It's the second straight day the fires north of the border have impacted sports in the Northeastern United States. The New York Giants also called off a practice Thursday that had been scheduled to be held in East Rutherford, New Jersey.
The New York Racing Association canceled live racing at Belmont Park two days before the Elmont, New York, facility is scheduled to host the final leg of the Triple Crown with the Belmont Stakes.
With weather systems expected to barely budge, the smoky blanket billowing from wildfires in Quebec and Nova Scotia and sending plumes of fine particulate matter as far away as North Carolina and northern Europe could persist throughout Thursday and possibly the weekend.
As previously announced, morning training was canceled Thursday at both Saratoga Race Course and Belmont Park. The conditions that necessitated the cancellation of training are likely to persist this afternoon and into the evening, according to the NYRA, and a twilight racing program that would kick off the 2023 Belmont Stakes Racing Festival has been canceled.
"Based on current forecast models and consultation with our external weather services, we remain optimistic that we will see an improvement in air quality on Friday," NYRA president & CEO David O'Rourke said in a statement.
New York Gov. Kathy Hochul warned that the Belmont Stakes could be called off if the air quality index exceeds 200 on its scale.
If the air quality is 150 to 200, only horses that pass an additional prerace veterinary examination will be permitted to race.
"People come from all over the country," Hochul said. "It's huge for the local economy. And so we ... hopefully can get this going, but there's no assurance of what the weather's going to be. So it's going to be a last-minute decision, I'm sure."
The Diamondbacks-Nationals contest, which was rescheduled for June 22 at Nationals Park, was the third game postponed by Major League Baseball over the past two days. The New York Yankees and Philadelphia Phillies had their Wednesday home games postponed.
"This postponement was determined following conversations throughout the day with medical and weather experts and the two impacted Clubs regarding clearly hazardous air quality conditions in Washington, D.C.," MLB said in a statement.
About 20 minutes before the game was called off, Nationals manager Dave Martinez said he took his dog for a walk earlier in the morning.
"Not good," Martinez said. "It was a quick one. ... It's pretty bad out there."
The game in New York between the White Sox and Yankees was rescheduled as part of a doubleheader Thursday, and the Phillies' game against the Tigers also was reset for Thursday, originally a day off for both teams.
MLB was monitoring the air quality in both cities Thursday morning, but the doubleheader in the Bronx started on time at 4:08 p.m. ET, and the Phillies' contest that was scheduled to start at 6:05 ET began on time as well.
Ahead of their junior welterweight title bout Saturday night in New York, WBO champion Josh Taylor told ESPN on Thursday that he wasn't concerned with the air quality, but challenger Teofimo Lopez said he has been taking extra precautions because he suffers from asthma.
"Just been staying in the hotel rooms and everything," Lopez said. "Staying away from the pollution of what's going on right now and everything with the wildfires in Canada. Just taking care of myself really. Making sure I don't have any problems going into the fight."
Top Rank Promotions arranged for transportation from Thursday's news conference at Madison Square Garden to the hotels roughly four blocks away and encouraged the fighters to forgo their usual walks back.
Paula Creamer, the 2010 U.S. Women's Open champion, was among several golfers wearing masks during a pro-am in Galloway, New Jersey, on Thursday, a day before the LPGA Classic was to begin.
Creamer also wore sunglasses during most of her nine holes as her eyes became irritated with the hazy, smoky conditions.
Creamer is accustomed to seeing the clear, Atlantic City skyline as she poses for a pro-am photo. This was different.
"You can't even see an outline of it," she said. "It's such a wild thing. I don't know if I've ever played in a tournament where we have to worry about the air and pollution, especially in the United States."
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 Giants' practice Friday also is likely to be canceled, according to coach Brian Daboll. The New York Jets still planned to practice Thursday and Friday at their indoor facility in Florham Park, New Jersey, some 30 miles west of East Rutherford.
"It is [wild times]," Giants offensive coordinator Mike Kafka said minutes after practice was called off. "Have not [seen anything like it] -- have not. Wednesday it was orange [outside]."
The air quality index outdoors in East Rutherford was 198 at 10 a.m. ET on Thursday -- a number that is considered unhealthy. An AQI of 200 and above is very unhealthy.
The New Jersey State Interscholastic Athletic Association delayed its nonpublic state championship baseball games from Thursday to Friday.
The Connecticut Interscholastic Athletic Conference has moved its 12 boys' and girls' state tournament semifinals from Thursday to Friday.
ESPN's Jordan Raanan and Mike Coppinger, The Associated Press and Reuters contributed to this report.