In the Pacific Northwest, large wildfires in Oregon and Washington state have sent up massive plumes of smoke that brought some of the world’s worst air quality to cities in the region. On Thursday, Seattle residents were warned to shutter windows, avoid exercise, and were cautioned to wear masks outdoors. Portland and other cities issued similar warnings about unhealthy air quality. This is Brian Harvey, professor of forest sciences at the University of Washington.

Brian Harvey: “As the climate continues to warm, we are going to see a lengthening of the fire season. And that’s been shown in many regions around the globe.”