Career fire hall exposures to diesel engine exhaust in Ontario, Canada

Firefighters are potentially exposed to many carcinogens while at fires. There is also concern that firefighters may be at risk of exposure to carcinogens at other times, such as exposure to diesel engine exhaust (DEE) within fire halls. The study objective was to evaluate DEE levels in career fire halls in Ontario, Canada. Twelve career fire halls from six cities across the province of Ontario, Canada were recruited. In each hall, 24-hr DEE area samples were collected using NIOSH method 5040 (modified) for respirable elemental carbon in three locations (vehicle bay, dormitory, living quarters). Sampling was conducted in both the summer and winter to assess seasonal differences. Factors that may influence DEE exposures were also collected including presence of local exhaust ventilation (LEV), emergency run data, vehicle bay design, and age of fire apparatus. LEV was assessed using a thermo-anemometer during both campaigns. Of the 69 samples collected, 16% had detectable elemental carbon concentrations, where all but one was taken within the vehicle bay (range: <0.5 µg/m³-2.7 µg/m³). The data indicates vehicle bay exposures may be higher in halls with LEV units, those that respond to more emergencies, have a back-in vehicle bay design compared to drive-through design, and during the summer season. Three samples (4.3%) exceeded the 1.03 µg/m³ proposed Dutch occupational exposure limit; however, the estimated exceedance fraction of the underlying vehicle bay exposure distribution was 17%. Eight halls had LEV units, where performance ranged from 3.6% to 85.3% (median = 54%) when compared to manufacturer recommendations. The results show that firefighters may be at an increased risk of exposure to DEE when in fire halls and that LEV units should be assessed regularly for efficiency. Although no occupational exposure limit for DEE is currently available for industrial/non-industrial workplaces in Ontario, fire departments should continue to implement DEE control strategies to reduce exposures to mitigate potential health risks. Additional exposure studies are recommended to better understand DEE exposure in fire halls.