How New York became the New Delhi of air pollution as Canadian wildfire smoke chokes city

New York's iconic skyline has been swallowed by a thick blanket of smoke as wildfire smoke drifting south from Canada cloaked the city in an eerie orange haze.

The Air Quality Index (AQI) surged above 200, pushing all five boroughs into the "Very Unhealthy" category and turning a routine commute into a health risk for millions of New Yorkers.

As visibility dropped to less than a mile and the smell of burning wood lingered across the city, authorities activated emergency measures.

Governor Kathy Hochul deployed the National Guard alongside personnel from the State Office of Emergency Management to distribute more than 40,000 N95-style masks at major transit hubs. The city also expanded access to free KN95 masks at public libraries across all five boroughs.

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Mayor Zohran Mamdani urged residents to take precautions as the smoke combined with soaring temperatures to worsen conditions.

"It’s dangerously hot and smoke from Canadian wildfires has worsened our air quality, which means New Yorkers need to be extra vigilant," Mamdani said. "Prioritise staying cool, seek air conditioning indoors, and limit time outdoors."

Health officials have advised everyone, not just vulnerable groups, to avoid strenuous outdoor activities. Schools cancelled outdoor recess and field trips, while poor visibility caused major flight delays at LaGuardia and Newark Liberty International airports.

The 'New Delhi' of the West?

For years, cities such as New Delhi have been held up as symbols of severe air pollution. This week, however, New York briefly found itself facing similar comparisons.

Data from global air quality monitor IQAir showed that New York City's pollution levels temporarily surpassed those of New Delhi and Baghdad, making it the world's most polluted major city for a short period.

For context, as of July 17, IQAir recorded New York's AQI at 185, while New Delhi's stood at 111.

The reasons behind the pollution, however, are very different.

Delhi's poor air quality is largely driven by vehicle emissions, industrial pollution and seasonal crop burning. New York's crisis, by contrast, has been caused by smoke drifting hundreds of kilometres from massive wildfires burning across Canada.

Despite the different sources, experts say both cities are exposed to high levels of PM2.5—fine particles that can travel deep into the lungs and even enter the bloodstream, increasing the risk of respiratory and heart diseases.

What is causing the wildfire smoke?

The smoke blanketing New York has travelled from northwestern Ontario, where more than 180 wildfires are currently burning, making it one of Canada's worst wildfire seasons in recent years.

Several factors have fuelled the fires.

Dry lightning from thunderstorms sparked dozens of blazes across remote forests. A powerful heat dome has trapped extremely hot air over the region, with temperatures approaching 38°C (100°F). At the same time, months of drought have left forests tinder dry, while strong winds have helped the fires spread rapidly.

One of the largest blazes, Thunder Bay 36, has already burned more than 350,000 hectares, making it the biggest active wildfire in Ontario.

How did the smoke reach New York?

The forests burning in Ontario are dominated by pine and spruce trees, which produce dense smoke when they catch fire.

Strong winds carried that smoke southeast across the Great Lakes, through southern Ontario and into the United States.

The smoke first affected cities such as Toronto before drifting across the border into the Midwest and the northeastern US, including New York City.

Because much of the smoke travelled high in the atmosphere before gradually sinking closer to the ground, it spread across much of the Northeast, leaving New York under a thick haze and pushing air pollution to dangerous levels.