Air quality index today: National AQI map shows hazardous conditions amid Canadian wildfires

Smoke drifting throughout the United States as a result of massive Canadian wildfires continues to leave millions of Americans at risk of exposure to extremely poor air quality.

As of Wednesday, more than 400 wildfires were burning across Canada, leading to air quality alerts −  indicators the air is unsafe to breathe for certain people − across much of the eastern U.S. All told, more than 100 million Americans from New England to the Southeast have been affected, the Environmental Protection Agency has said.

The smoke from the conflagration blanketing much of the nation has caused air quality in multiple U.S. cities to hit hazardous levels, increasing the risk of respiratory infections, heart disease and lung cancer, according to the World Health Organization.

In New York City, where a brownish haze has blanketed the sprawling metropolis, air quality was the worst among the world's major cities this week, according to IQAir, an air quality monitoring website. New York City Mayor Eric Adams said the city's air quality health advisory has been extended through Thursday night as New Yorkers woke up to the worst urban air quality in the world Thursday morning.

Live updates: Air quality alerts, wildfire smoke from Canada may linger in US for days

A person wearing a face mask takes photos of the skyline as smoke from wildfires in Canada cause hazy conditions in New York City on June 7, 2023. An orange-tinged smog caused by Canada's wildfires shrouded New York on Wednesday, obscuring its famous skyscrapers and causing residents to don face masks, as cities along the US East Coast issued air quality alerts.

In the Midwest, Detroit also had some of the worst air quality among the world's major cities as of Wednesday.

As a result of the smoke, northeastern U.S. residents have been urged to limit the time they spend outdoors.

Affected Americans should expect the conditions to linger, though some areas in the Northeast could see modest improvements Thursday and Friday, AccuWeather reports. However, the wind trajectory that's contributed to the smoky and hazy conditions could drift further West towards Pittsburgh, Cleveland and Detroit, according to AccuWeather.

How to stay safe: Wildfires in Canada are impacting U.S. air quality

U.S. Air Quality Index map

Contributing: John Bacon, USA TODAY

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at elagatta@gannett.com and follow him on Twitter @EricLagatta.

This article originally appeared on USA TODAY: Air quality index today: See national map of AQI amid Canada wildfires