Major League Baseball has announced it is postponing games in New York and Philadelphia on Wednesday night because of poor air quality caused by smoke from Canadian wildfires.

A National Women's Soccer League game in New Jersey and an indoor WNBA game set for Brooklyn were also called off Wednesday amid hazy conditions that have raised alarms from health authorities.

The New York Yankees' game against the Chicago White Sox was rescheduled as part of a Thursday doubleheader starting at 4:05 p.m. ET, and the Philadelphia Phillies' game against the Detroit Tigers was reset for 6:05 p.m. on Thursday, originally an off-day for both teams.

What Yankee Stadium normally looks like vs. what it look like today pic.twitter.com/uutCu4Znqh

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"These postponements were determined following conversations throughout the day with medical and weather experts and all of the impacted clubs regarding clearly hazardous air quality conditions in both cities," MLB said in a statement.

The National Weather Service issued an air quality alert for New York City, saying: "the New York State Department of Health recommends that individuals consider limiting strenuous outdoor physical activity to reduce the risk of adverse health effects." In Philadelphia, the NWS issued a Code Red.

"One thing we did right away was we canceled batting practice and we're going to do our stuff inside," Yankees manager Aaron Boone said Wednesday, a day after the Yankees and White Sox played through a lesser haze Tuesday night. "I don't know why I wanted to walk outside, but I just walked out and you know, see the orange coming through the doors and then you walk out, you're like, whoa."

Boone added there wasn't a specific protocol in place that led to the game being cancelled. There was a meeting between team and league executives with weather and health experts that led to the cancellation.

About a half-hour before the postponement was announced by MLB, Phillies manager Rob Thomson said he thought Wednesday night's game would be played. The Philadelphia skyline could not be seen from the ballpark because of haze and a smoky smell remained.

The WNBA said a game between the Minnesota Lynx and New York Liberty would not be played Wednesday, saying the decision was made to "protect the health and safety of our fans, teams and community." A makeup date wasn't immediately announced.

The NWSL postponed Orlando's match at Gotham in Harrison, New Jersey, from Wednesday night to Aug. 9.

"The match could not be safely conducted based on the projected air quality index," the NWSL said.

At nearby Belmont Park, the New York Racing Association said training went on as planned ahead of Saturday's Triple Crown horse race.

"NYRA utilizes external weather services and advanced on-site equipment to monitor weather conditions and air quality in and around Belmont Park," spokesperson Patrick McKenna said Wednesday. "Training was conducted normally today, and NYRA will continue to assess the overall environment to ensure the safety of training and racing throughout the Belmont Stakes Racing Festival."

New York's NFL teams, the Giants and Jets, both had Wednesday off from offseason workouts. The Giants had been planning to practice inside Thursday, and the Jets said they are also likely to work out indoors Thursday.

ESPN's Joon Lee and The Associated Press contributed to this report.