Many areas of the country are in violation of the National Ambient Air Quality Standards (NAAQS) for particulate matter (PM) < 10 μm in aerodynamic diameter (PM-10). In many cases, the PM-10 problems are a result of fugitive particulates from three primary sources: paved and unpaved roads, agricultural activities, and construction activities. As a result of the recently promulgated NAAQS for PM < 2.5 μm in aerodynamic diameter (PM-2.5), additional measures may be necessary for current or new non-attainment areas. Currently, there are few PM-10 emission source strengths known for construction-related fugitive particulate sources, and none for PM-2.5. In this paper, measurements are presented for PM emission particle size profiles from scraper loading and unloading operations. The exposure profiling technique was used to measure emissions. This technique for source testing of open PM sources is based on the isokinetic profiling concept that is used in conventional (stack) testing. The passage of airborne pollutant immediately downwind of the source is measured directly by means of simultaneous multipoint sampling over the cross section of the open dust source plume. This technique uses a mass flux measurement scheme similar to EPA Method 5 stack testing rather than requiring indirect emission rate calculation through the application of a generalized atmospheric dispersion model. Within field measurement capabilities, several types of particulate collection devices were utilized to validate the test procedure and enhance the quality assurance goals of the testing program. The resulting emission source strength developed during the field study not only expanded the data base of PM-10 emission source strengths but, for the first time, determined the relative importance of PM-2.5 emissions in the construction industry. These data are essential for emission inventory and air quality modeling programs for state and local air pollution control agencies.
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