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News Releases from Region 05

EPA and IDEM Announce Terre Haute Area Now Meets Federal Air Quality Standard for Sulfur Dioxide

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Joshua Singer (

Terre Haute, Ind. – Today, the U.S. Environmental Protection Agency (EPA) announced its approval of Indiana’s request to formally redesignate the Terre Haute area to attainment of the National Ambient Air Quality Standard (NAAQS) for sulfur dioxide. Recent air monitoring data show the Terre Haute area now meets the national standard set to protect public health. 

“The air in the Terre Haute area is cleaner as a result of the cooperation between the state and federal governments,” said EPA Region 5 Administrator Cathy Stepp. “Terre Haute is a great example of the successful partnership between states, industry and the EPA to protect human health and the environment, and also spur economic development. In Region 5, working with our state partners, we are making such significant improvements in air quality that in the past two years have been able to redesignate eight areas.”

“With this action by EPA, we are happy to officially redesignate the Terre Haute area as meeting ambient air quality standards,” said Indiana Department of Environmental Management (IDEM) Commissioner Bruno Pigott. “We appreciate the collaborative effort between our agency and EPA to provide cleaner air to Hoosiers.”

In 2013, the Terre Haute area was designated as nonattainment for the sulfur dioxide air quality standard. Since then, IDEM worked collaboratively with EPA to reduce air pollution in the area. Major sulfur dioxide reductions came from the closing of a coal-fired power plant, operational limits on other power plants, and fuel switches from coal to natural gas, reducing sulfur dioxide emissions in Terre Haute by 99%. EPA has now determined that the Terre Haute area has attained the 2010 sulfur dioxide NAAQS, based on the most recent three years of certified air quality data. Once an area has been redesignated, businesses seeking air permits face fewer permitting restrictions.

The largest source of sulfur dioxide in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. Short-term exposures to sulfur dioxide can harm the respiratory system and make breathing difficult. Children, the elderly, and those who suffer from asthma are particularly sensitive to effects of sulfur dioxide. High concentrations of sulfur dioxide in the air generally also lead to the formation of other sulfur oxides. Sulfur oxides can react with other compounds in the atmosphere to form small particles that contribute to particulate matter pollution, which may penetrate deeply into sensitive parts of the lungs and cause additional health problems. Sulfur dioxide and other sulfur oxides can contribute to haze and acid rain, which can harm sensitive ecosystems.

Nationally, average concentrations sulfur dioxide has decreased 79% from 2000 to 2017.

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