Concentrations, particle-size distributions, and indoor/outdoor differences of polycyclic aromatic hydrocarbons (PAHs) in a middle school classroom in Xi’an, China - Hongmei Xu; Benjamin Guinot; Xinyi Niu; Junji Cao; Kin Fai Ho; Zhuohui Zhao; Steven Sai Hang Ho; Suixin Liu (Environmental Geochemistry and Health, 2015)