As Canadian wildfire smoke travels down to US, here's why it can be so dangerous

Pedestrians walk on the Stone Arch Bridge as a haze from Canadian wildfire smoke causes poor air quality in Minneapolis, June 3, 2025. Tim Evans/Reuters

As hundreds of wildfires burn across Canada, Americans' health could be impacted.

As of Wednesday, 203 wildfires were burning in Canada, according to the Canadian Interagency Forest Fire Centre .

The smoke forced health officials in the U.S. to send air quality alerts across parts of the Upper Midwest on Tuesday and caused hazy conditions in New York, according to National Weather Service NY .

Readings from AirNow show air quality alerts in the Northeast, Midwest and Great Plains range from "moderate" to "unhealthy."

Inhaling toxic smoke and ash from wildfires could cause damage to the body -- including the lungs and heart -