National Ambient Air Quality Standards (NAAQS) for PM

Rule Summary

03/12/2025 - Trump EPA Announces Path Forward on National Air Quality Standards for Particulate Matter (PM2.5) to Aid Manufacturing, Small Businesses
Fact Sheet - Reconsideration of National Ambient Air Quality Standards for Particulate Matter (pdf) (132.6 KB)

On February 7, 2024, EPA strengthened the National Ambient Air Quality Standards for Particulate Matter (PM NAAQS) to protect millions of Americans from harmful and costly health impacts, such as heart attacks and premature death. Particle or soot pollution is one of the most dangerous forms of air pollution, and an extensive body of science links it to a range of serious and sometimes deadly illnesses. EPA is setting the level of the primary (health-based) annual PM_2.5 standard at 9.0 micrograms per cubic meter to provide increased public health protection, consistent with the available health science.

EPA is not changing the current:

primary and secondary (welfare-based) 24-hour PM_2.5 standards,
secondary annual PM_2.5 standard, and

primary and secondary PM₁₀ standards.

EPA is also revising the Air Quality Index to improve public communications about the risks from PM_2.5 exposures and making changes to the monitoring network to enhance protection of air quality in communities overburdened by air pollution.