When will air quality improve in northern Illinois?

An air quality alert is in effect until midnight Thursday for Will, McHenry, Kane, DeKalb, Ogle, Kendall, La Salle and DuPage counties in Northern Illinois, said Rick Castro, a meteorologist for the National Weather Service Chicago.

But that doesn’t mean the Illinois Environmental Protection Agency won’t extend it, he said.

“It’s possible things will improve tomorrow. Obviously, that’s the hope as well.”

—  Rick Castro, National Weather Service

Much of the area is in the unhealthy to very unhealthy range, Castro said. When that air quality might improve depends on how quickly smoke from Canadian wildfires will leave the area.

”The conditions are pretty stagnant right now. The air is not moving, just sloshing it around.”

Castro said visibility at Chicago O’Hare International Airport is only 1 mile, which is really low.

“This is uncharted waters for us in terms of this dense smoke,” Castro said. “It all depends on this plays out.”

[ Canadian wildfires continue to wreak havoc on northern Illinois’ air quality ]

Castro said parts of Northern Illinois may see some thunderstorms Thursday. But that doesn’t guarantee the smoke will wash away.

”It’s possible things will improve [Thursday]. “Obviously, that’s the hope, as well.”

An improvement doesn’t necessarily mean great air quality, Castro said. But air quality may improve from unhealthy for everyone to unhealthy for sensitive groups, he said. But it’s up to the IEPA to determine the air quality.

According to AirNow, sensitive groups include people with heart or lung disease, as well as “older adults, children and teenagers, minority populations and outdoor workers.”

While air quality remains unhealthy, people in sensitive groups should avoid outdoor physical activity, according to AirNow. Everyone else should avoid strenuous outdoor activity and take frequent breaks. All people should consider staying inside as much as possible, according to AirNow.

To monitor the air quality in your area, visit airnow.gov.