Napa, CA – Wildfires exacerbated by climate change are not just a threat to the environment but a major public health crisis, contributing to thousands of deaths and economic costs in the United States, according to a new study published in Nature Communications Earth & Environment.
The study, which analyzed data from 2006 to 2020, found that climate change has been responsible for approximately 15,000 deaths due to wildfire smoke and particulate matter exposure over the past 14 years. The economic toll, tied to the health impacts of wildfire smoke, is estimated at around $160 billion. The study also revealed that the annual number of deaths linked to wildfire smoke exposure varied widely, ranging from 130 to over 5,000 per year, with the highest mortality rates occurring in states like California and Oregon.
“We’re seeing a lot more of these wildfire smoke events,” said Nicholas Nassikas, a physician and professor at Harvard Medical School, who contributed to the study. He emphasized the urgency of understanding the relationship between wildfire smoke and health outcomes in an increasingly volatile climate. “What does it really mean in a changing environment for things like mortality, which is kind of the worst possible health outcome?” he added.
The study focuses on the health impacts of fine particulate matter, known as PM2.5, which is a key pollutant found in wildfire smoke. These tiny particles can penetrate deep into the lungs, leading to short-term symptoms like coughing and itchy eyes, and long-term effects such as exacerbation of chronic health conditions, including respiratory diseases and heart problems. Vulnerable groups, including children, the elderly, pregnant individuals, and outdoor workers, are especially at risk.
Lisa Thompson, a professor at Emory University who studies air pollution and climate change, praised the study for its groundbreaking approach to isolating the impact of climate change on mortality. “This is one of the first studies I’ve seen that isolates the effect of climate change on mortality,” she said. “Looking at the impacts across time and space makes it unique.”
The health risks associated with PM2.5 from wildfire smoke are growing more severe, with some studies suggesting that it may be even more toxic than other forms of air pollution. When wildfires move into urban areas, burning cars and other toxic materials, the danger is amplified. In the Western U.S., where wildfires have become more frequent and intense due to drought and heat, the public health burden is particularly heavy.
The study is a stark reminder of how climate change is directly influencing the frequency and intensity of wildfires. Global warming, driven by human activities like the burning of fossil fuels, has led to hotter temperatures, longer droughts, and drier vegetation that act as fuel for fires. As these conditions worsen, wildfires have become larger, more frequent, and more devastating—along with the dangerous smoke they release into the air.
A Wake-Up Call for Action
Experts are not surprised by the findings, but the scope of the impact is nonetheless alarming. Jacob Bendix, a professor emeritus of geography at Syracuse University, commented, “These numbers are really significant. There’s a tendency for people outside of the areas actually burning to see increasing fires as a distant inconvenience. This study drives home how far-reaching the impacts are.”
The research team behind the study used advanced modeling to estimate how much of the area burned by wildfires could be attributed to climate change. They compared the real climate conditions that contributed to the wildfires with a scenario in which climate change had not occurred, ultimately quantifying the number of deaths and calculating the economic costs tied to PM2.5 exposure.
The findings suggest that approximately 10% of the 164,000 deaths related to wildfire smoke between 2006 and 2020 were attributable to climate change. The highest mortality rates were found in certain Western U.S. states, where the frequency of wildfires has been exacerbated by changing climate conditions.
However, some experts have raised concerns about the study’s methodology and conclusions. Marshall Burke, a professor at Stanford University, acknowledged the strong evidence linking climate change to increased wildfire activity but expressed caution about the study’s methodology, particularly the link between burned area and smoke. “It’s tricky to predict exactly how smoke will spread based on wind conditions,” he noted.
Patrick Brown, a lecturer in climate and energy policy at Johns Hopkins University, raised concerns about the study’s emphasis on climate change as the primary driver. He warned that policymakers might mistakenly conclude that reducing greenhouse gas emissions is the sole solution, overlooking other vital strategies such as fuel management, prescribed burns, and improving public health measures to mitigate smoke exposure in the short term.
Despite these critiques, the study makes it clear that the problem of wildfire smoke will only worsen if greenhouse gas emissions continue to rise. The authors argue that while immediate solutions like land management practices and public health interventions are important, long-term efforts to reduce emissions remain essential.
“The problem of deaths from wildfire smoke will only get worse without the reduction of greenhouse gas emissions,” Nassikas said. “Part of the study is raising awareness, and once we understand the scale of the problem, we can start thinking about interventions at the personal, community, and global levels.”
As wildfires continue to intensify in the U.S. and beyond, the study highlights the growing need for coordinated action on both mitigation and adaptation strategies to reduce the health and economic toll of wildfire smoke. With climate change continuing to fuel these deadly fires, the time to act is now.