January 20, 2012 1 DRAFT: DO NOT CITE OR QUOTE

MEMORANDUM

TO: Conrad Chin, U.S. Environmental Protection Agency, OAQPS

FROM: Jeff Harris, Beth Friedman, EC/R

DATE: January 20, 2012

SUBJECT: Determination of a Ratio for Estimating PM2.5 Emissions based on PM Emissions from 

Ferroalloys Facilities

The purpose of this memorandum is to describe available data regarding the ratio of PM2.5 emissions to 

PM emissions and their use in preparation of cost estimates for revisions to the National Emissions 

Standards for Hazardous Air Pollutants (NESHAP) for the Ferroalloys Production source category. 

During the development of the proposed Ferroalloys regulation, two documents and sources on the 

particle size distribution for the ferroalloys industry were reviewed and deemed to contain relevant data:

1) "Engineering and Cost Study of the Ferroalloy Industry" (EPA-450/2-74-008), May 1974 

This document includes information on particle size distribution from sources in the Ferroalloys 

industry, specifically on the particle size distribution from uncontrolled tapping of a silicomanganese 

furnace. Table D-5 (page D-13) cites the fractional weight distribution for four samples, with 

percentage of PM 2.5 ranging from 49% to 78%. Table 1 shows the data from this source, with 

additional calculations showing PM2.5 as a percentage of total PM emissions. The percentage of PM2.5 

ranges from 49% to 78%.

2) "Emissions of particles, metals, dioxins and PAH in Sweden", Kindbom, et. al, for the Swedish 

Environmental Protection Agency, 2001.

This document contains particle size information specific to the ferroalloys industry, for a facility in 

Sweden. Data are reported for over twenty years, and include emissions of Total Particulate and PM2.5. 

Table 2 shows the data from this source, with additional calculations showing PM2.5 as a percentage of 

total PM emissions. The percentage of PM 2.5 is consistently 74-75%.

Conclusion:

For the purposes of cost estimation, using a lower ratio of PM2.5 to TSP results in a more conservative 

estimate of the cost effectiveness of controls with respect to PM2.5. Accordingly, we believe that it is 

appropriate to select a PM2.5/TSP ratio at the lower end of the range in the cited data sources. For 

future cost estimates, we propose to use a PM2.5/TSP ratio of 50% for Ferroalloys facilities.
January 20, 2012 2 DRAFT: DO NOT CITE OR QUOTE

Particle Size (μm) C-18 C-19 C-20 C-21

0 - 0.3 4.2 11.7 4.2 12.2

0.3 - 0.6 6.4 9.5 4.8 9.5

0.6 - 1.0 6.9 8 5.3 7.4

1.0 - 1.5 6.4 5.8 4.8 6.4

1.5 - 2 4.8 3.7 4.2 3.2

2 - 2.5 3.2 2.4 2.9 2.65

2.5 - 3 3.2 2.4 2.9 2.65

 3 - 6 9 5.3 9 4.8

 6 - 10 3.7 2.1 5.8 2.1

10+ 5.2 2.1 9.1 2.1

Total PM 53 53 53 53

Total PM2.5 31.9 41.1 26.2 41.35

Percentage PM2.5 60% 78% 49% 78%

Source: "Engineering and Cost Study of the Ferroalloy Industry" (EPA-450/2-74-008), Table D-5

Sample #

Table 1: Particulate Emissions By Particle Size From

Uncontrolled Tapping of a SiMn Furnace (lb/tap) Year

Production 

(Kton Alloy)

TSP 

(ton)

PM2.5 

(ton)

% PM2.5 

(PM2.5/TSP)

1980 94.8 127 95 75%

1981 113 151 113 75%

1982 139 186 140 75%

1983 107 143 107 75%

1984 118 158 118 75%

1985 123 164 123 75%

1986 118 158 118 75%

1987 122 164 123 75%

1988 143 191 143 75%

1989 124 166 125 75%

1990 128 85 64 75%

1991 136 91 68 75%

1992 136 91 68 75%

1993 136 91 68 75%

1994 146 98 73 74%

1995 147 99 74 75%

1996 156 104 78 75%

1997 120 80 60 75%

1998 139 93 70 75%

1999 133 91 68 75%

2000 153 101 76 75%

2001 128 85 64 75%

Average % PM2.5 75%

Table 2: Activity data for ferro alloys production, 

and emissions of particulate matter, 1980-2001.

Source: "Emissions of particles, metals, dioxins and PAH in Sweden", 

Swedish Environmental Protection Agency