Vehicle emissions standards
Regulatory guidance and rulemaking
Ecology temporarily paused portions of some vehicle emissions standards in response to recent federal actions.
During this pause we’re continuing our clean vehicles rulemaking and hosting ZEVergreen dialogue sessions to develop new clean vehicle strategies for Washington.
Washington is one of 17 states that adopt more stringent regulations on vehicle pollution from California known as “vehicle emissions standards.”
These standards apply to automakers — not individuals or businesses. Over time, they’ll increase the number of new clean vehicles available to Washingtonians. They also ensure that any new combustion-engine vehicles sold in our state produce less air pollution and fewer greenhouse gases. They don’t regulate used or off-road vehicles or ban the continued use of gas- or diesel-powered vehicles.
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Light-duty standards vs. medium- and heavy-duty standards
Both low-emission and zero-emission vehicle standards treat light-, medium-, and heavy-duty vehicles differently based on their use cases and the expected pace of technological advancement.
- Light-duty vehicles are typically passenger vehicles ranging from four-door sedans up to smaller pick-up trucks. To learn more, visit our light-duty standards page.
- Medium- and heavy-duty vehicles are typically commercial vehicles ranging from delivery vans to long-haul semitrucks. To learn more, visit our medium- and heavy-duty standards page.
Limiting greenhouse gas emissions
Our vehicle emissions standards are part of a strong suite of climate policies that work together to achieve Washington’s legal limits on greenhouse gas emissions. By law, we're required to reduce statewide emissions 45% by 2030, 70% by 2040, and 95% by 2050.
Transportation is our state’s biggest source of greenhouse gas emissions, so transitioning to clean vehicles is an essential part of addressing climate change. It also improves air quality.
Low-emission standards vs. zero-emission standards
Washington has different low- and zero-emission vehicle standards for light-, medium-, and heavy-duty vehicles. These industry classifications are based on size and the maximum weight at which a vehicle can operate. Our standards also consider the expected pace of technological advancement for each vehicle class.
Regulating new on-road vehicles
Under the federal Clean Air Act, states can either follow federal emissions standards or adopt California’s more stringent standards, but they can’t create their own.
In 2005, the Washington Legislature passed a law directing Ecology to implement California’s low-emission vehicle standards. In 2020, the Legislature passed another law requiring us to implement California’s zero-emission vehicle standards.
We’ve implemented four low- and zero-emission vehicle standards through the following regulations:
- Advanced Clean Cars
- Advanced Clean Cars II
- Heavy Duty Low-NOx Omnibus
- Advanced Clean Trucks
Together, these standards regulate all new on-road vehicles sold in Washington.
Related links
- Learn how we're planning for vehicle electrification
- States that have adopted California's vehicle regulations
- Responding to climate change
- Focus on medium- and heavy-duty low- and zero- emission vehicle standards
Contact information
Caroline Halter
Communications Manager
Caroline.Halter@ecy.wa.gov
564-669-8947
Dustin Watson
Mobile Source Air Quality Specialist
CleanVehicles@ecy.wa.gov