Extreme heat and wildfire smoke pose separate risks to human health, but a new study published in Science Advances suggests that the combination of these hazards is even more dangerous, particularly for certain communities. The research, conducted by scientists from the Scripps Institution of Oceanography at the University of California, San Diego and the UCLA Fielding School of Public Health, highlights the disproportionate impacts on low-income communities and racially marginalized residents, such as Latino, Black, and Asian populations.
The study focuses on California, where climate change has contributed to an increase in both extreme heat and wildfires. The researchers found that the simultaneous exposure to extreme heat and wildfire smoke led to an increase in hospitalizations for cardiovascular and respiratory issues. The authors attribute this disparity to various factors, including structural racism, discriminatory practices, lack of medical insurance, limited understanding of the health risks, and a higher prevalence of multiple existing health conditions.
The impact of these hazards is also influenced by infrastructure, surrounding environments, and available resources. Buildings with air conditioning and neighborhoods with tree canopy cover tend to provide better protection against extreme heat. Similarly, certain buildings are equipped with filters to reduce smoke from wildfires and improve insulation. Access to cooling centers, such as libraries, also offers additional protection.
Tarik Benmarhnia, a study author and climate change epidemiologist at UC San Diego, emphasizes that even individuals who are highly susceptible to the health effects of extreme heat and wildfire smoke have opportunities to avoid hospitalization or emergency room visits. However, residing in remote areas with limited social services and amenities can exacerbate the risks.
Experts warn that climate change will increase the frequency and intensity of extreme weather events, such as heatwaves and wildfires, further amplifying their simultaneous occurrence. While the study focused on California, similar patterns are observed in other parts of the western United States, including Oregon and Washington state, as well as regions with a Mediterranean climate.
The researchers analyzed health records from various ZIP codes in California between 2006 and 2019. They found that hospitalizations for cardiorespiratory issues increased by 7% on days when both extreme heat and toxic air from wildfires were present. The impact was particularly pronounced in ZIP codes with higher poverty rates, nonwhite populations, dense living conditions, and limited access to healthcare.
Certain regions in California, such as the Central Valley and the state’s northern mountains, experience higher incidences of both extreme heat and wildfires. This is likely due to the prevalence of forest fires in the surrounding mountains. Residents in the Central Valley, known for its agricultural activities, are especially vulnerable due to increased exposure to pesticides and other environmental hazards.
Apart from the immediate health risks, hospitalizations also have significant consequences, such as lost work or school hours and hefty medical bills.
On extremely hot days, the body’s ability to cool itself through sweating is compromised, leading to dehydration and increased heart rate and blood pressure. Wildfire smoke contains particles that can enter the respiratory system, causing inflammation and exacerbating cardiovascular issues.
A separate study conducted by the University of Southern California in 2022 found that the risk of death increased significantly on days when extreme heat and air pollution coincided. During heatwaves, the likelihood of death rose by 6.1%, while extreme air pollution increased the risk by 5%. On days when both conditions were present, the threat of death skyrocketed to 21%.
Dr. Catharina Giudice, an emergency physician and fellow at the Harvard T.H. Chan School of Public Health, has observed an increase in emergency room visits from patients with various health conditions on extremely hot days and during wildfires. She expresses concern for low-income and minority communities, which are less equipped to handle the impacts of climate change.
The authors of the study suggest issuing joint warnings for extreme heat and toxic air, as separate advisories can be confusing and may not adequately address the compounded risks.
As climate change continues to worsen extreme weather events, it is crucial to address the social injustice aspects and prioritize the protection of vulnerable communities.
