Schools across the U.S. East Coast canceled outdoor activities, airline traffic slowed and millions of Americans were urged to stay indoors on Wednesday as smoke from Canadian wildfires drifted south, blanketing cities in thick, yellow haze.
The U.S. National Weather Service issued air quality alerts for virtually the entire Atlantic seaboard. Health officials from Vermont to South Carolina and as far west as Ohio and Kansas warned residents that spending time outdoors could cause respiratory problems due to high levels of fine particulates in the atmosphere.
"It's critical that Americans experiencing dangerous air pollution, especially those with health conditions, listen to local authorities to protect themselves and their families," President Joe Biden said on Twitter.