Air Plan Approval; Maryland; Clean Data Determination for the Baltimore, MD Nonattainment Area for the 2015 Ozone National Ambient Air Quality Standards

The Environmental Protection Agency (EPA) is proposing to determine that the Baltimore, Maryland nonattainment area (the Baltimore Area or the Area) has clean data for the 2015 8-hour ozone national ambient air quality standards (2015 ozone NAAQS or standard). This proposed clean data determination (CDD) under the EPA's Clean Data Policy is based upon quality-assured, quality-controlled, and certified ambient air quality monitoring data showing that the Baltimore Area has attained the 2015 ozone NAAQS based on 2022-2024 data available in the EPA Air Quality System (AQS) database. If finalized, this proposed CDD would suspend the obligations of the State of Maryland (MD) to submit certain attainment area planning requirements for as long as the Baltimore Area continues to attain the 2015 ozone NAAQS. As part of this rulemaking, the EPA also proposes to take final agency action on portions of exceptional events requests submitted by MD on February 2, 2024 and concurred on by the EPA on November 12, 2025. The proposed CDD is based upon the EPA's concurrence on portions of the exceptional events demonstrations. This action is being taken under the Clean Air Act (CAA).