EPA Splits Philly Ozone Zone to Help Maryland and Delaware Breathe Easier
Published Date: 1/2/2026
Proposed Rule
Summary
The EPA is proposing to split the big Philadelphia ozone pollution area into three smaller zones covering the same land, based on requests from Maryland and Delaware. This change affects Cecil County, MD, and New Castle County, DE, and includes new clean air data showing improvements. Comments on this plan are open until February 2, 2026, and the update helps local communities breathe easier without adding new costs right now.
Analyzed Economic Effects
5 provisions identified: 4 benefits, 1 costs, 0 mixed.
Philadelphia Ozone Area Split Into Three
If you live in the Philadelphia-Wilmington-Atlantic City ozone area, the EPA proposes splitting that large area into three separate nonattainment areas: Cecil County, MD; New Castle County, DE; and a revised Philadelphia-Atlantic City PA-NJ area. The proposal keeps each area's current nonattainment classifications (Marginal for the 2008 standard and Serious for the 2015 standard) and is meant to reflect local air quality differences.
Requirement: Serious Area Plans Due Jan 1, 2026
For the 2015 ozone standard the Philadelphia nonattainment area is classified as Serious and each state in that area must provide a Serious nonattainment plan to EPA by January 1, 2026, showing how the area will come into attainment by the Serious-area attainment date of August 3, 2027. This applies to the states in the Philadelphia nonattainment area (Pennsylvania, New Jersey, Maryland, and Delaware).
Cecil County Clean Air Finding Suspends Plans
If you live in Cecil County, MD, the EPA proposes a clean data determination (CDD) showing the county's 2022-2024 ozone design value is 67 ppb and that the county is attaining the 2015 and 2008 ozone standards. If finalized, Maryland would be suspended from submitting certain attainment planning requirements (like attainment demonstrations, RACM, RFP plans, and contingency measures) for Cecil County so long as the county continues to attain the standards.
New Castle County Clean Air Finding Suspends Plans
If you live in New Castle County, DE, the EPA proposes a clean data determination (CDD) showing the county's highest recent three-year ozone design value is 68 ppb and that the county is attaining the 2015 and 2008 ozone standards. If finalized, Delaware would be suspended from submitting certain attainment planning requirements (like attainment demonstrations, RACM, RFP plans, and contingency measures) for New Castle County so long as the county continues to attain the standards.
Small Entities: No Significant Economic Impact
The EPA states this proposed action does not impose additional requirements and is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act. The agency also says the action does not impose an unfunded mandate or significantly affect small governments.
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