Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

PREFACE
National Ambient Air Quality Standards (NAAQS) are promulgated by the United States
Environmental Protection Agency (EPA) to meet requirements set forth in Sections 108 and 109
of the U.S. Clean Air Act. Those two Clean Air Act sections require the EPA Administrator
(1) to list widespread air pollutants that reasonably may be expected to endanger public health or
welfare; (2) to issue air quality criteria for them that assess the latest available scientific
information on nature and effects of ambient exposure to them; (3) to set “primary” NAAQS to
protect human health with adequate margin of safety and to set “secondary” NAAQS to protect
against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade
materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS
for a given listed pollutant or class of pollutants.
Lead was first listed in the mid-1970’s as a “criteria air pollutant” requiring NAAQS
regulation. The scientific information pertinent to Pb NAAQS development available at the time
was assessed in the EPA document Air Quality Criteria for Lead; published in 1977. Based on
the scientific assessments contained in that 1977 lead air quality criteria document (1977 Lead
AQCD), EPA established a 1.5 µg/m 3 (maximum quarterly calendar average) Pb NAAQS in
1978.
To meet Clean Air Act requirements noted above for periodic review of criteria and
NAAQS, new scientific information published since the 1977 Lead AQCD was later assessed in
a revised Lead AQCD and Addendum published in 1986 and in a Supplement to the 1986
AQCD/Addendum published by EPA in 1990. A 1990 Lead Staff Paper, prepared by EPA’s
Office of Air Quality Planning and Standards (OPQPS), drew upon key findings and conclusions
from the 1986 Lead AQCD/Addendum and 1990 Supplement (as well as other OAQPSsponsored
lead exposure/risk analyses) in posing options for the EPA Administrator to consider
with regard to possible revision of the Pb NAAQS. However, EPA chose not to revise the Pb
NAAQS at that time. Rather, as part of implementing a broad 1991 U.S. EPA Strategy for
Reducing Lead Exposure, the Agency focused primarily on regulatory and remedial clean-up
efforts to reduce Pb exposure from a variety of non-air sources that posed more extensive public
health risks, as well as other actions to reduce air emissions.
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