Comparison of personal diesel and biodiesel exhaust exposures in an underground mine.

This study aimed to compare personal exposures to diesel fuel and a biodiesel blend exhaust in an underground mine. Personal exposure monitoring was performed in a non-operational, hard rock underground mine during use of a load-haul-dump vehicle. Eight-hour time-weighted average (TWA8 ) exposure concentrations of ultra-low sulfur diesel and 75% biodiesel/25% diesel blend (B75) fuels were compared.  Compared to diesel, use of B75 was associated with relative percent reductions of 22 and 28% in median respirable (r) diesel particulate matter (DPM) and nitrogen dioxide and 25 and 23% increases in median total DPM and nitric oxide TWA8 exposure concentrations, respectively. Diesel was associated with a slightly greater total geometric mean mass concentration and lower mean surface area concentration.  Although further testing is needed, B75 has the potential to reduce rDPM exposures.