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Ozone Designations

Learn About Ozone Designations

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Ozone designations process

Breathing air containing ozone can reduce lung function and increase respiratory symptoms, thereby aggravating asthma or other respiratory conditions. Ozone exposure also has been associated with increased susceptibility to:

  • respiratory infections,
  • medication use by asthmatics,
  • doctor and emergency department visits, and
  • hospital admissions for individuals with respiratory disease.

Ozone exposure may contribute to premature death, especially in people with heart and lung disease. High ozone levels can also harm sensitive vegetation and forested ecosystems.

Along with states and tribes, we are responsible for reducing ozone air pollution. Current and upcoming federal standards and safeguards, including pollution reduction rules for power plants, vehicles and fuels, assure steady progress to reduce ozone-forming pollution and protect public health in communities across the country.

Title I of the Clean Air Act requires that within two years of after we have issued a new or revised National Ambient Air Quality Standard (NAAQSHelpNAAQSStandards established by EPA for maximum allowable concentrations of six "criteria" pollutants in outdoor air. The six pollutants are carbon monoxide, lead, ground-level ozone, nitrogen dioxide, particulate matter, and sulfur dioxide. The standards are set at a level that protects public health with an adequate margin of safety.), we must designate areas in the United States as being in “attainment” (i.e., meeting) or “nonattainment” (i.e., not meeting) with the standard. For the 2015 ozone standards, EPA intends to designate areas by October 1, 2017. 

The Clean Air requires states to submit, and gives tribes the opportunity to submit, initial area designation recommendations within 12 months after we have issued a new or revised NAAQS.  Tribes are not required to provide recommendations but are invited to do so and to participate in the process.  If EPA plans to issue a designation that modifies a state recommendation, EPA must notify the state no later than 120 days before the final designation.  EPA intends to issue this notification letter by June 2017.  States submit their recommendations, along with technical support and data as appropriate. 

Basis for air quality designations

EPA’s final designations will be based on:

  • air quality monitoring data,
  • recommendations submitted by the states and tribes, and
  • other technical information.

States and tribes are encouraged to base their area recommendations on the three most recent years of air quality monitoring data available (2013 - 2015).  Preliminary air quality data may be available for 2016 that states can use to inform their recommendations.  As in recent designations, when making boundary recommendations, EPA encourages air agencies to evaluate five factors:

  1. air quality data,
  2. emissions and emissions-related data,
  3. meteorology,
  4. geography/topography, and
  5. jurisdictional boundaries.