EPA is taking direct final action to approve revisions to the State of Maryland State Implementation Plan (SIP). The revisions pertain to adoption through incorporation by reference of the national ambient air quality standards (NAAQS) by the State of Maryland. EPA is approving these revisions that adopt the NAAQS for ozone (O<INF>3</INF>), sulfur dioxide (SO<INF>2</INF>), nitrogen dioxide (NO<INF>2</INF>), lead (Pb), particulate matter (PM) and carbon monoxide (CO) as well as the relevant reference and equivalent monitoring methods through incorporation by reference into the Code of Maryland regulations (COMAR) on an "as amended" basis which will prospectively incorporate all future revisions and additions to the NAAQS in accordance with the requirements of the Clean Air Act (CAA).