2024 No Children exposure to indoor ultrafine particles in urban and rural school environments https://doi.org/10.1007/s11356-016-6555-y Rufo, João Cavaleiro Europe Exposure Observational Students Elementary (K-5) Particulate Matter (PM) Other Ultrafine particles Primary schools Indoor air Children exposure Traffic-related UFP Rural environment Ultrafine particles (UFPs) were measured in 8 Portuguese primary schools. Urban classrooms had nearly double the UFP counts of rural ones. Source factors included traffic proximity and materials. Results support building design to reduce UFP exposure in children. 2016