Air Plan Approval; Maryland; Clean Data Determination for the Baltimore, MD Nonattainment Area for the 2015 Ozone National Ambient Air Quality Standards
Key claim: The EPA has determined that the Baltimore, MD nonattainment area attained the 2015 8-hour ozone NAAQS based on 2022–2024 monitoring data, suspending related planning requirements under the Clean Data Policy.
Abstract
(Rule · Environmental Protection Agency) The Environmental Protection Agency (EPA) is determining that the Baltimore, Maryland (MD) nonattainment area (the Baltimore Area or the Area) has clean data for the 2015 8-hour ozone national ambient air quality standard (NAAQS or standard). This determination is based upon quality-assured, quality-controlled, and certified ambient air monitoring data for the 2022-2024 design value (DV) period showing that the Baltimore Area attained the 2015 ozone NAAQS, with the exclusion of certain monitoring data impacted by exceptional events. The EPA is taking final agency action on portions of three exceptional event (EE) requests submitted by the Maryland Department of the Environment (MDE) on February 2, 2024, on behalf of MD, and concurred on by the EPA on November 12, 2025. As a result of the clean data determination (CDD), under the EPA’s Clean Data Policy, the EPA is suspending the requirements for the Baltimore Area to submit attainment demonstrations and associated Reasonably Available Control Measures (RACM), Reasonable Further Progress (RFP) plans, contingency measures, and other planning SIPs related to attainment of the 2015 ozone NAAQS, for as long as the Baltimore Area continues to attain the standard.
Why this matters
Clean Data Determinations pause costly nonattainment SIP obligations (attainment demonstrations, RFP plans, contingency measures) without formally redesignating the area, offering states interim regulatory relief when monitors show compliance. For the Baltimore area, this reduces near-term planning burdens on Maryland while preserving the underlying nonattainment classification and its permitting consequences until a full redesignation with maintenance plan is pursued.