LOS ANGELES (AP) — Extreme heat and wildfire smoke are individually harmful to the human body, but together their impact on the cardiovascular and respiratory systems is more dangerous and affects some communities more than others.
A study published Friday in the journal Science Advances said climate change is increasing the frequency of both hazards, especially in California. The authors found that the combined damage from extreme heat and wildfire smoke inhalation increased hospitalizations and disproportionately impacted low-income communities and Latino, Black, Asian and other racially marginalized residents.
The reasons are varied and complicated, 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. Structural racism, discriminatory practices, lack of health insurance, less understanding of health damage and a higher prevalence of multiple co-existing conditions are some of the reasons.
Infrastructure, environment and available resources are also factors. Air-conditioned homes and workplaces and neighborhoods with tree canopies are better protected from extreme heat, and some buildings filter smoke from wildfires and insulate heat more efficiently. Areas with access to cooling centers, such as libraries, also offer more protection.
“Even if you’re very susceptible — you have a lot of comorbidities — you may have a lot of chances of not being affected, not being hospitalized, not having to go to the ER, but if you go to a If you live in a place that’s quite remote, doesn’t have access to many social services or amenities, … it can pose more problems,” said Tarik Benmarhnia, a study author and climate change epidemiologist at UC San Diego.
Experts warn that climate change – which is exacerbating extreme weather events such as droughts, heatwaves and forest fires – will increase the frequency and intensity with which they occur simultaneously.
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, Benmarhnia said .
Researchers analyzed California’s health records — broken down into 995 zip codes covering most of the state’s population — during periods of extreme heat and toxic air from wildfires. They found that between 2006 and 2019, hospitalizations for heart and respiratory problems increased by 7% on days when both conditions existed, and were higher than in zip codes where people were likely to be poor, non-white, live in densely populated areas and lack health had. concern.
California’s Central Valley and the state’s northern mountains saw higher incidences of both warm weather and wildfires, likely driven by more wildfires in the surrounding mountains.
Residents of the Central Valley’s agricultural heartland are particularly vulnerable to the adverse health effects of both because they are more likely to work outdoors and are exposed to pesticides and other environmental hazards, Benmarhnia said.
In addition to the health risks, hospitalization has other important consequences, such as losing hours of work or school, or incurring high medical bills.
During extremely hot days, the human body has a harder time cooling itself through sweating, says Christopher T. Minson, a professor of human physiology at the University of Oregon, who was not part of the study. The body can dehydrate, causing the heart to beat faster, which increases blood pressure.
“If you’re dehydrated or you have cardiovascular disease, … you’re going to be less able to tolerate that heat stress, and that heat stress can become very, very dangerous,” he said.
Some particles found in wildfire smoke can easily enter through the nose and throat and eventually end up in the lungs, according to the Environmental Protection Agency. The smallest particles can even enter the bloodstream.
The combination of heat and smoke can cause inflammation in the body, Minson said, which “worsens the whole cardiovascular regulation, and you’re even more at risk for heart attacks and other problems, like long-term bad conditions.” health outcomes thereof. So there is certainly a snowball effect.”
A 2022 study from the University of Southern California found that the risk of death increased dramatically on days when extreme heat and air pollution coincided. During heat waves, the risk of death increased by 6.1%; when air pollution was extreme, it increased by 5%; and on days when the two were combined, the threat shot up to 21%.
When Dr. Catharina Giudice worked at a hospital in Los Angeles, she noticed an increase in emergency room visits from patients with various health problems on extremely hot days. When wildfires broke out, she saw more people with worsened asthma and other respiratory conditions.
As climate change fuels the intensity and frequency of heat waves and wildfires, Giudice worries about low-income and minority communities who are less adapted.
“For a variety of reasons, they tend to experience climate change much worse than other communities that are not disadvantaged, and I think it’s really important to highlight this socially unjust aspect of climate change,” said the emergency physician and Harvard fellow 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 separate advisories and warnings on days of extreme heat and toxic air. But they argue that “it would be useful to issue a joint warning earlier, given the exposure to compound substances.”
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