Air quality alerts have been issued for states across the Northeast.
Hazy and dangerous fumes from ongoing wildfires in Canada have engulfed the skies over much of the East Coast, prompting serious air quality alerts in over a dozen states.
Canadian officials said firefighters are scrambling to put out the blazes. So far this wildfire season, Canada has seen more than 8.7 million acres burned -- an area larger than the state of Vermont.
The National Zoo in Washington, D.C., is closed on Thursday as dangerous smoke moves through the capital.
"Today's air quality is extremely unhealthy," the Department of Energy & Environment warned. "Everyone should stay indoors as much as possible, especially sensitive groups such as children, elderly, pregnant women and people with heart or lung conditions like asthma and bronchitis."
Flights from the Northeast, Ohio and the Mid-Atlantic bound for the Philadelphia International Airport and New York City's LaGuardia Airport have been paused due to the smoke, the Federal Aviation Administration said Thursday morning.
The FAA cautioned, "We will likely need to take steps to manage the flow of traffic safely into New York City, DC, Philadelphia and Charlotte."
Waves of smoke will continue to move south Thursday from New York City to Philadelphia to Washington, D.C.
By Friday morning the AQI levels will drop for New York City. Smaller smoke plumes will linger from Detroit to Pittsburgh to D.C.
By Saturday and Sunday, the winds will begin to switch and blow smoke away from the U.S.
-ABC News' Max Golembo
Some school districts in New Jersey and New York announced closures or updated schedules for Thursday amid the heavy smoke in the area.
In New York, school has been canceled in the Freeport, Long Beach and Yonkers districts, according to New York ABC station WABC.
In New Jersey, school has been canceled in the Newark, Elizabeth, Union and Orange districts, WABC reported.
Officials at Elizabeth Public Schools said they'd attempted to continue a normal schedule by holding indoor recess on Wednesday.
"As the day advanced and the air quality worsened, we consulted with both health officials who updated their recommendation to close school buildings tomorrow, Thursday, June 8," Superintendent Olga Hugelmeyer said in a letter to parents.
