Environmental justice concerns have prompted renewed scrutiny of pollution exposure disparities. This ecological study utilized satellite data and ground-based monitors to map PM2.5 levels in 42 neighborhoods of Nairobi, Kenya. Findings showed that low-income areas had mean annual PM2.5 concentrations 1.8 times higher than affluent districts (p < 0.001). Residents in high-exposure zones reported increased respiratory symptoms and absenteeism. Policy implications include integrating air quality monitoring with community health programs and urban planning. Reducing exposure inequality requires intersectoral collaboration between public health authorities and environmental agencies.