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Medium- and Heavy-Duty Vehicle Emissions

Medium- and heavy-duty vehicles include large pickup trucks, vans, delivery trucks, box trucks, school and transit buses and long-haul delivery trucks. Diesel emissions from these vehicles produce harmful air quality pollutants, such as particulate matter and nitrogen oxides, which contribute to the formation of smog. Because these diesel emissions are classified as air toxics in Oregon, it is important to reduce exposure to them. They impact public health and are the fastest growing source of greenhouse gases, particularly as the number of truck miles traveled on our roads is forecast to continue to grow significantly in the coming decades. 

​​​The Oregon Environmental Quality Commission adopted the Clean Truck Rules on Nov. 17, 2021. It incorporated two critical rules to accelerate the transition to lower emitting medium and heavy-duty vehicles: the Advanced Clean Trucks (ACT) Rule and the Heavy-Duty Engine and Vehicle Omnibus (HD Omnibus) Rule.

  • The ACT Rule requires medium- and heavy-duty vehicle manufacturers to sell zero-emission vehicles as a certain percentage of new vehicles, beginning with the 2025 model year.
  • The HD Omnibus Rule lowers emission standards for conventionally fueled new heavy-duty vehicle engines for NOx and PM2.5. (A temporary rule to delay adoption of these rules until 2025 was adopted by the Environmental Quality Commission on Nov. 16, 2023)

FAQ: New Rules for Medium- and Heavy-Duty Vehicles and Engines​

Clean Truck Rules Forum, Nov. 30, 2023 

Clean Truck Rules Forum, Sept. 29, 2023

Funding is available to replace, retrofit or repower older diesel vehicles and equipment, including charging infrastructure.

House Bill 2007 (2019) established deadlines, after which certain older model diesel engine vehicles cannot be titled or registered in Clackamas, Multnomah and Washington Counties.

  • Starting Jan. 1, 2023, medium- or heavy-duty vehicles equipped with a 1996 or older diesel engine cannot be registered, unless retrofitted and approved by DEQ.
  • ​Starting Jan. 1, 2025, the Oregon Department of Transportation will not issue a new certificate of title for medium-duty vehicles equipped with a 2009 or older diesel engine or for heavy-duty vehicles equipped with a 2006 or older diesel engine, unless retrofitted and approved by DEQ.

Vehicles subject to these rules can continue to renew registration or be titled if they participate in the DEQ Retrofit Compliance Program and meet DEQ-approved retrofit requirements.

For questions about vehicle registration renewal or exemptions for:
  • Medium-duty vehicles, contact the Oregon Driver and Motor Vehicle Division at 503-945-5000.
  • Heavy-duty vehicles, email the Oregon Department of Commerce and Compliance at  or call 503-378-6699.


Eric Feeley, Air Quality Planner
Gerik Kransky, Air Quality Planner

Additional Resources 

Supporting Businesses in Reducing Diesel Emissions Task Force (created under HB 2007)