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News Releases from Region 05

EPA and Illinois Announce that St. Louis Area Now Meets Federal Air Quality Standard for Fine Particulate Matter

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Joshua Singer (

CHICAGO – Today, the U.S. Environmental Protection Agency (EPA) announced its approval of Illinois’ request to formally redesignate the state’s portion of the St. Louis area to attainment of the National Ambient Air Quality Standard for fine particulate matter. Recent air monitoring data show the entire St. Louis area now meets the national standard set to protect public health. 

“People in the St. Louis area are breathing cleaner air as a result of the cooperation between the state and federal governments,” said EPA Region 5 Administrator Cathy Stepp. “This action will help create jobs and benefit the region’s economy.”

“As part of our commitment to providing a cleaner and healthier environment for Illinois residents, we have officially achieved attainment of the fine particulate matter standard throughout the State,” said Illinois EPA Acting Director John J. Kim.  “Illinois continues to see a declining trend in fine particulate matter emissions statewide and we expect additional air quality benefits as we develop and expand climate policies and reduce greenhouse gases in Illinois.”

Recent monitoring data show that the St. Louis area is currently attaining the 1997 annual National Ambient Air Quality Standard for fine particulate matter. EPA is approving Illinois’ request to redesignate the state’s portion of the St. Louis area to attainment, as well as their plan to ensure that the area will continue to meet the fine particulate matter standard. The EPA redesignated the Missouri portion of the bi-state St. Louis area, effective October 2, 2018. Once an area has been redesignated, businesses seeking air permits face fewer permitting restrictions.

The St. Louis area was designated as a fine particulate matter nonattainment area in 2004 based on a multifactor analysis, including air-quality monitoring data. Several federal regulations pertaining to fuel standards and power plants decreased emissions in the St. Louis area to help achieve the standard. Additionally, two federal consent decrees required emissions reductions from a local refinery and power plant.

EPA has now redesignated all nonattainment areas for fine particulate matter in Illinois. Nationally, the concentration of fine particulate matter has decreased 41% from 2000 to 2017.

Fine particulate matter are inhalable particles with diameters smaller than 2.5 micrometers. Most particles form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles. Inhaling fine particulate matter can affect the lungs and the heart. People with pre-existing heart or lung diseases, children and the elderly are most likely to be affected by exposure to particulate matter.  Additionally, fine particulate matter is a major component of haze which can reduce visibility.

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