[Identification of air toxics from indoor and outdoor measurements of volatile organic compounds in one elementary school in Beijing].

Concentrations and characteristics of 82 volatile organic compounds (VOCs) were measured in indoor and outdoor air in one elementary school of Beijing by method TO14/15 recommended by USEPA in 2007 summer. And the toxic VOCs for children's health were identified. The study illuminates that the concentration level of total VOCs were higher in indoor air than in outdoor air. Alkanes were most abundant VOCs species accounting for 32.8% of total measured VOCs on average. The chemical speciation of VOCs in indoor air was similar to the outdoor, and the dominant species were isopentane, benzene, toluene, propanal, propene and dichloromethane. In the indoor air, m/p-dichlorobenzene and cyclohexane likely came from indoor sources, proved by the indoor/outdoor concentration ratios of p-dichlorobenzene (65.8) and cyclohexane (10.5), and the large distance between the concentrations of m-dichlorobenzene in indoor air (2.02 x 10(-9)) and outdoor (lower than the detected limit) air. 1, 3-butadiene, chloride vinyl, benzene and chloromethane, whose average cancer risk values were 1.3 x 10(-5), 6.4 x 10(-6), 5.1 x 10(-6) and 3.3 x 10(-6) respectively, exceeded the cancer risk value 1 x 10(-6) in all samples sites. The cumulative cancer risk in indoor air, outdoor air and children house were 24-39 times bigger than 1 x 10(-6). Acrolein was the only non-carcinogenic hazardous species which exceeded its benchmark concentration by 13-72 times in all sites.