According to a study released in the journal Environmental Research: Climate, roughly 16.5 million people in California were exposed at least once to a combination of extremely high temperatures and high levels of fine particulate matter from wildfires during the state's record-breaking 2020 fire season. Researchers said that people living in less populated areas close to forests prone to wildfires were disproportionately affected.

Deer in Wildfire
(Photo: John McColgan/Wikimedia Commons)
Deer in Wildfire


Impact of Excessive Heat and Wildfires on California Residents

Noam Rosenthal, a doctorate student at the UCLA Institute of the Environment and Sustainability, the lead study author, noted that between June and November 2020, these incidents of concurrent smoke and excessive heat affected 68% of California's total land area.

A report in Statista stated that with over a million acres burned, the August Complex fire in 2020 was the biggest California wildfire in history.

According to projections, Rosenthal warned that wildfires and heat waves would become more powerful due to climate change, which will also increase the number of situations where excessive heat and smoke co-occur.

Health Risks of Exposure to Wildfires and Extreme Heat 

Extreme heat can contribute to ailments like heat stress, heat stroke, cardiovascular disease, and even kidney failure. Wildfires generate fine particulate matter that can cause respiratory and circulatory issues. 

The elderly, people with preexisting diseases, and other vulnerable populations are particularly at risk from this phenomenon, as prior studies have shown that the mixture of high heat and air pollution can increase health risks beyond what would be expected by the combination alone.

Environmental Protection Agency claims that the health impacts of wildfire smoke can range from eye and respiratory tract irritation to more severe conditions, such as decreased lung function, worsening of asthma and heart failure, and premature deaths.

Rosenthal said, "It's not just one plus one equals two. It might be one plus one equals four."

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Research Findings on the Effects of Wildfires

For their smoke-related findings, the authors excluded pollution from other sources, such as cars and power plants, to concentrate on fine particulate matter from wildfires alone. These PM2.5 particles from fires, which have a width of 0.0025 millimeters or smaller, can penetrate deeply into the lungs and are considered particularly hazardous to respiratory health.

To determine where smoke from wildfires was concentrated, their study merged smoke distribution models with satellite data on fires' radiative power, which is a measurement of the rate at which heat is released during a fire.

According to Rosenthal, it is unclear exactly how and why smoke and severe heat presence might have a negative synergistic effect on health. The combined effects may be caused by heat-related factors that make someone more susceptible to smoke exposure or vice versa.

The authors advise that public health recommendations and climate adaptation policies consider these co-exposures, particularly as they increase in frequency and intensity. More research is required to determine the precise health effects of the combination of extreme heat and smoke, but the authors believe that they should be considered.

Rosenthal noted that nothing operates alone, and extreme heat and wildfires are interconnected and overlap.



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