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News Releases from Region 04

EPA Announces Significant Air Quality Improvement in Jefferson County, Kentucky

Area now meets the 2010 1-Hour Federal Air Quality Standard for Sulfur Dioxide

Contact Information: 
Jason McDonald (
404-562-9203, 404-562-8400

LOUISVILLE, Ky. (August 10, 2020) – Today, the U.S. Environmental Protection Agency (EPA) and the Kentucky Department of Environmental Protection announced the formal redesignation of the Jefferson County area from non-attainment to attainment of the most recent federal air quality standard for sulfur dioxide. Air monitoring data from 2016-2019 and dispersion modeling show the area now meets the National Ambient Air Quality Standard (NAAQS) for sulfur dioxide set to protect public health. Attaining the standard means cleaner air, improved health outcomes and greater economic opportunities for cities and communities. 

“Reduced sulfur dioxide in the atmosphere means cleaner, healthier air for the citizens of Jefferson County, especially children, the elderly and other sensitive groups,” said EPA Region 4 Administrator Mary S. Walker. “The air quality improvements and resulting redesignation of the Jefferson County area was realized through the combined efforts of federal, state and local agencies working with local industry.”

“This is welcome news, especially as Gov. Beshear has put an emphasis on a healthier Kentucky,” said Kentucky Energy and Environment Cabinet Secretary Rebecca Goodman. “That this area now meets national clean air standards for sulfur dioxide is good for the public’s health, good for the environment, and good for economic development.”

“As a city powered by coal in a coal-mining state, getting air quality well below the NAAQS for sulfur dioxide is a great benefit and achievement for our community,” said Louisville Metro Air Pollution Control District Director Keith Talley. “This is a significant milestone and a testament to the power of the Clean Air Act and a credit to the people in this community who never stopped demanding cleaner air.”

Under President Trump, combined emissions of criteria and precursor pollutants in the U.S. have dropped 7%, and the amount of sulfur dioxide in our air decreased 10%. Nationally, since the beginning of the Trump Administration, EPA has redesignated 53 areas from non-attainment (or “unclassifiable”) to attainment for the criteria air pollutants that make up the NAAQS. These four proposed redesignations, when finalized, will continue that progress.

The largest sources of sulfur dioxide emissions are from fossil fuel combustion at power plants and other industrial facilities. The Louisville Gas & Electric Mill Creek Generating Station (Mill Creek) is the only point source of sulfur dioxide emissions within the non-attainment area. Reduction of sulfur dioxide emissions at Mill Creek has helped bring the Jefferson County area into attainment.

Short-term exposures to sulfur dioxide can harm the human respiratory system and make breathing difficult. People with asthma, particularly children, are sensitive to these effects of sulfur dioxide. Control measures that reduce sulfur dioxide emissions can also help reduce the formation of small particles that can contribute to fine particulate matter pollution. Fine particulates may penetrate deeply into the lungs and lead to health problems.

For 50 years, the EPA has maintained its commitment to maintaining public health by improving air quality and reducing air pollution. Since 1990, the national average concentration of SO2 has dropped by 90%. Reduced levels of sulfur dioxide and other sulfur oxides are also good for the environment. A decrease in these compounds means less chances of haze and acid rain, which can harm sensitive ecosystems. All other air pollutants regulated under the NAAQS – ozone, carbon monoxide, lead, nitrogen dioxide, and particulate matter – have also significantly decreased thanks to the various air quality management and control strategies developed and implemented at the local, state, regional and national level.

For more information about the Jefferson County area final 2010 1-Hour sulfur dioxide redesignation, visit docket number EPA-R04-OAR-2020-0003 at

For more information about sulfur dioxide pollution:

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