MEMORANDUM
DATE:	December 2019
TO:		Docket ID No. EPA-HQ-OAR-2018-0794
FROM:	Barrett Parker
		US EPA / OAQPS / SPPD / MPG
SUBJECT:	Non-mercury Metals Content of Filterable Particulate Matter
As mentioned in the Emission Factor Development for RTR Risk Modeling Dataset for Coal- and Oil-fired EGUs memorandum, available at EPA-HQ-OAR-2018-0794-0010 at www.regulations.gov, EPA developed ratios of non-mercury metal and filterable particulate matter (PM) emissions for use in estimating emissions from coal- and oil-fired electric utility steam generating units (EGUs) without current non-mercury metal emissions data.  These ratios, identified as PM ratios in Tables 2 and 3 of the memorandum, were determined by dividing the fuel-specific averages of the 2010 MATS Information Collection Request (ICR) non-mercury metals data, combined by control technique where possible, by the filterable PM emissions data.  The ratios represent the amount of non-mercury metals present in filterable PM.  
By identifying the highest PM ratios for each of the non-mercury metals and then summing those values, one can estimate the largest amount of non-mercury metals expected in an EGU's filterable PM.  The chart below shows the highest PM ratio for each non-mercury metal for coal-fired EGUs.   
                               Non-mercury metal
                               Highest PM ratio
                                   Antimony
                                   1.21E-04
                                    Arsenic
                                   2.70E-04
                                   Beryllium
                                   1.61E-05
                                    Cadmium
                                   2.94E-05
                                   Chromium
                                   1.37E-03
                                    Cobalt
                                   1.01E-04
                                     Lead
                                   2.08E-04
                                   Manganese
                                   1.65E-03
                                    Nickel
                                   7.41E-04
                                   Selenium
                                   3.44E-03
Total
                                   7.95E-03

The sum of the highest PM ratios is 7.95E-03, which expressed as a percentage, is less than eight-tenths of a percent.  Using this value, one can estimate that less than eight-tenths of a percent of filterable PM contains non-mercury metals, meaning that 1,000 pounds of filterable PM would contain less than 8 pounds of non-mercury metals.
