"Extreme." "Unprecedented." "Historic." Those are just a few of the words being used to describe the start of this year's fire season in North America.
The wildfires are centered in the northwest of the continent, but their consequences are far-reaching. Thick smoke has blanketed parts of Wisconsin and North Dakota. It's triggered air alerts in Minnesota and Montana and muddied skies as far south as Tennessee and Colorado.
And, of course, things are even worse at the source.