More than 120 million Americans are currently on a “very unhealthy” air quality warning, with Chicago, Cleveland, Maryland and Pittsburgh being the hardest hit.
Smoke from Canada’s raging wildfires has drifted south in recent days, leaving dozens of states in the country’s northeast under a thick blanket of smog.
A code red alert warning of unhealthy air was issued for much of the Midwest and Washington DC on Wednesday.
According to AirNow, several cities in Wisconsin, Pennsylvania and Iowa also experienced “very unhealthy air.”
The National Weather Service has warned that poor air quality is likely to continue with no end in sight to Canada’s wildfires.
This comes amid fears the smoke could add to the already ongoing travel chaos over the 4th of July weekend.
Chicago: The windy city is currently considered the place with the worst air quality on Earth, pictured Wednesday
A map from AirNow shows the red areas indicating unhealthy air, yellow for moderate and orange for unhealthy air for vulnerable groups
Washington DC: A group of masked people walk past the US Supreme Court building this morning
New York City: An early morning haze shrouded the skyline as the sun rose behind midtown Manhattan
According to the World Air Quality Index, five cities in the United States are now among the ten places with the worst air quality on earth.
Chicago is currently the worst city with an air quality score of 166, while Washington DC is third with a score of 151.
Minneapolis currently has an air quality rating of 111, Detroit is just below at 107, and New York City follows with a score of 98.
According to an online calculator from Berkeley University, it was found that an AQI score of 64 means one cigarette was smoked within 24 hours.
According to these calculations, people in Chicago currently smoke 2.5 cigarettes a day due to smoke levels.
The smoke consists of dangerous nanoparticles small enough to enter the bloodstream, and people have reported side effects such as eye and throat irritation and breathing problems.
The New York City Department of Health is urging people to take precautions as the smoke is expected to “significantly affect” air quality and warns it could reach dangerous levels.
On Wednesday, eerie images showed the US Capitol engulfed in thick smoke from the wildfires.
According to the Forest Fire Center, there are currently 500 active fires in Canada, with five new fires breaking out today – 257 of which have been classified as out of control, 84 are under control and a further 159 are under control.
Washington DC: A man walks his dog this morning as smoke casts a haze over the National Mall
Milwaukee: A haze can be seen over the Milwaukee Art Museum Tuesday due to the wildfires
According to the World Air Quality Index, there are now five cities in the United States that rank among the top ten places with the worst air quality on earth
Chicago: In this aerial photograph, Marine One flies over hazy Chicago with US President Joe Biden on Wednesday
Detroit: A freighter navigates the Detroit River on Wednesday as smoke fills the sky obscuring views of Windsor, Ontario
There are currently 500 active fires in Canada, according to the Forest Fire Center, and five new fires have broken out today.
Of these, 257 were deemed out of control, 84 were held and a further 159 were under control.
It comes just three weeks after New York City was engulfed in smoke that turned the sky an apocalyptic orange hue and prompted numerous health warnings.
At the time, health experts warned that inhaling the mist could be as harmful as smoking 22 cigarettes a day.
This comes as travelers at airports across the country faced hardship in the week leading up to the Fourth of July celebrations, leaving scores of would-be passengers stranded.
Although the weather is cited as the reason for the delays and cancellations, the smoke could make the problems worse.
When the smoke hit the east coast of the United States earlier this month, the Federal Aviation Administration announced ground stops for the New York LaGuardia.
Flights to Philadelphia were also impacted by the smoke, causing passenger delays.