Volatile organic compounds in residential indoor environments in winter: a field investigation in Beijing

Many volatile organic compounds (VOCs) are harmful to human health. Exposure to VOCs primarily occurs indoors. Indoor VOC pollution is thus of particular importance for public health. In this study, indoor air samples in the winter were collected for 24 h in 32 urban residences in Beijing. The concentrations of 52 VOCs in indoor air were analyzed. The most abundant species in terms of geometric mean concentration were d-limonene (33.3 μg/m³), toluene (19.7 μg/m³), acetaldehyde (13.3 μg/m³), formaldehyde (13.0 μg/m³), ethyl acetate (8.0 μg/m³), α-terpene (7.5 μg/m³), benzene (7.1 μg/m³), acetone (6.9 μg/m³) and ethylbenzene (6.7 μg/m³). The monitoring results were compared to those in the summer. It was found that the concentrations of terpenes in the winter were significantly higher, whereas those of alkanes, halogenates and carbonyls were significantly lower. The species such as decanal and nonanal, which are products of O₃-initiated reactions indoors, were below detection limit in the winter. Factor analysis and General linear model (GLM) revealed that the origins of those VOCs included emissions of wooden products, emissions of wall coverings, cooking, household cleaning and disinfection products, smoking in indoor spaces as well as vehicular and industrial emissions outdoors. In addition, significantly higher concentrations of 1, 4-dichlorobenzene were found in the dwellings that were renovated more than 10 years ago. It is likely due to more popular use of flooring and furniture made of solid wood in the past.