Research ReportCRS ReportVersion 23
RL32431
Particulate Matter (PM2.5): Implementation of the 1997 National Ambient Air Quality Standards (NAAQS)
Published Aug 24, 2010Updated Jun 20, 2025
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The Congressional Research Service is a nonpartisan policy and legal analysis arm of the Library of Congress. CRS reports are written for members of Congress and their staff, not the public — but they’re made available openly through Congress.gov.