by LOS ANGELES (AP) – The extreme heat and wildfire smoke are independently damaging to the human body, but combined their effects on the cardiovascular and respiratory systems are more dangerous and affect some communities more than others.
A study published Friday in the journal Science Advances said climate change is increasing the frequency of both hazards, particularly in California. The authors found that the combined harm from extreme heat and wildfire smoke inhalation increased the number of hospitalizations and disproportionately affected low-income communities and Latino, Black, Asian, and racialized residents other marginalized.
The reasons are varied and complex, according to the authors from the Scripps Institution of Oceanography at the University of California, San Diego and the UCLA Fielding School of Public Health. Among the reasons are structural racism, discriminatory practices, lack of medical insurance, less understanding of health damages and a higher prevalence of multiple co-existing conditions.
Infrastructure, surrounding environment and available resources are also factors. Homes and workplaces with air conditioning and neighborhoods with tree canopy cover are better protected from extreme heat, and some buildings filter smoke from wildfires and insulate heat more effectively. Areas with access to cooling facilities, such as libraries, also offer more protection.
“Even if you’re extremely susceptible — you have a lot of co-morbidities — you might have a lot of opportunities to not get affected, not be in the hospital, not go to the ER, but if you live in a fairly remote place that doesn’t have access to a lot of social services or amenities, … there may be more trouble,” said Tarik Benmarhnia, study author and climate change epidemiologist at UC San Diego.
Experts warn that climate change — which is worsening extreme weather events such as droughts, heat waves and wildfires — will simultaneously increase their frequency and intensity.
Although the study focused on California, similar patterns can be found in other parts of the western United States such as Oregon and Washington state, in parts of Canada including British Columbia, and in regions with a Mediterranean climate, which said Benmarhnia.
Researchers analyzed California health records – broken down by 995 ZIP codes covering most of the state’s population – during episodes of extreme heat and toxic air from wildfires. They found that between 2006 and 2019, hospitalizations for cardiorespiratory issues increased by 7% on days with both conditions, and were higher in ZIP codes with people have a better chance of being poor, non-white, living in dense and unhealthy areas. care.
California’s Central Valley and the northern mountains of the state had higher incidences of hot weather and wildfires, and were likely driving more forest fires in the surrounding mountains.
Residents in the agricultural heartland of the Central Valley are particularly vulnerable to the adverse health effects of both because they are more likely to work outside and be exposed to pesticides and other environmental hazards, Benmarhnia said.
Beyond the health risks, being in the hospital has other significant consequences, such as missing work or school hours, or being left with large medical bills.
During very hot days, the human body has a harder time cooling itself through sweating, said Christopher T. Minson, a professor of human physiology at the University of Oregon, who was not part of the study. The body can become dehydrated, which forces the heart to beat faster, which raises blood pressure.
“If you’re dehydrated or have any kind of cardiovascular disease, … you’re not going to be able to tolerate that heat stress as well, and heat stress can become very dangerous,” he said .
Some particles found in wildfire smoke can easily enter through the nose and throat, eventually reaching the lungs, according to the Environmental Protection Agency. Even the smallest particles can enter the bloodstream.
The combination of heat and smoke can cause inflammation in the body, Minson said, which “will make your whole cardiovascular regulation worse, and you’ll be at even greater risk of heart attacks and other problems like long-term problems , poor. health outcomes from that. So it’s definitely a snowball effect.”
A study conducted by the University of Southern California in 2022 found that the risk of death increased on days when heat and air pollution occurred at the same time. During heat waves, the probability of death increased by 6.1%; when air pollution was high, it rose 5%; and on days when the two met, the threat increased to 21%.
When Dr. Catharina Giudice worked at a Los Angeles hospital, she noticed that emergency room visits from patients with various health conditions increased on very hot days. When wildfires burned, she saw more people with worse asthma and other respiratory diseases.
As climate change drives the intensity and frequency of heat waves and wildfires, Giudice worries about the less adapted low-income and minority communities.
“For various reasons, they feel climate change much worse than other underserved communities, and I think it’s really important to emphasize this aspect of the social injustice of climate change,” said the emergency doctor and another man at Harvard TH Chan. School of Public Health, which was not part of the study.
The authors noted that agencies such as the National Weather Service and local air quality districts issue specific advisories and warnings on extreme heat days and toxic air. But they argue that “it would be beneficial to issue an earlier notice considering the compound disclosure.”
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