In this document, the Environmental Protection Agency (EPA or Agency) is taking three separate but related actions. First, EPA is finalizing its determination that the Libby fine particulate matter (PM<INF>2.5</INF>) nonattainment area (Libby Area) is attaining the 1997 Annual PM<INF>2.5</INF> national ambient air quality standards (NAAQS or standard) based on 2014-2021 data. Secondly, EPA is finalizing approval of Montana's plan for maintaining the 1997 Annual PM<INF>2.5</INF> NAAQS (limited maintenance plan).

The Environmental Protection Agency (EPA) is redesignating the Oakridge, Oregon nonattainment area to attainment for the 2006 24-hour fine particulate matter (PM<INF>2.5</INF>) National Ambient Air Quality Standard (NAAQS). The EPA is also approving a maintenance plan for the area that demonstrates continued compliance with the PM<INF>2.5</INF> NAAQS through the year 2035, which Oregon submitted along with the redesignation request for inclusion into the Oregon State Implementation Plan (SIP).

The Environmental Protection Agency (EPA) is taking final action to approve the ``FINAL SIP Revision: Nogales PM<INF>2.5</INF> Maintenance Plan and Redesignation Request (2006 Fine Particulate NAAQS)'' (``Nogales Maintenance Plan'' or ``Plan'') as a revision to the state implementation plan (SIP) for the State of Arizona. The Nogales Maintenance Plan includes, among other elements, an emissions inventory consistent with attainment, a maintenance demonstration, contingency provisions, and a motor vehicle emissions budget for the ten-year maintenance period.

The Environmental Protection Agency (EPA) finds that the Cincinnati, Ohio-Kentucky area (Area) is attaining the 2015 ozone National Ambient Air Quality Standard (NAAQS or standard) and is acting in accordance with a request from the Ohio Environmental Protection Agency (OEPA) to redesignate the Ohio portion of the Area to attainment for the 2015 ozone NAAQS because the request meets the statutory requirements for redesignation under the Clean Air Act (CAA).