At least 17 states in the U.S. are under air quality alerts due to wildfire smoke from Canada wafting southward. People are advised to stay indoors with their windows closed.

There are currently at least 17 states under air quality alerts due to wildfire smoke from 🇨🇦Canada spreading southward.

Air quality alerts range from Minnesota to the Northeast. Some of the worst conditions are expected in Detroit, Cleveland, Pittsburgh, Philadelphia and Chicago as there are more than 100 wildfires are burning in 🇨🇦Canada.

The National Weather Service (NWS) and state environmental agencies issued air quality alerts for the following States: Connecticut, Indiana, Illinois, Maine, Maryland, Massachusetts, Minnesota, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, West Virginia and Wisconsin.

By Friday, the smoke is expected to spread even further south into Ohio, Virginia and the Washington, D.C., and Baltimore areas.

The groups most at risk from wildfire smoke include children, older adults, pregnant people and anyone with heart or lung disease, health experts said.

Fine particle pollution can trigger coughing, shortness of breath, dizziness and fatigue while worsening asthma, heart disease and other chronic conditions.

People are being advised to stay indoors when possible, keep windows closed, use an air purifier or air conditioning with a clean filter, and wearing a well-fitting N95 mask if outside.