Vehicle emissions

We protect the air by implementing the Zero Emission Vehicle standards, Clean Car Law, reducing diesel exhaust, and managing the Volkswagen enforcement actions that resulted from federal and state Clean Air Act violations.


Transportation is Washington's largest source of air pollution and greenhouse gases.

Zero emission vehicle standards (ZEV)

Increasing the number of zero emission vehicles on the state's roads will reduce total greenhouse gas emissions by the equivalent of 1 million metric tons of carbon dioxide a year by 2030. 

On March 25, 2020, Gov. Jay Inslee signed the Motor Vehicle Emission Standards – Zero Emission Vehicles (ZEV) bill. This bill directs Ecology to adopt California vehicle emission standards, including zero emission vehicle standards that require a percentage of the vehicles sold in Washington to be zero emission. Once the standards are adopted, consumers will have more zero emission vehicles to choose from starting with the 2025 model year.

Clean Car Law

The Clean Car Law passed in 2005. Cars, light duty trucks, and passenger vehicles (SUVs and passenger vans) manufactured after Jan. 1, 2009 must meet strict clean air standards to be registered, leased, rented, licensed, or sold in Washington. The law helps reduce air pollution and greenhouse gases.

Diesel exhaust

Diesel exhaust is one of the most harmful air pollutants. Seventy percent of cancers caused by airborne pollution come from diesel exhaust. It puts healthy people at risk for respiratory diseases and complicates health conditions for people with asthma, heart, and lung disease. Over four million people in Washington live and work near diesel exhaust. We are working to reduce diesel emissions and protect your health:

  • Reduce idling.
  • Use cleaner fuels.
  • Install equipment to clean up diesel exhaust (retrofitting).
  • Replace older engines with new, cleaner ones.

Volkswagen enforcement actions

Volkswagen violated federal and state clean air laws by installing illegal emissions software on some diesel vehicles. In January 2016, the U.S. Department of Justice, working for EPA, filed a lawsuit against VW. After admitting fault, VW reached multiple settlements with EPA and Washington.

Washington is managing $140 million in settlement funds to reduce air pollution from transportation.

Emission check program

After 38 years, Washington's vehicle emission check program ended Jan. 1, 2020. An emissions test is no longer required before renewing your vehicle registration.

Find out why the legislature ended the emission check program.