Issue 4: Wildfires & Health

Wildfires are ravaging the western US at a record-breaking pace, spurred on by climate change and decades of problematic fire suppression policy. In this long-awaited issue, we cover the health effects of wildfires and wildfire smoke.
Image: The Atlantic

The majority of the top 20 largest California fires on record have occurred in just the last two years, a vivid reminder that the climate crisis has already begun wreaking havoc on our ecosystems. Climate change can intensify droughts, boost wind power, and increase the frequency of lightning strikes. When combined with rapid expansion of housing in at-risk wildland-urban interface (WUI) areas, decades of aggressive fire suppression policy, and public messaging that all fires are bad (*cue Smokey the Bear, the world's most charming villain*), messaging that has failed to recognize the wisdom of Indigenous fire-control practices, it doesn't take much to ignite record-setting blazes. And climate-driven wildfires create reinforcing feedback loops, turning carbon sinks into carbon sources that amplify climate change, increasing the likelihood of more wildfires. This is an example of why 1.5 degrees of warming has been established as a “tipping point”, beyond which its effects are likely to be irreversible.

The health risks of wildfires arise from direct exposure to fires and habitat destruction, from exposure to wildfire smoke, and from chronic exposure to toxic chemicals in the water and soil that are unleashed by fire destruction of homes and buildings. Fine particules from wildfire smoke are notably associated with increased respiratory events, including asthma attacks, COPD exacerbations, and respiratory infections. Spending a day outside in an AQI measurement of 150 is equivalent to smoking about 7 cigarettes, according to Kari Nadeau, a Stanford researcher. But beyond the lungs, there is data supporting associations between exposure to the particulate matter in wildfire smoke and low birthweight, preterm birth, cardiovascular and cerebrovascular ED visits, and atopic dermatitis. Data are lacking on long-term health risks, but one study reported that 10 years after people were exposed to forest fires in Indonesia, they had poorer lung capacity and self-reported general health. Another study in rhesus monkeys demonstrated that exposure to wildfire smoke in infancy led to immune dysregulation and compromised lung function in adolescence. The psychological effects can also be persistent; one 20-year follow-up study demonstrated that exposure to wildfires during childhood was associated with mental illness in adulthood.

This week's visual summary highlights some of these associations:
Clinician's Corner

Wildfires are increasing in severity and frequency in the American West, but wildfire smoke exposure extends to other parts of the U.S., occurring as far away as New England. All physicians should therefore be prepared to counsel their patients on how to minimize their exposure to wildfire smoke. An article published in the New England Journal of Medicine outlines the efficacy of various interventions to minimize smoke exposure, summarized in their figure below. Children, older adults, pregnant people, and people with preexisting health conditions are especially vulnerable to the the health dangers posed by wildfire smoke. Clinicians should consider distributing patient-facing guides, such as this resource from the American Thoracic Society, and counseling their patients on how to modify their activity level according to the area's AQI. In areas that are more directly affected by wildfires, residents should be counseled to avoid drinking from the tap until local authorities confirm the water is safe and not contaminated by pathogens, damaged pipes, and volatile organic compounds.
Image: Xu et al
Wildfires & Inequity

Although wildfires can affect anyone, inequitable mitigation, adaptation, and recovery processes lead to disproportionate effects on certain communities. The majority of Americans in wildfire hazard zones are White and socioeconomically secure; however, census tracts that are majority Black, Hispanic, or Native American have a 50% greater vulnerability to wildfires when taking into account wildfire hazard potential and adaptive capacity (see image below). Contributing to these disparities are inequitable and discriminatory practices by government agencies like FEMA in distributing fire protection and disaster recovery resources. Disasters and associated aid can amplify wealth inequality; for example, years after significant disaster damage, White people in counties receiving FEMA assistance had an increase in personal wealth, while Black people lost wealth.

Though studies on disparities in wildfire smoke exposure are limited, there are many possible reasons for the greater exposure experienced by low-wealth communities and communities of color. Mean indoor concentration of PM2.5 triples during wildfire events, and in addition to having less robust home ventilation systems, lower-SES households may not be able to afford expensive air filters. Low-wealth individuals are also more likely to have inflexible outdoor working conditions with high smoke exposure. As one extreme example, people who are incarcerated comprise up to 30% of California's wildland firefighting crews, receiving only $2 to $5 a day despite the health risks.
Image: Davies et al
What We're Reading: UC Researchers On Fire

Given the burden of wildfires in California, it is no surprise that researchers at UCSF and the larger UC community are increasingly studying the effects of these events on our health. This week, we’re highlighting several of these researchers and their work, in hopes of opening channels for scientific discourse and future collaboration:

  • Raj Fadadu (UCSF School of Medicine) and colleagues found that exposure to air pollution during the 2018 Camp Fire was associated with more clinic visits for atopic dermatitis and itch- an 82% greater rate for pediatric patients and a 29% greater rate for adult patients. This study was featured on NPR and in the NYTimes!
  • Large wildfire occurrences were also associated with 18% to 22% greater rates of invasive fungal infections in California compared to months without a fire, Jennifer Mulliken (San Francisco VA Medical Center) and colleagues in the UCSF infectious disease department found.
  • John Balmes of UC Berkeley and UCSF discusses the myriad effects of exposure to wildfire smoke on health, from acute respiratory and cardiovascular outcomes to neurologic, metabolic, and mental health outcomes, in this perspective piece. He suggests physicians should advise even their healthy patients to stay indoors and avoid prolonged activity, and that at-risk communities should prepare for wildfires by improving escape routes and creating fuel breaks around neighborhoods.
  • A recent review, also co-authored by John Balmes, suggests that wildland firefighters may be at increased risk for acquiring SARS-CoV-2, and for more severe COVID-19 illness when infected. Possible mechanisms are particulate matter-based transport of SARS-CoV-2, as well as up-regulation of angiotensin-converting enzyme II (ACE-2) which allows the virus to enter into epithelial cells.
Learn More & Spark Action

  • Especially in California, wildfire season presents an opportunity to talk about climate change with your patients. Consider using messaging like: "Due to climate change, wildfires are becoming more common, and therefore so is wildfire smoke. Smoke can travel a long distance and can be dangerous for everyone, but especially those with [heart disease / lung disease / other condition]." For more clinical climate messaging, see this guide from the Climate and Health Alliance.
  • Learn about the Controlled Burning techniques by Indigenous Communities in California and connect to the Indigenous People’s Burning Network. Advocate for the use of these practices in your community.
  • Check out the How to Save a Planet episode Fighting Fire with Fire, which describes how we got here and raises policy considerations going forward. For example, how can we implement housing solutions that reduce pressures (amplified by the pandemic) driving people to relocate to at-risk Wildland Urban Interface (WUI) areas? For more information, they recommend visiting
  • Create your wildfire preparedness action plan. The California Department of Forestry and Fire Protection, better known as CalFire, has resources to help you prepare your home, prepare for possible evacuation, and more
  • The Latino Community Foundation provides support for Latinx-led organizations that are helping Latinx and immigrant families who have been displaced by fires throughout the state. You can donate here.
Do you have other resources you use to learn about climate change and solutions, action items that you’d like us to share, feedback or ideas for our newsletter? Please share them here!
This newsletter was created by Karly Hampshire, Sigal Maya, Lawrence Huang, Simona Martin, and Alia Badawi, and edited by Sheri Weiser, Arianne Teherani, Jennifer Monroe Zakaras, and Naomi Beyeler, on behalf of the UC Center for Climate, Health and Equity.