Characterization of Indoor Environmental Quality in Primary Schools in Maia: A Portuguese Case Study

Scientific evidence associates indoor environment pollutants with respiratory effects (asthma and allergies), and children constitute one of most sensitive groups. Indoor air quality (IAQ) in schools may indeed be a significant health factor for children, with effects on school attendance and performance. Our aim was to characterize IAQ of classrooms in Maia County (north of Portugal) for which there was no information available. The study was conducted in 21 of the 40 primary schools, selected by stratified random sampling. Depending on the dimension, one or two classrooms were tested at each school. Walkthrough surveys of school grounds, buildings, and individual classrooms were done. Continuous measurements were taken of temperature, relative humidity, airborne respirable particles, total volatile organic compounds, and carbon dioxide, whereas bioaerosols were counted on Plate Count Agar during regular school activities. The indoor arithmetic mean for PM₁₀, CO₂, TCOV, and bioaerosol concentrations were 0.14 mg/m³, 999 ppm, 0.41 mg/m³, and 4140 UCF/m³, respectively. The values of PM₁₀ and CO₂ were close to their acceptable maximum values, but bioaerosols were much higher. This study supports previous studies conducted in school environments and emphasizes the need for proactive indoor air quality audits in school buildings.