As smoke continues to shroud parts of the north-eastern US, the nation’s financial and media capital has recorded its worst air pollution level, which Governor Kathy Hochul called it an “emergency”.

On Wednesday evening, at 7 p.m. (local time), New York was the city with the world’s worst air pollution, hitting 241 on the Air Quality Index (AQI), far higher than the 179 recorded by Lahore, which came next on the index.

On Thursday morning at 10 a.m., it continued to hold the record of the most polluted city with a reading of 182, according to IQAir, which monitors air quality around the world in real time.

“What we’re experiencing right now with the sub-standard air quality, (is) a crisis, it is also a dangerous situation,” Hochul said on Wednesday.

The crisis was caused by forest fires in Canada, which ironically celebrated Wednesday as Clean Air Day with the motto, “Clean Air Everywhere” while smoke streamed south towards its southern neighbour.

Describing the condition in New York, Hochul said: “The haze and the smoke from the fires, you could feel it even sitting indoors here, it’s clogging much of our air. In fact, it’s almost impossible to see the sunset or see the sky.”

The National Weather Service (NWS) tweeted: “It is recommended to limit time outdoors. Wearing a mask may help limit irritation for those suffering from respiratory illnesses. More smoke expected Thursday and Friday.”

In many places, the sky took on an eery orange glow prompting an NWS unit in New York State to tweet: “This is not Mars.”

“Sun is no longer visible, everything’s orange”, it said.

New York, with a population of about 8.5 million in the city and 20 million in the metro area, even shut its zoos and beaches because of the air quality, while schools in many surrounding cities and towns were ordered closed on Thursday.

Major sports events were postponed on Wednesday.

Flights to and from New York area airports were delayed because of poor visibility, according to the Federal Aviation Administration.

Speed limits were reduced on some highways around New York City because of low visibility.

Among hard-hit cities, Washington and Philadelphia issued Code Red alerts because of the air quality conditions.

Canada’s own cities were saved from the worst because of the wind directions.

Toronto recorded only 156 on the AQI on Wednesday evening.