Nearly 90million people across the US are under unhealthy air quality warnings – as 18million acres of wildfires burn in Canada, sending smoke across the states.
Canada has recorded its worse fire season on record with hundreds of wildfires currently raging across the country.
Smoke has again crossed into the US and has now triggered air alerts for the entire states of Iowa, Wisconsin, Illinois, Indiana, Michigan, Delaware and Maryland.
Parts of Kansas, Missouri, Minnesota, Ohio, Pennsylvania, New York and Virginia are also under warnings, with residents being advised to stay indoors when possible.
Yesterday, New York Gov Kathy Hochul and New York City Mayor Eric Adams both issued warnings that the smoke that covered the city earlier this month is to return.
Haze from Canadian wildfires blankets the downtown Pittsburgh skyline as seen from West End Overlook in Elliott
The typical Pittsburgh skyline is completely hidden behind the wall of smoke that has descended down from Canada
Haze from Canadian wildfires blankets the Chicago skyline as seen from the city’s South Loop neighborhood
A freighter passes through the Detroit River as smoke fills the sky reducing visibility to Windsor, Ontario, earlier today
People in Chicago have resorted to wearing masks as the smoke from the wildfires filter into the city
Chicago had also recorded the worst air quality in the world yesterday as it too was consumed by smoke from the fires.
A reading recorded on Tuesday by the World Air Quality Index ranked Chicago as having the worst quality globally.
The city had been marked as having unhealthy air with a reading of 175 AQI, with parts of Michigan reaching higher.
The index is a measure of five common pollutants and runs on a scale from 0 to 500, with a rating over 150 considered ‘unhealthy.’
It has since been kicked off the top spot by Dubai in the United Arab Emirates, and is ranked third behind Detroit.
According to the index, Washington D.C., Minneapolis, Chicago and Detroit are all in the top ten for the worst air quality on the planet.
Advice given by Air Now, is urging people to stay indoors and reduce activity levels due to the air outside.
The New York City Health Department is urging people to take precautions as the smoke is expected to ‘significantly impact’ air quality and warned it could reach hazardous levels.
Firefighters battle fires in northern Quebec on Sunday, as more than 480 fires burn across the nation
Four cities across the United States near enough make up the majority of the ten worst places in the world right now for air quality
The above map from AirNow shoes what states the smoke is effecting the most, with a high concentration around the mid west
This map supplied by AirNow shows just how far the smoke from Canada has been able to reach
Video shared on social media on Tuesday shows downtown Chicago under smoke, with a thick haze visible around the area.
Current figures from the Canadian Interagency Forest Fire Centre say there is currently 483 active fires in the country.
252 of these are classified as being out of control, with 155 under control and a further 76 being held.
Smoke from the blazes also crossed the Atlantic Ocean and reached western Europe earlier this week.
The smog that has made its way into Europe has done so via the jet stream – strong winds in the upper levels of the atmosphere.
This means the smoke will not lead to dramatically worse surface air quality like the Northeast US experienced a few weeks ago.
Smoke rises from Internal hotspots flaring up in the Kimiwan wildfire complex in Northern Sunrise County, Alberta, Canada
The Met Office said that the smoke would not have the same effect it had on the north east of the US as it is too high in the atmosphere
Earlier this month New York City was blanketed in a thick orange mist, after haze and smoke from the wildfires shrouded the Manhattan skyline
The UK Met Office said that while the smoke is high up in the atmosphere, it may make for some vivid sunrises and sunsets.
Earlier this month, the north east of the United States was covered in smoke from the fires which placed 100 million people under a air quality warning.
At the time, health experts warned breathing the fog can be as damaging as smoking 22 cigarettes a day.
Nanoparticles from the smog are so small they can penetrate the lungs and bloodstream, with side effects also including irritation to the eyes and throat as well as breathing problems.
A sheet of smoke from the wildfires descended on New York leaving those in Manhattan unable to see the New Jersey skyline across the Hudson River.
As well as sending New Yorkers inside, air quality alerts were also introduced in states including Massachusetts, New Hampshire, Pennsylvania, Maryland, Illinois, Virginia and the Carolinas, according to the National Weather Service.
The conditions in Chicago are expected to continue overnight but should be slowly pushed south through and diminish according to the National Weather Service.