The U.S. Environmental Protection Agency (EPA) is granting two requests from the California Air Resources Board (CARB) for waivers to implement and enforce its Advanced Clean Cars II (ACC II) regulations for light-duty vehicles, and its “Omnibus” low-NOx regulation for heavy-duty highway and off-road vehicles and engines. Under the Clean Air Act, California is afforded the ability to adopt emissions requirements independent from EPA’s regulations to meet its significant air quality challenges. The state must seek a waiver from EPA for new motor vehicle emission standards.
After reviewing the information provided by California, reviewing comments submitted by the public, and applying the limited criteria for waiver review under the Clean Air Act, EPA determined in each case that it would be appropriate to grant both waiver requests. The records, included in the waiver decisions, contain public comments on the programs’ feasibility, including costs to manufacturers and the lead time provided. EPA’s review found that opponents of the waivers did not meet their burden to show how either program is inconsistent with the Clean Air Act.
The ACC II program is a single coordinated package of requirements for model year 2026 through 2035 and beyond for on-road light- and medium-duty engines and vehicles. The ACC II regulations include revisions to both California’s Low Emission Vehicle (LEV) and Zero Emission Vehicle (ZEV) regulations.
CARB projects that the ACC II program will reduce smog and soot-causing pollutants – including fine particulate matter (PM2.5) as well as oxides of nitrogen (NOx) and hydrocarbons (HC), which are precursors of ground-level ozone – as well as reduce greenhouse gases and toxic air pollutants.
EPA has taken public comment on both the ACC II and Low-NOx regulation waiver requests from state and local governments, health and environmental organizations, industry, and other stakeholders. These final decisions are based on those comments, as well as EPA’s evaluation of CARB’s requests according to Clean Air Act requirements and other information in the record, including that submitted by California. EPA maintains a webpage for information on California waivers and authorizations that sets out EPA’s administrative process for California waivers and authorization.
EPA continues reviewing additional waiver requests from California and is working to ensure its decisions are durable and grounded by law.
Published January 2025
