PM 2.5 Program


What is PM 2.5?

Fine Particulate Emissions and Public Heath

PM 2.5 refers to fine particles, less than 2.5 microns in diameter, that can lodge deeply into the lungs and pose health risks. Potential health impacts include: premature death in people with heart or lung disease, nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function and increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing. Roughly one third of the U.S. population is at high risk of experiencing PM 2.5-related health effects.


Technology Certification Requirements

Cleaner diesel technologies must be verified or certified by either the U.S. Environmental Protection Agency (EPA) or California Air Resources Board (CARB).

CMAQ Funding Webinar Presentation

Clean Diesel Technologies Grant Program

TDOT’s Clean Diesel Technologies Program provides funding to reduce air pollution from diesel engines. Federal aid can be used to modernize your fleet and create health benefits for your employees and the public.

TDOT Program Goals:

  • Increase Freight Participation
  • Reduce Diesel Emissions
  • Limit Fine Particulate Emissions





Funding is available to both public and private entities in counties in TDOT Regions 1 and 2 that are designated as non-attainment or maintenance for PM 2.5. Typical projects include replacing older diesel vehicles with new, cleaner vehicles, diesel engine replacements, and add on technologies.  Road diesel vehicles like tractor trailers, buses, garbage trucks, and delivery vehicles are among those available for PM 2.5 funding. Other diesel equipment like locomotives, marine engines, freight handling equipment, road construction equipment, and airport and port equipment are also eligible.


Benefits for Fleet Owners

  • Reduced cost of fleet upgrades
  • Reduced worker exposure to dangerous diesel exhaust
  • Increased vehicle useful life
  • Reduction in fuel consumption

Matching Requirements

Funding is available to both public and private operators of diesel engines. Public sector diesel operators are eligible for project expenses up to 80 percent of total project cost. Private sector diesel operators can receive up to 50 percent of total project cost.



CARB Verified Technologies List:

Program Requirements

  • Owners need to provide basic information on their current diesel engines and proposed technology the owner will use to reduce emissions.
  • A minimum 20 percent match is required for most public entities and a 50 percent match for private operators.
  • Vehicles and equipment must be operated in a Tennessee 2.5 non-attainment or maintenance areas as shown in the map.

How to Apply

The Cleaner Diesel Technologies Grant Program has closed. Please contact for more information.