Millions of people across the United States and Canada have seen their air quality suffer this week because of wildfire smoke originating from Canada.
The conditions in some areas are so bad that officials have been urging people to limit their time outdoors and mask up for safety. Flights have been delayed, and outdoor events have been postponed or canceled.
More than 9 million acres have been charred by wildfires this year across Canada— about 15 times the normal burned area for this point in the year.
Wildfires that lead to such poor air quality have become more common and severe as the planet warms from the impacts of human-induced climate change, experts have said.
Here are some of the stories that made headlines over the past week, as well as some photos that caught our eye.