The Washington Department of Ecology has adopted changes to vehicle emission standards known as Advanced Clean Trucks and Heavy-Duty Low NOx Omnibus, which expand access to new zero-emission semi-trucks and other medium- and heavy-duty commercial vehicles. Ecology is keeping these policies current as the state challenges illegal federal actions attempting to overturn them and has temporarily paused enforcement as the litigation makes its way through the courts.
Transportation is Washington’s largest source of carbon pollution, and heavy-duty vehicles like semi-trucks are the biggest contributor to diesel emissions, which are amongst the most harmful form of air pollution, contributing to serious health issues ranging from asthma to cancer.
“Here in Washington, we’re not backing away from our obligation to protect public health and advance clean transportation. Keeping our clean trucks rules current will set manufacturers up for success when the standards come back into effect,” said Ecology Director Casey Sixkiller.
There are zero-emission options available for all types of medium- and heavy-duty vehicles, and there are already thousands of these vehicles on Washington’s roads. In 2024, nearly 20% of new medium- and heavy-duty vehicles sold in Washington ran on zero-emission technology, but adoption rates vary across different categories.
Electric delivery van sales have been strong, for example, while sales of heavier zero-emission vehicles like semi-trucks have been slower to progress. Because of this, the updated rule lowers sales requirements for semi-trucks, and the state will continue to help finance heavier zero-emission trucks and charging infrastructure to support them.
This year, Washington is investing nearly $160 million from the Climate Commitment Act and the Volkswagen federal settlement to help drivers and companies buy zero-emission trucks and charging infrastructure—the second largest investment of its kind in the nation. This funding, some of which is dedicated to small businesses, will overcome initial cost barriers and help companies realize the long-term savings generated by zero-emission vehicles. It aligns with the launch of ZEVergreen, a new statewide effort led by Gov. Bob Ferguson and Ecology. An additional $26.3 million of federal, state and private funding will go toward building an electric charging and hydrogen refueling corridor for commercial vehicles that will span the entire West Coast.
Ecology extended the enforcement pause for Advanced Clean Cars II, Advanced Clean Trucks, and Heavy-Duty Low NOx Omnibus through June 2026. Ecology will continue to update the regulations and plans to begin a rulemaking to consider additional changes in the coming months.