February 15, 2024

EPA Finalizes Revised PM2.5 Standard

EPA has announced changes to one of its air quality standards for fine particulate matter (PM2.5). The revised standard includes a 25 percent reduction in the allowable national PM2.5 concentration from 12 µg/m3 to 9 µg/m3 calculated as the annual arithmetic mean averaged over three years. The 12 µg/m3 standard has been in place since 2012.

EPA’s Air Quality Index (AQI), which designates categories of air pollution based on concentrations, will be updated to reflect new cutoffs between categories. For example, the PM2.5 concentration associated with the AQI value of 200, which designates “very unhealthy” air, will change from 150 µg/m3 under the current standard to 125 µg/m3 under the revised standard.

According to EPA, the revised standard will prevent up to 4,500 premature deaths, 800,000 cases of asthma, and 290,000 lost workdays. States would need to demonstrate compliance with the new standard by 2032. Data associated with wildfires would not count toward the determination of PM2.5 concentrations under the revised standard. EPA is also changing its air monitoring practices to better protect populations at elevated risk for PM2.5-related health effects.

The revised standard is one of the National Ambient Air Quality Standards, or NAAQS. The NAAQS include annual and 24-hour standards and can be designated as “primary” or health-based standards for protecting groups of sensitive people or “secondary” standards for protecting the public welfare.

The revised standard is an annual primary standard. EPA is retaining its annual secondary standard for PM2.5 of 15 µg/m3 as well as its primary and secondary 24-hour standards of 35 µg/m3. The primary and secondary 24-hour standards for PM10 are also unchanged at 150 µg/m3.

For more information, read EPA’s press release and other resources available on the agency website.