| Emission Factor Tests |
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We have conducted a number of studies to develop new, more accurate
emission factors for stationary sources. These tests have involved
innovative techniques to ensure high efficiency capture of fugitive
emissions. U.S. EPA reference methods have been applied to quantify the
emission factors. Two of the major programs are summarized below. National Sand, Stone and Gravel Association PM2.5 and PM10 Emission Factors for Tertiary Crushers, Screening Operations, and Conveyor Transfer Points Air Control Techniques, P.C. personnel have conducted all of the National Sand, Stone and Gravel Association (NSSGA) sponsored emission factor testing since 1991. These tests involved the development of refined fugitive emission capture techniques to accurately measure PM10 emission factors. EPA has fully accepted all of the new PM10 emission factors and has replaced all of the out-of-date, high emission factors with these new, more accurate emission factors. These new emission factors were published in AP-42 Section 11.19.2 in January 1995. Additional PM10 emission factor data and new PM2.5 emission factor data were added to Section 11.19.2 in August 2004. Cement Industry PM10 and PM 2.5 Emissions Factors Air Control Techniques, P.C. has served as a consultant to the Portland Cement Association to compile accurate PM10 and PM2.5 emission factor data and chemical characterization data. The scope of the testing program includes cement kilns, alkali bypass streams, clinker coolers, finish mills, raw mills, coal mills, silos, bagging operations, and loadout operations. To ensure consistency of the data, a recently developed PCA emission test protocol was used at the plants participating in the program. This protocol was developed for PCA by Air Control Techniques, P.C. based on draft EPA PM2.5 test procedures released in 1989. EPA has adopted the Air Control Techniques, P.C. test method as Conditional Method 040. The preliminary results of tests conducted at five cement plants indicate that the emissions of filterable PM10 are approximately one-sixth of the value of the limited PM10 emission factor data published in the Fifth Edition of AP-42, Section 11.6. The measured emissions of filterable PM2.5 were very low. The air emission test data compiled from 1997 to 1999 for the PCA test program represent the most accurate and complete analyses of portland cement industry particulate emissions that are presently available. PM4 Crystalline Silica Emission Factors Air Control Techniques, P.C. has developed a method to measure crystalline silica in the PM4 size fraction. This method has been used to measure PM4 crystalline silica emission factors from tertiary crushers, screening operations, and conveyor transfer points. The measurement method has also been used to evaluate upwind-downwind PM4 crystalline concentrations across aggregate plants. |