Unlike other gaseous air pollutants, ground level ozone is not directly emitted by any sources. Ozone is formed when volatile organic compounds (VOCs) and nitrogen oxides (NOx) react with extreme sunlight. Sources of ozone precursors include coal-fired power plants, gas stations, natural sources and fuel combustion in cars and trucks.

oxygen reacts with sunlight, VOCs and NOx to produce Ozone

Effects on Health

Ozone impacts the respiratory system causing irritation to the nose, throat and lungs. The long-term effects of ozone are due to the inflammation of the lungs when ozone is inhaled. This type of exposure can be compared to repeated sunburns and can lead to permanent scarring of lung tissue, loss of lung function and reduced lung elasticity.

Effects on Metro Atlanta

Over the last several decades, the country has witnessed a substantial increase in the number of automobiles and the associated increase in the number of vehicle-miles traveled (VMT). Atlanta has experienced tremendous growth, adding more than a million people since the turn of the century. As a result, ozone has become a particularly persistent problem.


In Georgia, the ozone monitoring season is March 1 – October 31, when temperatures are the highest. However, for sensitive people ozone can be a problem year-round. EPD maintains ozone monitoring data in Georgia.

EPA Ozone Classification System

The current standard for 8-hour ozone is 0.070 ppm. This standard was set in 2015 by the USEPA.

The Clean Air Act has established a nonattainment area classification system for ozone based on the severity of the ozone problem. The more severe the designation, the more time an area is provided to demonstrate attainment, but the implemented controls must be more stringent. The metro region is currently classified as a Moderate 8-hour ozone nonattainment area, effective June 3, 2016 under the 2008 Ozone standard. 

Ozone Design Value


Changing Boundaries

In 2013, the Atlanta region was able to demonstrate attainment to the 1997 ozone standard.  As a result, the ozone nonattainment area boundary changed, removing Carroll, Spalding, Walton, Barrow and Hall counties.  When designations for the 2008 standard became effective, those counties not part of the new boundary were removed from the requirements associated with ozone transportation conformity.

As of August 15, 2016, the region is meeting the 2008 ozone standard and the state has prepared a plan to designate the region as a maintenance area. Meanwhile, EPA has promulgated a new stricter 2015 ozone standard. Areas will be designated for this standard in October 2017. While the exact boundary is uncertain, some portion of the region will likely be classified as a nonattainment area for the new standard.

© 2016 Atlanta Regional Commission   |   40 Courtland Street NE - Atlanta, GA 30303   |   404.463.3100   |   www.atlantaregional.com