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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
1978 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"
2008 73 FR 66964 Nov 12, 2008	Primary and Secondary	Pb-TSP	3 month period	0.15 µg/m³	maximum arithmetic mean of 3 consecutive monthly means in a 3-year period
2016 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).

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

Lead Air Pollution