Wildfires raging across Canada have caused thick smoke to spread southward across the United States and bring dangerous levels of air pollution to the most populated parts of the country.
Hazy fog blanketed skies in parts of the Northeast and Midwest and reached New York, Philadelphia, Detroit, Baltimore, the Ohio Valley and Virginia.
And the smoke reached as far west as Minnesota, South Carolina and the Georgia-Florida border.
About 100 million people face unhealthy levels of air quality and environmental agencies across the United States have issued alerts warning people to stay indoors.
But everyone wonders when the sky will return to normal? Here are the answers to some of the most popular thick mist questions.
New York City was blanketed in a thick layer of smoke on Tuesday night due to record wildfires in Canada
Hazy skies caused by wildfires in Canada cover Washington’s landmarks and skyline
The GM Renaissance Center in Detroit is seen through haze and smoke on Tuesday
The Boston skyline pictured shrouded in smoke at sunset, in Boston, Massachusetts on June 6, 2023
What causes smoke?
Much of the smoke pouring into America comes from Canada which has been ravaged by forest fires, particularly in the province of Quebec.
There are currently 416 active fires in Canada and 240 have been classified by the Canadian Interagency Wildfire Center as “out of control”. The fires have burned more than 8 million acres, about the size of 8 million football fields.
As of Tuesday morning in Quebec, more than 160 wildfires were burning and at least 114 were out of control, most of which started in the past week.
Canadian officials rank this year as one of the worst fire seasons in the country.
Experts blamed a warmer, drier spring as the reason for the high number of wildfires.
And these conditions are expected to continue throughout the summer, which is concerning.
Smoke billows from a major wildfire in Fort Nelson, British Columbia, Canada, June 3, 2023
Canada is currently experiencing its worst wildfire season in recent memory, with more than 6.7 million acres burned since the start of the year
The city of Halifax in eastern Canada, Nova Scotia, declared a local state of emergency late Sunday after a wildfire caused evacuations and power outages.
A map showing active wildfires across Canada that have spread across 8.4 million acres of land
When will the smoke go away?
It is not known how long the sky will remain covered in smoke, and it depends on the direction in which the wind is moving.
Some cities in Michigan, Indiana and Ohio should see some improvement by Wednesday morning, but others like Virginia, Pennsylvania, Tennessee and the Carolinas will see the heavy haze persist.
The situation could even worsen in the north until Thursday as wildfires continue to burn in Canada.
The smoke could spread to New York, Philadelphia, Newark, Washington, Richmond, Virginia and Baltimore, adding to very poor air quality.
Visibility and sky conditions will improve Friday through Saturday as the winds become more northwesterly, but that won’t completely dissipate the smoke.
Where are the areas affected by the haze?
New York City was at one point the most polluted city in the world on Tuesday as its skies were covered in smoke from wildfires and it was followed by Detroit.
A thick sheet of smoke from the wildfires first descended on New York City on Tuesday before thickening throughout the afternoon, leaving Manhattan residents unable to see the New York skyline. Jersey across the Hudson River.
Air quality alerts have also been introduced in Massachusetts, New Hampshire, Pennsylvania, Maryland, Virginia and the Carolinas, according to the National Weather Service.
The city of Detroit, Michigan was also in the top five metros with the worst air quality on Wednesday, as many U.S. cities continued to be plagued by smog.
Washington DC was heavily affected by clouds of smoke spreading across southern Canada, leaving landmarks in the distance covered in thick haze
A woman walks her dog along the Ottawa River in Ottawa as smoke from wildfires obscures Gatineau, Quebec
Why did the smoke travel so far?
Many of the fires that started the smoke crisis have been burning for weeks, but have started to push south in recent days due to a storm system blowing across Nova Scotia.
The weather has pushed much of the smoke to the East Coast, and this is expected to continue for the next several days.
The Manhattan skyline is seen through thick clouds of smoke from Canada’s wildfires
The Schuylkill County Courthouse in Pottsville, Pennsylvania is shrouded in smoke and haze
Who is most at risk?
Children, the elderly, pregnant women and people with respiratory or cardiovascular diseases are the most affected by smoke.
Authorities have urged these vulnerable people to only go out if they have a high-quality mask.
For those who live in cities with dangerous levels, residents are advised to exercise indoors and wear a good quality mask when outside.
The effects of breathing in wildfire smoke and air pollution can be extremely damaging, causing symptoms such as chest pain and eye, nose and throat irritation.
The effects are understandably worse at the source of the wildfires, as Environment Canada issued its strongest possible air quality warning by placing Ottawa under a “very high risk” alert.
Thousands of people have also been evacuated across the country, and fires have also been reported in British Columbia, Alberta, Ontario, Nova Scotia and the Northwest Territories.
Smoke from wildfires in Canada has caused dangerous levels of air pollution in the Northeast. Pictured is a map showing Air Quality Index levels on Tuesday evening. Purple areas are where levels were between 201 and 300. Red areas were between 151 and 200
What precautions should I take?
The blanket of smoke in the sky poses huge risks to people, especially the vulnerable, and officials have urged people to stay safe.
People are advised to stay indoors and avoid all outdoor work and exercise.
You should also make sure all windows and doors are completely closed to keep smoke out of the house, and use air purifiers or air conditioners with high-efficiency filters if possible.
And for those who venture outside, they are asked to wear an N95 mask to reduce the amount of polluted air they are exposed to.