Growing up in areas with high levels of air pollution may affect more than children’s physical health – it could be impacting their ability to learn and remember.
A recent study from the University of Southern California (USC) finds that certain types of fine particulate matter, or PM2.5, appear linked to poorer cognitive performance in children, with effects extending to learning and memory.
The research, published in Environmental Health Perspectives, focused on PM2.5, particles less than 2.5 micrometers in diameter, which can easily enter the body, pass through the lungs, and circulate in the bloodstream.
Among these particles, the study identified ammonium nitrate, a byproduct of agricultural emissions, as particularly harmful to brain function in 9- and 10-year-old children.
“No matter how we examined it, on its own or with other pollutants, the most robust finding was that ammonium nitrate particles were linked to poorer learning and memory,” said senior author Megan Herting, an associate professor of population and public health sciences at the Keck School of Medicine of USC. “That suggests that overall PM2.5 is one thing, but for cognition, it’s a mixture effect of what you’re exposed to.”
The study involved data from the Adolescent Brain Cognitive Development (ABCD) Study, which tracks brain development and health in a diverse group of American youth. Using data from 8,500 children across various states, the USC research team explored the relationship between specific PM2.5 pollutants and cognitive outcomes, focusing on both individual chemicals and pollution sources.
Ammonium nitrate, produced when ammonia gas from agricultural activities and nitric acid from fossil fuel combustion react in the atmosphere, emerged as the most concerning factor. This component of PM2.5 was not only linked to impaired memory and learning in children but has also been previously associated with heightened Alzheimer’s and dementia risk in adults. The implication is that PM2.5 may pose cognitive risks throughout a person’s life.
Historically, PM2.5 has been a well-established marker for air quality and respiratory health risks. These particles, which consist of dust, soot, organic compounds, and metals, primarily originate from fossil fuel combustion. In urban areas, they come from car exhaust, industrial emissions, and, increasingly, agricultural practices.
Unlike larger particulates, PM2.5 is small enough to pass through the body’s natural defenses, reaching the bloodstream and even crossing the blood-brain barrier – a mechanism meant to protect the brain from foreign substances.
Herting’s research builds on earlier studies that largely focused on PM2.5’s physical health implications. In a 2020 study, she and her colleagues examined PM2.5 as a whole but found no consistent link with children’s cognition. However, by breaking down the components of PM2.5 in the latest study, they discovered that ammonium nitrate had an unexpectedly strong association with cognitive harm.
“Our study highlights the need for more detailed research on particulate matter sources and chemical components,” Herting stated. “It suggests that understanding these nuances is crucial for informing air quality regulations and understanding long-term neurocognitive effects.”
The findings add urgency to debates on air quality standards, especially in agricultural areas where ammonium nitrate pollution is more prevalent. While fossil fuel emissions have long been under scrutiny, agricultural sources of pollution have gained attention in recent years for their role in releasing harmful chemicals. PM2.5 particles, particularly from these sources, may impact cognitive health far earlier in life than previously recognized.
For their next project, the researchers aim to investigate how various sources of PM2.5 and their chemical makeup correlate with differences in children’s brain development patterns. By studying how pollution exposure maps onto distinct brain phenotypes, Herting and her colleagues hope to better understand which areas of the brain are most vulnerable to specific pollutants.
Journal Reference: Kirthana Sukumaran, Katherine L. Botternhorn, Joel Schwartz, Jim Gauderman, Carlos Cardenas-Iniguez, Rob McConnell, Daniel A. Hackman, Kiros Berhane, Hedyeh Ahmadi, Shermaine Abad, Rima Habre, Megan M. Herting, ‘Associations between Fine Particulate Matter Components, Their Sources, and Cognitive Outcomes in Children Ages 9–10 Years Old from the United States’, Environmental Health Perspectives 132 (10) (2024). DOI: 10.1289/EHP14418
Article Source:
Press Release/Material by University of Southern California (USC)
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