Des centaines d'incendies mettent en garde des millions de personnes au Canada et aux États-Unis contre la dégradation de la qualité de l'air.

Millions of people across Canada and the United States face health risks due to severe air quality degradation caused by hundreds of active wildfires burning in Canada. The smoke has spread into the U.S., triggering air pollution alerts across large parts of the Midwest, the Great Lakes region, and the Northeast, areas home to more than 100 million residents. On Thursday, Toronto recorded the worst air quality globally according to Swiss monitoring firm IQAir, with Chicago, Detroit, and New York also among the five cities with the poorest air quality in the same ranking. According to Canada’s Forest Fire Information System, there are currently 858 active wildfires in the country, including 30 new fires reported on Thursday. Most of these blazes remain uncontained. Intense fires in northwest Ontario have produced massive plumes of smoke that have crossed the border, enveloping Canadian and American cities in thick haze. In the United States, the National Weather Service has issued air quality warnings for the Upper Midwest, the Great Lakes region, and the Northeast. Smoke initially affected states such as Minnesota, Wisconsin, and Michigan before moving eastward and southward, reaching cities like New York, Boston, Buffalo, Philadelphia, Detroit, Milwaukee, and Green Bay. Conditions are also expected to worsen in Cleveland, Columbus, Baltimore, and Washington D.C. The U.S. Air Quality Index classified conditions as "hazardous" in wide areas of Michigan and Minnesota, prompting officials to advise residents to stay indoors to minimize exposure to fine particles in the smoke. In New York and Boston, the smoke covered the skyline, leading to alerts over unhealthy levels of pollution. The situation also impacts New York ahead of the 2026 World Cup final between Spain and Argentina, scheduled for Sunday. However, no restrictions have been announced for the match's proceedings so far. This summer, smoke from wildfires had already impacted regions in the West, the Great Plains, and the Midwest of the United States. However, the current intense pollution episode affecting the Great Lakes region and the Northeast originates primarily from wildfires burning in Canada, particularly in Ontario. Although wildfire activity in Canada this year remains below the exceptional levels recorded in 2023, the combination of fires in Ontario and a heat dome over central parts of the United States is facilitating the accumulation and movement of smoke toward the south. Wildfires have become increasingly common in recent years, often linked to prolonged droughts and higher temperatures driven by climate change. These factors contribute to drier vegetation, which burns more easily and intensely. As a result, the frequency and severity of wildfires have risen, posing challenges for firefighting efforts and public health management. Authorities in both countries continue to monitor the situation closely, issuing regular updates and advisories to ensure public safety. Emergency services are preparing for potential increases in calls related to respiratory issues and other health concerns linked to poor air quality. Meanwhile, environmental experts warn that without significant action to address climate change, such extreme weather events and their associated risks are likely to become more frequent and severe in the future. Residents in affected areas are being urged to take precautions, including limiting outdoor activities, using air purifiers, and keeping windows closed to prevent polluted air from entering homes. Schools and businesses in some regions have considered implementing contingency plans to protect vulnerable populations, though specific measures vary depending on local conditions and resources available. As the smoky conditions persist, the focus remains on mitigating immediate health risks while also addressing the broader environmental and climatic factors contributing to the crisis. Scientists emphasize the need for long-term strategies to reduce greenhouse gas emissions and enhance resilience against extreme weather events. For now, however, communities across North America are grappling with the tangible effects of a rapidly evolving environmental challenge.