1

United States Environmental Protection Agency

Research Triangle Park, NC 27711

MEMORANDUM

SUBJECT: Emission Standards for Meeting the Ninety Percent Requirement Under Section 

112(c)(6) of the Clean Air Act

FROM: Nathan E. Topham, Environmental Engineer

Metals and Minerals Group, SPPD (D243-02)

TO: DOCKET ID: EPA-HQ-OAR-2004-0505

DATE: February 18, 2011

Section 112(c)(6) of the Clean Air Act (CAA) requires that EPA promulgate emission 

standards assuring that sources accounting for not less than ninety (90) percent of the aggregate 

emissions of each of the hazardous air pollutants (HAP) enumerated in section 112(c)(6) are 

subject to emission standards under section 112(d)(2) or (d)(4).1 This memorandum describes 

how the Agency is satisfying this obligation under CAA section 112(c)(6) for all seven HAP. 

This document describes the 1990 base-year emissions inventory that is used as the baseline for 

determining whether EPA has promulgated sufficient standards to meet the section 112(c)(6) 90 

percent requirement (hereinafter referred to as the “1990 baseline inventory” or “section 

112(c)(6) baseline inventory”). Specifically, the document discusses the 1998 Federal Register 

notice that presents this 1990 baseline inventory and the source categories determined at the time 

to be needed to meet the 90 percent requirement for each of the seven HAP in section 112(c)(6). 

The document also describes updates made to the 1990 baseline inventory since the 1998 notice, 

and any associated changes to the source category list. Appendix I to this memorandum presents 

the updated 1990 baseline inventory for section 112(c)(6) and the source categories that EPA has 

 

1The seven HAP enumerated in section 112(c)(6) of the CAA are: Polycyclic organic matter (POM), 2,3,7,8-

tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), polychlorinated biphenyls (PCBs), 

mercury, hexachlorobenzene (HCB) and alkylated lead compounds.
2

concluded are needed to meet the 90 percent requirement for each of the seven section 112(c)(6) 

HAP. Appendix II provides the name of the emission standards and Code of Federal Regulation 

reference for each of the source categories identified in Appendix I. 

In 1998, EPA issued a document entitled Source Category Listing for Section 112(d)(2) 

Rulemaking Pursuant to Section 112(c)(6) Requirements, 63 FR 17838, 17839 (1998). In that 

document, EPA explains how it developed a 1990 base-year emissions inventory for the seven 

HAP enumerated in section 112(c)(6) of the CAA as the baseline for determining whether 90 

percent of those emissions are subject to standards. In the same notice, based on that inventory, 

EPA identified the source categories that EPA believed at the time were necessary to meet the 90 

percent requirement in section 112(c)(6). That 1990 baseline inventory and the category listing 

have undergone several updates since their initial publication in 1998. For example, in a notice 

dated November 8, 2002, EPA identified five area source categories that were no longer needed 

to meet the section 112(c)(6) ninety percent requirement. National Emission Standards for 

Hazardous Air Pollutants: Revision of Source Category List for Standards Under Section 

112(c)(6) and 112(k) of the Clean Air Act, 67 FR 68124 (2002).2 Further, in the same notice, 

EPA removed the Open Burning of Scrap Tires source category from the 1990 baseline 

inventory. Due to some of these updates, EPA promulgated emission standards for several 

additional source categories while determining that certain categories or subcategories are not 

necessary to meet the 90 percent requirement under section 112(c)(6). These updates and 

resulting actions are described in more detail below.

 

2 The five area source categories are as follows: (1) asphalt hot-mix production; (2) fabricated metal products; (3) 

paint and allied products; (4) paper coated and laminated; (5) packaging and transportation equipment 

manufacturing. Open burning of scrap tires was also removed from the 112(c)(6) and 112(c)(3) inventories. Open 

burning of scrap tires results from arson, accident, or lightning. There is no industry that uses open burning of scrap 

tires (this practice is banned in all 50 states). Therefore, it is not considered a source appropriate for regulation under 

section 112 of the CAA. 
3

I. Additional section 112(c)(6) Source Categories

A. Electric Arc Furnaces 

Electric arc furnace (EAF) steelmaking was not included in the section 112(c)(6) baseline 

inventory published in the 1998 notice. Mercury emissions from EAF during 1990 were 

evaluated during the development of the EAF area source rule pursuant to section 112(c)(3) and 

(k)(3)(B) of the CAA. Based on scrap steel charged in EAFs during 1990 (38 million tons) and a 

revised emission factor3from scrap steel, the 1990 base-year mercury emissions from this 

category were estimated to be 7.8 tons. As shown in Appendix I, we determined that we needed 

the EAF area source category to meet the 90 percent requirement for mercury under section 

112(c)(6). Accordingly, in December 2007, EPA promulgated emission standards for EAF area 

source steelmaking facilities. National Emission Standards for Hazardous Air Pollutants for 

Area Sources: Electric Arc Furnace Steel Making Facilities, 72 FR 74088 (2007). This rule 

included mercury emission standards based on maximum achievable control technology 

(MACT), as required by section 112(c)(6), and standards based on generally available control 

technology to fulfill section 112(k)(3)(B) obligations for other HAP. 

B. Gold Mine Ore Production and Processing

The section 112(c)(6) baseline inventory published in 1998 did not include gold mine ore 

production and processing. At that time, there was very little available information on mercury 

emissions from gold mine ore production and processing. Since the 1998 notice, a substantial 

amount of data and information have become available on mercury emissions from this source 

category. For example, in 2000, the first estimates of mercury emissions from this source 

 

3

Prepared for U.S. Environmental Protection 

Agency, Office of Air Quality Planning and Standards, Sector Policies and Program Division, Metals and Minerals 

Group. July 18, 2007. Docket Item 0070 in EPA Docket Number OAR-2004-0083.
4

category were published in the Toxics Release Inventory (TRI), largely because of the lower TRI 

reporting threshold for mercury that went into effect about that time. Following this, from 2001 

to 2005, additional data and information were collected through the Voluntary Mercury 

Reduction Program (VMRP), which was a collaborative agreement between the State of Nevada 

Division of Environmental Protection (NDEP), EPA’s Region 9 Office, and four gold mining 

companies. Then, in 2005-2006 the EPA’s Office of Air Quality Planning and Standards 

(OAQPS) and the NDEP sent questionnaires to a number of companies seeking additional 

information and data on mercury emissions. Moreover, starting in 2007, the NDEP has been 

requiring all facilities in Nevada to conduct annual mercury emissions tests. 

Based on these data collected over the past several years, which included information 

about the industry processing and production levels and activities in the early 1990s, EPA has 

estimated that gold mine ore processing and production emitted about 4.4 tons of mercury in 

1990.4 These estimated mercury emissions in the 1990 inventory for gold mine ore processing 

and production are based on emissions from the following thermal processes at gold mine ore 

processing and production facilities: roasters, autoclaves, carbon kilns, pregnant storage solution 

tanks (“preg tanks”), electrowinning, melt furnaces, and retorts. 

As shown in Appendix I, we determined that we needed the gold mine ore production and 

processing area source category to meet the 90 percent requirement for mercury under section 

112(c)(6). Accordingly, in 2010 EPA promulgated MACT standards for mercury emissions 

from this source category. National Emission Standards for Hazardous Air Pollutants: Gold 

Mine Ore Processing and Production Area Source Category; and Addition to Source Category 

List for Standards-Final Rule, signed by the EPA Administrator on December 16, 2010.

C. Sewage Sludge Incineration (SSI)

 

4

See Docket ID EPA-HQ-OAR-2010-0239-0175.
5

In the 1998 notice, SSI was not among the source categories identified for regulation 

under section 112(c)(6). As discussed in this memorandum and shown in the inventory in 

Appendix I, there have been a number of updates to the section112(c)(6) baseline emission 

inventory for mercury since the 1998 notice. Based on the updated mercury baseline inventory, 

EPA has determined that additional source categories, including SSI, are needed to meet our 90 

percent requirement for mercury under section 112(c)(6).

II. Categories Not Needed to Meet the 90 Percent Requirement 

A. Gasoline Distribution (Aviation) 

In the 1998 notice, EPA identified the Gasoline Distribution (Aviation) source category 

for listing due to its alkylated lead emissions. Aircraft use two general types of fuel: aviation 

gasoline (avgas) and jet fuel. Avgas, which is used for powering piston engine aircraft, is the 

source of alkylated lead emissions in the source category. Alkylated lead is added to avgas to 

reduce engine knock and help lubricate internal engine components. Research is underway to 

find alternatives to lead for use in avgas. 

While characterizing evaporative emissions of alkylated lead compounds from aviation 

gasoline, we became aware of other alkylated lead compounds emissions associated with 

alkylated lead compounds production in 1990. There was one remaining U.S. facility that 

manufactured alkylated lead compounds in 1990. Through discussions with industry 

representatives and technical evaluation of the information supplied, we have been able to 

quantify an estimate of the 1990-base year alkylated lead emissions for the Alkylated Lead 

Production source category and have added this information and data to the section 112(c)(6) 

baseline inventory. Based on information provided in the Toxics Release Inventory (TRI), we 

identified reported annual emissions of total lead compounds from a single alkylated lead 
6

production facility of 22 tons in 1990. The TRI did not provide the amount of alkylated lead in 

the total. Further analysis of the emission inventory submitted to the State produced an estimate 

of actual alkylated lead emissions from this facility of approximately 18 tons in 1990. As shown 

in Appendix I, the Alkylated Lead Production source category contributed 99.7 percent of the 

alkylated lead compounds emissions in the updated 1990 baseline inventory.5 Alkylated lead 

compounds production is regulated by the Hazardous Organic NESHAP (HON), subpart F.6 

EPA has therefore met the 90 percent requirement under section 112(c)(6) for alkylated lead. In 

light of the above, we conclude that we do not need Gasoline Distribution (Aviation) to meet the 

90 percent requirement for alkylated lead under section 112(c)(6). 

Alkylated lead emissions from gasoline distribution source categories have also been 

updated since the 1998 notice. A review of the 1990 alkylated lead emissions from the 

distribution of leaded gasoline revealed that the inventory data were based on inaccurate 

estimates of equipment component counts and leak emission factors.7 Analysis showed that 

when the corrected equipment leak data are used, the total estimated 1990 alkylated lead 

emissions from leaded gasoline distribution would be less than 1⁄2 the estimate in the 1990

inventory published in the 1998 notice. We have revised the alkylated lead baseline emission 

 

5

In addition to adding the baseline emissions for the Alklylated Lead Production source category, the other updates 

to the section 112(c)(6) baseline inventory for alkylated lead include addition of the Upstream Gasoline Distribution 

(Aviation) (see section IV.B) and revised baseline emission estimates for Gasoline Distribution Stage I (see section 

II.B) and Gasoline Distribution (Aviation) discussed in this section.

6We further note that U.S. production of alkylated lead compounds ended in 1993.

7

In the 112(c)(6) inventory published in 1998, the baseline alkylated lead emissions estimate for the Gasoline 

Distribution (Aviation) source category was based on emission factors from a 1994 proposed major source standard 

for gasoline distribution stage I (Background Information Document (BID) Volume I, Proposed National Emission 

Standards for Hazardous Air Pollutants for Gasoline Distribution (Stage I), EPA-453/R-94-002a). Based on 

analysis of public comments on that proposed rule, EPA applied updated equipment leak emission factors for the 

promulgated major source standard for Gasoline Distribution (Stage I) (BID Volume II, Promulgated National 

Emission Standards for Hazardous Air Pollutants for Gasoline Distribution (Stage I), EPA-453/R-94-002b). The 

updated emission factors were also applied in the promulgation of area source standards for Gasoline Distribution 

Stage I (Area Source).
7

estimates for all gasoline distribution source categories, including Gasoline Distribution 

(Aviation), accordingly. 

B. Gasoline Distribution Stage I (area sources)

Alkylated lead compounds and POM are the only two of the seven CAA section 

112(c)(6) pollutants that were identified in gasoline. In the 1998 notice, we did not include 

Gasoline Distribution Stage I area source category in the section 112(c)(6) source category 

listing, noting the ban on leaded gasoline in on-road vehicles. However, in a notice dated 

November 8, 2002, we provided a revised 1990 baseline inventory for 16-PAH (sum of 16 

polycyclic aromatic hydrocarbons), an indicator for POM, and, as a result, we determined that 

we needed the Gasoline Distribution Stage I area source category to meet the 90 percent 

requirement for POM under section 112(c)(6). 

As explained in the proposal preamble to the area source Gasoline Distribution Stage I 

rule8, naphthalene is the only 16-PAH estimated and reported in the 1990 inventory that is 

emitted from gasoline distribution facilities. That proposed rule also explained that we revised 

the 1990 inventory of naphthalene from this source category (major and area sources) based on 

additional data received and concluded that gasoline distribution facilities (area sources) 

contribute only 1.73 tons, about 0.02 percent of the total 16-PAH baseline inventory. We 

concluded in that rulemaking that we did not need this source category to meet the 90-percent 

requirement for POM under section 112(c)(6). 

Alkylated lead emissions from this source category have also been updated since the 

1998 notice in a manner consistent with Gasoline Distribution (Aviation), discussed in the 

 

8 National Emission Standards for Hazardous Air Pollutants for Source Categories: Gasoline Distribution Bulk 

Terminals, Bulk Plants, Pipeline Facilities, and Gasoline Dispensing Facilities. November 2006, 71 FR 66064.
8

previous section. A review of the 1990 alkylated lead emissions from the distribution of leaded 

gasoline revealed that the inventory data were based on inaccurate estimates of equipment 

component counts and leak emission factors.9 Analysis showed that when the corrected 

equipment leak data are used, the total estimated 1990 alkylated lead emissions from leaded 

gasoline distribution would be less than 1⁄2 the estimate in the 1990 inventory published in the 

1998 notice. We have revised the alkylated lead baseline emission estimates for all gasoline 

distribution source categories, including Gasoline Distribution Stage I (Area Source), 

accordingly.

C. Area Source Wood/Wood Residue and Oil Boilers

In the 1998 notice, EPA had identified wood/wood residue (biomass) and oil boilers as 

needed to meet the 90 percent requirement for mercury and POM. There have been a number of 

significant updates to the 1990 baseline inventory for mercury. As discussed in Section I.B, EPA 

has added EAF and Gold Mine Ore Production and Processing to the 1990 baseline inventory for 

mercury and promulgated mercury MACT standards for these categories. Section IV.A of this 

memorandum discusses other significant updates to 1990 baseline emissions for mercury. Due 

to these updates, which are reflected in Appendix I, we have determined that we do not need to 

regulate mercury emissions from area source biomass and oil boilers to meet the 90 percent 

requirement for mercury under CAA section 112(c)(6). In addition, as discussed below in 

section III, we are using 16-PAH as the baseline inventory for POM. Based on the 16-PAH 

baseline inventory, we have determined that we do not need to regulate POM emissions from 

area source biomass and oil boilers to meet the 90 percent requirement for POM under CAA 

section 112(c)(6). 

III. Use of 16-PAH Inventory for Polycyclic Organic Matter

 

9

See footnote 6.
9

In the Clean Air Act, POM is defined as “organic compounds with more than one 

benzene ring and which have a boiling point greater than or equal to 100°C”. As shown in the

1998 notice, we created three inventories (7-PAH10, 16-PAH11, and extractable organic matter 

(EOM) 12) to represent baseline POM emissions. Of the three POM baseline inventories, the 16-

PAH inventory is the most robust, with data on 16-PAH emissions for 94 categories. In contrast, 

we have very limited data on EOM, with data on EOM emissions for only18 source categories.13 

The lack of available data on EOM emission creates a distorted picture of the relative 

contributions of source categories for which there are available EOM data. The lack of source 

categories making up the total EOM inventory makes the relative contribution of the few 

categories that do have data unrealistically inflated. We therefore cannot say with confidence 

that, by using the baseline inventory for EOM, we are capturing 90 percent of the baseline POM 

emissions, as required by section 112(c)(6). Similarly, we have data on 7-PAH for 32 categories, 

considerably fewer than the 94 categories for which we have 16-PAH data. Therefore, the 16-

PAH inventory allows for the most accurate representation of the universe of categories that emit 

POM. Because the use of all three baseline inventories is neither required nor necessary, and in 

light of the concern described above with the EOM and 17-PAH inventories, we have decided to 

use only the 16-PAH baseline inventory for determining the 90 percent threshold for POM under 

section 112(c)(6). 

IV. Other Updates to Baseline Emission Inventory 

 

10 composed of benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, 

dibenz(a,h)anthracene, and indeno(1,2,3-cd)pyrene

11 composed of benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, 

dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, acenaphthene, acenaphthylene, anthracene, benzo(ghi)perylene,

fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene

12 any methylene chloride extractable organic matter, measured gravimetrically

13 When justifying its use in the 1998 inventory background document, we said that EPA would undertake an effort 

to develop a robust inventory for EOM sources to feed into the CAA section 112(c)(6) inventory. Had more data 

been gathered, perhaps EOM would have proved to be a more useful indicator of POM. However, the anticipated 

inventory was not developed. 
10

A. Updates to the 1990 baseline emission inventory for mercury

As mentioned above, EPA added 1990 mercury emission estimates for EAF and Gold 

Mine Ore Production and Processing area source categories into the section 112(c)(6) total 

baseline inventory for mercury. In addition, EPA discovered that the 112(c)(6) inventory for 

mercury published in the 1998 Federal Register notice included inaccurate estimates for a 

number of source categories and updated these estimates. These updates are discussed below.

1. Industrial/Commercial Boilers

The estimate of mercury emissions from Industrial/Commercial Boilers that was 

presented in the 1998 Federal Register notice for 112(c)(6) was 28.9 tons of mercury for year 

1990. There were a number of technical problems with this estimate, especially for coal fired 

boilers. One significant issue is that the activity level (2820 trillion BTUs) used in the 

calculations in the 112(c)(6) inventory background document was incorrect. This activity level 

represented all coal use in industry, including boilers and other uses (e.g., coke ovens). The 

activity level used should have been for boilers only. A more accurate activity level for 1990 

would be about 1633 trillion BTUs.14

Additionally, we also believe that the emissions factors used to calculate the original 

estimate from coal-fired boilers were inaccurate. The emission factors were based on an 

assumption of zero control and did not account for coal washing. EPA stated at the time that 

“because mercury reductions from coal washing and any other reductions that may occur across 

existing control devices are not accounted for, the emissions may be overestimated”. 15 Applying 

 

14 Estimate based on 1990 historical statistics from the Department of Energy’s Energy Information Administration 

website of coal use in industrial/commercial sectors (not including coke plants).

15 Mercury Study Report to Congress. December 1997. Available at http://www.epa.gov/hg/report.htm.
11

emission factors used in the development of the major and area source Boiler NESHAP16 to the 

revised activity level for coal fired boilers yields roughly 2 tons and 1 ton for major and area 

sources, respectively. Emissions factors for oil-fired boilers (6.8 lb/trillion BTUs and 7.2 

lb/trillion BTUs) were also too high. Converting these emission factors into mercury 

concentrations in oil results in an estimate of about 100 ppb mercury concentrations in oil. 

However, based on data gathered and analyzed for the 1998 EPA Utility Air Toxics Report to 

Congress, the average mercury concentration in oil is about 10 ppb. Moreover, the emissions 

factor for residual oil-fired boilers (of 0.4 lbs per trillion BTUs) provided in the 1997 EPA 

Locating and Estimating document17 is about 10 times lower than the emission factors used for 

the original 112(c)(6) estimates for oil-fired boilers. The information discussed above suggests 

that the estimate shown above for oil-fired boilers was overestimated by an order of magnitude. 

A more accurate estimate is about 0.6 tons.

2. Aerospace Industries (surface coating) 

Aerospace Industries (surface coating) had an estimate of 4 tons of mercury in the 

112(c)(6) inventory published in the 1998 notice. Other inventories developed for year 1990 for 

other regulatory purposes (including the 112(k) 1990 inventory and the 1990 NEI) had much 

lower estimates for this category (0.0026 and 0.0030 tpy, respectively). Because of the large 

discrepancy, we reviewed the 112(c)(6) inventory data for this category, including reviewing the 

original emissions factor and calculations and consulting with an industry representative. The 

estimate in the 1998 notice was based on an extremely conservative assumption. According to a 

 

16 The revised emission factor for major source boilers for this inventory was generated using a weighted average of 

the six emission factors for various types of control used in the February 21, 2011 Boiler NESHAP. The revised 

emission factor for area sources was the uncontrolled group in the Boiler NESHAP because these sources were 

largely uncontrolled with respect to mercury emissions in 1990.

17 US EPA (1997): Locating and estimating air emissions from sources of mercury and mercury compounds. Report 

EPA-454/R-97-012, (NTIS PB98- 117054), Office of Air Quality Planning and Standards, Research Triangle Park, 

NC. Available at: http://www.epa.gov/ttn/chief/le/index.html
12

1997 docket memo,18 the emissions estimate was derived from reviewing Material Safety Data 

Sheets (MSDS) from five of the major coating suppliers. One of these MSDS showed trace 

amounts of mercury in only two products (0.00002% by weight), which was rounded up five 

orders of magnitude to 1% in the inventory analysis. 

In light of the above, we concluded that this original estimate of mercury emissions (or 4 

tons) from Aerospace was substantially overestimated. Therefore, we searched and gathered 

information to calculate a more reasonable estimate. We obtained information on sales of 

aerospace coatings and mercuric mildewcides in 1990. Using these data, potential mercury 

emissions for 1990 were calculated, as follows. 

In 1990 aerospace coatings accounted for 0.1% of the volume of coatings produced. In

1990 approximately 400,000 lbs. of mercuric mildewcide/fungicide (as mercury) was sold into 

the entire coatings market (this amount substantially decreased after 1990 to nearly zero). 

Assuming these were used throughout the industry - 0.1% * 400,000 lbs. = 400 lbs. of mercuric 

mildewcides/fungicides used in aerospace coatings. Thus, the maximum emissions would have 

been 400 lbs. of mercury assuming 100% of mercury in coatings were released. However, 

mildewcides/fungicides are intended to retard the growth of fungi on applied surfaces over time. 

They are intended to remain to a large extent in the coating substrate. We believe that at least 

50% of the mildewcide/fungicide remains in the substrate. Therefore, mercury releases from 

aerospace coatings are estimated to be up to 200 lbs in 1990. Given this information and 

calculations, we estimate that this source category emitted about 0.1 tons of mercury in 1990.

3. Industrial Turbines and Internal Combustion Engines 

 

18 Memo from Dave Reeves, Midwest Research Institute to Barbara Driscoll, U.S. Environmental Protection 

Agency, Office of Air Quality Planning and Standards regarding HAP emission estimates for aerospace surface 

coating. November 17, 1997.
13

In the 1998 notice, the mercury emissions from industrial turbines and internal 

combustion engines fired by natural gas were 1.6 tons and 4.7 tons, respectively. The emissions 

factors used in those original estimates for these two source categories were 6.63 x 10-6

lb/MMBtU and 1.14 x 10-5lb/MMBtU, respectively. However available data19 indicate that the 

level of mercury in natural gas is very low and, therefore, mercury emissions from this category 

are very low. Based on this information, we updated the 1990 mercury emissions for this 

category. As shown in Appendix I, the revised mercury emissions from these two source 

categories are 0.001 and 0.009 tons, respectively.

4. Human Crematories

The mercury emissions from human crematories in the baseline 112(c)(6) inventory 

(.000377 tons per year) were revised based on data used to calculate mercury emissions in the 

112(k) area source inventory. This emission factor led to a value of 0.6 tons of mercury in 1990 

emitted from human crematories.

5. Blast Furnaces and Steel Mills

Mercury emissions from blast furnaces and steel mills were reported as 0.25 tons in the 

baseline 112(c)(6) inventory. Further review of this estimate led to revision of the mercury 

estimate from blast furnaces and steel mills as well as electric arc furnace steelmaking (as 

discussed in section I.A above). Based on a revised emission factor20 from scrap steel, the 

mercury emissions are 3.1 tons for blast furnaces and steel mills.

6. Portland Cement

 

19 Mercury Study Report to Congress. December 1997. Available at http://www.epa.gov/hg/report.htm. 

Locating and Estimating Air Emissions from Sources of Mercury and Mercury Compounds. December 1997. 

Available at http://www.epa.gov/ttnchie1/le/.

20 Analysis of Mercury Data fo Prepared for U.S. Environmental Protection 

Agency, Office of Air Quality Planning and Standards, Sector Policies and Program Division, Metals and Minerals 

Group. July 18, 2007. Docket Item 0070 in EPA Docket Number OAR-2004-0083.
14

We believe the estimate for mercury emissions from Portland Cement Manufacturing 

non-hazardous waste kilns (4.13 tons) in the 1998 notice was slightly underestimated. We used 

the mercury emissions and installed clinker capacity from 200621 to generate a ratio of mercury 

emissions per ton of clinker and applied this ratio to the 1990 clinker capacity. The mercury 

emissions in 1990 were revised upward to 5.64 tons for this category.

B. Alkylated lead emissions from Upstream Gasoline Distribution (Aviation)

Upstream Gasoline Distribution (Aviation) is being added to the section 112(c)(6) 

inventory for emissions of alkylated lead. At the time we issued the 1998 notice, we believed 

that avgas was transported directly from refineries to the airport terminals. Thus, we did not 

estimate alkylated lead emissions from the distribution of avgas “upstream” of the airport 

facilities in the section 112(c)(6) emission inventory published in 1998. However, we have 

since learned that avgas is distributed through bulk terminals located at refineries, as well as 

through some stand-alone bulk terminals, prior to being delivered to airport facilities. We have 

therefore updated the 112(c)(6) baseline inventory for alkylated lead to include estimated 1990-

base year alkylated lead emissions from the distribution of avgas “upstream” of the airport 

facilities. The alkylated lead emissions for this category are presented in Appendix I. 

C. Updates to the 1990 baseline inventory for HCB

On August 3, 2000 EPA published a notice in the Federal Register summarizing a finding 

that tire production (renamed rubber tire manufacturing) emits no HCB (65 FR 47725). 

 

21 Estimate of 2006 installed clinker capacity: 94,690,000 metric tons clinker per year. Estimate of 2006 mercury 

emissions from major and area sources: 7.27 tons. Estimate of 1990 installed clinker capacity: 73,518,000 metric 

tons clinker per year.
15

APPENDIX I – Updated 112(c)(6) 1990 Baseline Inventory

This appendix presents the updated 1990 baseline inventory for the 112(c)(6) pollutants. Table I.1 shows 

categories that are used to meet our 90% requirement while Table I.2 shows other source categories not needed 

to reach our 90% requirement.
16

Table I.1 – Updated 112(c)(6) 1990 Baseline Inventory

Table I.1 (Continued)
17

Table I.1 (Continued)
18

Table I.1 (Continued)
19
20

Appendix II – Section 112(c)(6) Source Categories and Associated Standards

This appendix includes tables that cross-reference 112(c)(6) category names with the 

associated emission standards (which may reference a source category by a name different from 

that used in the section 112(c)(6) baseline inventory and source category listing) (Table II.1). 

Additionally, this appendix identifies the Code of Federal Regulation subparts for the emission 

standards counted towards reaching the 90% requirement for each of the 112(c)(6) pollutants 

(Table II.2).

Table II.1 – Index of section 112(c)(6) Categories and Section 112 or 129 Source Categories22

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

Aerospace Industry (Surface 

Coating)

National Emission Standards for 

Hazardous Air Pollutants for the 

Aerospace Industries

40 CFR part 63 

subpart GG

Alkylated Lead Production National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry

40 CFR part 63 

subpart F

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry for Process 

Vents, Storage Vessels, Transfer 

Operations, and Wastewater

40 CFR part 63 

subpart G

National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment 

Leaks

40 CFR part 63 

subpart H

National Emission Standards for Organic 

Hazardous Air Pollutants for Certain 

Processes Subject to the Negotiated 

Regulation for Equipment Leaks

40 CFR part 63 

subpart I

 

22 Because many of these standards were developed to meet EPA's obligation under CAA section 112(d)(1), EPA 

had not focused on what was needed to meet its section 112(c)(6) obligation at the time of these rulemakings, 

Therefore, EPA did not reference section 112(c)(6) in the preambles to these rules. 
21

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

Asphalt Roofing Production National Emission Standards for 

Hazardous Air Pollutants for the Asphalt 

Roofing Manufacturing

40 CFR part 63 

subpart LLLLL

Blast Furnace and Steel Mills National Emission Standards for 

Hazardous Air Pollutants for the 

Integrated Iron and Steel Manufacture

40 CFR part 63 

subpart FFFFF

Chemical Manufacturing: 

Cyclic Crude and Intermediate 

Production

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry

40 CFR part 63 

subpart F

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry for Process 

Vents, Storage Vessels, Transfer 

Operations, and Wastewater

40 CFR part 63 

subpart G

National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment 

Leaks

40 CFR part 63 

subpart H

National Emission Standards for Organic 

Hazardous Air Pollutants for Certain 

Processes Subject to the Negotiated 

Regulation for Equipment Leaks

40 CFR part 63 

subpart I

Chlorinated Solvents 

Production

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry

40 CFR part 63 

subpart F

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry for Process 

Vents, Storage Vessels, Transfer 

Operations, and Wastewater

40 CFR part 63 

subpart G

National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment 

Leaks

40 CFR part 63 

subpart H
22

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

National Emission Standards for Organic 

Hazardous Air Pollutants for Certain 

Processes Subject to the Negotiated 

Regulation for Equipment Leaks

40 CFR part 63 

subpart I

Coke Ovens: By-Product 

Recovery Plants

National Emission Standard for Benzene 

Emissions from Coke By-Product 

Recovery Plants

40 CFR part 61 

subpart L

Coke Ovens: Charging, 

Topside & Door Leaks

National Emission Standards for 

Hazardous Air Pollutants for Source 

Categories and for Coke Oven Batteries

40 CFR part 63 

subpart L

National Emission Standards for 

Hazardous Air Pollutants for Coke 

Ovens: Pushing, Quenching, and Battery 

Stacks

40 CFR part 63 

subpart CCCCC

Coke Ovens: Pushing, 

Quenching & Battery Stacks

National Emission Standards for 

Hazardous Air Pollutants for Source 

Categories and for Coke Oven Batteries

40 CFR part 63 

subpart L

National Emission Standards for 

Hazardous Air Pollutants for Coke 

Ovens: Pushing, Quenching, and Battery 

Stacks

40 CFR part 63 

subpart CCCCC

Commercial Printing: Gravure National Emission Standards for 

Hazardous Air Pollutants: Printing and 

Publishing Industry

40 CFR part 63 

subpart KK

Electric Arc Furnaces (EAF) -

Secondary Steel 

National Emission Standards for 

Hazardous Air Pollutants for Area 

Sources: Electric Arc Furnace 

Steelmaking Facilities

40 CFR part 63 

subpart YYYYY

Fabricated Metal Products National Emission Standards for 

Hazardous Air Pollutants: Surface 

Coating of Miscellaneous Metal Parts 

and Products

40 CFR part 63 

subpart MMMM

Gasoline Distribution (Stage 1) National Emission Standards for 

Hazardous Air Pollutants for Gasoline 

Distribution Facilities (Bulk Gasoline 

Terminals and Pipeline Breakout 

Stations)

40 CFR part 63 

subpart R
23

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

Gold Mines National Emission Standards for 

Hazardous Air Pollutants: Gold Mine Ore 

Processing and Production Area Source 

Category

40 CFR part 63 

subpart EEEEEEE

Hazardous Waste Incineration National Emission Standards for 

Hazardous Air Pollutants from 

Hazardous Waste Combustors

40 CFR part 63 

subpart EEE

Industrial Organic Chemicals 

Manufacturing

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry

40 CFR part 63 

subpart F

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry for Process 

Vents, Storage Vessels, Transfer 

Operations, and Wastewater

40 CFR part 63 

subpart G

National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment 

Leaks

40 CFR part 63 

subpart H

National Emission Standards for Organic 

Hazardous Air Pollutants for Certain 

Processes Subject to the Negotiated 

Regulation for Equipment Leaks

40 CFR part 63 

subpart I

Industrial Stationary IC 

Engines - Diesel 

National Emission Standards for 

Hazardous Air Pollutants for 

Reciprocating Internal Combustion 

Engines

40 CFR part 63 

subpart ZZZZ

Industrial Stationary IC 

Engines - Natural Gas 

National Emission Standards for 

Hazardous Air Pollutants for 

Reciprocating Internal Combustion 

Engines

40 CFR part 63 

subpart ZZZZ

Industrial/Commercial/Instituti

onal Boilers 

National Emission Standards for 

Hazardous Air Pollutants for Industrial/ 

Commercial/Institutional Boilers and 

Process Heaters

40 CFR part 63 

subpart DDDDD
24

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

National Emission Standards for 

Hazardous Air Pollutants for Area 

Sources: Industrial, Commercial, and 

Institutional Boilers

40 CFR part 63 

subpart JJJJJJ

Lightweight Aggregate Kilns National Emission Standards for 

Hazardous Air Pollutants from 

Hazardous Waste Combustors

40 CFR part 63 

subpart EEE

Medical Waste Incineration Standards of Performance and Emissions 

Guidelines for Hospitals / Medical / 

Infectious Waste Incinerators 

40 CFR part 60 

subpart Ce, Ec; & 

40 CFR part 62 

subpart HHH 

Mercury Cell Chlor Alkali 

Production

National Emission Standards for 

Hazardous Air Pollutants: Mercury 

Emissions from Mercury Cell Chlor 

Alkali Plants

40 CFR part 63 

subpart IIIII

Municipal Waste Combustion Standards of Performance for New 

Stationary Sources and Emission 

Guidelines for Existing Sources: Large 

Municipal Waste 

40 CFR part 60 

subpart Cb, Ea, Eb; 

& 40 CFR part 62 

subpart FFF 

Standards of Performance for New 

Stationary Sources and Emission 

Guidelines for Existing Stationary 

Sources: Small Municipal Waste 

Combustion Units

40 CFR part 60 

subpart AAAA, 

BBBB & 40 CFR 

part 62 subpart JJJ

Naphthalene Production National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry

40 CFR part 63 

subpart F

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry for Process 

Vents, Storage Vessels, Transfer 

Operations, and Wastewater

40 CFR part 63 

subpart G

National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment 

Leaks

40 CFR part 63 

subpart H
25

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

National Emission Standards for Organic 

Hazardous Air Pollutants for Certain 

Processes Subject to the Negotiated 

Regulation for Equipment Leaks

40 CFR part 63 

subpart I

Paints and Allied Products 

(Major)

National Emission Standards for 

Hazardous Air Pollutants: Miscellaneous 

Organic Chemical Manufacturing

40 CFR part 63 

subpart FFFF

Paper Coated and Laminated, 

Packaging 

National Emission Standards for 

Hazardous Air Pollutants: Paper and 

Other Web Coating

40 CFR part 63 

subpart JJJJ

Pesticides Manufacture & 

Agricultural Chemicals

National Emission Standards for 

Hazardous Air Pollutants: Pesticide 

Active Ingredient Production

40 CFR part 63 

subpart HHH

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry

40 CFR part 63 

subpart F

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry for Process 

Vents, Storage Vessels, Transfer 

Operations, and Wastewater

40 CFR part 63 

subpart G

National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment 

Leaks

40 CFR part 63 

subpart H

Petroleum Refining: All 

Processes

National Emission Standards for 

Hazardous Air Pollutants from Petroleum 

Refineries

40 CFR part 63 

subpart CC

National Emission Standards for 

Hazardous Air Pollutants for Petroleum 

Refineries: Catalytic Cracking Units, 

Catalytic Reforming Units, and Sulfur 

Recovery Units

40 CFR part 63 

subpart UUU

Phthalic Anhydride Production National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry

40 CFR part 63 

subpart F
26

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

National Emission Standards for Organic 

Hazardous Air Pollutants from the 

Synthetic Organic Chemical 

Manufacturing Industry for Process 

Vents, Storage Vessels, Transfer 

Operations, and Wastewater

40 CFR part 63 

subpart G

National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment 

Leaks

40 CFR part 63 

subpart H

National Emission Standards for Organic 

Hazardous Air Pollutants for Certain 

Processes Subject to the Negotiated 

Regulation for Equipment Leaks

40 CFR part 63 

subpart I

Plastics Material and Resins 

Manufacturing

National Emission Standards for 

Hazardous Air Pollutants for Group IV 

Polymers and Resins

40 CFR part 63 

subpart JJJ

Portland Cement Manufacture: 

Hazardous Waste Kilns

National Emission Standards for 

Hazardous Air Pollutants from 

Hazardous Waste Combustors

40 CFR part 63 

subpart EEE

Portland Cement Manufacture: 

Non-Hazardous Waste Kilns

National Emission Standards for 

Hazardous Air Pollutants for the Portland 

Cement Manufacturing Industry

40 CFR part 63 

subpart LLL

Primary Aluminum Production National Emission Standards for 

Hazardous Air Pollutants for Primary 

Aluminum Reduction Plants

40 CFR part 63 

subpart LL

Pulp and Paper – Kraft 

Recovery Furnaces

National Emission Standards for 

Hazardous Air Pollutants for Chemical 

Recovery Combustion Sources at Kraft, 

Soda, Sulfite, and Stand-Alone 

Semichemical Pulp Mills

40 CFR part 63 

subpart MM

Pulp and Paper – Lime Kilns National Emission Standards for 

Hazardous Air Pollutants for Chemical 

Recovery Combustion Sources at Kraft, 

Soda, Sulfite, and Stand-Alone 

Semichemical Pulp Mills

40 CFR part 63 

subpart MM

Secondary Aluminum 

Smelting

National Emission Standards for 

Hazardous Air Pollutants for Secondary 

Aluminum Production

40 CFR part 63 

subpart RRR
27

Section 112(c)(6) Category 

Name

Emission Standard Name(s) CFR Part and 

Subpart

Secondary Lead Smelting National Emission Standards for 

Hazardous Air Pollutants for Secondary 

Lead Smelting

40 CFR part 63 

subpart X

Sewage Sludge Incineration Standards of Performance for New 

Stationary Sources and Emission 

Guidelines for Existing Sources: Sewage 

Sludge Incineration Units

40 CFR part 60 

subparts LLLL, 

MMMM

Ship Building and Repair 

(Surface Coating)

National Emission Standards for 

Hazardous Air Pollutants for 

Shipbuilding and Ship Repair (Surface 

Coating)

40 CFR part 63 

subpart II

Transportation Equipment 

Manufacturing (SICs 

Combined) 

National Emission Standards for 

Hazardous Air Pollutants: Surface 

Coating of Automobiles and Light Duty 

Trucks (Surface Coating of Plastic Parts 

and Products) 

40 CFR part 63 

subpart PPPP

Wood Household Furniture 

Manufacturing

National Emission Standards for 

Hazardous Air Pollutants from Wood 

Furniture Manufacturing Operations

40 CFR part 63 

subpart JJ

Table II.2 – Subparts Used to Reach 90% for 112(c)(6) Pollutants.

112(c)(6) Pollutant Percent 

Subject to 

Regulation

Code of Federal Regulations 

Part and Subpart

Alkylated Lead Compounds 99.7% 40 CFR part 63 subparts F, G, 

H, I 

Polycyclic Organic Matter (Using 16-PAH 

Inventory)

90.0% 40 CFR part 63 subparts F, G, 

H, I, L, R, X, CC, GG, II, JJ, 

KK, LL, MM, EEE, JJJ, LLL, 

MMM, UUU, FFFF, JJJJ, 

MMMM, PPPP, ZZZZ, 

CCCCC, DDDDD, FFFFF, 

LLLLL, JJJJJJ; 40 CFR part 60 

subpart Cb, Ce, Ea, Eb, AAAA, 

BBBB; 40 CFR part 62 subpart 

FFF, HHH, JJJ

Hexachlorobenzene 100% 40 CFR part 63 subparts F, G, 

H, I, HHH
28

112(c)(6) Pollutant Percent 

Subject to 

Regulation

Code of Federal Regulations 

Part and Subpart

Mercury Compounds 90.3% 40 CFR part 63 subparts X, GG, 

LL, MM, EEE, LLL, DDDDD, 

IIIII, YYYYY, JJJJJJ, 

EEEEEEE; 40 CFR part 60 

subpart Cb, Ce, Ea, Eb, AAAA, 

BBBB, LLLL, MMMM; 40 

CFR part 62 subpart FFF, HHH, 

JJJ

Polychlorinated Biphenyls 94.5% 40 CFR part 63 subparts EEE; 

40 CFR part 60 subpart Cb, Ce, 

Ea, Eb, AAAA, BBBB; 40 CFR 

part 62 subpart FFF, HHH, JJJ

2,3,7,8-Tetrachlorodibenzofurans (furan) and 

2,3,7,8-Tetrachlorodibenzo-p-dioxin (dioxin)

95.3% 40 CFR part 63 subparts X, LL, 

EEE, LLL, MMM, DDDDD, 

JJJJJJ; 40 CFR part 60 subpart 

Cb, Ce, Ea, Eb, AAAA, BBBB; 

40 CFR part 62 subpart FFF, 

HHH, JJJ