Smoke causes inflammation by triggering the body’s immune system to go into overtime to fight the irritant. Scientists have found it can harm the brain, the skin and men’s sperm, with almost no system of the body spared.

Chicago’s air quality has fallen out of the “hazardous” range but remains at unhealthy levels as winds began pushing wildfire smoke from Canada and Minnesota northeast.

The Illinois Environmental Protection Agency has issued an air pollution action day for the northeastern part of the state.

Night Out in the Parks events and Movies in the Park have been cancelled as well.

Last fall, the Chicago Department of Public Health and the University of Illinois Chicago joined forces to install 277 air quality monitors around the city, the largest system of its kind in the United States.

Last week, the Trump administration delivered a catastrophic blow to U.S. climate policy by repealing the longstanding scientific finding that planet-warming pollution poses a danger to humans. Now comes the yearslong race through the courts.

The EPA repealed the key underpinning of greenhouse gas emission regulations. Now environmental and health advocates are taking the agency to court.

Birders inadvertently provided researchers at Loyola University with a key bit of documentation related to invasive species and microplastics.

In a reversal from previous years’ pollution reductions, the United States spewed 2.4% more heat-trapping gases from the burning of fossil fuels in 2025 than in the year before, researchers calculated in a study released Tuesday.

The plan, if finalized next year, would significantly reduce fuel economy requirements, which set rules on how far new vehicles need to travel on a gallon of gasoline, through the 2031 model year.

The proposal is opposed not only by business groups but also labor organizations, including the Chicago Federation of Labor, which are concerned that the measure would snarl new and expanding businesses in red tape, preventing them from creating new jobs.

A key split is whether the treaty should require cutting plastic production, with powerful oil-producing nations opposed; most plastic is made from fossil fuels. They say redesign, recycling and reuse can solve the problem, while other countries and some major companies say that’s not enough.

The National Weather Service issued an air quality alert for the city on Thursday and kept extending it through Sunday night. There was no alert Monday.

Smoke from Canadian wildfires settled over Chicago Thursday, with air quality reaching “unhealthy” levels for everyone. Air quality was far worse in parts of Canada closer to the fires.

The particles are likely the result of the degradation of plastic-filled objects such as carpet, curtains, furniture and textiles and the plastic parts of car interiors, according to the study published Wednesday in the journal PLOS One.

“My kids grew up smelling dead animals and rotting fish,” said Ljiljana Radocaj, a mother and resident of the 10th Ward. “It’s the most horrific smell — you can’t even describe it. You can just run from it.”