Wildfire Pollution Linked to 24,100 Annual U.S. Deaths, Study Finds
A new study has linked chronic exposure to wildfire pollution to an average of 24,100 deaths annually in the United States between 2006 and 2020. The findings were published in the journal Science Advances.
Key Findings
Yaguang Wei, a study author and assistant professor at the Icahn School of Medicine at Mount Sinai, stated that wildfire smoke presents an increasing threat to human health.
"Wildfire smoke presents an increasing threat to human health."
Other scientists, including Michael Jerrett from UCLA, affirmed the reasonableness of these estimates, emphasizing the need for more studies to build scientific confidence.
Researchers focused on deaths associated with long-term exposure to fine particulate matter, or PM2.5, which is the primary concern from wildfire smoke. These microscopic particles can penetrate deep into the lungs and enter the bloodstream. While short-term exposure can cause immediate symptoms like coughing, long-term exposure can exacerbate existing health conditions and contribute to chronic and fatal issues such as respiratory illness, cardiovascular diseases, neurological disorders, and premature death.
Min Zhang, another study author from the Icahn School, noted that wildfire smoke PM2.5 has become a significant environmental hazard in the U.S., driven by increased wildfire frequency and intensity due to climate change. Jerrett added that decades of forest mismanagement and growing development in fire-prone areas have expanded the "urban wildland interface," increasing health risks.
Study Methodology
The study analyzed the correlation between annual average PM2.5 exposure from wildfire smoke and deaths across 3,068 counties in the lower 48 states. Researchers used federal mortality data for all causes of death, specifically examining circulatory, neurological, and respiratory diseases, along with mental and behavioral disorders, tumors, and endocrine, nutritional, and metabolic diseases.
They also included deaths from falls and transport accidents, which are not typically linked to smoke, to validate their observations. No association was found for car accidents or falls, while other diseases showed statistically significant effects, with neurological diseases seeing the largest increase.
The link between particulate exposure and death varied by season and demographics, showing a stronger association during cooler periods and increased vulnerability in rural areas and younger communities. The study found that a 0.1 microgram per cubic meter increase of PM2.5 correlated with approximately 5,594 additional deaths each year.
Jerrett acknowledged the study's large population size and inclusion of most causes of death in the U.S. However, he cautioned that county-level data might lead to over or underestimates due to the dynamic nature of wildfire smoke, which does not uniformly blanket large areas. The study also did not account for individual factors like smoking habits.
Policy Implications
Kai Chen, an associate professor at the Yale School of Public Health not involved in the study, highlighted the value of examining both smoke and non-smoke PM2.5, noting that wildfire PM2.5 often has greater health impacts than pollution from other sources like car emissions.
The study authors suggested that federal climate policy rollbacks, alongside the increasing frequency of destructive wildfires, pose critical risks. They emphasized that quantifying the deadly threat of wildfire-sourced PM2.5 necessitates effective and urgent mitigation strategies, supported by Environmental Protection Agency (EPA) monitoring and regulation.
"Quantifying the deadly threat of wildfire-sourced PM2.5 necessitates effective and urgent mitigation strategies, supported by Environmental Protection Agency (EPA) monitoring and regulation."
Chen agreed, underscoring the importance of controlling wildfire-sourced PM2.5, which is not currently regulated by the EPA as it is often considered a natural disaster.