MDEQ Announces DeSoto County in Attainment for Ozone Standard

(JACKSON, Miss.) – The Mississippi Department of Environmental Quality (MDEQ) announced Friday that the U.S. Environmental Protection Agency (EPA) has taken final action to approve the State of Mississippi’s request to redesignate DeSoto County as being in attainment for the ozone standard. The entire State of Mississippi now meets all EPA air standards.

In 2012, EPA designated a portion of DeSoto County as being in nonattainment even though MDEQ’s air monitoring data for the county was below EPA’s ozone standard of .075 parts per million (ppm). EPA contended DeSoto County was contributing to ozone nonattainment for the Memphis Metropolitan area or “Memphis Urban Area Metropolitan Planning Organization.”

As all air monitors in the area continued to meet EPA’s ozone standard, MDEQ began the redesignation process in 2015, and worked with EPA and other stakeholders including officials in Memphis and Arkansas.

“This redesignation is important news for DeSoto County, the Memphis Metropolitan area, and the State of Mississippi. We did not believe that DeSoto County significantly contributed to nonattainment in the Memphis area. As a native of DeSoto County I am keenly aware of the effect nonattainment could have as an unfair economic impact on the county. Many people in the public and private sectors worked diligently together to get this designation changed to protect public health and the environment but also to ensure the long-term viability of economic development,” said Gary Rikard, MDEQ Executive Director.

Ground level ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight. Ozone at ground level can be a harmful air pollutant because of its effects on people and the environment, and it is the main ingredient in “smog.”

In 2004, MDEQ formed the DeSoto County Air Quality Action Group, comprised of cities, county agencies, industries, government agencies, and public interest groups, to increase awareness of air quality issues. The group has developed outreach materials and promotional events to encourage air pollution reduction steps to protect air quality and maintain ozone levels below the standard.

From April to October MDEQ issues daily ozone forecasts for DeSoto County to keep residents and businesses apprised of the current ozone conditions and alert them if an Air Quality Action Day is forecast. Air Quality Action Days are those days when ozone levels are forecast to exceed the standard, and for those days residents and businesses can alter behavior to reduce air pollution. These forecasts are available on the MDEQ website at, MDEQ’s Twitter account (@MDEQ), and an email list.

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