Wildfire smoke, carrying noxious gases and particulate matter, poses serious health risks to millions of people across vast distances, according to health experts. The smoke, often more toxic than typical air pollution, can linger for weeks and travel thousands of miles from its source. It can contain not only burnt vegetation but also chemicals, metals, plastics, and other synthetic materials from burning vehicles and buildings.
Health Effects of Wildfire Smoke
Studies indicate that wildfire smoke can cause more inflammation and tissue damage than standard air pollution. Exposure has been linked to increased rates of heart attacks, strokes, and cardiac arrests, as well as a rise in emergency room visits for asthma. Research has also connected wildfire smoke to weakened immune defenses and poorer recovery rates after surgery. A 2023 study in Maryland found a spike in heart and lung illnesses associated with smoke originating up to 2,100 miles away. Eye and skin problems have also been reported.
Long-Term and Developmental Impacts
For pregnant individuals, wildfire smoke exposure has been associated with miscarriage, low birth weight, and preterm delivery. A California study linked such exposure during the first and second trimesters to cellular damage in placentas, and a separate study suggested that exposure during the third trimester may increase the risk of an autism diagnosis. The health effects can persist for years; following Australia's 2014 Hazelwood Coal Mine fire, heart disease rates remained elevated for two and a half years, and respiratory illnesses for five years. A 2026 U.S. study linked wildfire smoke exposure to elevated risks for lung, colorectal, breast, bladder, and blood cancers, with risk increasing alongside pollution levels. Exposure to California's 2018 Camp Fire was linked to changes in cognition and brain activity six to 12 months later, and several studies now connect longer-term smoke exposure to higher dementia risks. Data from California also indicates an increase in fungal infections in the months following smoke exposure, potentially due to spores within the smoke.
No Safe Exposure Level
Experts emphasize that there is no safe level of inhaled particles from wildfire smoke. Even at levels below national safety standards, these particles can cause illness. Any amount of inhaled particles can trigger inflammatory responses, with children, the elderly, and individuals with chronic illnesses being the most vulnerable. Even in healthy adults, immediate effects such as sore throats, coughing, headaches, and cognitive impairment can occur and persist long after the smoke has cleared.
Mitigation Strategies
To mitigate the risks, experts recommend wearing N95 masks when smoke is present and limiting outdoor activities, particularly strenuous exercise, as increased breathing draws more pollutants into the body. The use of indoor air purifiers capable of trapping fine particles (smaller than 2.5 microns) is also advised. For those unable to afford purifiers, simple DIY instructions are available. Information on reducing exposure can also be found through the EPA.
Indoor Air Quality Concerns
Particulates from wildfire smoke can penetrate most buildings, with indoor concentrations typically around half of outdoor levels. In poorly sealed buildings, indoor pollution can reach up to 70% of outdoor levels. Experts advise avoiding indoor activities that generate fine particles, such as smoking, frying food, burning candles, or vacuuming without a HEPA filter, during smoke events. Indoor exposure to wildfire smoke has been compared to exposure to secondhand tobacco smoke, as particles can settle on surfaces and continue to release into the air even after the visible smoke has dissipated.
Future Unknowns
With increasingly frequent wildfires, likely linked to climate change, prolonged and repeated exposure to smoke will become more common, but the long-term health effects across multiple seasons remain unclear. Predicting the full impact is challenging due to uncertainties about the number, duration, and composition of future fires. Researchers are investigating various aspects, including the effects of smoke particles in water supplies and on crops, the impact of urban wildfire smoke, the consequences of prenatal smoke exposure, and whether wildfire smoke exacerbates the health effects of extreme heat. Nutrients carried by smoke may also contribute to harmful algal blooms in downwind water bodies.