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The United States Environmental Protection Agency (“EPA”) in a March 13th Federal Register Notice announced the reclassification of the Independence County, Arkansas, unclassifiable area for the 2010 sulfur dioxide (“SO2) National Ambient Air Quality Standard (“NAAQS”) to attainment/unclassifiable. See 84 Fed. Reg. 8986.
EPA’s decision was based on an April 20, 2018, submission of information by the State of Arkansas through the Arkansas Department of Environmental Quality (“ADEQ”).
Section 108 and 109 of the Clean Air Act require that EPA identify air pollutants utilizing certain criteria and a set NAAQS for each. One of the prerequisites for classification as a criteria pollutant is that it be emitted from numerous or diverse mobile stationary sources. Criteria air pollutants are therefore by definition some of the most commonly encountered air pollutants. As a result, the criteria air pollutants have received a significant amount of EPA/state attention and resources in the history of the modern Clean Air Act.
The states are primarily responsible for ensuring attainment and maintenance of the NAAQS once established by the EPA. Each state is therefore required to formulate, subject to EPA approval, an implementation plan (“SIP”) designed to achieve each NAAQS. The SIPs will contain the measures and actions the state proposes to attain each NAAQS. The states are generally free to make their own choices as to how they will attain the NAAQS through their SIPs.
EPA states in the March 13th Federal Register Notice that ADEQ’s April 20, 2018, submittal included new information in support of the redesignation of the Independence County area to attainment/unclassifiable for the primary SO2 NAAQS. The federal agency states that it confirmed ADEQ’s modeling results appropriately characterized the air quality in Independence County. As a result, it states that predicted ambient SO2 concentrations are below the NAAQS.
A copy of the Federal Register Notice can be found here.
