Partial Approval and Partial Disapproval of Air Quality State Implementation Plans; Arizona; Infrastructure Requirements for Lead and Ozone

The Environmental Protection Agency (EPA) is partially approving and partially disapproving State Implementation Plan (SIP) revisions submitted by the State of Arizona to address the requirements of section 110(a)(1) and (2) of the Clean Air Act (CAA) for the 2008 Lead (Pb) and 2008 ozone national ambient air quality standards (NAAQS). Section 110(a) of the CAA requires that each State adopt and submit a SIP for the implementation, maintenance, and enforcement of each NAAQS promulgated by EPA. We refer to such SIP revisions as "infrastructure" SIPs because they are intended to address basic structural SIP requirements for new or revised NAAQS including, but not limited to, legal authority, regulatory structure, resources, permit programs, monitoring, and modeling necessary to assure attainment and maintenance of the standards.