National Ambient Air Quality Standards for Lead

Based on its review of the air quality criteria and national ambient air quality standards (NAAQS) for lead (Pb), EPA proposes to make revisions to the primary and secondary NAAQS for Pb to provide requisite protection of public health and welfare, respectively. EPA proposes to revise various elements of the primary standard to provide increased protection for children and other at-risk populations against an array of adverse health effects, most notably including neurological effects, particularly neurocognitive and neurobehavioral effects, in children. With regard to the level and indicator of the standard, EPA proposes to revise the level to within the range of 0.10 to 0.30 [mu]g/ m\3\ in conjunction with retaining the current indicator of Pb in total suspended particles (Pb-TSP) but with allowance for the use of Pb- PM<INF>10</INF> data, and solicits comment on alternative levels up to 0.50 [mu]g/m\3\ and down below 0.10 [mu]g/m\3\. 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-PM<INF>10</INF> and on the same broad range of levels on which EPA is soliciting comment for the Pb-TSP indicator (up to 0.50 [mu]g/m\3\). 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. Consistent with the terms of a court order, by September 15, 2008 the Administrator will sign a notice of final rulemaking for publication in the Federal Register.