Toronto, New York and Washington top list of most polluted cities as wildfires burn n blowing through Washington DCByEsme Stallard, Senior climate and science reporter, Erwan Rivault, Senior data designer and Pilar Tomas, Senior visual journalistPublished16 July 2026Updated 18 July 2026Cities across north-eastern Canada and the US are continuing to suffer from intense smoke brought on by hundreds of wildfires burning across Canada. On Saturday, Toronto, New York and Washington DC recorded some of the worst air quality levels in the world, prompting health warnings from local authorities urging people to limit time outdoors because of the risks posed by the smoke.Many of the wildfires remain out of control, forcing evacuations and destroying homes and infrastructure. The blazes left one tribal community completely decimated in northern Ontario, ripping through the Namaygoosisagagun First Nation with little warning.Canadian officials said on Saturday that fire activity in Ontario was beginning to ease, with air quality expected to improve in US cities later in the day.The smoke has also fuelled political tensions across the border.
US President Donald Trump has threatened to impose new tariffs on Canada to offset what he described as the "incalculable" cost of the smoke's impact on his country.Poor air quality in the New York region is also prompting concerns for Sunday's World Cup Final in New Jersey.Canada wildfires leave train 'encased in flames' as smoke drifts towards USPublished15 July from Canadian wildfires extending across eastern North America on 17 JulyWhere are the wildfires and how did they start?There are 955 wildfires actively burning across Canada - nearly 200 of those in Ontario - according to the latest numbers from the Canadian Interagency Forest Fire Centre.More than a dozen wildfires are actively burning along the northern edge of the bordering US state of Minnesota, spanning more than 73,000 acres. Officials have called the situation in Minnesota "unprecedented" and an emergency declaration is in place to help mobilise suppression efforts.In Ontario, the fires are north of Lake Superior in more remote parts of the province, but within or close to national parks and First Nation communities. Officials said on Saturday that the fire activity in the province was beginning to slow.
So far, six communities are under evacuation orders with reports of damage to properties. Matthew Hoppe, incident commander for the Namaygoosisagagun First Nation, told the BBC that his community was devastated by the wildfires in northern Ontario.Community members had to "self-evacuate" via small boats on Monday afternoon with the fire rapidly approaching, Hoppe said, adding that there were no deaths or direct injuries, he says, but the community has been "completely levelled".Wildfires are very common in Canada, but the number of outbreaks has rapidly increased in recent weeks. A sea of red indicating wildfires from earlier this weekThe National Interagency Fire Centre in the US and Natural Resources Canada predicted this was likely, external because of sustained hot weather at the end of June across northern Ontario, and below average rainfall, external.This hot weather is being caused by a heat dome - an area of high pressure that gets stuck trapping warm air and the smoke underneath.Extreme and long-lasting heat draws more moisture out of soils and plants – this dry vegetation acts as fuel for fires.But this hot air can also become unstable causing the risk of storms which can produce strong winds, external – causing the fires and smoke to spread.'Send help rather than complain,' Canada's Ford tells US as wildfire smoke blankets parts of North AmericaWhere is the smoke and what is the impact?High pressure further west across the Canadian prairies and the Northern Plains has kept the weather dry and hot, and allowed the wildfires to burn.Satellite images over the past few days show the wind carrying smoke primarily south-east from Ontario across to Toronto, New York State and reaching Boston.IQAir, a company which tracks global air quality, ranked Toronto, New York and Washington DC as the cities with the worst air quality in the world on Saturday due to the ongoing smokey haze hanging over.
Air quality in Minneapolis, Detroit, and parts of northern Minnesota was among the worst in the world earlier this week, but has improved significantly as of Saturday.Wildfire smoke is hazardous for humans as it contains a mixture of very small polluting particles like PM2.5 and nitrogen dioxide."These particles when they get into our system get all the way down into our lungs, all the way down to our tiny breathing tubes and… they cause inflammation," said Jim McDonald, New York State Department of Health commissioner, in a public address video on social media.The smoke can exacerbate existing respiratory, heart, kidney and eye conditions, according to the World Health Organization, external. Emergency responders, and vulnerable groups such as those with chronic illnesses and children – who are closer to the ground where the smoke can sink – are most at risk.Governments will issue warnings depending on the air quality level which advises people on precautions to take. For example, an orange alert means people are advised to:avoid strenuous outdoor activitiesstay indoors and close windowswear a well-fitting N95 maskseek medical attention for symptoms that include wheezing, breathlessness and chest painKN95 or N95 masks should be able to filter out 95% of these tiny particles – although there are still risks.
There are fraudulent copies being sold online so make sure it is government certified. Many cities have activated their air quality emergency protocols and are distributing masks at local centres.For further information on your local air quality alerts, consult this site, external
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