Once again, parts of the United States are engulfed by unhealthy air quality. On Friday, millions of people woke up to smoky conditions across the Midwest and Northeast.
Experts say three conditions create these large fires: Fuel like grass and trees, an ignition source from humans or lightning, and hot, dry, windy weather. "We've got this very, very dry condition in Canada that's triggering those wildfires and then the atmosphere is bringing the smoke down to us," said Walsh.
International efforts to fight the wildfires haven't stopped. More than 100 Mexican firefighters arrived in Ontario last week. Eight water bombers owned by Buffalo Airways are also providing air support there.
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