Smoke from Canadian wildfires is causing air quality concerns for millions of Americans in the Midwest and Northeast.

PM2.5 — is expected to push the Air Quality Index over 100, reaching levels unhealthy for sensitive groups, including children, older adults, and people with heart or lung conditions.

She explained that air quality is largely influenced by wind patterns. With wildfires burning in central Canada, northwesterly winds are carrying smoke into the northeastern U.S., impacting air quality across several states. That's why we're seeing air quality health advisories—like the one issued today for fine particulate matter.