Seasonal variation of airborne phthalates in classroom and dormitory, and its exposure assessment in college students

•This study reports the seasonal variation of airborne phthalates and its exposure assessment in college students.•DMEP and DnBP are the most abundant phthalates in the dormitory and classroom.•Airborne phthalates were relatively higher in the male dormitory in winter.•Airborne phthalates seasonally varied and were evident in winter.•Daily intake in dormitories and classrooms is the highest in winter. Phthalates are widely used as plasticizers in various products. However, only few studies have focused on its pollution in university dormitories and classrooms. In this study, we measured the airborne concentrations of phthalates in the dormitories and classrooms of a university in Beijing, China. We analyzed the pollution characteristics and possible sources of phthalates, used Monte Carlo simulation to estimate phthalate intake via inhalation and dermal absorption through direct air-through-skin pathways, and explored the seasonal variations in airborne phthalate concentrations and exposure levels. Di (2-methoxyethyl) phthalate and di-n-butyl phthalate were predominantly observed in the classroom and dormitory. Three possible phthalate sources existed in the classroom and dormitory. The airborne concentrations of high-molecular-weight phthalates were significantly higher in winter than those during spring and autumn. The room’s orientation weakly affected the indoor airborne phthalate concentrations. More surface sinks in female dormitories significantly affected the concentration of airborne phthalates, which is worthy of a comprehensive study. Low-molecular-weight phthalates in the dormitory significantly differed between urban and suburban areas. The influences of orientation, dormitory type, and geographic location on indoor phthalate concentrations are related to the seasons. The total daily intake of phthalates in dormitories was greater than that in classrooms. The daily intake of phthalates via dermal absorption was greater than that via inhalation, and was the highest during winter.