Do not inhale! How wildfire smoke 'affects the whole body'

Wildfire smoke poses a significant threat to human health, affecting the entire body, according to researchers. Yang Liu, a professor of environmental health at Emory University in Atlanta, explained that the smoke induces oxidative stress and can lead to the development or worsening of diseases.

A study conducted in January 2026 revealed that repeated exposure to moderate amounts of smoke increases the risk of stroke among older adults. Another study found that long-term exposure to wildfire smoke contributed to an average of 24,100 deaths per year in the United States between 2006 and 2020.

The primary culprit in wildfire smoke is fine particulate matter (PM2.5), consisting of soot, dust, and other substances that bind toxic metals and organic compounds. Inhaled PM2.5 particles can enter the lungs and bloodstream, causing inflammation and damaging various organs.

Pregnant women are particularly vulnerable to wildfire smoke, as it raises the risk of premature births and low birth weight. Fire PM2.5 is especially toxic due to the diverse mixtures of burning materials, differing between rural and urban fires.

Researchers found heavy metals like mercury and cadmium, carcinogenic compounds, and PFAS (per- and polyfluoroalkyl substances) in wildfire smoke. PFAS, synthetic chemicals used in many everyday products, have been linked to cancers and metabolic conditions. The researchers suggest that future studies should focus on developing treatments for vulnerable groups and those with chronic health conditions.

Wildfire smoke becomes more dangerous as it ages, undergoing chemical reactions that enhance its cell-damaging abilities. Smoke can also travel long distances and persist in the atmosphere for up to ten days or more, spreading to areas thousands of miles away.

During the Canadian wildfires of 2023, extensive fires burned 15 million hectares of land, releasing long-range PM2.5 pollution that spread across North America and even reached Europe and Asia. An estimated 5,400 acute deaths in North America and 64,300 chronic deaths in North America and Europe could be attributed to PM2.5 exposure from those wildfires.

However, other sources of air pollution, such as traffic exhaust fumes, industrial emissions, and cooking fuels, still cause more overall health problems because people are exposed to them daily. Cathryn Tonne, an environmental epidemiologist at the Barcelona Institute for Global Health, noted that wildfire smoke is uniquely toxic, especially for those living near areas prone to fires.

To minimize exposure, staying indoors during and after fires, using air filters, wearing N95-grade masks, and ensuring vulnerable people have emergency medication are recommended. Clearing properties of flammable materials and establishing neighborhood monitoring groups can also help prevent small fires from becoming catastrophic.