Chronic exposure to outdoor air pollution in youth linked to higher anti-inflammatory markers
Researchers at the Wayne State University School of Medicine have discovered that adolescents exposed to higher levels of outdoor air pollution had higher levels of anti-inflammatory markers, challenging the assumption that air pollution primarily triggers pro-inflammatory responses and is instead a modifiable environmental risk factor that may contribute to mental health symptoms in adolescence.
The collaborative effort was led by Clara Zundel, Ph.D., a postdoctoral research fellow in the Department of Psychiatry and Behavioral Neurosciences working in the lab of Associate Professor Hilary Marusak, Ph.D.
“Our findings suggest the need to expand how we think about immune dysregulation in environmental health and mental health research,” Dr. Zundel said. “We also found that recent PM2.5 exposure was linked to greater anxiety symptoms, but only in female participants.”
The researchers were surprised that higher exposure to PM2.5, an airborne particulate matter, was associated with anti-inflammatory lipid mediators in the blood, rather than the pro-inflammatory markers, like CRP or IL-6, that are more commonly studied in psychiatric research. The unexpected pattern aligns with emerging theories, including School of Medicine Professor of Pathology Dr. Krishnarao Maddipati’s “unalamation” framework, which proposes that chronic inflammation may result from impaired resolution, reflected by dysregulated pro-resolving lipid mediators, rather than simply increased pro-inflammatory signals.
“Outdoor air pollution and psychiatric symptoms in adolescents: a study of peripheral inflammatory marker associations,” is published in the journal Frontiers in Psychiatry.
Participants – a total of 78 adolescents aged 10 to 17 years old and one parent or guardian – were recruited from the Detroit area between 2021 and 2024.
“Conducting this work in Detroit allows us to study how real-world, chronic exposure to air pollution may affect mental health and biology during sensitive developmental periods. It also highlights the value of studying environmental health in settings where pollution exposure is a real and ongoing concern for residents,” Dr. Zundel said. “In recent years, we’ve also seen additional pollution from Canada wildfires, further increasing exposure levels.”
According to the American Lung Association’s 2025 State of the Air report, Detroit was ranked the sixth worst city in the nation for year-round particle pollution. Urban areas like Detroit often experience elevated air pollution due to industrial activity from nearby factories and power plants, as well as high traffic and vehicle emissions.
PM2.5 is particularly concerning due to its small size, which allows it to bypass the body’s natural barriers, including the blood-brain barrier, and embed more deeply in the lungs. While adverse physical mental health effects of PM2.5 have been documented across the lifespan in previous studies, adolescence is a particularly vulnerable period, when the brain may be especially sensitive to the adverse effects of PM2.5.
Dr. Maddipati performed the lipidomic work, and Assistant Professor of Environmental Health Sciences and of Pharmacology Michael Petriello, Ph.D., and postdoctoral fellow Zhao Yang, Ph.D., conducted the pro-inflammatory cytokine analyses.
“Their expertise was instrumental in helping us unpack the immune/inflammatory markers linked to air pollution exposure,” Dr. Zundel said.
Dr. Zundel is developing her next grant submission, which will examine these immune markers in a larger adolescent cohort and explore how they change in response to acute stress within a single session. She also plans to begin linking the peripheral immune changes to brain function to better understand how air pollution may contribute to mental health symptoms by altering interactions between the immune system and the brain during this sensitive period of development.
“She has done a fantastic job leading this important new line of work. The health effects of air pollution are an increasingly urgent issue, and Clara’s leadership on the psychiatric and neurodevelopmental impacts of environmental exposures is a significant contribution to public health,” Dr. Marusak said.
Inflammatory markers were measured by a blood sample, but the team used a spatiotemporal model developed at the University of Cincinnati to estimate daily PM2.5 concentrations at each participant’s residential address.
The model combines the U.S. Environmental Protection Agency’s monitoring data with weather and atmospheric information to provide high-resolution estimates of ambient pollution. The approach doesn’t account for time spent in other environments, like at school or indoors, yet they still observed significant associations using residential exposure alone, underscoring how impactful ambient pollution can be.
The study was made possible by early-career, internal funding the Department of Psychiatry and Behavioral Neurosciences.
“That kind of support is critical for launching new research directions and generating pilot data that can lead to larger, externally-funded projects. It’s also a great example of how cross-departmental collaboration at Wayne State can help move innovative, interdisciplinary science forward,” Dr. Zundel said.