Gaseous pollutants on rural and urban nursery schools in Northern Portugal

Indoor air quality in nursery schools is different from other schools and this has been largely ignored, particularly in rural areas. Urban and rural nursery schools have different environmental characteristics whose knowledge needs improvement. Thus, this study aimed to evaluate continuously the concentrations of CO2, CO, NO2, O3, CH2O and total VOC in three rural nursery schools and one urban, being the only one comparing urban and rural nurseries with continuous measurements, thus considering occupation and non-occupation periods. Regarding CO2, urban nursery recorded higher concentrations (739–2328 mg m−3) than rural nurseries (653–1078 mg m−3). The influence of outdoor air was the main source of CO, NO2 and O3 indoor concentrations. CO and NO2 concentrations were higher in the urban nursery and O3 concentrations were higher in rural ones. CH2O and TVOC concentrations seemed to be related to internal sources, such as furniture and flooring finishing and cleaning products. •This is the only study comparing gaseous pollutants continuously measured in urban and rural nurseries.•Children's risk of exposure occurs mainly in the urban nursery school.•Outdoor air was the main determinant of CO, NO2 and O3 indoor concentrations.•There is a need to implement measures to reduce critical situations regarding IAQ. Gaseous pollutant levels were higher in the urban nursery than in rural ones, except for O3. High concentrations were due to lack of ventilation, outdoor air and internal sources.