A new study involving 8,500 children from across the United States 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. The specific pollutant, ammonium nitrate, is also implicated in Alzheimer's and dementia risk in adults, suggesting that PM2.5 may cause neurocognitive harm across the lifespan.