Exposure to diesel engine exhaust continues to be a concern for employers who utilise either traditional (TDE) or new technology diesel (NTDE) exhaust-powered equipment. Such exposure may occur at elevated concentrations over a short period of time (acute) or at much lower concentrations on a daily basis over their working lifetime (chronic). Individuals in each of these exposure scenarios may present with different symptomology or health effects. In either case, accurately assessing an individuals exposure to diesel exhaust should be done in the context of appropriate toxicological endpoint of relevance (e.g., irritation, carcinogenicity, etc.).Methods
A review of the toxicological and industrial hygiene literature was conducted to identify historical trends in exposure sampling methodology and analytical surrogate chosen. Additional studies were reviewed which highlighted the important compositional distinctions between TDE and NTDE and also the reported symptomology which presented following acute exposures.Results
Historically, a number of analytical surrogates for diesel exhaust have been utilised to assess exposure including both particulate phase and gaseous compounds. While at the present time, sampling for elemental carbon or respirable elemental carbon (REC) is currently the most utilised surrogate, recent literature indicates that the elemental carbon fractions of TDE and NTDE may substantially differ. Furthermore, a number of studies noted that acute exposure to diesel exhaust may elicit transient irritant or neurophysiological effects indicative of exposure to gaseous components (e.g., aldehydes, NOx, SOx, CO) of diesel exhaust.Conclusion
This study highlights both the historical context and the current status of exposure sampling for diesel exhaust in the occupational setting. Development of exposure sampling plans in the workplace should take into account both the timeframe of exposure (e.g., acute or chronic) and the toxicological endpoints of concern (e.g., acute irritation or chronic ailment). Furthermore, the individual assessing exposure should be aware of, and account for the differences between traditional diesel engine exhaust (TDE) and new technology diesel engine exhaust (NTDE).