Exposure assessment of heavy-equipment operators to diesel particulate matter

Background-The OSHA/MSHA Hazard Alert that was released in January 2013regarding the carcinogenicity of diesel particulate matter suggested that employers monitor the diesel particulate matter exposure of at-risk employees. The at-risk employees identified at an elemental phosphorous plant included heavy-equipment operators, locomotive operators and heavy duty equipment mechanics. OSHA recommends sampling for the gas phase components (i.e. CO and NO2) of diesel exhaust to determine if at-risk employees are exposed to diesel particulate matter. A literature review suggested that the extrapolation of diesel particulate matter from CO or NO2 levels may not accurately assess exposure to diesel particulate matter.;Methods-Monitoring carbon monoxide, nitrogen dioxide and diesel particulate matter (elemental carbon) levels was conducted to assess the exposure of at-risk employees. All three diesel exhaust constituents (CO, NO2 and EC) were sampled at the same time within the cab or work area of the at-risk employees.;Results-A total of 13 samples were collected and analyzed. The samples collected were representative of the work environment that at-risk employees are exposed to. The statistical analysis of the data collected suggested that nitrogen dioxide time weighted average levels may serve as a predictor of diesel particulate matter, but carbon monoxide time weighted average measurement is not an accurate predictor of diesel particulate matter exposure.;Conclusions-The assessment of workplace exposures must be directly measured.