Particle Size Distribution Analyses of Agricultural Dusts and Report of True PM10 Concentrations

This study presents the results of the particle size distribution (PSD) analyses of dusts from two agricultural facilities using filters from collocated PM10 and total suspended particulates (TSP) samplers. Ideally, PM10 concentrations obtained using the PM10 sampler should be the same as those using the TSP sampler. However, it was observed from numerous sampling episodes that there exists a bias in the PM10 concentrations reported from the two samplers. The particle size distribution of dust collected by the TSP sampler was used to determine the true PM10 concentrations which were then compared with the PM10 concentrations obtained using the low volume PM10 sampler. Results showed that in all instances, the concentrations obtained from using the PM10 sampler were always higher than those obtained from using the TSP sampler. Specifically, the results of this study have indicated the following: (a) that the PM10 sampler consistently showed over sampling bias in both agricultural facilities; (b) that FRM PM10 samplers alone are not suitable for determining PM10 concentrations for agricultural dust with particles whose mass median diameter (MMD) is greater than 10μm; (c) that the lognormal distribution described well the PSD of agricultural dust; and, (d) that the use of the TSP sampler followed by measurement of MMD and geometric standard deviation (GSD) is the better approach for determining PM10 concentrations of agricultural dust.