More than 120 million Americans are now under ‘very unhealthy’ air quality alerts, with Chicago, Cleveland, Maryland and Pittsburgh the worst affected.
Smoke from Canada‘s raging wildfires have drifted south over the past few days leaving dozens of states in the north east of the country under a thick smog.
A Code Red alert, a warning of unhealthy air, was issued for much of the Midwest and Washington DC on Wednesday.
Several cities across Wisconsin, Pennsylvania and Iowa were also experiencing ‘very unhealthy air’ according to AirNow.
The National Weather Service has warned that, with no end in sight to the Canadian wildfires, poor air quality is likely to continue.
It comes amid fears that the smoke could compound already ongoing travel chaos over the July 4 weekend.
A map from AirNow shows the red areas indicating unhealthy air, yellow being moderate, and orange being unhealthy to sensitive groups
According to the World Air Quality Index, there are now five cities in the US that make up the ten worst places for air quality on Earth.
Chicago is currently ranked as the worst city, with an air quality of 166, while Washington DC takes the third spot with a reading of 151.
Minneapolis is currently recording an air quality of 111, Detroit is just below it with 107 and New York City follows with a reading of 98.
According to an online calculator created via Berkeley University, it was found that an AQI score of 64 translates to one cigarette smoked in a 24-hour period.
Based on those calculations, people in Chicago are currently smoking 2.5 cigarettes every day due to the smoke.
The smoke is made up of dangerous nanoparticles small enough to penetrate the bloodstream, and people have reported side-effects including irritation to the eyes and throat and breathing problems.
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.
On Wednesday, eerie pictures showed the US Capitol submerged in thick smoke from the wildfires.
Currently, there are 500 active fires in Canada according to the Forest Fire Centre, with five new fires popping up today – 257 of these have been classified as being out of control, with 84 being held and another 159 under control.
Milwaukee: People cross the street in downtown Milwaukee Thursday as Canadian smoke engulfs the horizon
Pittsburgh: Haze hangs over the PNC Park as baseball fans take their seats before Pirates game Thursday
Washington DC: A group of people wearing mask walk past the U.S. Supreme Court Building this morning
New York City: A woman stands on the bow of the Miss New York Ferry to the Statue of Liberty in New York on Thursday
New York City: An early morning haze shrouded the skyline this morning as the sun rose up behind midtown Manhattan Thursday
Currently, there are 500 active fires in Canada according to their Forest Fire Centre with five new fires popping up today.
257 of these have been classified as being out of control, with 84 being held and another 159 under control.
It comes just three weeks after New York City was enveloped by the smoke, turning the sky an apocalyptic shade of orange and triggering numerous health warnings.
At the time, health experts warned breathing the fog can be as damaging as smoking 22 cigarettes a day.
According to the Forest Fire Centre, there are still 500 active wildfires burning across the country
It comes as travelers at airports across the country have faced misery in the week leading up to the July 4 celebrations, with scores of would-be passengers left stranded.
While the reason given for the delays and cancellations is said to be weather related the smoke could exacerbate the issues.
When the smoke previously hit the east coast of the U.S. earlier this month, the Federal Aviation Administration announced ground stops for New York’s LaGuardia.
Flights into Philadelphia had also been impacted due to the smoke, delaying passengers.