AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
A Study of the Deficiencies of a DPM Personal Sampler Which Uses Impaction Size Selective Separation
EMANUELE CAUDA, Maura Sheehan, NIOSH
Abstract Number: 439 Working Group: Aerosol Exposure
Abstract The simultaneous presence of respirable mineral dust and Diesel Particulate Matter (DPM) in the mining environment is a challenge for assessing the exposure of miners to DPM. Studies conducted in the past by the National Institute for Occupational Safety and Health (NIOSH) identified two steps for conducting this assessment in non-coal mines in the United States: the size separation of the aerosol at a size of 0.8 micro-meter and the subsequent analysis of the collected smaller cut that is believed to be representative of the DPM portion with a minimal mine dust contribution. The analysis of the smaller size cut is conducted using the NIOSH5040 method. A sharp size separation is provided by a commercially available impaction stage. This study presents new evidence about the deficiency of the performance of this impactor when challenged with respirable dust levels typically present in an underground mine. Several impactors were exposed to different dust levels in a calm air chamber. The penetration efficiency of new clean impactors vs. impactors exposed to dust was investigated in a different chamber using spherical particles of known density. Finally, new clean impactors and impactors previously exposed to dust were used to sample DPM aerosol under controlled conditions. The collected DPM was analyzed with the NIOSH5040 method. Statistical analysis was used to compare the DPM aerosol quantified from the clean vs. loaded impactors. Results showed a significant difference in the penetration efficiency of the impactors previously exposed to dust. This difference causes significant differences in the collected DPM aerosol. The finding indicates that the impactor might produce an underestimation of the miners’ DPM exposure if respirable mining dust is present.