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Diesel Engine Exhaust

Why am I being warned about potential exposure to diesel engine exhaust?

  • Diesel engine exhaust is on the Proposition 65 list because it can cause cancer.
  • Exposure to diesel engine exhaust can cause lung cancer.
  • Proposition 65 requires businesses to determine if they must provide a warning about exposures to listed chemicals.

What is diesel engine exhaust?

  • Diesel engine exhaust is produced when engines, including those in vehicles and generators, burn diesel fuel.
  • It is a mixture of thousands of chemicals released as gases or particles (soot). 
  • More than 40 cancer-causing substances are present in diesel engine exhaust, including benzene, arsenic, formaldehyde, acetaldehyde, 1,3-butadiene, lead, and numerous polycyclic aromatic hydrocarbons (a class of chemicals created by burning fuels and other substances).

How does exposure to diesel engine exhaust occur?

  • Exposure occurs by breathing in air containing diesel engine exhaust.  Sources include diesel-powered motor vehicles, ships, trains, generators, and other diesel-powered equipment. 
  • Exposure also occurs through contact with diesel engine gases and exhaust particles, which may be absorbed through the skin or unintentionally ingested.  These contaminants may:
    • Be present on the surface of diesel-powered vehicles and equipment.
    • Enter vehicles, homes, and other structures, where they can settle on surfaces and be absorbed into dust particles.

Main ways you can be exposed to diesel engine exhaust:

How can I reduce my exposure to diesel engine exhaust?

  • Always start and operate a diesel engine in a well-ventilated area.
  • Avoid breathing in diesel engine exhaust.  Whenever practical, do not stand next to operating diesel engines.  Distance yourself from the source of the exhaust.
  • Avoid idling diesel engine vehicles, where possible.
  • Do not use diesel-powered engines in enclosed spaces.
  • Do not modify or tamper with a diesel engine’s exhaust system.
  • Install backup and portable diesel-powered generators well away from your home so that exhaust does not come in through open windows and doors.
  • Consider replacing diesel-powered engines with alternatives such as engines powered by natural gas, propane or electricity.
  • Perform regular maintenance and frequent tune-ups of all diesel-powered equipment.
  • When servicing or maintaining diesel-powered engines, prevent skin contact with exhaust by wearing gloves.  Wash your hands when done, and before preparing food and eating.

For more information:

General Diesel Engine Exhaust Fact Sheets and Resources

Scientific Information on Diesel Engine Exhaust

Proposition 65

  • California Environmental Protection Agency (CalEPA)
    Office of Environmental Health Hazard Assessment (OEHHA)
Posted December 2016
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