Comparing diesel and GDiesel® exhaust exposures in an underground mining laboratory

Diesel exhaust is a known carcinogen and has been linked to several negative health outcomes, yet it is commonly used in industrial settings such as underground mining. Alternative fuels such as GDiesel® (GD), a natural gas/diesel blend, have the potential to reduce health exposures and associated health effects. Mirroring a previous study in which use of GD in a 2005 Wagner load-haul-dump (LHD) vehicle with oxidation catalyst demonstrated significant reductions in diesel exhaust exposures, operator-location and area exposure samples were collected in an underground mining laboratory with diesel (D) and then GD fuel while operating a JCI LHD. Analytes of interest included total and respirable diesel particulate matter (tDPM and rDPM, respectively), total and respirable elemental and organic carbon (tEC, rEC, tOC, rOC, respectively), as well as formaldehyde (CH2O), nitric oxide (NO), and nitrogen dioxide (NO2). Use of GD resulted in non-significant reductions in median rOC, tDPM, tOC, and NO2 concentrations, non-significant increases in rDPM, rEC, tEC, and NO, and identical median CH2O concentrations. A significant decrease in NO2 exposure concentrations (p=0.012) and increase tEC and rEC exposure concentrations (p=0.023 and p=0.024, respectively) were observed. After controlling for environmental confounders there was no difference observed in analyte concentrations between the two fuels. Further research is needed to determine whether GD alone can significantly reduce human exposures across vehicles and pollution configuration types.