Ozone (Smog)

While ozone high in our atmosphere is important for protecting people from the sun’s ultraviolet radiation, at ground level it can be a significant health threat. Ground level ozone, or smog, is formed from a chemical reaction between nitrogen oxides and volatile organic compounds in the presence of heat and sunlight. These compounds are emitted into the atmosphere by places like power plants, refineries, and chemical plants, by mobile sources like cars, trucks, and trains, and by activities like lawnmowing, open burning, and the use of woodstoves. We may think of smog as a problem centered in industrial cities, but wind can carry ozone pollution far into rural areas as well.

Ozone is especially dangerous to children, older adults, and folks with asthma, emphysema, and bronchitis, but it can harm lung tissue in anyone who breathes it. The Clean Air Act requires the EPA to designate “non-attainment” areas in places where air quality does not meet federal health standards for ozone or where local emissions contribute to nearby areas’ failure to meet the standards. This “non-attainment” designation forces the state to create a clean-up plan.

What is ELPC Doing?

  • In 2018, the Trump EPA issued new designations and weakened clean air protections for several areas in southeast Wisconsin, McHenry and Monroe Counties, Illinois, and northwest Indiana. This move ignores the clear scientific evidence of persistent pollution, putting millions at risk of dangerous smog. In January 2019, ELPC filed a lawsuit against the Trump EPA for making these new designations unsupported by facts or sound science.
  • By declaring these counties to be in attainment, the EPA would let polluting areas off the hook without cleaning up the neighbors they’ve harmed. We don’t want to see folks burdened with cleaning up a mess they didn’t make or facing a sick population, so we’re fighting back.
  • ELPC continues to be a watchdog of the EPA, to ensure they do their job to make sure companies comply with the rules, to protect the American people.


AirNow Current Air Quality Map – U.S. EPA
Ozone – American Lung Association
2019 State of the Air Report – American Lung Association

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