Comparison of Respirable Samplers to Direct-Reading Real-Time Aerosol Monitors for Measuring Coal Dust

Abstract

Three types of respirable dust samplers were positioned side-by-side as area samplers within three coal-fired electric power generating facilities. Respirable dust readings were taken using two direct-reading aerosol monitors (MIE PDM-3 Miniram and the TSI Model 8520 DustTrak) and the results compared to side-by-side respirable coal dust concentrations. Both direct-reading instruments use optical sensors for detecting dust concentrations, and in this study the air was passed through a 10-mm cyclone prior to detection. Respirable samples were collected using a 10-mm cyclone with a 5-µm PVC filter connected to a constant flow pump calibrated at 1.7 L/min. The samples were collected for fifteen 8-hr shifts over a one-month period. Respirable dust concentrations ranged from 0.23 to 10.83 mg/m3. The responses of each of the direct-reading instruments were compared to the respirable values. Neither of the two direct-reading instruments provided values that were identical to each other or the respirable samplers, but regression analyses indicated high coefficient of determination (R2) values (0.85 and 0.94). Other statistical methods (analysis of variance, pair wise t-tests, and mixed effect models) found no significant differences (p>0.05) between the data sets for the direct-reading instruments and the respirable samples. It was concluded that the two direct-reading instruments can be used to measure respirable coal dust.