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Comment Period

Low Emission Vehicles, Chapter 173-423 WAC

Proposed rulemaking

June 22, 2021 - Aug. 2, 2021, 11:59 p.m.

Ecology proposes to update two rules:

• Chapter 173-423 WAC, Low Emission Vehicles (proposing title change to Clean Vehicles Program)
• WAC 173-400-025, Adoption of federal rules as written, in Chapter 173-400 WAC, General Regulations for Air Pollution Sources.

Washington is expanding its program by adopting California’s more protective vehicle emission standards for new vehicles — starting with model year 2025 and later — sold in Washington. Motor vehicles are the largest source of air pollution in Washington. Transportation contributes about 22 percent of total air pollution and 45 percent of greenhouse gas emissions throughout the state.

Rulemaking usually starts at the rule announcement phase. However, Ecology is starting this rulemaking at the rule proposal phase because the Legislature directed us to adopt California’s rules as written (RCW 70A.30.010).

Documents for review


We write rules to implement and enforce state and federal environmental laws and rules.  Ecology follows a three-phase process for rulemaking:

  1. Announcement and development
  2. Proposal
  3. Adoption

For each phase of the process, we update the rulemaking web page and notify interested parties. We also file notice in the Washington State Register. To learn more about Ecology’s rulemaking process, read the Frequently Asked Questions.

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Elena Guilfoil
Washington Department of Ecology
Air Quality Program
P.O. Box 47600
Olympia, WA 98504-7600
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Elena Guilfoil
Rulemaking Lead

To request ADA accommodation, contact Ecology's ADA Coordinator by email at ecyadacoordinator@ecy.wa.gov, or call 360-407-6831, 711 (relay service), or 877-833-6341 (TTY). More about our accessibility services.