Petition Summary

On December 20, 2016, EPA responded to petitions submitted by 20 state and local government agencies from across the country and other organizations.

EPA’s response acknowledged the need for further NOx reductions from heavy duty on-road trucks, buses, and other vehicles to reduce adverse health impacts from ground-level ozone and microscopic airborne particles; that the Clean Air Act directs EPA to revise standards from time-to-time in order to protect public health; and that it had been 16 years since EPA last revised its NOx standards for heavy-duty highway engines. Technical progress has been made in developing technologies and approaches that can reduce NOx emissions beyond the standards put in place in the 2000 rule. As a result, the EPA will initiate the work necessary to issue a Notice of Proposed Rulemaking with the intention of proposing standards that could begin in Model Year 2024. This timeframe is consistent with the lead-time requirements of the Clean Air Act, and is aligned with a milestone implementation year for the EPA heavy-duty Phase 2 GHG program.

The Agency’s goal is to develop a program that could be adopted by EPA and the California Air Resources Board, creating a 50-state program, which would streamline compliance for manufacturers. In developing the proposal, EPA will work with a broad range of stakeholders, including heavy-duty vehicle and engine manufacturers; the California Air Resources Board; labor groups; technology suppliers; environmental non-governmental organizations; state and local air quality agencies; truck dealerships; trucking fleets; and truck drivers and owners.

Read the South Coast et. al. petition and the San Joaquin petition.

Continued Action

In November 2018, EPA announced the Cleaner Trucks Initiative (CTI), which will include a future rulemaking to establish updated standards to address NOx emissions from highway heavy-duty trucks and engines. For more information, please go here.

Response to Petitions

• South Coast Cover Letter (PDF)(2 pp, 390 K, December 20, 2016)
• San Joaquin Cover Letter (PDF)(2 pp, 353 K, December 20, 2016)
• Memorandum (PDF)(20 pp, 192 K, December 2016)