NEW YORK — Smoke from Canadian wildfires poured into the US East Coast and Midwest on Wednesday, covering the capitals of both nations in an unhealthy haze, holding up flights at major airports, postponing Major League Baseball games and prompting people to fish out pandemic-era face masks.

Canadian officials asked other countries for additional help fighting more than 400 blazes nationwide that already have displaced 20 000 people.

Air with hazardous levels of pollution extended into the New York metropolitan area, central New York state and parts of Pennsylvania and New Jersey.

Massive tongues of unhealthy air extended as far as North Carolina and Indiana, affecting millions of people.

“I can taste the air,” Dr. Ken Strumpf said in a Facebook post from Syracuse, New York, which was enveloped in an amber pall. The smoke, he later said by phone, even made him a bit dizzy.

The air quality index, a U.S. Environmental Protection Agency metric for air pollution, exceeded a staggering 400 at times in Syracuse, New York City and Pennsylvania’s Lehigh Valley. A level of 50 or under is considered good; anything over 300 is considered “hazardous,” when even healthy people are advised to curtail outdoor physical activity.

In Baltimore, Debbie Funk sported a blue surgical mask as she and husband, Jack Hughes, took their daily walk around Fort McHenry, a national monument overlooking the Patapsco River. The air hung thick over the water, obscuring the horizon.

“I walked outside this morning, and it was like a waft of smoke,” said Funk.

Canadian officials say this is shaping up to be the nation’s worst wildfire season ever. It started early on drier-than-usual ground and accelerated very quickly, exhausting firefighting resources across the country, fire and environmental officials said.

Smoke from the blazes in various parts of the country has been lapping into the U.S. since last month but intensified with recent fires in Quebec, where about 100 were considered out of control Wednesday — which, unsettlingly, was national Clean Air Day in Canada.

The smoke was so thick in downtown Ottawa, Canada’s capital, that office towers just across the Ottawa River were barely visible. In Toronto, Yili Ma said her hiking plans were canceled and she was forgoing restaurant patios, a beloved Canadian summer tradition.

“I put my mask away for over a year, and now I’m putting on my mask since yesterday,” the 31-year-old lamented.