Proposed rule · 2025-20418

Air Plan Approval; Delaware; 2006 24-Hour Fine Particulate Matter Limited Maintenance Plan for the Philadelphia Nonattainment Area

The Environmental Protection Agency (EPA) is proposing to approve a limited maintenance plan (LMP) submitted by the Delaware Department of Natural Resources and Environmental Control (DNREC). This LMP is a revision to Delaware's state implementation plan (SIP) and addresses the New Castle County portion of the Philadelphia-Wilmington, PA-NJ-DE area (Philadelphia Area). The EPA is proposing to approve the New Castle County portion of the Philadelphia Area LMP because it provides for the maintenance of the 2006 24-hour fine particulate matter (PM<INF>2.5</INF>) national ambient air quality standard (NAAQS) through the end of the second 10-year maintenance period. In addition, the EPA is initiating the process to find the LMP adequate for transportation conformity purposes. This action is being taken under the Clean Air Act (CAA).