Indoor and outdoor air quality assessment in daycare centres in Ghent (Belgium) in view of outdoor sleeping in an urban environment

Abstract

Within Flanders, there is an increasing trend to let children sleep outdoors while in daycare. However, within an urban environment, the densely spread emission sources might affect the air quality and possibly limit the areas where outdoor sleeping is favourable. Nevertheless, there is a lack of data regarding the atmospheric pollution levels in and around daycare centres (DCC). Therefore, the focus of this study is to chemically characterize the air quality indoors, outdoors, and in specifically designed cubicles for outdoor sleeping at 12 DCCs spread over the city of Ghent (Belgium). The measuring of a very broad range of different pollutants, provides unique data for indoor and outdoor air quality at daycare centres in Ghent. The use of axial tube (for volatile organic compounds, VOCs) and Radiello (for NO2, SO2, O3) passive samplers enables multi-component sampling, resulting in time-weighted average concentrations for one week. Forty-seven VOCs are identified and, for the majority (40), indoor to outdoor concentration (I/O) ratios higher than one are found. For the remaining seven compounds (e.g. benzene) outdoor concentrations are a factor 1.3–17.9 (median) higher than indoors. Median indoor TVOC concentrations are 152 μg/m3 and 142 μg/m3 for the September and January campaign, respectively. Outdoors, these median TVOC concentrations are much lower (24.5 μg/m3 and 30.6 μg/m3). For NO2, no noticeable differences are observed between average indoor and outdoor concentrations (indoors 12 ± 3 μg/m3 and 13 ± 2 μg/m3 for the September and January campaign, respectively, and outdoors 11 ± 3 μg/m3 and 14 ± 4 μg/m3). The highest (outdoor) measured concentration is 21 ± 1 μg/m3. SO2 concentrations are below 2.62 μg/m3 (LOQ). Average indoor O3 concentrations are 4 ± 3 μg/m3 and 2 ± 2 μg/m3 for the September and January campaign, respectively. Much higher values are measured outdoors (46 ± 3 μg/m3 and 40 ± 11 μg/m3), but the concentrations stayed well below legal standards.