The Environmental Protection Agency (EPA) is approving most elements of State Implementation Plan (SIP) submissions from Massachusetts regarding the infrastructure requirements of the Clean Air Act (CAA or Act) for the 1997 ozone, 2008 lead (Pb), 2008 ozone, 2010 nitrogen dioxide (NO<INF>2</INF>), and 2010 sulfur dioxide (SO<INF>2</INF>) National Ambient Air Quality Standards (NAAQS). EPA is also conditionally approving three aspects of the Commonwealth's submittals. In addition, we are also making findings of failure to submit pertaining to various aspects of the prevention of significant deterioration (PSD) requirements of infrastructure SIPs. Lastly, we are removing 40 CFR 52.1160 as legally obsolete. This action is being taken in accordance with the Clean Air Act.