Indoor VOCs concentrations in a case-study of residential buildings

摘要

Indoor air quality (IAQ) plays an important role in the well-being of occupants and may affects their behavior and health. IAQ is strictly dependent on the occurrence of several chemicals, among which the volatile organic compounds (VOCs) represent one of the most important categories of pollutants. In the present study, 12 target VOCs (benzene, toluene, ethylbenzene, xylenes, ethylene glycolbutyl ether, 2-ethylhexanol, styrene, benzylether, α-pinene and d-limonene) were selected on the basis of their occurrence in typical indoor environments (e.g. residential buildings and offices) and their potential impact on human health and comfort. These compounds were subject to a solid adsorbent-based sampling and a fully quantitative determination by thermal desorption combined with gas chromatography and a flame ionization detector (TD-GC-FID). The TD-GC-FID method was optimized to obtain the separation of all the analytical peaks (including m- and p-xylene) and a satisfactory sensitivity, with low detection (between 0.14 and 0.31 ng) and quantification (between 0.47 and 1.02 ng) limits. The reproducibility of the whole procedure - from air sampling to thermal desorption and chromatographic quantification - was assessed with the analysis of four co-located tubes and results revealed a very low inter-tubes variability (relative standard deviations of parallel measurements <5%). The optimized protocol was subsequently used to quantify the indoor concentrations of the target VOCs in nine different homes during the dishwasher washing cycle (2-h sampling interval). The most abundant detected VOC in all dwellings was d-limonene (mean: 231 pg m-3; maximum: 611 pg m-3), whereas all the other compounds were found at concentration levels one or two orders of magnitude lower. In terms of health concern, the measured concentrations were always well below the safe levels established for the protection of the general population in living environments.