On October 15, 2008, the U.S. Environmental Protection Agency (EPA) substantially strengthened the National Ambient Air Quality Standards (NAAQS) for lead. The revised standards are 10 times lower than the previous standards and will improve health protection for at-risk groups with a particular focus on children. In conjunction with this strengthening of the lead NAAQS, EPA changed the existing lead ambient monitoring requirements to better identify locations where concentrations would have the potential to exceed the new NAAQS. This article discusses the revisions to both the lead NAAQS and the monitoring requirements.
History of the Lead NAAQS
On October 5, 1978, EPA promulgated the first primary and secondary NAAQS for lead under Section 109 of the U.S. Clean Air Act (CAA).1 Both primary and secondary standards were set at a level of 1.5 micrograms per cubic meter (μg/m3), measured as lead in total suspended particulate matter (Pb-TSP), not to be exceeded by the maximum arithmetic mean concentration averaged over one calendar quarter.
A review of the lead NAAQS was initiated in the mid-1980s and extended into the early 1990s. After consideration of the results of the review, and taking into account the dramatic decreases in ambient lead concentrations following the removal of lead from gasoline, EPA decided not to revise the lead NAAQS. Instead, the agency developed the broad multiprogram, multimedia, and integrated “U.S. Strategy for Reducing Lead Exposure.” As part of implementing this strategy, the agency focused its efforts primarily on regulatory and remedial cleanup actions aimed at reducing exposures from a variety of nonair sources judged to pose the most extensive public health risks, as well as actions to reduce lead emissions from significant lead sources such as smelters.
EPA initiated the most recent review of the lead NAAQS in the outdoor air in 2004. This process, described in detail in the lead NAAQS Final Rule, resulted in revisions to the primary and secondary NAAQS for lead that were published in the Federal Register on November 12, 2008.2 Specifically, EPA revised the NAAQS from a level of 1.5 μg/m3 to 0.15 μg/m3. EPA retained Pb-TSP as the indicator and revised the averaging time to a rolling threemonth period with a maximum (not-to-beexceeded) form, evaluated over a three-year period. EPA also revised the secondary standard to be identical in all respects to the revised primary standard.
EPA set the new standards with the goal of protecting against IQ loss in young children. The new standards are also expected to reduce the risk of a variety of health effects linked to lead exposure, such as neurological effects—including IQ loss—and cardiovascular and kidney effects in adults.