This OAQPS Staff Paper, prepared by staff in the U.S. Environmental Protection Agencys (EPA) Office of Air Quality Planning and Standards (OAQPS), presents factors relevant to EPAs current review of the primary (health-based) and secondary (welfare-based) lead (Pb) national ambient air quality standards (NAAQS) that were originally established in 1978. In this document, OAQPS staff evaluates the policy implications of the key studies and scientific information contained in the final document, Air Quality Criteria for Lead (USEPA, 2006a; henceforth referred to as the CD), prepared by EPAs National Center for Environmental Assessment, and presents and interprets results from several quantitative analyses (e.g., human exposure analyses, human health risk assessments and environmental assessments) that we believe should also be considered in EPA's review of the Pb NAAQS. Further, this document presents OAQPS staff conclusions and recommendations on a range of policy options that we believe are appropriate for the Administrator to consider concerning whether, and if so how, to revise the primary and secondary Pb NAAQS. The policy assessment presented in this Staff Paper is intended to help bridge the gap between the scientific assessment contained in the CD and the judgments required of the EPA Administrator in determining whether it is appropriate to retain or revise the NAAQS for Pb. In evaluating the adequacy of the current standard and a range of policy alternatives, OAQPS staff has considered the available scientific evidence and quantitative risk-based analyses, together with related limitations and uncertainties, and has focused on the information that is most pertinent to evaluating the basic elements of air quality standards: indicator, averaging time, form, and level. These elements, which together serve to define each standard, must be considered collectively in evaluating the health and welfare protection afforded by the Pb standards. The information, conclusions, and staff recommendations presented in this Staff Paper have been informed by comments and advice received from an independent scientific review committee, the Clean Air Scientific Advisory Committee (CASAC), in their reviews of an earlier draft of this document and drafts of related technical support documents, as well as comments on these earlier draft documents submitted by public commenters.

Replaces earlier draft: EPA-452/P-06-002. "November 2007." Final report. Includes bibliographical references. "EPA-452/R-07-013." PB2008-102572.