There is an increasing research interest in indoor air quality at schools as children who are among the most sensitive to air pollution spend a lot of time indoors. This study aims to estimate BTEX levels, sources, and assess their health risk at ten preschools in Hanoi, Vietnam. Two sampling campaigns were conducted in November and December, 2017, and May and June, 2018, with a total of 80 samples collected. BTEX were sampled by mini air samplers, and the analysis was performed by using GC/MS. During class, indoor concentrations of benzene, toluene, ethylbenzene, and xylene were within the range of 1.22–6.01, 1.6–63.4, 0.94–6.34, and 0.86–3.52 μg m⁻³, while corresponding values obtained in the absence of children were 1.62–6.90, 1.20–125.3, 0.58–25.1, and 0.60–6.65 μg m⁻³, respectively. Indoor/outdoor ratios of BTEX varied from school to school, and ranged from 0.4 to 14.2, implying the presence of indoor emission sources. Insignificant indoor sources of benzene were found in all examined schools, whereas there were sources of toluene, ethylbenzene, and xylenes, probably associated with paint’s solvents, glues, and cleaning agents. Outdoor BTEX originated from the common sources, being mainly composed of automobile traffic. There was insignificant cancer and non-carcinogenic risk to children at the monitored preschools, with LCR values within the range of 0.059–6.6 × 10⁻⁵, and HQ values below 0.31. Monte Carlo simulation revealed that indoor and outdoor concentrations of BTEX influenced the most the results on lifetime cancer risk for indoors and outdoors, with a typical contribution of more than 90% to LCR variance.

中文翻译：

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越南河内托儿所室内/室外BTEX的季节变化，来源和健康风险评估

随着对空气污染最敏感的孩子们在室内花费大量时间，学校对室内空气质量的研究兴趣越来越高。这项研究旨在评估越南河内十所幼儿园的BTEX水平，来源并评估其健康风险。在2017年11月和12月以及2018年5月和6月进行了两次采样活动，共收集了80个样本。用小型空气采样器对BTEX进行采样，并使用GC / MS进行分析。在上课期间，室内苯，甲苯，乙苯和二甲苯的浓度在1.22-6.01、1.6-63.4、0.94-6.34和0.86-3.52μgm ^{-3的范围内}，而在没有儿童的情况下获得的相应值为1.62–6.90、1.20–125.3、0.58–25.1和0.60–6.65μgm ^-3， 分别。BTEX的室内/室外比因学校而异，范围从0.4到14.2，这表明存在室内排放源。在所有接受检查的学校中，室内微量苯的来源均很少，而甲苯，乙苯和二甲苯的来源可能与涂料的溶剂，胶水和清洁剂有关。户外BTEX起源于常见的来源，主要由汽车交通组成。在受监测的学龄前儿童中，儿童的癌症和非致癌风险微不足道，LCR值在0.059–6.6×10 ^-5的范围内，且总部值低于0.31。蒙特卡洛模拟显示，室内和室外BTEX浓度对室内和室外终生癌症风险的影响最大，对LCR方差的典型贡献超过90％。