A smoky yellow haze generated by hundreds of Canadian wildfires hovered over a large swath of the United States on Thursday, causing breathing problems and flight disruptions and threatening to linger until the weekend and beyond.
The U.S. National Weather Service extended air quality alerts for another day for the East Coast from New England to South Carolina, as well as parts of the Midwest, including Ohio, Indiana and Michigan.
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.
As the smoke pushed southward, conditions were expected to improve in the Northeast on Thursday while worsening for residents in Pennsylvania, Maryland and Washington, D.C. In New York, a faint smell of burning wood lingered, even as patches of blue opened up in the morning skies.
The haze and low visibility prompted aviation officials to halt incoming flights to major airports in New York and Philadelphia from the Northeast, Mid-Atlantic region and Ohio for a second day.
All flights bound for the airport in Newark, New Jersey, a major New York-area airport, were delayed.