5-11-12 

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 areas 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 years of 

promulgating the NAAQS. However, if the Administrator has insufficient information to make 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 year after the promulgation of a new or revised NAAQS, each governor is 

required to recommend air quality designations, including appropriate area boundaries, to EPA. 

● Important factors that EPA recommends that states and tribes consider in making their 

recommendations include air quality data, emissions data, traffic and commuting patterns, growth 

rates and patterns, meteorology, geography/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 analysis deemed appropriate by EPA. 

● If EPA is considering modifications to a state’s initial recommendation, EPA is required to notify the 

state of any such intended modifications to its recommendation not less than 120 days prior to EPA’s 

promulgation of the final designation. 

● If the state does not agree with EPA’s intended modification, it then has an opportunity to respond to 

the EPA to demonstrate why it believes the modification proposed by EPA is inappropriate. 

● If 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, “any area that does not meet (or 

that contributes to ambient air quality in a nearby 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.” 

● Nonattainment 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 rules do not establish 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 any compliance 

costs for a specific area. Section 107(d)(2)(B) of the CAA exempts designations from notice-andcomment requirements of the Administrative Procedure Act. 

● OMB has determined designation actions are exempt from OMB review.