Chicago Now Ranks 16th Most Polluted City in the U.S.

CHICAGO, April 20, 2020 – The American Lung Association’s 2020 “State of the Air” report revealed that Chicago ranks the 16th most polluted city in the nation for ozone pollution, which is worse than last year’s report where the city was ranked 18th most polluted. The 21st annual report found that Chicago had a weighted average of 19.2 unhealthy ozone days between 2016-2018, which is significantly higher than 14.0 days from last year’s report.

“Chicagoans should be aware that we’re breathing more unhealthy air compared to last year’s report, mostly driven by vehicle emissions and extreme heat as a result of climate change, placing our health and lives at risk,” said Angela Tin, national senior director for clean air initiatives for the Lung Association and a member of Chicago Area Clean Cities’ executive board. “In addition to challenges here in Chicago, the 21st ‘State of the Air’ report highlights that nearly half of Americans live in counties that had unhealthy ozone or particle pollution in 2016-2018.”

The annual “State of the Air” report tracks Americans’ exposure to unhealthful levels of ozone or particle pollution, both of which can be deadly. This year’s report covers the most recent quality-assured data available collected by states, cities, counties, tribes and federal agencies in 2016-2018.

Each year the “State of the Air” provides a report card on the two most widespread outdoor air pollutants, ozone pollution, also known as smog, and particle pollution, also called soot. The report analyzes particle pollution in two ways: through average annual particle pollution levels and short-term spikes in particle pollution. Both ozone and particle pollution are dangerous to public health and can increase the risk of premature death and other serious health effects such as lung cancer, asthma attacks, cardiovascular damage, and developmental and reproductive harm.

Ozone Pollution in Chicago

  • Grade: F
  • Rank: 16th most polluted
  • 2 unhealthy ozone days

Compared to the 2019 report, Chicago experienced more unhealthy days of high ozone in this year’s report.

“Ozone pollution can harm even healthy people, but is particularly dangerous for children, older adults and people with lung diseases like COPD or asthma,” said Tin. “Breathing ozone-polluted air can trigger asthma attacks in both adults and children with asthma, which can land them in the doctor’s office or the emergency room. Ozone can even shorten people’s lives.”

This report documents that warmer temperatures brought by climate change are making ozone more likely to form and harder to clean up. Significantly more people suffered unhealthy ozone pollution in the 2020 report than in the last three “State of the Air” reports.

Particle Pollution in Chicago

  • Short-Term Particle Pollution
    • Grade: B
    • Rank: 44th most polluted
    • 7 unhealthy air quality days
  • Year-Round Particle Pollution
    • Grade: Pass
    • Rank: 20th most polluted

The 2020 report also found Chicago had the lowest levels ever of both year-round particle pollution and short-term particle pollution.

“Particle pollution is made of soot or tiny particles that come from coal-fired power plants, diesel emissions, wildfires and wood-burning devices. These particles are so small that they can lodge deep in the lungs and can even enter the bloodstream. It can trigger asthma attacks, heart attacks and strokes and cause lung cancer,” Tin said.

While the report examined data from 2016-2018, this 21st annual report online provides information on air pollution trends back to the first report. Learn more about Chicago’s rankings, as well as air quality across Illinois and the nation, in the 2020 “State of the Air” report at

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