Based on its review of the air quality criteria and national ambient air quality standards (NAAQS) for lead (Pb), EPA is making revisions to the primary and secondary NAAQS for Pb to provide requisite protection of public health and welfare, respectively. With regard to the primary standard, EPA is revising the level to 0.15 [mu]g/m<SUP>3</SUP>. EPA is retaining the current indicator of Pb in total suspended particles (Pb-TSP). EPA is revising the averaging time to a rolling 3-month period with a maximum (not-to-be-exceeded) form, evaluated over a 3-year period. EPA is revising the secondary standard to be identical in all respects to the revised primary standard. EPA is also revising data handling procedures, including allowance for the use of Pb-PM<INF>10</INF> data in certain circumstances, and the treatment of exceptional events, and 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 revising emissions inventory reporting requirements and providing guidance on its approach for implementing the revised primary and secondary standards for Pb.