Extreme heat and wildfire smoke are individually harmful to the human body, but when combined, their impact on cardiovascular and respiratory systems becomes even more dangerous, particularly for certain communities. A recent study published in Science Advances revealed that climate change is increasing the frequency of both hazards, especially in California. The researchers found that the combined harm of extreme heat and inhalation of wildfire smoke led to increased hospitalizations, disproportionately affecting low-income communities and racially marginalized residents, including Latino, Black, Asian, and other minority groups.
The reasons behind this disproportionate impact are complex and varied, as outlined by the authors from the Scripps Institution of Oceanography at the University of California, San Diego, and the UCLA Fielding School of Public Health. Structural racism, discriminatory practices, lack of medical insurance, limited understanding of the health risks, and a higher prevalence of multiple underlying conditions contribute to the disparities. Additionally, infrastructure, surrounding environment, and available resources play a role in determining the level of protection individuals have against extreme heat and smoke exposure. Homes and workplaces with air conditioning, neighborhoods with tree canopy cover, and buildings equipped with smoke filters and efficient insulation are better equipped to mitigate these risks. Access to cooling centers, such as libraries, also provides additional protection.
Tarik Benmarhnia, a study author and climate change epidemiologist at UC San Diego, emphasized that even individuals with a high susceptibility to these health risks can avoid hospitalization and emergency room visits if they have access to social services and amenities. However, those living in remote areas with limited resources may face more challenges.
Experts warn that climate change, which is intensifying extreme weather events like droughts, heat waves, and wildfires, will lead to a higher frequency and intensity of these hazards occurring simultaneously. While the study focused on California, similar patterns can be observed in other parts of the western United States, such as Oregon and Washington state, as well as in regions with a Mediterranean climate, including parts of Canada like British Columbia.
To conduct the study, researchers analyzed California health records from 995 ZIP codes, covering most of the state’s population, during episodes of extreme heat and toxic air from wildfires. They discovered that between 2006 and 2019, hospitalizations for cardiorespiratory issues increased by 7% on days when both conditions were present. Moreover, these hospitalizations were higher in ZIP codes with higher poverty rates, predominantly nonwhite populations, denser areas, and limited access to healthcare.
Certain regions in California, such as the Central Valley and the state’s northern mountains, experienced higher incidences of both hot weather and wildfires. The Central Valley, known as the agricultural heartland, is particularly vulnerable due to the outdoor work environment and exposure to pesticides and other environmental hazards.
Apart from the immediate health risks, hospitalization can have significant consequences, such as loss of work or school hours and substantial medical bills. Christopher T. Minson, a professor of human physiology at the University of Oregon, explained that during extremely hot days, the body struggles to cool itself through sweating, leading to dehydration and an increased heart rate, subsequently elevating blood pressure. Complementing this, fine particles in wildfire smoke can easily enter the respiratory system and even the bloodstream, causing inflammation and worsening cardiovascular regulation.
A study conducted by the University of Southern California in 2022 further highlighted the risks associated with extreme heat and air pollution. It revealed that the likelihood of death increased by 6.1% during heatwaves, 5% during extreme air pollution events, and a staggering 21% when both conditions coincided.
Dr. Catharina Giudice, an emergency physician and fellow at the Harvard T.H. Chan School of Public Health, expressed concern about the impact of climate change on low-income and minority communities, who are less adapted to such hazards. She emphasized the importance of highlighting the social injustice aspect of climate change, as these communities tend to experience its effects more severely.
The authors of the study recommended issuing joint warnings for extreme heat and toxic air earlier, as separate advisories and warnings from agencies like the National Weather Service and local air quality districts might not adequately address the compound exposure.
Climate change and the associated risks of extreme heat and wildfire smoke pose significant challenges to public health. Addressing these challenges requires a comprehensive approach that tackles the underlying social inequalities, improves access to healthcare, enhances infrastructure, and reduces greenhouse gas emissions to mitigate climate change. By taking proactive measures, communities can better protect themselves from the immediate and long-term health consequences of these hazards.
