Critical Review of Diesel Exhaust Exposure Health Impact Research Relevant to Occupational Settings: Are We Controlling the Wrong Pollutants?

Diesel exhaust emissions and exposure of workers in occupational settings are topics which have attracted increased attention after IARC classification as a group 1 carcinogen (IARC. Agents classified by the IARC monographs, Vols. 1-120. International Agency for the Research on Cancer. . Accessed 21 Feb 2018; 2018). There is ongoing debate over appropriate exposure limits for occupationally exposed workers. This review consolidates recent research findings relevant to setting appropriate exposure limits, with a specific focus on newer engine and after-treatment technologies. Appropriate online databases were searched for studies published since 2005 focussing on the health effects of whole diesel exhaust exposure. Engines that used exhaust after-treatment devices including both a diesel oxidation catalyst and a diesel particulate filter were classified as new technology engines. All other studies were classified as using older technology engines. Exposure to diesel exhaust from both engine classifications resulted in negative health impacts on the lungs, heart and brain. Study participants with asthma, allergy or respiratory disease were more at risk of negative effects caused by diesel exhaust exposure than healthy subjects. Based on the published literature, an occupational limit of an average diesel exhaust concentration below 50 mu g/m(3) of diesel exhaust particles, 35 mu g/m(3) of elemental carbon, is appropriate to limit health effects. To meet this limit, many diesel engines will need to be equipped with after-treatment technology such as a DPF. However, the use of a DPF had little to no impact on measured health effects despite the removal of over 90% by weight of particles. This negates the feasibility of using particle mass-based limits.

Automated summary

Exposure to diesel exhaust from both older and newer technology engines negatively impacts the lungs, heart, and brain. Individuals with asthma, allergies, or respiratory diseases are more vulnerable to these effects compared to healthy individuals. Current occupational exposure limits for diesel exhaust particles and elemental carbon may need to be adjusted to mitigate health risks.