Smoke and Shadows: How Wildfire Smoke is Impacting Our Youth’s Mental Health!

wildfire smoke mental health youth study

Study Finds Wildfire Smoke Linked to Increased Mental Health Problems in Youth

A Groundbreaking Investigation into the Effects of Particulate Pollution

A groundbreaking investigation into the effects of particulate pollution on the developing adolescent brain has emerged, involving a cohort of 10,000 young individuals. This pioneering study stands among the first to delve into the intricate connection between air pollution and youth mental health.

The Study and Findings

A team of researchers from the University of Colorado Boulder scrutinized the mental health of children aged 9 to 11, revealing a subtle yet concerning correlation: each additional day of exposure to wildfire smoke and other severe airborne pollutants incrementally raised the risk of mental health disturbances.

“Our research indicates that a higher frequency of days with fine particulate matter (PM2.5) levels exceeding EPA standards correlates with an uptick in symptoms of mental illness, both within the exposure year and persisting up to a year later,” remarked lead author Harry Smolker, a research associate at CU’s Institute of Cognitive Science.

Published in Environmental Health Perspectives, the findings are particularly timely, as smoke from Southern California wildfires has cast a dense pall over vast regions, including Las Vegas and Colorado. Although air quality has improved in recent years due to stricter emissions regulations, the rise of frequent wildfires introduces a new dilemma—an increase in days with hazardous levels of particulate matter.

wildfire smoke mental health youth study: A New Era of Increased Particulate Exposure

“We are entering a novel era, marked by repeated and unprecedented exposure to particulates,” Smolker warned. “It’s critical to understand the repercussions of these extreme events on the minds and behaviors of young people.”

The Link Between Pollution and Mental Health

While it’s long been established that air pollution detrimentally affects the respiratory and cardiovascular systems, its influence on cognition and behavior is a more recent avenue of inquiry. Some studies suggest that PM2.5—particles small enough to cross the blood-brain barrier—can inflame brain tissue, damage cells, and spark immune responses, potentially triggering both immediate and long-term neurological changes.

Previous research has already shown a rise in hospitalizations for depression, suicide attempts, and psychotic episodes among adults on highly polluted days. Furthermore, prenatal exposure to particulate matter has been linked to motor and cognitive deficits in children later in life.

Adolescent Brain Development and Air Pollution

Smolker’s research breaks new ground by focusing on adolescents, whose brains are still undergoing significant development. Drawing from data collected through the Adolescent Brain Cognitive Development (ABCD) Study, the largest longitudinal study of its kind in the U.S., the researchers examined air quality exposure for 10,000 pre-teens across 21 different sites, including CU Boulder.

wildfire smoke mental health youth study: Exposure Levels and Mental Health Risks

By analyzing residential histories and air quality data from 2016, the team identified how many days each participant had been exposed to PM2.5 concentrations exceeding 35 micrograms per cubic meter (35µg/m3)—the threshold the EPA deems unsafe. One-third of the youth experienced at least one day of unsafe air, with one individual subjected to such levels for 173 days. The highest recorded exposure exceeded 199µg/m3, a staggering fivefold increase over the EPA’s safety limit.

The researchers then evaluated parent-reported mental health surveys across four intervals over three years. Across genders, each additional day of exposure to unsafe air was associated with a heightened risk of internalizing symptoms—such as depression and anxiety—up to a year later. This link persisted even after adjusting for factors like race, socioeconomic background, and parental mental health. Interestingly, in many cases, the children reported symptoms even when their parents did not.

“This suggests that PM2.5 may have unique impacts on youth that differ from its effects on adults,” Smolker commented.

wildfire smoke mental health youth study: The Cumulative Effect

The study further revealed that cumulative exposure had a far greater impact on mental health risk than either annual averages or peak pollution levels. In fact, every additional day of exposure incrementally raised the risk by 0.1 points on a scale of 1 to 50.

While this increase may seem modest, Smolker cautioned against underestimating its significance. PM2.5 is but one of many environmental pollutants to which children are exposed, and the collective impact of these exposures can be substantial. Furthermore, some children may be genetically predisposed to be more vulnerable to the neurological and behavioral effects of pollution.

The Role of Wildfire Smoke

Although particulate matter originates from multiple sources, such as vehicular emissions and industrial activities, co-author Colleen Reid, a geographer at CU Boulder’s Institute for Behavioral Science, suspects that wildfire smoke was a primary contributor to the exposure observed in this study.

“Wildfire smoke events are increasingly frequent, and this research adds to the growing body of evidence suggesting their significant impact on public health,” Reid concluded.

Reference

“The Association between Exposure to Fine Particulate Air Pollution and the Trajectory of Internalizing and Externalizing Behaviors during Late Childhood and Early Adolescence: Evidence from the Adolescent Brain Cognitive Development (ABCD) Study” by Harry R. Smolker, Colleen E. Reid, Naomi P. Friedman and Marie T. Banich, published August 6, 2024, in Environmental Health Perspectives. DOI: 10.1289/EHP13427

This study was supported by the National Institutes of Health.