Diesel exhaust exposures in an underground mine
Résumé
The mining industry is a major contributor to the Quebec and Canadian economy. In Canada, more than 400,000 workers are involved directly or indirectly in the mining industry. Health and safety challenges in underground mines are unique regarding the complexity of the environment. Exposure to diesel engine exhaust is a major concern in underground mines due to the presence of off-road diesel-powered machinery. Diesel engine exhaust has been linked to cardiopulmonary diseases and was classified as a human carcinogen by the International Agency for Research on Cancer in 2012. Here we present the results of a preliminary study conducted in an underground gold mine in the province of Quebec in 2014-15 to assess diesel engine exhaust exposures among mine workers. The goal of this study was 1) to compare three surrogates of diesel engine exhaust exposure (total carbon, elemental carbon and respirable combustible dust) and 2) to assess diesel exhaust concentrations among the similar exposure groups and the variability of the exposures. Results were also compared to the Ontario and Quebec occupational exposure limits for compliance purposes. Environmental and breathing zone measures were taken. Average environmental results of 0.31 mg/m3 in total carbon, 0.24 mg/m3 in elemental carbon, and 0.17 mg/m3 in respirable combustible dust were obtained. Average breathing zone results of 0.32 mg/m3 in total carbon, 0.19 mg/m3 in elemental carbon and 0.36 mg/m3 in respirable combustible dust were obtained. Highest exposures were obtained in the conventional, scooptram and jumbo workers. The average total carbon/elemental carbon ratio was 1.3 for environmental measures, and 1.9 for breathing zone measures. The variability observed in the total carbon/elemental carbon ratio shows that interferences from non-diesel related organic carbon can skew the interpretation of results when relying only on total carbon data. More data is needed however to support this.
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