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.

Breathing in polluted air for extended periods of time can pose a serious health risk for people, especially for vulnerable populations.

Canadian wildfires are the cause of an air quality alert that’s in effect for the tri-state area, according to health officials. New York City’s air quality index is at 118 on Tuesday, AirNow’s tracker indicates.