A "very unhealthy" air quality alert was issued for Washington, DC on Thursday over the impact of ongoing Canadian wildfires.
"During a Code Purple alert, the air quality is very unhealthy," DC Homeland Security and Emergency Management said on Twitter, citing airnow.com, which provides information about air quality.
All age groups should stay indoors as much as possible, said the authority.
"Those that must work outside should reduce work outside if possible, and if not wear a mask (N95 or K95 equivalent)," it warned, referring to better-quality face masks that were popular and sometimes required during the COVID-19 pandemic.
More than 400 wildfires in Canada have resulted in plumes of smoke soaring throughout the U.S. Northeast, making New York the city with the worst air pollution worldwide and sending a haze over the nation's capital. More than half of the fires, 239, are burning out of control, according to Canadian authorities.
Millions of people in the U.S. are under air quality advisories, with the affected air spreading as far south as North Carolina, the state just south of Virginia, which is adjacent to Washington, DC.