Volatile Organic Compounds in Homes in Shanghai, China: Identification of Pollutant Sources and Impact of Air Purifier Use on Pollutant Levels

Abstract

Although Chinese residents spend the majority of their time indoors, pollutants in the indoor environment have not been studied as extensively as their outdoor counterparts. This is especially true of volatile organic compounds (VOCs), many of which are associated with adverse health outcomes and have indoor sources. For this study, 20 homes with asthmatic children were recruited from the suburbs of Shanghai, China. This study explored pollutants and the impacts of air filtration on pollutant levels. Air purifiers were installed twice, for two-week periods, in the child’s bedroom – once with all levels of filtration (pre-filter, HEPA filter, carbon filter) and again with only a coarse pre-filter. During both periods, indoor and outdoor samples were collected simultaneously on Tenax and DNPH tubes in the early morning using pump packages developed at Duke University. Of the 900+ compounds detected, 117 were detected in 10 or more samples. Total VOCs were higher indoors than outdoors in most homes under both conditions (median values [in mg m-3] - sham, in/out: 235/59; true, in/out: 119 /77). There was a significant reduction in indoor-outdoor ratios during true compared to sham filtration indicating a potential benefit of filtration (median reduction: 36%, range: -224%, 96%). Non-negative matrix factorization was used to identify groupings of compounds (features) illustrative of sources. Of the features identified, two indicate outdoor sources with certain compounds detected in most outdoor samples but seldom detected indoors. The other three features point to indoor sources. Preliminary analyses indicate compounds detected predominantly indoors may relate to cleaning or personal care products, although analysis is ongoing. This work provides new insight to potentially harmful compounds in Chinese homes, as most previous studies have focused on assessment of total VOCs or select, well-characterized VOCs including BTEX and formaldehyde.