Authorities warned residents in the eastern part of the United States to stay indoors and limit their exposure to outside air as wildfires rage in Canada, sending smoke across the border.

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Alerts have been issued for millions of Americans in more than a dozen states, with officials warning of reduced air quality as far south as Georgia.

Delaware tells residents to use caution

Update 7:19 p.m. EDT June 7: Delaware is advising residents to use caution when going outside, CNN reported.

The Delaware Department of Natural Resources and Environmental Control issued an alert due to the unhealthy air quality that is expected Thursday throughout the state.

Broadway production of ‘Hamilton’ canceled

Update 6:58 p.m. EDT June 7: The Broadway production of “Hamilton” and a Shakespeare in the Park production of Hamlet were canceled on Wednesday evening, according to The New York Times.

“Hamilton” announced the cancellation at 6:45 p.m. EDT, stating that “so many” cast members had called in sick.

“Tonight’s performance of Hamilton will not go on as scheduled,” Shane Marshall Brown, a spokesman for the production, said in a statement. “The hazardous air quality in New York City has made it impossible for a number of our artists to perform this evening. Shows will resume as scheduled tomorrow. We apologize for the inconvenience and encourage you to visit your point of purchase for refund or exchange.”

The Public Theater canceled the final dress rehearsal for “Hamlet” on Wednesday night, adding that previews for the play on Thursday and Friday also have been canceled.

‘Stay indoors,’ NYC mayor urges residents

Update 6:46 p.m. EDT June 7: New York City Mayor Eric Adams urged residents to stay indoors, The New York Times reported. Adams said during a second news conference on Wednesday that the air quality level in the city had hit a hazardous level at 484.

Adams added that smoke levels in the city were expected to improve on Thursday morning but could deteriorate by the afternoon.

Upstate in Syracuse, the air-quality index topped 400 for most of the day. The Syracuse Mets canceled its Wednesday night game as a result, according to the newspaper.

Accoriding to school officials in Syracuse, all outdoor activities for Thursday were canceled, including recess, sporting events, field trips and after-school activities.

-- Bob D’Angelo, Cox Media Group National Content Desk

Sporting events postponed in NYC, Philadelphia

Update 4:42 p.m. EDT June 7: The New York Yankees, citing poor air quality, postponed Wednesday night’s baseball game at Yankee Stadium between the Yankees and the Chicago White Sox.

The game was rescheduled as the first game of a single-admission doubleheader for Thursday at 4:05 p.m. EDT.

Also, a WNBA game between the Minnesota Lynx and New York Liberty was postponed because of air quality issues that were affecting conditions at Barclays Center in Brooklyn, The New York Times reported.

Major League Baseball also announced that the Philadelphia Phillies’ home game against the Detroit Tigers was rescheduled for 6:05 p.m. EDT on Thursday, ESPN reported.

A National Women’s Soccer League game in Harrison, New Jersey, between Orlando and Gotham was also called off due to the hazy conditions. That game will be played on Aug. 9, ESPN reported.

“The match could not be safely conducted based on the projected air quality index,” the NWSL said in a statement.

-- Bob D’Angelo, Cox Media Group National Content Desk

NYC has worst air in world

Update 3:25 p.m. EDT June 7: Air quality monitoring site IQAir on Wednesday deemed New York City to have the worst air quality in the world.

As of 3:25 p.m. Wednesday, the city had an air quality index number of 355, marking the air as hazardous. According to the U.S. government’s AirNow, air quality index numbers of 300 and above encapsulate “emergency conditions” in which “everyone is more likely to be affected.”

A time-lapse shared by the National Weather Service’s New York office showed the severity of the situation.

As of Wednesday afternoon, Dubai in the United Arab Emirates had the second-worst air quality in the world, with an air quality index number of 168.

Air traffic bound for Philadelphia slowed

Update 3:20 p.m. EDT June 7: Officials with the Federal Aviation Administration delayed air traffic headed for Philadelphia on Wednesday due to reduced visibility caused by wildfire smoke.

The decision came after the FAA earlier slowed traffic to and from New York City-area airports.

Earlier Wednesday, officials with the National Weather Service’s Mount Holly office warned that thicker smoke was blowing into the area and likely to “expand across the rest of our area this afternoon (and) evening.”

Officials with the Pennsylvania Department of Environmental Protection warned people across the state to limit their outdoor activities due to the air quality.

FAA slows flights to, from NYC-area airports

Update 2:40 p.m. EDT June 7: Reduced visibility caused by wildfire smoke blowing into the U.S. from Canada prompted officials to slow traffic to and from airports in the New York City area on Wednesday.

The Federal Aviation Administration said the slowdown was prompted by low visibility.

Satellite images from the National Weather Service earlier showed heavy smoke continuing to move over central New York and northern Pennsylvania. Officials warned people to “expect a reduction in visibility, poor air quality (and) the smell of smoke.”

New York City Mayor Eric Adams said in a social media post on Wednesday that an air quality advisory for the city had been extended until late Thursday night.

“Mask up and limit your outdoor activities,” he said.

Original report: Wildfires in Canada, particularly in southern Quebec, are creating the smoke. According to the National Weather Service, the area’s fires are producing a large amount of high-density smoke that has drifted over much of the eastern U.S. and parts of the Southeast and Midwest. Fires in British Columbia and Washington were also producing smoke that authorities described as “mainly light.”

According to IQAir, a site that tracks air quality worldwide, New York City and Detroit were among the top 10 cities with the worst air quality on Wednesday.

Forecasters told The New York Times that air quality is likely to be at unhealthy levels for days. It is likely to improve later in the week, according to the NWS.

Officials urged people to check the air quality forecast for their area before going outdoors.

“Poor air quality can be hazardous to anyone, and it can aggravate health problems such as asthma, heart disease, and lung disease,” officials with the NWS said.

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Smoke From Canadian Wildfires Blows South Creating Hazy Conditions On East Coast ARLINGTON, VIRGINIA - JUNE 07: Hazy skies caused by Canadian wildfires blanket the monuments and skyline of Washington, DC on June 7, 2023 as seen from Arlington, Virginia. The Washington DC area is under a Code Orange air quality alert indicating unhealthy air for some members of the general public. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)