The U.S. Environmental Protection Agency said it plans to retain the National Ambient Air Quality Standards for particulate matter, including both fine particles (PM2.5) and coarse particles (PM10). The standards were last revised in 2012.
EPA administrator Andrew Wheeler said that the U.S. has made great strides in reducing particulate matter concentrations and that the proposal to retain existing particulate matter standards will ensure the continued protection of public health and the environment.
The Clean Air Act requires the EPA to set NAAQS for “criteria pollutants.” Currently, particulate matter and five other major pollutants are listed as criteria pollutants. The law requires the EPA to periodically review the relevant scientific information and the standards and revise them, if appropriate, to ensure that the standards provide the requisite protection for public health and welfare.
As a result of Clean Air Act programs and efforts by state, local and tribal governments, as well as technological improvements, average PM2.5 concentrations in the U.S. fell by 39% between 2000 and 2018, while average PM10 concentrations fell by 31% during the same period.
In the previous review of the particulate matter standards, which was completed in 2012, the EPA revised the level of the primary annual PM2.5 standard from 15.0 to 12.0 mg/m3.
More information about particulate matter standards can be found here.