PDF _ RL34479 - Revising the National Ambient Air Quality Standard for Lead
24-Oct-2008; James E. McCarthy; 19 p.

Update: Previous editions:
July 28, 2008

Abstract: The Administrator of the Environmental Protection Agency (EPA), under a court order to review the National Ambient Air Quality Standard (NAAQS) for lead, proposed to revise the standard on May 1, 2008, reducing it from 1.5 micrograms per cubic meter (?g/m3) to within the range of 0.10 to 0.30 ?g/m3. The proposal’s publication in the Federal Register, May 20, began a 75-day public comment period. The agency must promulgate a final standard by October 15, 2008.

NAAQS are standards for outdoor (ambient) air that are intended to protect public health and welfare from harmful concentrations of pollution. If the Administrator ultimately strengthens the lead standard, he will be concluding that protecting public health and welfare requires lower concentrations of lead pollution in ambient air than the level previously held to be safe. Lead particles can be inhaled or ingested, and, once in the body, can cause lower IQ and effects on learning, memory, and behavior in children. In adults, lead exposure is linked to increased blood pressure, cardiovascular disease, and decreased kidney function.

Regulation of airborne lead is often described as one of the key successes of the Clean Air Act and of the Environmental Protection Agency. In 1970, when lead was widely used as a gasoline additive, emissions of lead nationwide totaled 224,100 tons. Lead was also present then in many consumer products, and thus was emitted to the air in industrial processes and from waste incinerators. The phasing out of lead from gasoline, paint, and other products, as well as stricter controls on industrial emissions, reduced lead emissions 98%, to 4,228 tons in 2000.

The reduction in lead emissions and ambient concentrations have led some to suggest that there is no longer a need for an ambient air quality standard for lead. Others, including the Clean Air Scientific Advisory Committee (CASAC), an independent panel of scientists who advise the EPA Administrator, conclude that the current NAAQS (established in 1978) is far too lenient, that lead in ambient air still poses a threat to public health, and that the NAAQS should be significantly strengthened. CASAC recommended that the standard be reduced from 1.5 ?g/m3 to no higher than 0.2. In proposing a more stringent NAAQS, the Administrator sided with the scientists, rejecting the argument that the standard is no longer needed; but his proposed range is, in part, not as stringent as they recommended. His decision appears to rest, in part, on a potentially controversial interpretation of the statutory requirement to “protect ... public health” with “an adequate margin of safety.”

The May 2008 proposal follows a multi-year review of the science. Assuming a new standard is promulgated, nonattainment areas will first be identified (not expected to occur until October 2011), following which there will be a 5-10 year-long implementation process in which states and local governments will identify and implement measures to reduce lead in the air. EPA has also proposed expanding the monitoring network for lead. Only about 3% of U.S. counties have lead monitors.

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Topics: Air, Federal Agencies

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