A new study from the University of Southern California, involving 8,500 children from across the USA, has revealed that a form of air pollution, largely the product of agricultural emissions, is linked to poor learning and memory performance in 9 and 10 year-olds.

Ammonium nitrate Is the specific component of fine particle air pollution (PM_2.5).  It, is also implicated in Alzheimer’s and dementia risk in adults, suggesting that PM_2.5 may cause harm to brain function across the lifespan. Ammonium nitrate forms when ammonia gas and nitric acid, produced by agricultural activities and fossil fuel combustion, respectively, react in the atmosphere.

PM_2.5: A danger to the lungs

PM_2.5, a key indicator of air quality, is a mixture of dust, soot, organic compounds and metals that come in a range of particle sizes less than 2.5 micrometers in diameter. PM_2.5 can travel deep into the lungs, where these particles can pass into the bloodstream, and bypass the blood-brain barrier, causing serious health problems.

Fossil fuel combustion is one of the largest sources of PM_2.5, especially in urban areas, but sources like wildfires, agriculture, marine aerosols and chemical reactions are also important.

In 2020, an earlier study did not find a relationship between PM_2.5 as a whole, and its potential impact on cognition in children. For this study, however, they used special statistical techniques to investigate 15 chemical components in PM_2.5 and their sources. That’s when ammonium nitrate—which is usually a result of agricultural and farming operations—in the air appeared as a prime suspect.  The most robust finding was that ammonium nitrate particles were linked to poorer learning and memory.

 More information: Kirthana Sukumaran et al, 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 (2024). DOI: 10.1289/EHP14418

Journal information: Environmental Health Perspectives 

Provided by Leigh Hopper, University of Southern California 

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