Climate

Newsweek -   Poor air quality has spread across multiple U.S. states in recent days as smoke from Canadian wildfires, regional wildfires and summer ozone pollution combine to create potentially unhealthy conditions for millions of people.

The recent alerts are not being driven by one single factor. Smoke from wildfires in Canada has drifted south into parts of the Midwest and Northeast, while wildfires burning in the western U.S. are also producing localized smoke.

As of July 19, 2026, the National Interagency Fire Center (NIFC) reported 40,560 wildfires in the U.S. so far this year. These fires have torched more than 3.8 million acres.

At the same time, hot, stagnant air can worsen ground-level ozone pollution, which forms when sunlight and heat react with pollutants from vehicles, industrial activity, and other sources. Light winds can then prevent that pollution from dispersing, allowing ozone and fine particles to build up near the ground

National Weather Service (NWS) Air Quality Alerts, which were issued around July 19 and July 20, and show air quality warnings or advisories across parts of several states, including: 

Indiana
Illinois
Ohio
Pennsylvania
Colorado
Idaho
Washington
West Virginia
Michigan
Minnesota
Iowa
Wisconsin
Oregon