d)(6), and risk based standards under Section 

112(f)(2). They believe that the complexity of this rulemaking affects the amount of time 
181

reasonably necessary to review and comment on the supplemental proposal, in addition to the 22 

separate requests in the supplemental proposal for comment. 

The commenter (0272) also added that EPA only provided a portion of the technical basis for the 

supplemental proposal and failed to provide the digital files necessary to reproduce and 

meaningfully review the air modeling and risk assessments that were used for this rulemaking. 

They believe that the items that were put in the docket only provided EPA’s conclusions, but did 

not provide enough information to understand how and why these conclusions were reached. 

Response: The preamble to the proposed rule originally provided for a 45-day comment period. 

The EPA received numerous requests for extending the public comment period and, based on the 

information provided in the requests, the EPA determined that an extension of 29 days was 

appropriate. In addition to the files in the docket, we provided additional digital data summary 

files to the commenters that allowed them to review and reproduce the findings in the 

supplemental proposal. We believe that the extended public comment period and the digital data 

summary files have been sufficient as evidenced by the detail of the responses received.

7.3 Object to Additional Testing or Data Gathering

Comment: Commenter 0069 states that they complied with the EPA’s April 2010 information 

collection request, including performing an extensive stack and solids test program. The 

commenter (0069) notes that the EPA reserves the right to gather additional information on the 

non-manganese producing ferroalloy facilities, and objects to the gathering of additional 

information from these "other types of ferroalloys production facilities," noting that they were 

subject to the same extensive ICR test program as the two ferrosilicomanganese facilities, and

they do not believe that any additional mandatory testing or data gathering should be imposed on 

the remainder of the industry.

The commenter (0069) states that the EPA has not identified the legal basis for its authority to 

require additional data collection from the ferroalloy industry, and reserves its right to object to 

duplicative or excessively burdensome data requests in the future. The commenter (0069) 

reminds EPA that it must have the approval of the Office of Management & Budget before 

requiring ferroalloys facilities to incur additional data collection costs.

Response: The EPA will conduct any future information gathering consistent with the authority 

provided by section 114 of the CAA.

7.4 Citizen Involvement in the Rulemaking Process

Comment: Two commenters (0077, 0099) state that they are glad that the EPA collected 

emission information to use in this rulemaking from the industry. The commenters (0077, 0099) 

add that as members of a local group, Neighbors for Clean Air, in Marietta, Ohio, they have 

worked on this issue for over 10 years. The commenters (0077, 0099) wish that that the EPA had 
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contacted them about this rulemaking so that they could have provided information sooner in the 

EPA’s process. 

Response: The agency believes that it is important to work closely with community 

organizations, local and state governmental agencies and with its regional offices, to ensure that 

the public is made aware of its rules and policies and is provided with the opportunity to provide 

feedback. Additionally, part of the agency’s community outreach strategy is to disseminate 

information to the public in a manner that is accessible to everyone. The agency will continue to 

conduct outreach with communities on the Ferroalloys rule, and we encourage your participation 

in these efforts.

7.5 Other

Comment: Commenter 0107 provides information on several compliance and violation issues 

associated with the Eramet facility, including an incident in 2008 when an Ohio EPA official 

took photographs of a substantial brown, reddish cloud coming from the facility and released 

them. The commenter (0107) states that the facility was unable to identify the cause of this 

incident and the community continues to be concerned about uncontrolled emissions. The 

commenter (0107) provides additional compliance and violation information that is in the record, 

including OH EPA orders from 2005, 2007, and 2009.

Response: We have made several revisions to the existing rule that we believe will substantially 

improve the capture and control of emissions from both plants in this source category. We have 

also provided enhanced monitoring provisions that will help the plants maintain the performance 

of their control systems by providing timely feedback in the need for system adjustments and 

repairs.

Comment: In their comments on the supplemental proposal, commenter 0272 believes that they 

should not be compelled to publish Method 9 opacity test results on its company website and/or 

“State dashboards.” They stated that the EPA cites no statutory authority under Section 112 or 

otherwise for the premise that it may dictate the information private parties place on their 

websites, including the specific location within those websites, nor is the commenter aware of 

such authority. Since the results of compliance tests will be provided to regulatory authorities, 

who are free to publish such results in a variety of ways, including through their own websites, 

this concept amounts to government-compelled private speech without any substantial 

justification.

Response: The final rule does not contain any requirements for the facility to publish Method 9 

opacity results on its company website and/or “State Dashboards.”