Manhattan skyline covered in haze caused by wildfire in Canada
Manhattan skyline covered in haze caused by wildfire in CanadaREUTERS/Amr Alfiky

Schools across the US East Coast canceled outdoor activities, flights were halted and millions of Americans were urged to stay indoors on Wednesday as smoke from Canadian wildfires blanketed American cities in a thick yellowish haze, Reuters reported.

The US National Weather Service issued air quality alerts for virtually the entire Atlantic seaboard. Health officials in states from Vermont to South Carolina and as far west as Ohio and Kansas warned residents that spending time outdoors could cause health problems.

New York's world-famous skyline, usually visible for miles, appeared to vanish underneath the otherworldly veil of smoke, which some residents said made them feel unwell.

New York Governor Kathy Hochul called the situation an "emergency crisis," noting that the air pollution index for parts of her state were eight times above normal.

She said the foul air was likely to persist for days, and that "people need to prepare for this over the long haul."

New York City Mayor Eric Adams warned New Yorkers against the “dangerously high levels of wildfire smoke” and cautioned residents to wear masks outside and prioritize remaining indoors with their windows shut.

“This is something that has never impacted [the city] on this scale before,” Adams said at a press conference Wednesday morning, according to Reuters.

Adams cautioned residents to remain inside with air conditioning “to the greatest extent possible,” and to wear masks if they needed to venture outside.

“This is not the day to train for a marathon or do an outside event with your children,” he added.

The reduced visibility caused by the haze forced the Federal Aviation Administration to slow or halt some flights into New York City at LaGuardia International Airport and Newark Liberty International Airport.

A Broadway matinee of "Prima Facie" was halted just 10 minutes into its performance after actress Jodie Comer experienced difficulty breathing due to poor air quality.

Major League Baseball was impacted as well, as the New York Yankees and the Philadelphia Phillies both postponed home games scheduled for Wednesday.

While wildfires are common in Canada's West, there have been blazes across the country, especially in the eastern province of Quebec.

About 9.4 million acres have already burned and more than 120,000 people have been forced from their homes.