PARTICLE SIZE DISTRIBUTION OF PARTICULATE MATTEREMITTED BY AGRICULTURAL OPERATIONS: IMPACTS ONFRM PM10 AND PM2.5 CONCENTRATION MEASUREMENTS

摘要

The EPA approved federal reference methods (FRM) for measuring particulate matter concentrations of PM10 and PM2.5 areaffected by the particle size distribution (PSD) of the particulate matter (PM) present in ambient air. The PSD of PM in theambient air emitted by agricultural operations (rural areas) is significantly larger than that of PM present in urban areas.Typically, urban PM will have a mass median diameter (MMD) less than 10 μm aerodynamic equivalent diameter (AED)whereas, agricultural PM will have an MMD larger than 10 μm AED. An MMD of as high as 24 μm AED has been reportedfor PM emitted through agricultural operations. The EPA- approved FRM PM10 and PM2.5 samplers have been shown to exhibitover-sampling problems for particles having MMDs of greater than 10 μm such as agricultural dust. As a consequence,agricultural operations are not being regulated fairly. This work presents some procedures that can be done to correct thisover sampling problem.