CLIMATEWIRE | Summer across the American West has become synonymous with extreme heat and poor air quality — and that combination can be particularly deadly, according to a recent study.

Researchers at the University of Southern California analyzed more than 1.5 million deaths in California between 2014 and 2019, and found that the risk of death increased by 21 percent on days when there was both extreme heat and high air pollution. The results — published in the American Journal of Respiratory and Critical Care Medicine — highlight the grim toll on human health as temperatures rise, droughts worsen and wildfires become more frequent.

“This is an important co-exposure that’s likely going to increase in frequency with the changing climate, and it’s important to implement different public health interventions and policies to help protect people and save lives,” said Erika Garcia, the study’s lead author and an assistant professor of population and health sciences at USC.

Garcia and her co-authors used temperature and air quality data to calculate how much deaths increased when temperatures were high or air quality low. They found that the risk of death increased by about 6 percent on days with extreme high temperatures and by about 5 percent on days with high concentrations of fine particulate matter, also known as PM2.5.

But risk approximately quadrupled on days when there was both extreme heat and high air pollution. The researchers attributed the higher death rates in part to the increased risk of cardiovascular and respiratory issues, including systemic inflammation and oxidative stress. People older than 75 were the most likely to die amid high temperatures and pollution levels.

The study defined extreme heat as a daily maximum temperature that was in at least the 90th percentile, and extreme PM2.5 exposure as a daily particulate matter concentration that was in at least the 90th percentile.

The results will hopefully inform policymakers as they develop plans to adapt to hazardous climate conditions and protect vulnerable populations, Garcia said.

“This co-occurrence of both [exposures] is really important when thinking about health effects, but also for thinking about, ‘What are interventions and policies that could be implemented to protect folks?’” Garcia said. She suggested that local or state governments could send residents alerts and safety tips when both conditions exist.

Garcia and other USC researchers are working on follow-up studies that look at how extreme weather affects the health of various communities and how extreme heat and air pollution affect mental health.

The study’s findings come at a time when millions of Americans are suffering from above-average temperatures and more frequent wildfires, which send particulate matter into the atmosphere, bringing down air quality in surrounding areas and even other states.

An ongoing heat wave covering much of the West and South triggered heat advisories and excessive heat warnings yesterday from the National Weather Service, affecting millions of people in parts of Texas, Louisiana, Arkansas, Utah, Nevada and other states. Texas’ electricity operator asked residents to voluntarily lower their consumption to prevent blackouts.

In California, where the Washburn Fire is threatening Yosemite National Park, a persistent and historic drought has made wildfires more destructive. The eight largest wildfires in California history occurred in 2017 or later, according to the California Department of Forestry and Fire Protection, the state’s firefighting service.

The California Air Resources Board estimates that 90 percent of Californians breathe unhealthy levels of air pollutants at some point each year, and that reducing PM2.5 levels to “background levels” would save 7,200 lives and prevent 1,900 hospitalizations yearly. Nationwide, disadvantaged communities, including low-income people and people of color, are more likely to face health issues as a result of extreme weather and air pollution (Climatewire, Dec. 10, 2020).

The Biden administration has pledged to cut the country’s planet-warming emissions in half by 2030 and to put the United States on track for net-zero emissions by 2050. But climate experts and policy analysts have expressed pessimism about Congress’ ability to pass climate legislation that would put the country on track to achieve meaningful emissions reductions (Climatewire, July 8).

Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2022. E&E News provides essential news for energy and environment professionals.