On April 24, 2026, California Attorney General Rob Bonta alongside the California Air Resources Board led a coalition of 11 attorneys general as well Harris County Texas and the City of New York in filing a lawsuit against the United Stated Environmental Protection Agency (EPA) over its failure to implement a life-saving 2024 Clean Air Act rule that would strengthen national ambient air quality standards (NAAQS) for fine particulate matter (PM2.5), commonly known as soot. 

Soot is a deadly air pollutant emitted from a variety of sources including combustion-engine vehicles, factories, and construction sites. Because of the particles’ small size, once inhaled, they can penetrate the lower parts of lungs, move out of the respiratory system, and affect other organs. As a result, soot exposure can lead to myriad health problems, including shortened lifespans, heart attacks, asthma attacks, and cancer. These health effects fall disproportionately on lower-income communities and communities of color. 

Under the Clean Air Act, the EPA is required to set NAAQS for several pollutants, including fine particulate matter, at a level that protects public health and welfare. When NAAQS are updated, the Clean Air Act gives EPA a specific deadline to designate areas of the country that are in violation of the updated standard as “nonattainment.” This designation provides key support for state programs to reduce dangerous pollution levels to safer levels. 

Reductions in soot are associated with decreases in the risk of mortality and increases in life expectancy. In 2024, EPA strengthened the soot NAAQS based on overwhelming scientific evidence.  Shortly after EPA adopted the 2024 standard, a coalition of Republican states and chambers of commerce asked a federal court to strike down the updated soot standard. California led a lawsuit to defend the standard. Currently, the case is pending, and the 2024 standard remains in effect. In February 2026, the EPA missed its deadline for designating areas with soot levels that exceed the 2024 standard, denying coalition states important tools to reduce air pollution.     

The coalition’s lawsuit alleges that the EPA violated the Clean Air Act by failing to designate areas in the United States as in or out of attainment with the 2024 standard. The lawsuit seeks both declaratory and injunctive relief, asking the Court to declare EPA’s failure to implement the 2024 standard as unlawful and order it to carry out its responsibility to make attainment designations within 150 days of the court order. 

The science is clear: When air quality worsens, hospital visits rise. Children struggle to breathe. Lives are cut short. And these devastating impacts fall most heavily on lower-income communities and communities of color. This is the reality when this life-saving national soot standard is not implemented.Attorney General Rob Bonta