Under the Clean Air Act Amendments of 1977, the EPA is required to review and if appropriate revise the air quality criteria for the primary (health-based) and secondary (welfare-based) national ambient air quality standards (NAAQS) every five years. On January 5, 2015, EPA published a lead NAAQS proposed rule, proposing to retain the current NAAQS. The public comment period ended in April of 2015. This review has included the preparation of an Integrated Review Plan, an Integrated Science Assessment, and a Policy Assessment Document by the EPA, with opportunities for review by EPA's Clean Air Scientific Advisory Committee and the public. These documents informed the Administrator's proposed decision as to whether to retain or revise the standards. The Administrator's final decisions will take into consideration these documents and public comment on the proposed decision.