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Area Designations for 2008 Ground-level Ozone Standards

National Air Quality Standards for Ozone, 120-Day Letters - Questions and Answers


On December 9, 2011, the U.S. Environmental Protection Agency, working closely with the states and tribes has taken the next step to implement the air quality standards for smog, also known as ground-level ozone. These standards were initially put in place in 2008 by the previous administration. In September, the Office of Management and Budget returned to EPA the draft final rule addressing the reconsideration of the 2008 ozone standards, which were put in place by the previous administration. In letters to state and tribal representatives, EPA has identified which areas it anticipates will be meeting the 2008 ozone standards and those which are not. States, tribes and the public will have an opportunity to comment on these proposed decisions before the agency issues final designations in spring 2012. These proposed decisions are based on air quality monitoring data, recommendations submitted by the states and tribes, and other technical information. EPA will work closely with states and tribes throughout this process using a routine and common sense approach that improves air quality, maximizes flexibilities and minimizes burden on state and local governments as they strive to meet these long standing standards.

On January 31, 2011, EPA revised its responses to recommendations from Illinois, Indiana and Wisconsin on area designations for the 2008 National Ambient Air Quality Standards for ozone. These revised letters are based on updated ozone air quality data submitted by the state of Illinois.

Breathing air containing high levels of ozone can reduce lung function and increase respiratory symptoms, aggravating asthma or other respiratory conditions. Ozone exposure also has been associated with increased susceptibility to respiratory infections, medication use by asthmatics, doctor visits, and emergency department visits and hospital admissions for individuals with respiratory disease. Ozone exposure may also contribute to premature death, especially in people with heart and lung disease.


What areas does this action affect?

EPA is sending a letter to each state indicating its proposed decisions regarding whether areas within the state should be designated as meeting or not meeting the ozone standards. EPA’s proposed decisions are based on initial recommendations made by the states and, in some cases, tribes.  Under the 2008 air quality standards for smog, EPA anticipates designating 44 areas in 26 states and the District of Columbia as not meeting the standards.

More than 30 of the 44 areas are already designated as nonattainment for ozone.  Nine are considered “maintenance” areas, meaning that ozone air quality in those areas exceeded a previous ozone standard. Only three areas in two states (California and Wyoming) have not violated previous ozone standards. Wyoming is the only state that is new to the ozone nonattainment designations process.

What happens next in the process?

States and tribes now have time to review these letters and provide EPA with information to support any further changes to EPA's responses. For the responses that EPA sent to states and tribes on December 9, EPA also published a notice in the Federal Register announcing the availability of the letters and provided for a public comment period. EPA extended that public comment period until February 3, 2012. For the revised responses EPA sent to Illinois, Indiana, and Wisconsin on January 31, 2012, EPA will be publishing a notice in the Federal Register to announce the availability of the letters and to provide for a public comment period limited to the revised responses. The public will have 30 days after the notice is published in the Federal Register to comment on the letters. EPA will consider all of this information before taking final action on these designations in spring 2012.

What can states do to come into attainment?

Each area that is designated as not meeting the 2008 standards (nonattainment) is assigned a classification based on how close they are to meeting the standards. These classifications range from marginal (closest to meeting the standards) to extreme (farthest from meeting the standards).

Based on air monitoring data, EPA expects many of the nonattainment areas would be classified as marginal, which means they would be expected to meet the standards within three years, and in some cases solely as a result of federal pollution control measures already in place.

The remaining nonattainment areas may need to implement additional measures to control emissions of nitrogen oxides and volatile organic compounds – the pollutants that react in the atmosphere to form ozone. 

How does EPA determine which areas are meeting or not meeting the standards?

After EPA sets a new National Ambient Air Quality Standard or revises an existing standard, the Clean Air Act requires the agency to formally determine whether areas are meeting the standards (attainment), not meeting the standards (nonattainment) or there is not enough information to make a determination at this time (unclassifiable). EPA is implementing the 2008 standards - 75 parts per billion - as required by the Clean Air Act.  A nonattainment area is one where air quality does not meet the ozone health standard or where sources in that area contribute to poor air quality in a nearby area.

EPA works closely with the states and tribes to make these decisions. States and, in many cases, tribes submit recommendations to the agency. The recommendations for the 2008 ozone standards were submitted in 2009. EPA has updated these recommendations with the most current air quality data; some states also provided updated information.  For the majority of the areas, EPA proposes to agree with the states’ recommendation.  In some cases, EPA is proposing changes based on its review of air quality and other information.

Why is EPA implementing the 2008 ozone standards now?

Under the Clean Air Act, EPA is legally required to implement the 75 parts per billion standards that were adopted and have been in effect since 2008. These standards will provide additional public health benefits while the agency continues to work on the next regular review of the smog standards. 

Working closely with the states and tribes, EPA is implementing the standards using a common sense approach that will improve air quality and minimize the burdens on state and local governments. Federal safeguards like the Mercury and Air Toxics Standards and the Cross-State rule and existing vehicle engine and tailpipe standards will significantly help areas meet these standards without requiring additional action. 

What is EPA doing to help the states meet the 2008 ozone standards?

History shows that cleaner air, better health and economic growth go hand-in-hand. Working closely with the states and tribes, EPA is implementing the 2008 ozone standards using a common sense approach that improves air quality, maximizes flexibilities and minimizes burden on state and local governments.

EPA recognizes that it shares the responsibility with the states and tribes for reducing ozone air pollution.  Current and upcoming federal standards and safeguards, including pollution reduction rules for power plants, industry, vehicles and fuels, will assure steady progress to reduce smog-forming pollution and will protect public health in communities across the country.

EPA will be assisting state, local and tribal air agencies by identifying existing emission reduction measures as well as relevant information concerning the efficiency and cost-effectiveness of the measures. State, local and tribal agencies will be able to use this information in developing emission reduction strategies, plans and programs.  

For more information on these letters and the ozone designation process, please visit: www.epa.gov/ozonedesignations/



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