AQ Programs

The Clean Diesel Initiative was formed to work with fleet owners and operators to offer ways they can take advantage of the benefits of diesel engines, while reducing their impact. Fleets get help choosing the right mix of strategies for their business and in some cases, the fuel savings pays for the strategy, especially when combined with tax credits (and grants when available). Strategies for reducing diesel exhaust are categorized under three primary approaches: burning less fuel, burning cleaner fuel and burning fuel cleaner.


The easiest way to reduce diesel exhaust and to save money is to burn less fuel. Simple steps such as reducing unnecessary idling can result in significant savings in fuel costs, and reduced pollution.

  • Don't idle. Stopping unnecessary idling saves money in fuel and maintenance costs. One gallon of fuel is burned for every hour of idling.
  • Perform regular maintenance to improve efficiency and engine life. It can also prevent equipment failure.
  • Track fleet inventory. Tracking vehicle model year, usage, fuel consumption, average mileage and other baseline information allows fleet managers to make decisions about operational improvements.
  • Use auxiliary power units, which provide the utility of an engine idling with far less pollution and fuel use.
  • Driver training, which can include driver incentive programs, is often overlooked as a way to use less fuel, but is an important way to ensure fuel savings measures are being followed and to maximize vehicle efficiency.
  • Employ on-board diagnostic systems, which are getting more sophisticated at tracking fuel use and driver behavior.
  • Apply fuel savings measures such as low-rolling resistance tires, automatic tire inflation and other aerodynamic features are part of EPA's Smartway program for shippers and carriers.

There are an increasing number of cleaner fuels available for diesel engines, starting with ultra low sulfur diesel fuel. This fuel is required for highway trucks and nonroad applications such as construction equipment.

There are other fuels, such as biodiesel, compressed natural gas, ethanol, propane and electricity that provide environmental benefits on their own; however, exhaust from a diesel engine is most effectively reduced at the lowest cost when clean fuels are combined with exhaust controls.

These alternative fuels have operational advantages in specific circumstances and can be an excellent solution for a fleet to lower their emissions, and in some cases, offer operational savings. For fleets that remain committed to diesel, cleaner fuels like ultra low sulfur diesel and biodiesel can be combined with advanced exhaust controls to make the most environmentally cost effective solution.

This approach refers to installing advanced exhaust controls (retrofitting vehicles and equipment), or replacing (repowering) engines.

Of the three approaches (burn less fuel, burn cleaner fuel, burn fuels cleaner), retrofitting is the most cost-effective strategy on a cost per ton of pollutant reduced basis. Typically, diesel retrofits involve adding a device to remove emissions from the engine exhaust.Retrofits can be very effective, eliminating up to 90% of pollutants, depending on the device.Some examples of devices are diesel oxidation catalysts, diesel particulate filters, and closed crankcase ventilation systems.

DEQ offers technical assistance on these approaches and can refer fleets to vendors and other resources for more information. Grant monies may be available to help with costs.

 Latest information on HB 2007

Diesel engine exhaust is a complex mixture of gases and particles. Nitrogen oxides (NOx) and fine particulate matter (PM2.5) are the diesel combustion byproducts that are of most concern. Each has specific health, environmental and climate impacts. In addition, the amount of diesel particulate pollution in the Portland region is above Oregon clean air health goals. Because diesel particulate matter is classified as an air toxic in Oregon, it is important to reduce the community’s exposure to this priority pollutant. The 2019 Oregon Legislature responded to the concerns around diesel and passed HB 2007 to reduce diesel emissions in Oregon.

The bill describes a phase-out schedule for certain older-model diesel engines that are titled or registered in Portland Metro-area counties. In addition, HB 2007 directs investment of funds received by the State from the Volkswagen Environmental Mitigation Fund to support that transition. Oregon Department of Environmental Quality will lead rulemaking efforts on some of the regulations included in the new legislation.


HB 2007 authorizes DEQ to fully disburse Oregon's remaining Environmental Mitigation Funds. DEQ will conduct a rulemaking to create a new grant program in order to distribute them. The funds will be used to support retrofitting or replacement of older diesel vehicles and equipment. The new program will specify grant application requirements, project selection criteria and other conditions, including those in the bill. 

These funds will help reduce air pollution associated with older diesel vehicles and equipment in Oregon. The overall goal of the Environmental Mitigation Fund at the national level is to reduce nitrogen oxide emissions from mobile sources with a focus on medium- and heavy-duty diesel engines. Oregon's current plan prioritizes benefits for vulnerable populations, areas of the state with the highest levels of pollution from diesel engines, and cost effectiveness of treatment.

Oregon DEQ plans to engage the public and stakeholders in a rulemaking process throughout 2020 and launch the new grant program in early 2021. The rulemaking process will provide an opportunity for diesel equipment owners and operators, community groups, and affected individuals to have input on many of the grant program details. DEQ intends to make grant funding available approximately two years prior to the January 1, 2023 deadline for phasing out vehicles powered by diesel engines that are model year 1996 or older, as specified in HB 2007. Each project that receives funding will achieve lower diesel emissions, as required by the Environmental Mitigation Fund. DEQ will continue to support projects until all statutory requirements are met and all the funds are spent.

DEQ's diesel school bus replacement program

​HB 2007 establishes deadlines, after which certain older model, diesel-engine vehicles cannot be titled or registered in Clackamas, Multnomah and Washington counties, unless they meet retrofit requirements. The gross vehicle weight rating for diesel vehicles categorized in HB 2007 are:

  • Medium Duty (14,000-26,000 lbs.)
  • Heavy Duty (>26,000 lbs.)

Gross vehicle weight rating means the value specified by the manufacturer as the maximum loaded weight of a single or a combination vehicle.

The legislation allows a vehicle to be registered or titled after the phase-out deadlines, if it is equipped with DEQ/EQC-certified retrofit technology. The legislation also exempts certain vehicle types from phase-out deadlines. For vehicles regulated by HB 2007, DEQ will complete a rulemaking to establish criteria for certification of approved retrofit technologies by 2021.

The engine model years and deadlines for registration of approved retrofit options are:

  • Jan. 1, 2023:
    Publicly and privately owned medium- and heavy-duty trucks with an engine model year 1996 or older cannot be registered
  • Jan. 1, 2025:
    • Medium-duty trucks with an engine model year 2009 or older cannot be titled
    • Heavy-duty trucks with an engine model year 2006 or older cannot be titled
  • Jan. 1, 2029:
    • Publicly and privately owned medium-duty trucks with an engine model year 2009 or older cannot be registered
    • Publicly owned heavy-duty trucks with an engine model year 2009 or older cannot be registered
    • Privately owned heavy-duty trucks with an engine model year 2006 or older cannot be registered

For information: Rick Reznic, operations and policy analyst, or visit DEQ's Vehicle Inspection homepage.

​HB 2007 directs DEQ to develop a voluntary labeling program that will demonstrate the emissions performance of non-road diesel equipment used in construction. Owners and operators will be able to place a sticker on their diesel-powered equipment during their construction projects in order to show that their equipment meets certain engine standards. DEQ will complete a rulemaking establishing the program elements regarding emissions control labels with an estimated program launch date in 2021.