In one of the most comprehensive pictures yet of the growing health risks associated with wildfire smoke, new research suggests ash and soot from burning wildlands has caused more than 41,000 excess deaths annually from 2011 to 2020.
By 2050, as global warming makes large swaths of North America hotter and drier, the annual death toll from smoke could reach between 68,000 and 71,000, without stronger preventive and public health measures.
“The numbers are very big, and it definitely surprised us,” said Minghoa Qiu, lead author and assistant professor at Stony Brook University. “We find that wildfire smoke is already killing a lot of people.”
During the 2020 wildfire season, the worst in California’s modern history, wildfires scorched more than 4.2 million acres statewide.
Many Californians, locked down during the COVID-19 pandemic, encountered choking air when they ventured outside. Bay Area residents remember the sickly orange sky they woke up to five years ago this month. The jet streams carried pollution thousands of miles east to the Atlantic Coast.
In the span studied, millions of people were exposed to unhealthful levels of air pollution. When inhaled, this microscopic pollution not only aggravates people’s lungs, it also enters the bloodstream, provoking inflammation that can induce heart attacks and stroke.
For years, researchers have struggled to quantify the danger the smoke poses. In the paper published in Nature, they report it’s far greater than public health officials may have recognized.
Yet most climate assessments “don’t often include wildfire smoke as a part of the climate-related damages. And it turns out, by our calculation, this is one of the most important climate impacts in the U.S.”
California, in particular, is projected to see the largest increase in smoke-related mortality, with over 5,000 excess deaths annually. The state’s vast forests and perennially dry climate make it the most fire-prone state in the nation. With 39 million residents, many Californians find themselves downwind.
The study also estimates a higher number of deaths than previous work in part because it projected mortality up to three years after a person has been exposed to wildfire smoke.
It also illustrates the dangers of smoke drifting from fire-prone regions into wetter parts of the country, a recent phenomenon that has garnered more attention with large Canadian wildfires contributing to hazy skies in the Midwest and East Coast in the last several years.
“Everybody is impacted across the U.S.,” Qui said. “Certainly the Western U.S. is more impacted. But the Eastern U.S. is by no means isolated from this problem.”
Elected officials and climate experts have called for reducing carbon emissions from burning fossils to prevent worsening effects from climate change. But because the concentration of greenhouse gases continues to climb each year and emissions are rising, not falling, some degree of warming is now unavoidable. Much of the carbon dioxide from a diesel tailpipe today, for example, will stay in the atmosphere for more than a century.
“Because of the inertia of the Earth’s [climate], even if we reduce the CO2 tomorrow, we are still going to see a considerable level of temperature increase,” Qiu said.
But that’s not to say nothing can be done. Qiu said it highlights the importance of adapting for a warmer planet, while working to reduce planet-warming emission.
Studies have shown air purifiers can drastically improve indoor air quality during wildfires. And states with a high fire risk, like California, should continue to fund prescribed burns, fires intentionally set by forestry professionals to clear away flammable vegetation and avoid larger wildfires.
“The tricky thing is, prescribed fires also generate smoke,” Qiu said. “So it’s going to be a trade-off. We are going to have some smoke, but the hope is it can reduce a much larger smoke burden due to [an actual] wildfire.”
