What you may have heard
Inhalation of diesel exhaust can cause cancer.
What science tells us
Diesel is a type of fuel derived from crude oil and is used in most large engines (such as trucks, trains, buses, construction equipment, and ships). The gas portion of diesel is made up of carbon dioxide, carbon monoxide, nitric oxide, nitrogen dioxide, sulfur oxides, and hydrocarbons (such as polycyclic aromatic hydrocarbons or PAHs). The soot portion of diesel exhaust is made up of particles (such as carbon, organic compounds such as PAHs, and traces of metallic compounds).
In human studies, workers exposed to diesel exhaust have shown significant increases in risk of lung cancer (ACS). Both the International Agency for Research on Cancer (IARC) and the Environmental Protection Agency (EPA) view diesel exhaust as carcinogenic to humans.
Laboratory Evidence/Supporting Evidence
Both the gas and soot portions of diesel fuel can cause DNA changes in the lab (which can lead to cancer), and long-term exposure to diesel can cause lung cancer in lab animals (ACS). Some studies have shown that exposure to diesel exhaust and long-term inhalation has caused lung cancer in animals (Heinrich et al.).
IARC Carcinogen Classification: Group 1 (carcinogenic to humans).
How to reduce your risk
People are most often exposed to diesel exhaust on the roads and highways, or in certain occupations. As a result, organizations such as the EPA have taken some steps to reduce diesel emissions on the highway through legislation, and experts in this subject advocate for additional exposure reductions.
In terms of exposure in the workplace or in your own vehicle, try to reduce the time you are exposed to diesel exhaust, and reduce your time spent idling, as this can be very dangerous, especially in enclosed, indoor spaces (ACS).
Diesel exhaust is carcinogenic. Vehicles are required to meet federal guidelines for exhaust systems to reduce diesel emissions. Avoid older exhaust systems as they can be dangerous, especially in enclosed spaces. Choose vehicles with low emissions, including electric vehicles, and support national policies to reduce emissions to further reduce risks.
Learn More From These Trusted Sources
American Cancer Society (ACS): Diesel exhaust and cancer
Silverman et al.: Diesel Exhaust Causes Lung Cancer – Now What?
Environmental Protection Agency (EPA): EPA to Reexamine Health Standards for Harmful Soot
Published: July 7, 2021
Verified/updated: August 22, 2022