Controlling Diesel Particulate Matter from On-Road Diesel Engines

Diesel engine exhaust is a complex mixture of toxic gases and particulates produced from the combustion of diesel fuel. It is classified as a Group 1 definite human carcinogen by the International Agency for Research on Cancer (IARC) [IARC, 2014]. Exposure to diesel engine exhaust causes lung cancer, and there is limited evidence that it may cause bladder cancer. Diesel engines are widely used in many different on-road applications. According to CAREX Canada, the largest industrial groups exposed to diesel engine exhaust are truck transportation (206,000 Canadians exposed), transit and ground passenger transportation (110,000 exposed) and local public administration (42,000 exposed) [CAREX Canada, 2014].

The diagram below showcases the control strategies available for diesel engine exhaust in on-road applications, including transportation, public works yards, emergency medical services stations, and fire services stations, among others. It incorporates the Hierarchy of Controls, where control strategies are ranked from most effective (elimination or substitution) to least effective (personal protective equipment). The diagram also distinguishes between proactive controls (which eliminate or reduce diesel emissions before they enter workplace air) and reactive controls (which reduce the concentration of diesel emissions already present in workplace air, or reduce the likelihood that workers will inhale the emissions). Proactive controls are generally considered to be more effective than reactive controls. An effective emissions control program utilizes multiple controls from across the Hierarchy, and includes a monitoring program to evaluate the effectiveness of the program.

This resource was created in collaboration with the Public Services Health & Safety Association (PSHSA) and the Ontario Occupational Disease Action Plan (ODAP) Diesel Working Group.


IARC (2014). IARC Monographs on the Carcinogenic Risks to Humans Volume 105: Diesel and Gasoline Engine Exhausts and Some Nitroarenes. International Agency for Research on Cancer, Lyon, France.

CAREX Canada (2014). Diesel Engine Exhaust: Occupational Estimate.