AG Bonta and the California Air Resources Board, leading a coalition of 19 AGs and 4 cities, submitted a comment letter to the U.S. Environmental Protection Agency opposing its proposed rule that would delay implementation of the Tier 4 emissions standards for light-duty and medium-duty vehicles. If finalized, EPA’s proposal would give manufacturers two additional years before they must begin implementing these health-protective standards. Under the current, state-of-the-art “Tier 4” standards, which EPA adopted in 2024, manufacturers must ensure that vehicles emit fewer harmful pollutants, including nitrogen oxides, particulate matter, hydrocarbons, and carbon monoxide.

“Every day the EPA delays the phase-in schedule, the harms to the public will continue to grow. This especially jeopardizes our most vulnerable communities, which bear the brunt of transportation-related pollution and suffer the resulting health consequences. The longer EPA delays these requirements, the greater the human and economic costs will be on its watch. The EPA must move forward with the phase-in schedule immediately.” -AG Bonta