New Delhi, July 13 -- Smoke from Canadian wildfires has covered parts of the Midwest, making the air dangerous to breathe.

About 22 million people in Minnesota, Wisconsin, and Michigan have air quality alerts telling them to stay inside.

The smoke comes from over 100 wildfires burning in Canada's Manitoba province, where fires have already burned 4.8 million acres, nearly 11 times more land than average.

The air contains tiny harmful particles called PM2.5 that can go deep into your lungs. Some areas in Minnesota and Michigan saw "very unhealthy" or "hazardous" air, with one town hitting an alarming air quality score of 940.

Doctors warn that children, older adults, pregnant women, and people with asthma or heart problems should avoid...