Children's exposure to indoor air in urban nurseries - Part II: Gaseous pollutants' assessment

This study, Part II of the larger study “Children's exposure to indoor air in urban nurseries”, aimed to: (i) evaluate nursery schools' indoor concentrations of several air pollutants in class and lunch rooms; and (ii) analyse them according to guidelines and references. Indoor continuous measurements were performed, and outdoor concentrations were obtained to determine indoor/outdoor ratios. The influence of outdoor air seemed to be determinant on carbon monoxide (CO), nitrogen dioxide (NO2) and ozone (O3) indoor concentrations. The peak concentrations of formaldehyde and volatile organic compounds (VOC) registered (highest concentrations of 204 and 2320 µg m−3 respectively), indicated the presence of specific indoor sources of these pollutants, namely materials emitting formaldehyde and products emitting VOC associated to cleaning and children's specific activities (like paints and glues). For formaldehyde, baseline constant concentrations along the day were also found in some of the studied rooms, which enhances the importance of detailing the study of children's short and long-term exposure to this indoor air pollutant. While CO, NO2 and O3 never exceeded the national and international reference values for IAQ and health protection, exceedances were found for formaldehyde and VOC. For this reason, a health risk assessment approach could be interesting for future research to assess children's health risks of exposure to formaldehyde and to VOC concentrations in nursery schools. Changing cleaning schedules and materials emitting formaldehyde, and more efficient ventilation while using products emitting VOC, with the correct amount and distribution of fresh air, would decrease children's exposure.