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As wildfires continue to ravage Los Angeles and other parts of California in the United States, their destruction extends beyond the charred landscapes, destroyed homes and displaced families. A Stanford University report has shed light on the severe and often underappreciated health impacts of wildfire smoke, highlighting its toxicity and the long-term risks it poses.
The report, published by the Stanford Woods Institute for the Environment, compiled insights from experts across environmental science, medicine and public health. It emphasised that wildfire smoke is approximately ten times more toxic than regular air pollution from fossil fuels, with no safe level of exposure.
“The more exposure we get, the worse a range of health outcomes,” said Marshall Burke, an associate professor in the Stanford Doerr School of Sustainability, who studies air quality impacts to human health and recently published a preprint study on the growing wildfire-derived particulate matter pollution across the US.
Wildfire smoke contains harmful pollutants, including fine particulate matter, benzene and heavy metals, which can penetrate deep into the lungs and bloodstream. According to Jessica Yu, a research scientist at the Stanford Woods Institute for the Environment’s Climate and Energy Policy Program, these toxins can damage multiple body systems, including the cardiovascular and nervous systems.
Children are particularly vulnerable. Lisa Patel, a clinical associate professor of paediatrics at the Stanford School of Medicine, warned that repeated exposure to wildfire smoke could lead to reduced lung function and increased healthcare utilisation in children.
“While we don’t know long-term outcomes for what these repeated exposures mean for children, each new study that comes out should increase our concern,” she added.
Infants and young adults breathe more air per unit of body weight, making them more susceptible to adverse effects, Yu explained. “It’s important to recognise that the toxicological impacts of wildfire smoke on developing respiratory systems extend beyond young children to include adolescents, teens and young adults,” she said.
Using air quality index threshholds may be insufficient in estimating when to limit exposure, pointed out Sharon Chinthrajah, an associate professor of medicine and pediatrics, who studies allergies and asthma. “With repeated exposures, we need to examine these approaches to make sure we are truly limiting exposure over time,” she said.
The Stanford experts unanimously pointed to climate change as a key driver of the increasing frequency and intensity of wildfires. Rising temperatures and erratic rainfall have heightened fuel aridity, creating ideal conditions for wildfires to spread.
Burke noted that climate change amplifies risks exacerbated by other factors, such as historical fire suppression practices and increased human activity in wildland-urban areas. “Climate change, and in particular increasing fuel aridity brought about by hotter temperatures and variable rainfall, is playing a central role in the recent rapid increase in wildfire activity,” he stated.
The report also highlighted inequities in how different communities respond to wildfire smoke. Wealthier areas tend to access more information and take protective measures, such as installing air filtration systems, compared to lower-income neighbourhoods. Patel underscored the need for targeted public health interventions, including multilingual communication strategies and alert systems for vulnerable populations.
The experts recommended several measures to mitigate the health impacts of wildfire smoke, such as portable air filtration. Installing portable air cleaners or HVAC systems in schools and homes can reduce indoor air pollution. Using protective masks, like well-fitting N95 ones, can limit exposure during outdoor activities.
Policy interventions are also necessary. Governments should implement stricter air quality thresholds and ensure accessible healthcare for affected populations. Opt-in health alerts and community outreach can raise awareness and encourage timely action, particularly in underprivileged areas.
The experts stressed the importance of integrating climate resilience into public health strategies. As wildfires become an increasingly common threat, Patel emphasised the importance of thinking about what health systems can do to better reach vulnerable patients.