How Chicago air quality has improved in the last decade

Air quality in the Chicago metro area, as measured by fine particle pollution, has improved since 2012, but is still higher than the national average.

Why it matters: Fine particles, generated from fossil fuel-burning and other sources, can enter our bodies when we breathe, making their way to the lungs or bloodstream and causing myriad health problems.

• They are linked to nearly 11,000 excess deaths across the U.S. annually, by one estimate.
• Non-white and low-income Americans are at a higher risk of death from exposure to fine particle pollution compared to other groups, per a 2022 study published in Nature.
• Fine particles — also known as PM2.5 due to their tiny size of 2.5 micrometers — are the most hazardous form of particulate matter.

By the numbers: The three-year rolling annual average concentration of the pollution across Chicago amounted to 9 micrograms per cubic meter as of 2021 (the latest year for which data is available), compared with 11 in 2012.

• Concentrations below 12 micrograms per cubic meter are considered healthy, the EPA says — though it is seeking to tighten that standard.

Flashback: In March, the Guardian released an analysis showing that Northwest Indiana and parts of Chicago's South and West Sides had the third and fourth worst particulate air pollution in the nation.

The big picture: Air quality generally improved nationwide during the height of the COVID-19 pandemic, in part because fewer people were driving.

• But as the pandemic ebbs and people's behaviors and activities return to normal, air quality nationally is worsening accordingly.

What's next: The EPA in January proposed reducing its fine particle pollution standard from 12 micrograms per cubic meter to "a level between 9 and 10."

• Changing the standard to 9 micrograms would prevent up to 4,200 premature deaths per year and 270,000 lost workdays per year, and result in as much as $43 billion in net health benefits in 2032, the agency says.

• The EPA is also taking other steps to improve air quality, including via newly proposed vehicle emissions standards.

Yes, but: Public health advocacy groups say the fine particulate standard should be even lower than the EPA's proposed range.

• The agency's proposal "misses the mark and is inadequate to protect public health from this deadly pollutant," the American Lung Association said in a statement.

The other side: Industry groups argue that lowering the standard would be overly burdensome.

The bottom line: As the fight over lowering the fine particle standard heats up, the EPA once again finds itself at the heart of the climate change and public health debate.