What to know about the Canadian and US wildfires and their impact

Image source, Cole Burston/ AFP/Getty ImagesImage caption, Wildfire smoke is expected to continue affecting air quality in Toronto and US cities throughout the weekByEsme Stallard, Senior climate and science reporter, Erwan Rivault, Senior data designer and Pilar Tomas, Senior visual journalistPublished16 July 2026Updated 5 hours agoCities across north-eastern Canada and the US are suffering from intense smoke brought on by hundreds of wildfires burning across Canada. Many of the blazes are burning out of control, with some causing evacuations and damage. The blazes left one tribal community completely decimated in northern Ontario, ripping through the Namaygoosisagagun First Nation with little warning.In the US and across parts of Canada, a blanket of thick smoke has remained due to the fires, hiding prominent city skylines and causing many to don facemasks. On Friday, Detroit, Chicago, Washington DC, and New York topped the list for the worst air quality in the world, drawing warnings from local officials to limit time outdoors due to potential health impacts of inhaling the fumes. The cross-border effects are also causing a row between Canadian and US officials with President Trump threatening new tariffs to cover the cost of the smoke damage, which he claimed was "incalculable". Canada wildfires leave train 'encased in flames' as smoke drifts towards USPublished2 days agoWhere are the wildfires and how did they start?There are currently about 888 wildfires actively burning across Canada – nearly 200 of those in Ontario - according to the Canadian Interagency Forest Fire Centre.Along the northern edge of Minnesota, there are 15 fires that are still burning 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.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.Image caption, 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?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 Detroit, Toronto and Minneapolis as the cities with some of the worst air quality in the world due to the ongoing smokey haze hanging over. 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 if you're in Canada, and here if you're in the US, external.The far-reaching impacts of wildfire smoke – and how to protect yourselfUS and Canadian leaders clash over wildfiresImage source, Getty ImagesImage caption, The Lincoln Memorial in Washington, DC blanketed by smoky hazeThe fires are also reigniting existing tensions between the North American neighbours. US President Donald Trump on Friday threatened to impose new tariffs on Canada over what he called the country's "willful negligence" in stopping the wildfire threat. "The United States is being unnecessarily invaded by filthy, polluted, and unhealthy air," Trump said, adding he would call Prime Minister Mark Carney over the country not engaging "in basic Forest Management". The threat followed complaints by US lawmakers over the wildfires. This week, four Republican lawmakers from Michigan state, which borders Ontario, wrote an open letter to Carney criticising Canada and "demanding immediate action" contain the fires' impacts."American lungs are paying the price for Canadian inaction, year after year," they wrote. Carney did not respond directly to the claims, but said that both countries had a responsibility to fight climate change.Canada's forests are largely controlled by the provinces; not the central government. Ontario's premier Doug Ford issued a response to the complaints and pushed back on claims Canada wasn't doing enough to fight the threat, noting the massive response to the blazes and the region spending more than $1bn in recent years to mitigate wildfires. "Maybe what you should do rather than complain is send support, send help, because we have done the exact same thing for our American friends," Ford said.He said Canada had helped the US battle its own wildfires and hurricanes in the past.Experts have told the BBC, blaming Canada for wildfire smoke misses the bigger picture."Weather doesn't care about international borders," says Patrick James from the University of Toronto. Once smoke reaches the atmosphere, it travels wherever the winds take it - and smoke from major US wildfires has also affected Canada in recent years.Experts also say many of the current fires are burning in Canada's vast, remote forests, where fires can be difficult to detect or contain before they become too large.While better forest management can reduce wildfire risk in some areas, particularly near communities, it cannot prevent fires across an ecosystem of this scale.How long is it expected to last?Wind patterns suggest that the smoke will start to move south down to Virginia and parts of North Carolina – with their exposure ramping up until Friday.The Commissioner for the New York Department of Environmental Conservation, Amanda Lefton, said on social media: "Much of New York will see visible smoke throughout the state. This will likely be a prolonged effect, and we might see even worst air quality."There was some concern that smoke might still linger on Sunday when the final for the football World Cup is scheduled at MetLife Stadium in New Jersey - especially because it is an open-air venue. But rain coupled with a change in wind direction is likely to help conditions in the area. The long-term fire outlook, external for the season suggests the wildfire risk will continue to be above normal in the Canadian Northwest Territories, Ontario and Quebec throughout July and August.Are Canadian wildfires getting worse?Image source, Government of Manitoba /Handout/Getty ImagesImage caption, The 2025 Canadian wildfires were among the most severe on recordWildfires are a natural part of boreal forests – of which Canada has vast swathes. However, they have worsened in recent years.The 2023 fires razed 15 million hectares (37 million acres) – an area larger than England – while the 2025 blazes burned 8.3 million hectares (20.5 million acres).In Canada, half of wildfires are sparked by lightning and the rest from human activity – but drier soils and vegetation increase the likelihood.Increasing global temperatures as a result of climate change is making heatwaves more frequent and severe, contributing to such conditions.Climate change is also increasing the temperature over winter. These milder conditions in the first part of the year can stimulate earlier plant growth providing more fuel for burning, and reduces the amount of snow cover. Snow, with its very white surface, helps to reflect the sun's radiation and has a cooling effect. The less snow, the hotter it becomes.Will the smoky haze affect the World Cup final?The World Cup final is set to take place in the New York - New Jersey area, a region that has been affected by the smoky haze. Officials have been handing out free protective masks and warned residents to limit outdoor activities.At one point on Friday morning, New York City had the fourth most-polluted air in the world, according global air monitoring index IQ Air. The conditions were discussed at a meeting between White House officials and Fifa ahead of Sunday's final match.But conditions have improved and rain is forecasted that could potentially help clear up the skies before Spain and Argentina take to the pitch.Figure caption, Timelapse shows World Cup final stadium nearly vanish in smoky hazeWith additional reporting from Bernd Debusmann Jr, Kwasi Gyamfi Asiedu, and Rebecka Pieder.Related topicsAir pollutionWildfiresClimateCanadaUnited StatesMore on this storyCanada wildfires spread smoke across North America, sparking air quality alertsPublished1 day ago