Runners on the Green Bay Trail, families headed to Gillson Park, concertgoers at the Chicago Botanic Garden: check the air before you go outside.

Canadian wildfire smoke has triggered an air quality alert across Cook and Lake counties through at least Thursday morning, July 16, with the Illinois Environmental Protection Agency warning that surface smoke could reach northeastern Illinois by early that day. The alert covers North Shore communities in our coverage area — Glencoe, Winnetka, Kenilworth, Wilmette, and Northfield.

The IEPA has declared an Air Pollution Action Day, meaning ozone and particulate levels are expected to reach "unhealthy for sensitive groups" on the Air Quality Index. That category includes children, older adults, pregnant people, and anyone with asthma or heart or lung conditions.

"We recommend residents get into the habit of checking the daily Air Quality Index at the same time you check the weather each morning, especially if you are part of a sensitive group such as having asthma or another lung disease," Illinois EPA Director James M. Jennings said Monday, July 14.

The smoke originates from roughly 850 wildfires burning in Canada — many of the largest in Ontario — and more than a dozen blazes in northern Minnesota. As of Wednesday, July 15, Canada reported 835 active fires, 112 of them out of control, with 4.7 million acres burned, according to Reuters. The Washington Post reported the smoke event is affecting an estimated 100 million people across the Midwest, Northeast, and Mid-Atlantic through Friday, July 17.

What it means for North Shore outdoor life

The National Weather Service said its models show smoke "stalling near the I-90 or I-88 corridors by daybreak Thursday," placing the North Shore directly in the path of potential surface smoke. The IEPA said the Thursday forecast may need to be adjusted upward depending on smoke levels.

The Chicago Botanic Garden at 1000 Lake Cook Road in Glencoe — with 385 acres of outdoor grounds — had its Evening Music on the Esplanade concert (Third Coast Bluegrass, 6–7:30 p.m.) scheduled for Wednesday, July 15, during the active alert. The Garden has not issued a public statement about programming changes; residents can check chicagobotanic.org or call (847) 835-6801 for updates.

The Glencoe Festival of Art, featuring more than 100 juried artists, a live music stage, and a Kids Art Zone, is scheduled for Saturday, July 18, and Sunday, July 19, from 10 a.m. to 5 p.m. in downtown Glencoe at Park Avenue and Vernon Avenue. Admission is free. The National Weather Service says a weather pattern shift and possible rain Friday afternoon could improve air quality by the weekend, but Amdur Productions, which produces the festival, has not publicly addressed contingency plans. Check amdurproductions.com for updates.

The Green Bay Trail — the cycling and walking corridor running through all five communities — and lakefront parks including Gillson Park in Wilmette and the Wilmette Harbor are all exposed to the same conditions. The National Weather Service noted that Lake Michigan breezes may provide modest afternoon relief along the shoreline.

How to protect yourself

If the air quality index moves to "red" (unhealthy), the IEPA advises all residents to stay indoors with windows and doors closed, set air conditioners to recirculate rather than draw in fresh air, use high-efficiency filters, and avoid indoor activities that create particulate matter such as smoking or burning candles. Anyone who must go outside should choose shorter, less intense activities and consider wearing an N-95 or N-100 mask.

Heat compounds the risk. A heat advisory remains in effect with heat indexes reaching 100 to 105 degrees through Thursday, according to the National Weather Service.

Residents can check real-time air quality for their specific zip code at AirNow.gov or through the AIRNow app.