Gov. Kathy Hochul and state officials are warning New Yorkers to stay inside or wear an N-95 mask to protect themselves as it remains unclear when smoke from hundreds of Canadian wildfires blanketing the state will dissipate. 

The state's air quality index reads 200 in several parts of the state Thursday. It typically hovers between 35 and 50, the governor said. New York City's air quality index hit nearly 400 — marking the worst reading in state history.

Incoming rain is expected to help ease the presence of smoke, but officials do not know when the Canadian flames — ravaging remote areas proving difficult for emergency personnel to access — will be extinguished.

"This is not over," Hochul said. "We might get a little respite, but I don't want people to let down their guard and be complacent about this. We have to be prepared for the winds to shift. This is unknown."

Nine state Department of Environmental Conservation forest rangers will be sent to Quebec from Saratoga Springs on Friday to assist with the wildfires burning millions of acres.

Air quality conditions continue to suffer statewide, but are worst in New York City, on Long Island, the Hudson Valley, Central and Western New York, the governor said.

The airborne smoke casting dense smog across the state is unhealthy for any person to breathe in, but is especially concerning for senior citizens, young children and people with underlying respiratory conditions.

"Every place is unhealthy except for the Adirondacks — that's the only place in the state with clean air right now," Hochul said. "...It's not safe to be outside, expecially for younger children."

State officials are encouraging outdoor school activities to be canceled through the end of the week. But the Belmont Stakes Racing Festival scheduled for this weekend is continuing as planned — for now. A final decision will be made last-minute, Hochul said.

Gaming Commission Equine Medical Director Scott Palmer is directing all thoroughbred and standardbred racetracks statewide to implement additional emergency protocols. All horse racing tracks were directed to cease workouts and training. Racing will not occur at any facility in the state if the air quality exceeds 200.

"If it's 150 to 200, only horses that pass an additional pre-race vet examination will race," Hochul said. "This is huge for the local economy. We hope we can get this going."

Emergency rooms have not seen a spike in patients related to the smoke to date, as state Health Department officials continue to monitor visits. But Hochul warned that could change if the air quality stays "unsafe."

"It is early yet," she said. "This has a cumulative effect. People who insist on being outside day after day, it's perhaps too early for us to assess the health impact."

Hochul and state Health Department Commissioner Dr. James McDonald encourage New Yorkers to wear N-95 masks to shield themselves from harmful particulate matter, which can cause coughing, tightness in the chest, a runny nose and other symptoms.

The governor is encouraging state agencies to adjust state workers' assignments and take precautions depending on the air quality conditions in their region.

People can check the weather app on their mobile devices to see local air quality index updates in real-time.

"You need to keep the masks in your house and keep your phone handy," Hochul said. "The best thing to do is stay indoors. You won't have the discomfort of the smoke fill your lungs."

The state DEC is monitoring its 126 weather monitoring stations around the state, and the agency's 54-station monitoring program to track pollutants.

"When you're picking up your phone [to check air quality updates], you're looking at DEC monitoring data," Commissioner Basil Seggos said. "All of that comes together to give us a good picture."