Reducing diesel emissions

Diesel exhaust is the most harmful air pollutant in Washington. It contributes more than 70 percent of the total cancer risk from toxic air pollution. Diesel exhaust causes or contributes to asthma, heart and lung diseases, and cancer. To reduce diesel emissions, we provide grant funding to help fleet managers replace old engines, install exhaust retrofit equipment, reduce idling, and use cleaner fuels.


Port equipment, ships, and large trucks emit large amounts of diesel pollution.

Washington's largest sources of diesel exhaust

Nearly five million people live or work close to transportation corridors where they are exposed to high levels of diesel exhaust. 

Washington's largest sources of diesel exhaust are:

  • Heavy duty trucks
  • Ships
  • Construction equipment
  • Locomotives
  • Farm equipment
  • Buses

How we are reducing diesel emissions

There are many options available to fleet managers to reduce their diesel emissions:


An engine getting retrofitted to reduce emissions.