UCL Institute for Environmental Design and Engineering


Indoor air quality in London schools. Part 1: ‘performance in use’


1 January 2015


This study aims to assess the adequacy of current guidelines, framed around thermal comfort, estimated ventilation rates, and CO2 levels, for the provision of indoor air quality (IAQ) in school classrooms. It draws on detailed monitoring data from a sample of 18 classrooms from 6 London schools. Overheating during the non-heating season was identified in eight south-, south-east-, and east-facing classrooms in two Victorian and two contemporary schools. Four classrooms in these contemporary schools also failed to keep average indoor CO2 levels below 1500 ppm in the non-heating season. During the heating season, eight classrooms exceeded the daily average indoor CO2 levels. Mean indoor particulate matter (PM)10 and PM2.5 levels recorded in all classrooms in both seasons were higher than 20 and 10 μg/m3, respectively, indicating that school exposure during an academic year may exceed annual recommended WHO [2006. Air Quality Guidelines: Global Update 2005: Particulate Matter, Ozone, Nitrogen Dioxide, and Sulfur Dioxide. Copenhagen: WHO Regional Office for Europe; 2010. WHO Guidelines for Indoor Air Quality: Selected Pollutants. Copenhagen: WHO Regional Office for Europe.] guideline values in all classrooms. In both seasons, all classrooms were found to have indoor total volatile organic compounds levels (median: 269 ppb and interquartile range: 64–408 ppb) above guideline thresholds (130 ppb) associated with sensory irritations. Identification of specific volatile organic compounds indicated the presence of strong indoor sources including furniture, cleaning products, and teaching materials. Findings suggest that these school classrooms often have poor IAQ due to a combination of sub-optimal building operation and management practices. Furthermore, while CO2 and ventilation rates are a useful tool for IAQ assessment, findings indicate that consideration of specific pollutants is necessary to ensure a healthy indoor environment.

Indoor air quality in London schools. Part 1: ‘performance in use’. Intelligent Buildings International, 7 (2-3), 101-129. 

Chatzidiakou, E., Mumovic, D., Summerfield, A.J., Altamirano, H.M. (2015).