A wave of toxic air flowing in from Canada to the US has transformed three major cities into the most unbreathable places on Earth.

Wildfires in Canada are pouring thick clouds of smoke into the US and will usher in unhealthy air quality for millions of people in Northeast and Midwest.

Wildfires in Canada are pouring thick clouds of smoke into the US and will usher in unhealthy air quality for millions of people in Northeast and Midwest.

States warned residents about air quality issues that could last for days

A massive plume of smoke from wildfires burning across Canada has swept into the United States, degrading air quality across the Midwest, Northeast and Mid-Atlantic.

The smoke from the Canadian wildfires is causing air quality issues in the U.S. See where.

Over 100 wildfires are burning in Canada, with winds carrying the smoke southeast. Warnings about unhealthy air extend from Minnesota through Toronto and into New York.

Warnings about dangerous, unhealthy air extended Wednesday from Minnesota through Toronto and into New York.

Warnings about dangerous, unhealthy air extended Wednesday from Minnesota through Toronto and into New York.

TORONTO/NEW YORK: Toronto’s air quality ranked the worst among major cities globally on Wednesday as wildfire smoke from northwestern Ontario blackened skies and spread into the…

Fires in parts of Canada are blanketing several cities with smoke. Experts recommend limiting time outside, purifying indoor air and wearing a respirator if outside.

A thick orange haze hung over Toronto on Wednesday 15 July as smoke from wildfires in northwestern Ontario engulfed Canada's largest city, giving it the worst air quality of any…

Massive plumes of Canadian wildfire smoke have started to pour over the border into the United States, bringing dangerous air quality to more than 100 million people in the…

Monitor ranks Toronto as having the worst air quality on earth, surpassing Kinshasa, DR Congo, and New Delhi, India.

Toronto recorded among the worst air quality of all major cities worldwide on Wednesday as thick smoke from wildfires in Ontario blanketed its skyline and drifted into the US,…

Detroit and Minneapolis rank among the top major cities for poor air quality.

Wildfire smoke from Ontario has severely degraded air quality across the northeastern United States. Chicago recorded "Very Unhealthy" levels of fine particulate pollution on…

Wondering why it smells like smoke outside? Canadian wildfires are impacting millions in Ontario, Minnesota, Toronto, New York, Michigan, Wisconsin and Boston.

Millions of Americans face air quality alerts from Minnesota to New York as authorities urge people to stay indoors

Climate change means bad air pollution, wildfires, and extreme heat are all happening at once. Here's what to know and how to stay safe.

Large swaths of the US remain under air quality warnings