REVIEW OF SAMPLING AND EVALUATION TECHNIQUES FOR DIESEL EXHAUST PARTICULATE MATTER IN THE MINING INDUSTRY AND THE APPLICATION OF A VAPOR PHASE ORGANIC CARBON CORRECTION FACTOR

The health effects associated with diesel exhaust exposure have been documented for decades. However, methods used to assess diesel exhaust have experienced considerable revision over the past twenty years. The latest sampling methodology considers particulate matter elemental carbon (EC) and organic carbon (OC) analysis along with the vapor phase OC analysis. The objective of this study was to evaluate the influence of vapor phase OC on the current National Institute for Occupational Safety and Health (NIOSH) method 5040 sampling and evaluation techniques for diesel exhaust particulate matter. A pilot study was conducted as part of a larger study evaluation biodiesel exhaust particulate matter in an underground metal/non-metal mine in the northwest United States. Seventeen area samples were collected and analyzed via the NIOSH 5040 method for EC and OC. In addition to the primary quartz filter, the backup filter was also analyzed in accordance with the NIOSH method 5040 for OC concentrations. A regression analysis revealed no correlation between the top filter and backup filter in terms of OC concentrations (R2=0.005) (P=0.017). In addition, no correlation was observed in OC concentrations on the top and backup filter when a mean medium sample blank concentration of 17.8 μg/sample was subtracted from the backup filter (R2=0.005) (P=0.000). These data suggest that when analyzing for biodiesel particulate matter via the NIOSH 5040 method, there is no correlated contribution of OC from the top filter to the backup filter, which implies that the OC collected on the backup filter is not derived from gas phase OC vapors from the active sampling, but from the quartz filters themselves