EPA Final Area Designations for National Ambient Air Quality Standards

June 5, 2018

On April 30, 2018, the U.S. Environmental Protection Agency (EPA) published their Final Area Designations for the National Ambient Air Quality Standards for Ozone Established in 2015. EPA has designated 51 additional counties in 22 states as ozone nonattainment areas.

The Clean Air Act directs state air agencies to take steps to control ozone pollution in nonattainment areas based on the severity of the air quality at the time of designation. Classifications range from “marginal” to “extreme” based on air quality monitoring data. There are two methods states may use to meet federal ozone emission standards: 1) to mandate reformulated gasoline or 2) impose lower RVP requirements for conventional gasoline during the summertime ozone season beginning June 1 through September 15 each year.

The EPA strengthened federal ozone standard in 2015 by lowering the attainment level for ground level ozone from 75 parts per billion to 70 parts per billion measured over an 8- hour period. Last November, EPA indicated that 85 percent or 2,646 counties nationwide would be in attainment with the new 70 parts per billion standard. The remaining 51 counties are designated as nonattainment. Eight remaining counties in San Antonio, Texas area will be classified in July 2018, according to the EPA.

Nonattainment areas are required to meet the 70 parts per billion ozone standard as quickly as possible, but no later than the maximum attainment date associated with each classification. The maximum attainment date for each classification are:

  • 3 years for marginal areas;
  • 6 years for moderate areas;
  • 9 years for serious areas;
  • 15 years (or 17 years)  for severe areas; and
  • 20 years for extreme areas.

States must detail how they will comply with the 70 parts per billion standard in revised state air quality implementation plans (SIP) submitted to the EPA for approval. Areas classified as Marginal are not required to submit plans demonstrating how they will meet the ozone standards. For all other nonattainment areas, states have three to four years after the effective date of final designations to develop and submit required SIP elements to EPA, depending on area classification.

  • To see EPA’s Ozone Designation website, click here
  • To see the EPA Fact Sheet, click here
  • To see a detail list of the newly designated nonattainment areas, click here.

To see a map of the newly designated nonattainment areas, click here.