This week, white-clad first responders have finally begun to leave Paradise, California, where they’ve been searching the rubble for human remains. This year has become the state’s most destructive fire season ever, topping even last year’s lethal record-setting. Two of the state’s ten deadliest wildfires of all time have been in the last five months, and according to the California Department of Forestry and Fire Protection, over a million and half acres have burned. Wildfires now destroy more than 7 million acres a year in the United States, a number only expected to increase. “We’re in a new abnormal,” California governor Jerry Brown said during a press conference after Paradise burned. “This new abnormal will continue."
But we may not be accurately calculating the true death tolls of all this incineration. Researchers are still trying to puzzle out the many components of wildfire smoke, which can include paint, heavy metals, and thousands of different chemicals. But what is clear is that wildfires generate dangerous fine particulate matter; impacts from exposure can range from mild eye and lung irritation to asthma, bronchitis, and permanent decreases in lung function. Chronic exposure to fine particles has also been linked to many other neurologic and metabolic disorders. “The overall impact is much larger than the direct impacts observed,” says Tarik Benmarhnia, an environmental epidemiologist at University of California San Diego. Those caught in the flames are “just the tip of the iceberg.”
Particulates are harmful for everyone, but some—people who live or work outside, like homeless populations or farmworkers—are far more vulnerable than others. For example, in a photo that went viral in early November, farmworkers work their way through rows of crops under an ominous shade. As they bend over the plants, smoke billows behind them, blotting out the sun. Though miles south of the Hill and Woolsey Fires, these workers—statistically more likely to be people of color and less able to access health care due to immigration or economic status—are on the front lines.
“First of all, because of their work, they’re more exposed," Benmarhnia says, "and in addition, because of pre-existing conditions, they’re more vulnerable.” Toxicologically, health impacts of air pollution are cumulative, meaning if you already live near a highway or work in heavy industry, wildfire smoke is more likely to make you sick. Taken together, it’s a grim picture. Benmarhnia says simply, “Wildfire is going to exacerbate existing inequalities.”
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A flurry of new research supports the idea that smoke vulnerability is not equally distributed. An article published in the American Journal of Epidemiology in 2017 analyzed hospital admissions for respiratory issues in the western United States from 2004 to 2009, and found that black Americans living in urban counties in California were the most likely to be exposed to wildfire smoke pollution. In fact, black people were about 14 percent more likely to be admitted to hospitals for respiratory problems due to wildfire smoke. “Our study raised important environmental justice issues that can inform public health programs,” the authors wrote.
A University of Washington study published in PLOS suggests that black, latinx, and Native American communities face a 50 percent greater vulnerability to wildfires than white communities. And a third study, published in Environmental Research by scientists at the School of Public Health, University of California, Berkeley, examined emergency department visit rates during the 2008 wildfires in northern California, and found that median income also had an effect, “with the highest effects observed in in the ZIP codes with the lowest median income.”
While research on the health impacts of wildfires is still in the early stages, epidemiologists have been raising the alarm about air pollution in the developing world for a long time. “We know health effects associated with fine particles, whether they’re coming from a fire or just car emissions, are similar,” Benmarhnia says. Air pollution kills more than 2.9 million people a year, and both acute exposures and chronic exposures have been associated with increased risk for mortality. Terrifyingly, particulate matter appears to have no safe threshold—health effects have been recorded at levels lower than the most conservative air quality standards.
The health impacts of fine particles can be far-reaching—and they're an often overlooked part of racial health disparities. Benmarhnia has found, for example, that one of the reasons black women may be more likely to have babies prematurely than white women is particulate matter. “The individual contribution of PM2.5 is comparable in magnitude to any single individual or neighborhood level factor,” he writes. Early preterm birth has been shown to have long-lasting impacts on children’s brains, stress, and behavior for years. “Air pollution is associated with so many problems,” Benmarhnia explains. “Life expectancy, dementia, cardiovascular disease.” He suggests this makes a silver lining out of a problem—because there are so many linked issues, the benefits of addressing air pollution are also huge.
Parsing who is most at risk is an important part of minimizing the consequences. The Centers for Disease Control and Prevention, for example, is currently working on developing an online tool to combine short-term forecasts of smoke concentrations with data on population-level vulnerability. The goal is to provide doctors and emergency responders with access to exposure and health datasets to better manage wildfire responses. As climate change lengthens fire seasons—in the last 35 years, the season in California has already expanded by a month—it’s increasingly important to understand.
As Benmarhnia says of California’s farmworkers, many of whom continued to work long days in the field, while white-collar families fled San Francisco, “Of course, wildfire is a problem, but so is the fact that they don’t have the capacity or capability to adapt to fire.” When it comes to designing policies to help keep people safe in a new climate, “These details matter.”
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