Comparison of sampling methods to measure exposure to diesel particulate matter in an underground metal mine

Diesel is an efficient fossil fuel converting a large fraction of its available energy into useable work. A negative aspect to the use of diesel fuel is the resultant emissions and their role as an adverse environmental agent. Medical studies have documented adverse health effects of exposure to diesel emissions. In 1988, the National Institute for Occupational Safety and Health [NIOSH] recommended that diesel exhaust be regarded as a “potential occupational carcinogen”, and stated that reductions in workplace exposures would reduce cancer risks. Diesel emissions are aerosols that consist, in part, of an elemental carbon (EC) carrier particle onto which adsorbed organic chemicals are bound. These bound organic chemicals make up approximately 30-40% of the particle and are classified as organic carbon (OC). The sum of EC and OC characterize the total carbon (TC) fraction of diesel emissions and TC is the surrogate commonly used when performing air sampling to estimate occupational exposure to diesel particulate matter (DPM). Diesel powered equipment is used in 14,000 mining operations in the United States and the Mine Safety and Health Administration (MSHA) estimates that approximately 230,000 mine workers are potentially exposed to DPM. Currently, the MSHA-approved air-sampling protocol to appropriately quantify exposure to DPM employs the use of an SKCimpactor (cutpoint = 0.9μm). The use of this device inherently involves a lag-time before an accurate exposure determination can be made. Currently no standardized sampling method exists that would provide real-time DPM exposure results. The purpose of this study is to investigate the presence of a correlation between a TSI DustTrakTM real-time aerosol monitor and an SKC impactor when measuring DPM concentrations in an underground mine.