Air Quality Alert in Effect for Several Counties

CHICAGO – An Air Quality Alert is in effect until midnight Wednesday night for the following counties: McHenry, Lake (IL), Kane, DuPage, Cook, Kendall, Grundy, Will, Lake (IN), Porter, Newton, and Jasper. 

The 2025 Fire Season in Canada

The 2025 fire season in Canada has been quite active thus far, and the reason why might be a little hazy. Let’s go over why!

Chicago ended July with the worst air quality worldwide, and the first week of August has not provided as much of a relief as hoped for.

Digging Deeper into the Issue

Dig deeper:

The red pixels are indicative of what are known as “hotspots.” 

Through a collaborative effort between NOAA and NASA, infrared satellites are able to identify heat sources. The map is then filtered for known industrial fires, so that only vegetative wildfires appear as a hotspot.

Approximately 15,472,999 acres have burned this year, more than doubling the 10-year average. 

Understanding the Weather Pattern

During the summer months, a common weather pattern often sets up across the continental United States. 

This pattern typically includes a high-pressure system (anticyclone) aloft over the central U.S., while a low-pressure system forms just to the north, where cool air from Canada clashes with warmer air from the United States. While this setup can lead to stormy weather near the low, it also creates stronger northerly wind flow into the Great Lakes region.

When wildfire activity increases across Canada, this wind pattern can transport smoke southward into areas like Chicago. Once it arrives, the smoke may linger near the surface, especially due to the Urban Heat Island Effect.

The Urban Heat Island Effect

The Urban Heat Island Effect occurs in cities with extensive concrete, asphalt, and buildings, which absorb and retain more heat than natural surfaces like forests or fields. 

Think of it like wearing a dark T-shirt on a sunny day, It absorbs more sunlight and feels hotter compared to a lighter one. In this analogy, Chicago behaves like a dark T-shirt, heating up faster than surrounding rural areas.

As the city’s surface warms, it heats the air above it, causing that air to rise. This rising motion can pull in smoke-laden air from the north, bringing it down to the surface.  (College of DuPage Visible Satellite )

As the city’s surface warms, it heats the air above it, causing that air to rise. This rising motion can pull in smoke-laden air from the north, bringing it down to the surface. 

This process, combined with stagnant summer weather, helps explain why Chicago is especially prone to poor air quality and frequent Air Quality Alerts during wildfire season.

Conclusion

In conclusion, the 2025 fire season in Canada has been active, and the weather pattern has contributed to poor air quality in Chicago. The Urban Heat Island Effect has played a significant role in trapping smoke near the surface, making it essential for residents to stay informed about Air Quality Alerts and take necessary precautions to protect their health.

FAQs

Q: What is an Air Quality Alert?

A: An Air Quality Alert is issued when the air quality is expected to be poor, posing a health risk to sensitive individuals, such as those with respiratory issues.

Q: What is the Urban Heat Island Effect?

A: The Urban Heat Island Effect is a phenomenon where cities absorb and retain more heat than natural surfaces, leading to warmer temperatures and poor air quality.

Q: How can I stay safe during an Air Quality Alert?

A: Stay indoors, avoid strenuous activities, and follow the instructions of local authorities to minimize exposure to poor air quality.

Q: What is the role of NOAA and NASA in monitoring wildfires?

A: NOAA and NASA collaborate to identify heat sources using infrared satellites, which helps to detect and track wildfires.