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**What are the CAA requirements for air quality designations?** ● When EPA promulgates a new or revised national ambient air quality standard (NAAQS ) , the Clean Air Act (CAA) requires EPA to designate all area s in the nation as either nonattainment, attainment, or unclassifiable, pursuant to section 107(d)(1). ● The CAA requires EPA to complete the initial area designation process within 2 y ears of promulgating the NAAQS. However, if the Administrator has insufficient information to m ake these designations within that time frame, EPA has the authority to extend the deadline for designation decisions by

up to 1 additional year. ● By not later than 1 ye ar after the promulgation of a new or revised NAAQS, each governor is required to re commend air quality designations, including appropriate area boundaries, to EPA. ● Important factors that EPA recommend s that states and tribes consider in making their recommendations include air qualit y data, emissions data, traffic and commuting patt erns, growth rates and patterns, meteorology , geograph y/topography , and jurisdictional boundaries. ● EPA reviews the state recommendations and is authorized to make any modifications the Administrator deems necessary . The statute does not define the term “necessary ,” but EPA interprets this to authorize the Administrator to modify designations that did not meet the statutory requirements or were otherwise inconsistent with the facts or anal ys is deemed appropriate by EPA. ● If EPA is considering modificat ions to a state’s initial recommendation, EPA is required to notify the state of an y such intended modifications to its recommendation not less than 120 day s prior to EPA’s promulgation of the final designation. ● If the state does not agree with EPA’s i ntended modification, it then has an opportunity to respond to the EPA to demonstrate why it believes the modification proposed by EPA is inappropriate. ● I f a state fails to provide any recommendation for an area, in whole or in part, EPA still must promulgate a designation that the Administrator deems appropriate. ● Section 107(d)(1)(A)(i) of the CAA defines a nonattainment area as, “an y area that does not meet (or that contributes to ambient air quality in a nearb y area that does not meet) the national primary or secondary ambient air quality

standard for the pollutant.” If an area meets either prong of this definition, then the EPA is obligated to designate the area as “nonattainment.” ● N onattainment areas are subject to planning and emission reduction requirements as specified in the CAA. EPA works with states and tribes to share the responsibility of reducing the air pollution. ● Designation rule s d o not est ablish any control requirements . They do not create any additional requirements beyond those of the CAA and the NAAQS . Rather, regulatory plans adopted by

states in response to the CAA’s requirements for designated areas will form the basis for an y compliance costs for a specific area. Section 107(d)(2)(B) of the CAA exempts designations from notice - and comment requirements of the Administrative Procedure Act. ● OMB has determined designation actions are exempt from OMB review.