EPA Proposes Lead NAAQS Between 0.1 - 0.3 Micrograms/M3

May 1: U.S. EPA announced it is taking steps toward revising the national ambient air quality standards (NAAQS) for lead (Pb) for the first time in 30 years, proposing to "dramatically strengthen the standards" to reflect the latest science on lead and health. EPA Administrator Stephen Johnson said, "By tackling lead emissions, EPA is keeping America's clean air progress moving forward. With today's proposal, we can write the next chapter in America's clean air story."

EPA is under a judicial order in Missouri Coalition for the Environment, v. EPA (No. 4:04CV00660 ERW, Sept. 14, 2005). The order governing the review, entered by the court on September 14, 2005 and amended on April 29, 2008, specifies that EPA sign, for publication, notices of proposed and final rulemaking concerning its review of the Pb NAAQS no later than May 1, 2008 and September 15, 2008, respectively. EPA will accept public comment for 60 days after the proposal is published in the Federal Register. The agency will hold two public hearings on June 12, 2008: one in St. Louis and one in Baltimore.

According to EPA the proposal would tighten the primary standard to protect public health by 80 to 93 percent. It would revise the existing standard of 1.5 micrograms per cubic meter of air to a level within the range of 0.10 to 0.30 micrograms per cubic meter. The Agency is taking comment on alternative levels within a range from less than 0.10 to 0.50 micrograms per cubic meter. With regard to the averaging time and form of the standard, EPA proposes two options: to retain the current averaging time of a calendar quarter and the current not-to-be-exceeded form, revised to apply across a 3-year span; and to revise the averaging time to a calendar month and the form to the second-highest monthly average across a 3-year span.

EPA also solicits comment on revising the indicator to Pb-PM10 and on the same broad range of levels on which EPA is soliciting comment for the Pb-TSP indicator (up to 0.50 µg/m3). EPA also invites comment on when, if ever, it would be appropriate to set a NAAQS for Pb at a level of zero. EPA proposes to make the secondary standard identical in all respects to the proposed primary standard.

EPA is also proposing corresponding changes to data handling procedures, including the treatment of exceptional events, and to ambient air monitoring and reporting requirements for Pb including those related to sampling and analysis methods, network design, sampling schedule, and data reporting. Finally, EPA is providing guidance on its proposed approach for implementing the proposed revised primary and secondary standards for Pb.

EPA notes that since 1980, emissions of lead to the air have dropped nearly 98 percent nationwide, largely the result of the Agency's phaseout of lead in gasoline. And average levels of lead in the air are far below the level of the 1978 standard. Lead in the air today comes from a variety of sources, including smelters, iron and steel foundries, and general aviation gasoline. About 1,300 tons of lead are emitted to the air each year, according to EPA's most recent estimates.

Lead that is emitted into the air can be inhaled or, after it settles out of the air, can be ingested. Ingestion is the main route of human exposure. Once in the body, lead is rapidly absorbed into the bloodstream and can affect many organ systems. More than 6,000 studies since 1990 have examined the effects of lead on health and the environment. Evidence from health studies indicates that lead in the blood can cause harm at much lower levels than previously understood. Exposure to lead is associated with a broad range of health effects, including harm to the central nervous system, cardiovascular system, kidneys and immune system. Children are particularly vulnerable: Exposures to low levels of lead early in life have been linked to effects on IQ, learning, memory and behavior. Lead also can cause toxic effects in plants and can impair reproduction and growth in birds, mammals and other organisms.

Access a release from EPA (click here). Access the 452-page proposed rule (click here). Access additional information including a fact sheet and background documents (click here). Access more information on lead in air (click here). [*Air]