Comparison of Measured Concentrations from Collocated TSP, PM10, and PM2.5 Samplers in the Presence of Agricultural Particulate Matter

Abstract

Accurate measurement of particulate matter (PM) concentrations in ambient air is becoming increasingly important as regulatory agencies continue to tighten limits on PM concentrations to which the public may be exposed. However, previous theoretical research has indicated that significant biases are associated with the use of federal reference method (FRM) PM samplers in the presence of large PM such as that generated by many agricultural operations. The objective of this paper is to analyze the concentrations of PM10, PM2.5, and PM10-2.5 measured from a cattle feedyard in the Panhandle of Texas using collocated FRM PM10 and PM2.5 samplers and compare them to the concentrations of similar particulates determined using a total suspended particulate (TSP) sampler and particle size analysis in order to accurately characterize sampler bias in a practical sampling scenario. The average mass median diameter (MMD) and geometric standard deviation (GSD) of the PM collected on the TSP samples were 9.5 0.2 m and 2.0 0.02, respectively. No significant difference was detected between the mean true PM10 concentration and the mean FRM PM10 concentration measured using an FRM PM10 sampler. Significant differences were detected between true and measured PM2.5 concentrations. Positive correlations were observed between the MMD of PM sampled and the over-sampling bias of FRM samplers.