Impacts of contemporaneous air pollution exposure on cognitive performance in Kenya.

We estimate the short-term cognitive effects of fine particulate matter (PM2.5) exposure using novel exposure data collected during cognitive testing in Kenya. Unlike most existing studies that rely on satellite-based or fixed monitoring station data, we measure highly localized ambient pollution using portable monitors deployed at cognitive testing sites and link these readings directly to Harmonized Cognitive Assessment Protocol (HCAP) scores. Higher PM2.5 exposure during testing is associated with lower cognitive performance, particularly in executive function, memory, and visuospatial tasks. Binned exposure models suggest a monotonic pattern, with more negative estimates at higher exposure levels. Notably, effects are significantly larger among more educated individuals, possibly due to greater task demands or lower chronic exposure that limits physiological adaptation. Given that cognitive impairment is evident even at PM2.5 levels below Kenya's mean annual regulatory threshold of 35μg/m3, the findings suggest that short-term exposure may impose underappreciated human capital costs that current regulatory standards fail to mitigate. The results highlight the potential cognitive and economic returns to interventions that reduce air pollution exposures in low-resource settings.