Catastrophic wildfires, such as those recently seen in France and Spain, not only pose an immediate threat from flames but also present serious long-term health risks from smoke, even for individuals located hundreds of miles away. Mounting evidence suggests that inhaling wildfire smoke can lead to cardiovascular issues, including strokes and heart failure, with damage potentially occurring within days of exposure.
A study published in the European Heart Journal analyzing health records of nearly 25 million Americans aged 65 and older found that individuals exposed to higher average levels of wildfire smoke had a significantly increased risk of stroke. This risk was nearly double that associated with pollution from traffic and industry, with wildfire smoke estimated to contribute to approximately 17,000 additional strokes annually in the U.S. The study indicated that even moderate levels of wildfire pollution could elevate this danger.
Further research published in The Lancet Planetary Health examined daily smoke levels from wildfires and death records across 32 European countries. This study found a rise in the risk of death from any cause within seven days of increased wildfire pollution. Researchers noted that particles released by fires appear to be more harmful than those from conventional sources like traffic or industry. When accounting for the increased toxicity of wildfire smoke particles, the estimated number of deaths attributed to it rose significantly compared to standard air pollution calculations.
Wildfire smoke contains fine particulate matter, known as PM2.5, which can penetrate deep into the lungs. This can trigger an inflammatory response in the airways, leading to respiratory symptoms like coughing and breathlessness. Crucially, this inflammation can spread throughout the body, potentially damaging blood vessel linings, increasing blood clotting, and raising the risk of heart attacks and strokes.
Another study in the Journal of the American College of Cardiology, which observed over 65 million Americans aged 65 and older, found that moderate exposure to wildfire pollution was associated with a 4% greater risk of hospitalization for cardiovascular problems. At higher exposure levels, the risk of heart failure increased by at least 20%. Scientists suggest that smaller, chemically reactive particles in wildfire smoke may enter the bloodstream, further irritating blood vessels, intensifying inflammation, and potentially destabilizing the heart's electrical rhythm, leading to arrhythmias.
Experts emphasize that the distance from a wildfire is not a reliable indicator of exposure. Strong updrafts can carry smoke thousands of miles, with weather patterns later bringing the pollution down to breathable air. This was evident in 2023 when smoke from Canadian wildfires reached Europe, leading to elevated particle pollution levels for millions. In the U.S., the Centers for Disease Control and Prevention reported a 17% increase in asthma-related emergency room visits during periods of unhealthy air quality caused by Canadian wildfire smoke.
While smoke from current fires in France and Spain is not expected to reach the UK, scientists warn that the UK may increasingly face degraded air quality from distant wildfires. This trend is linked to global warming, which is expected to lead to more frequent and larger fires, increasing the public health impact of smoke pollution.