In California, days that experienced both extreme heat and wildfire smoke at the same time have seen disproportionate numbers of hospitalizations for heart and lung ailments, a new study found. The research highlights the public health dangers of distinct climate threats that can have a compound effect when they occur simultaneously.
The research, published on Friday in the journal Science Advances, also found that this compounding effect was greater in communities with lower levels of income, education, health insurance coverage and tree cover.
Background: Global warming is intensifying both threats.
As humans warm the planet, both heat waves and wildfires are becoming more severe and longer-lasting in the American West. That also means they are more likely to overlap. Researchers have estimated that two-thirds of California’s land area experienced broiling heat and heavy wildfire smoke concurrently at some point during the state’s record fire year of 2020.
Both hazards are harmful to health on their own: Heat stress increases cardiac strain, and inhaling wildfire smoke can aggravate lung conditions. The new study, led by researchers at the Scripps Institution of Oceanography at the University of California, San Diego, looked at the health effects when the two threats appeared in tandem.
On exceptionally hot and smoky days, staying indoors doesn’t always help, and certainly not for people who don’t have air-conditioners and air purifiers, said Tarik Benmarhnia, an environmental epidemiologist at Scripps and one of the study’s authors. “Air pollution doesn’t stay politely outside,” he said. “It gets inside, interacts with a lot of indoor air pollutants and can lead to a lot of issues.”
The Findings: Compounding harms, and unequal ones, too.
The researchers took state data on unscheduled hospitalizations between 2006 and 2019 and combined it with detailed readings of temperatures and wildfire smoke.