STORY: The U.S. capital was shrouded in a haze of smoke on Thursday, as hundreds of Canadian wildfires continued to push clouds of harmful air across much of the eastern U.S.
Health officials in more than a dozen states have warned millions of residents that spending time outdoors could cause respiratory issues due to the high levels of fine particulates in the atmosphere.
''This is the worst air quality we've had, at least since the 1960s when we started monitoring."
New York State Governor Kathy Hochul urged residents in affected areas - particularly the five boroughs of New York City - wear masks when outside and limit outdoor activity to protect themselves.
"That is why I'm announcing we are making available 1 million N95 masks that we made available at state facilities. We have over 400,000 distributed to members of the public at state parks, MTA stations, Javits Center."
New York City saw pollution similar to that found in perennially smoggy cities such as Dhaka and Delhi, according to Swiss technology company IQAir.
Winds are carrying the smoke south from Canada, which is experiencing its worst-ever start to the wildfire season on record.
Thousands of Canadians have been forced from their homes and the country's minister for emergency preparedness said about 9.4 million acres have already burned, roughly 15 times the 10-year average.
U.S. President Joe Biden on Thursday said he'd spoken with Canadian Prime Minister Justin Trudeau about the crisis, and hundreds of U.S. firefighters and equipment were assisting Canadian crews battling the blazes.
Biden urged residents to heed health warnings.
"It's very important that affected communities to listen to the guidance of state and local officials, from this point forward."
The wildfire smoke in Washington forced Biden's White House Pride Month celebration to be postponed, according to officials, moving the event from Thursday evening to Saturday.
Smoky conditions are likely to persist until Sunday, when a new storm system shifts the direction of prevailing winds.