An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Lead Air Pollution

Timeline of Lead (Pb) National Ambient Air Quality Standards (NAAQS)

History of the NAAQS for Pb
Final Rule/Decision Primary/Secondary Indicator1 Averaging Time Level2 Form

43 FR 46246 
Oct 5, 1978
Primary and Secondary Pb-TSP Calendar Quarter 1.5 µg/m3 Not to be exceeded
1991 Agency released multimedia "Strategy for Reducing Lead Exposures"

73 FR 66964
Nov 12, 2008
Primary and Secondary Pb-TSP 3-month period 0.15 µg/m3 Not to be exceeded

81 FR 71906
Oct 18, 2016
Primary and secondary standards retained, without revision.

1. Pb-TSP = Lead in total suspended particles

2. Units of measure are micrograms per cubic meter of air (µg/m3).