Chemical Compositions and Sources of Indoor Airborne PM2.5 at a Middle School in China

Abstract

To investigate the indoor air quality on middle school campus in China, PM2.5 samples in a classroom and a laboratory during summer and winter at a y middle school in a coastal city of China were collected and analyzed for their chemical composition and sources. Our results showed that the average winter and summer PM2.5 concentrations in the classroom and the laboratory ranged from 11-24 μg/m³ during the observation periods, which is slightly higher than the WHO recommended value of 10 μg/m³, suggesting a necessary for improving campus indoor air quality. Due to increased window ventilation, a greater outdoor air intrusion in summer led to PM2.5 concentrations in both classroom and laboratory higher in summer than in winter. Moreover, we found that the proportions of Ca²⁺ and Na⁺ in classroom and laboratory PM2.5 were higher than outdoors due to an enhanced indoor dust resuspension. Moreover, the campus indoor PM2.5 contained high levels of phthalate plasticizers, which are several times outdoors, indicating a plasticizer pollution in indoor campus air, which mainly originate from the volatilization of plastic flooring and wall coatings. Since these substances are reproductively toxic and teenagers are vulnerable, reducing the use of such plasticizers is necessary for improving indoor air quality.