When the Air Turns Toxic: The Rising Toll of Wildfire Smoke on Global Health

In recent years, the world has watched skies turn orange from California to Canada, Australia to Greece. The smell of burning forests, once a distant problem, now drifts into cities thousands of miles from the flames. Wildfire smoke has become one of the most visible and dangerous signs of a warming planet and it’s reshaping the way we think about air, health, and preparedness.

A Growing Global Threat

Wildfires are not new, but their frequency, size, and intensity have increased sharply over the past two decades. Hotter temperatures, longer droughts, and changing weather patterns have created the perfect fuel for fire. The World Health Organization (WHO) estimates that exposure to landscape fire smoke already causes hundreds of thousands of premature deaths each year, a number expected to rise as climate change accelerates.

Unlike local pollution, wildfire smoke doesn’t stay put. Tiny airborne particles can travel hundreds or even thousands of kilometres, crossing borders and affecting people far from the burn zone. In 2023, smoke from massive Canadian wildfires turned the skies of New York and Washington, D.C. an eerie shade of orange. Air quality alerts reached as far as Europe.

What’s in the Smoke?

To understand the danger, it helps to know what’s in wildfire smoke. It’s a complex mixture of gases and microscopic particles released when vegetation and man-made materials burn. The most harmful component is fine particulate matter, known as PM2.5, particles so small they can penetrate deep into the lungs and even enter the bloodstream.

Wildfire smoke also contains carbon monoxide, nitrogen oxides, and volatile organic compounds. Together, these pollutants trigger inflammation, reduce oxygen delivery, and worsen existing respiratory and cardiovascular diseases. During major smoke events, breathing outdoor air can be roughly equivalent to smoking several cigarettes a day, even for people who don’t leave their homes.

How Smoke Affects Health

Lungs and Airways

People with asthma, chronic obstructive pulmonary disease (COPD), or other respiratory conditions are among the most vulnerable. Smoke exposure can cause coughing, throat irritation, and shortness of breath, and it often leads to spikes in emergency room visits for breathing difficulties. Even healthy individuals may notice reduced exercise tolerance or chest discomfort during smoky periods.

Heart and Circulation

Fine particles don’t stop at the lungs. Once they enter the bloodstream, they can trigger systemic inflammation, raise blood pressure, and increase the risk of heart attacks and strokes. Studies have shown that cardiovascular hospitalizations can rise within days of heavy smoke exposure.

Beyond the Obvious

Emerging evidence suggests wildfire smoke may also affect brain health, pregnancy outcomes, and immune function. Children, older adults, and outdoor workers face the greatest risks. For pregnant women, exposure has been linked to lower birth weights and preterm births.

Unequal Burdens

Like many environmental hazards, wildfire smoke doesn’t affect everyone equally. Low-income communities often live in older homes with poor insulation and limited access to air filtration. Outdoor workers, including firefighters, agricultural laborers, and delivery drivers, are frequently exposed without adequate protection. Indigenous populations may face unique challenges, as many live in rural or forested regions where fires are increasingly common.

Public health experts warn that these inequities deepen existing health disparities. Access to clean indoor air, masks, and timely information can make the difference between mild symptoms and life-threatening complications.

Protecting Yourself During Smoke Events

When air turns smoky, small, simple actions can greatly reduce exposure:

• Check air quality daily. Apps and websites such as AirNow, IQAir, or local meteorological services provide real-time Air Quality Index (AQI) updates.

• Stay indoors when possible. Keep windows and doors closed, and use air conditioning in recirculate mode.

• Create a clean-air room. Use a HEPA air purifier or a DIY filter box made from a fan and HVAC filter.

• Wear a proper mask. A well-fitted N95 mask can significantly reduce inhaled particles when outdoors.

• Limit outdoor exercise and avoid heavy physical activity on high-AQI days.

These steps are especially important for children, older adults, and people with lung or heart conditions.

From Individual Action to Public Policy

While personal protection is essential, experts emphasize that the root of the problem lies in environmental management and climate policy. Drought-resistant landscapes, responsible land clearing, and forest management practices can reduce the risk of large-scale fires. Investing in early warning systems and public communication campaigns also helps communities respond faster and more safely.

At a global level, reducing greenhouse gas emissions is critical. Warmer, drier conditions are directly linked to the increased frequency and severity of wildfires. Without strong climate action, wildfire smoke exposure could become a defining health challenge of the century.

A Call to Awareness

Clean air is something most people take for granted. But as wildfire smoke becomes a recurring seasonal event, awareness and preparation can save lives. Checking the AQI may soon be as routine as checking the weather forecast, and understanding the health impacts of smoke should become a basic part of public health literacy.

We can’t stop every fire, but we can act on what we know: protect those most at risk, improve the air we breathe, and push for policies that address the warming world fuelling these disasters. The air we share connects us all and keeping it clean may be one of the most important public health challenges of our time.

References

• British Columbia Centre for Disease Control. Composition of Smoke: Wildfire Fact Sheet. BCCDC; 2024. Available at: https://www.bccdc.ca/resource-gallery/Documents/Guidelines%20and%20Forms/Guidelines%20and%20Manuals/Health-Environment/BCCDC_WildFire_FactSheet_CompositionOfSmoke.pdf

• Chen H, Samet JM, Bromberg PA, Tong H. Cardiovascular health impacts of wildfire smoke exposure. Part Fibre Toxicol. 2021;18(1):2. Published 2021 Jan 7. doi:10.1186/s12989-020-00394-8

• Johnston FH, Henderson SB, Chen Y, et al. Estimated global mortality attributable to smoke from landscape fires. Environ Health Perspect. 2012;120(5):695-701. doi:10.1289/ehp.1104422

• Liang W, Hansen K. A haze over North America. NASA Earth Observatory. May 31, 2025. Available at: https://earthobservatory.nasa.gov/images/154383/a-haze-over-north-america

• Ryan D. Health impacts of wildfire smoke. Stanford Woods Institute for the Environment. October 15, 2020. Available at: https://woods.stanford.edu/news/health-impacts-wildfire-smoke

Assessed and Endorsed by the MedReport Medical Review Board