Each additional day of exposure to wildfire smoke and other extreme forms of dirty air boosts risk of mental illness—yes, mental illness—in young people, according to a new study published as wildfires sweep through vast areas of Southern California.
It also threatens adults and younger people with chronic conditions such as asthma, emphysema, heart disease and COPD.
“We found that a greater number of days with fine particulate air pollution levels above EPA standards was associated with increased symptoms of mental illness, both during the year of exposure and up to one year later,” said Harry Smolker, a research associate with the University of Colorado's Institute of Cognitive Science.
Average air quality has generally improved in recent decades due to limits on emissions from combustion engines, but more frequent fires have created a new problem: more days with severe levels of tiny particles of burnt things —a.k.a. particulate matter—in the air.
“We are entering a new age in which we are experiencing unprecedented levels of exposure to particulates multiple times a year,” said Smolker. “We need to understand what these extreme events are doing to young people, their brains and their behavior.”
The study looked at 10,000 9 to 11 year olds. It was published in Environmental Health Perspectives. Previous studies have reached similar conclusions.
The link to mental health
While scientists have known for years that air pollution can harm lung and heart health, they’ve only recently begun to explore its impact on cognition and behavior.
Some studies show that PM2.5, particulate matter with a diameter of less than 2.5 micrometers, may be small enough to slip across the blood-brain barrier, inflaming tissue, damaging cells and igniting an immune response that can fuel both acute and longer-term brain changes.
Hospital admissions for depression, suicide attempts and psychotic episodes have been shown to increase in adults on high pollution days. And when pregnant people are exposed to high levels of particulates, their children are more likely to have motor deficits and cognitive impairments later in life, studies suggest.
Smolker’s study is among the first to look at potential impacts on adolescents, whose brains are still developing.
About one-third of those studied were exposed to at least one day above the EPA standard. One participant was exposed to unsafe levels for 173 days. The highest level of exposure reported was 199 micrograms/m3 – more than five times the level deemed safe.
When looking at parent questionnaires at four time points over three years, the researchers found that, across both genders, each additional day of exposure at unsafe levels boosted the likelihood of a youth having symptoms of depression, anxiety and other “internalizing symptoms” up to one year later.
Each day counts
Repeated high levels of exposure had a far greater influence on risk than annual averages or maximum levels did, suggesting that each additional day of breathing poor air counts.
For each day of unsafe exposure, risk went up .1 points on average on a scale of 1 to 50.
“This is relatively small, but not trivial,” Smolker said, noting that PM2.5is just one of the myriad pollutants a child encounters. “Collectively they can add up.”
Some youth may be genetically predisposed to be even more vulnerable to the cognitive and behavioral impacts of air pollution, he notes.
What to do
Besides the affect on mental health, wildfire smoke can exacerbate the symptoms of respiratory conditions like asthma and chronic obstructive pulmonary disease. If you have these conditions, you may want to be especially cautious when the air is smoky.
Adults and children should stay inside as much as possible when it's smoky, particularly if you are at higher risk of illness. If you need to go outside, wear a high-quality, tightfitting mask, like an N95.
If you’re able to stay inside, “you definitely want to try to make your indoor environment as smoke free as possible,” said Laura Corlin, an associate professor of public health and community medicine at Tufts University School of Medicine, in a New York Times account.
That means making sure windows are tightly shut. Run an air purifier if you have one. If you do not, turning on the air conditioning can help. But if you have a central air system that takes in air from outside, close the outside air damper, or switch the system to recirculate mode, so that you are not pulling air that is tainted with smoke into your home