Wildfire smoke deaths in Canada surge 275% since early 2000s, Lancet report finds
A new report published in The Lancet reveals that deaths linked to wildfire smoke in Canada have risen by approximately 275% since the early 2000s, alongside significant increases in tree cover loss and dangerous heat exposure driven by climate change.
Deaths associated with wildfire smoke in Canada have increased by about 275 per cent since the early 2000s, according to a report on the health impacts of climate change published Tuesday in The Lancet. Between 2021 and 2025, an average of approximately 4,000 deaths each year were linked to wildfire smoke, compared to an average of only 1,050 annually between 2003 and 2012.
Ian Hamilton, chair in planetary health at the George Institute for Global Health at Imperial College in London and co-author of the study, contributed to the research detailing these trends. The findings indicate that wildfires are reversing progress previously made on improving air quality, leading to increased mortality during wildfire smoke periods.
The environmental toll has also escalated sharply. Canada lost approximately 5.2 million hectares of tree cover in 2024, representing a 148 per cent increase in tree cover loss compared to 2016. Wildfires accounted for 86 per cent of that loss. This reduction in tree cover diminishes natural cooling systems such as shade, compounding the risks posed by rising temperatures.
Exposure to extreme heat is another growing concern highlighted in the report. The number of hours people in Canada were exposed to potentially dangerous heat during physical activity increased by 36 hours annually between 2016 and 2025 compared to the 1990s. This shift places athletes and children at higher risk of heat-related illness and mortality. Dr. Anna Gunz, a pediatrician in London, Ont., reported a case of a young patient dying from cardiac arrest while playing outside due to asthma exacerbated by humidity.
Experts attribute these worsening conditions to fossil fuel-driven climate change. The report notes that 80 per cent of Canada's heatwave days in 2025 were directly attributable to climate change. Dr. Courtney Howard, chair of the Global Climate and Health Alliance and president-elect of the Canadian Medical Association, is among those emphasizing the severity of the crisis.
To address the escalating health threats, the report points to a need for increased investment in air conditioning and upgraded health facilities.