Association between classroom ventilation mode and learning outcome in Danish schools

Associations between learning, ventilation mode, and other classroom characteristics were investigated with data from a Danish test scheme and two widespread cross-sectional studies examining air quality in Danish schools. An academic achievement indicator as a measure of the learning outcome was calculated from the scores of a standardized Danish test scheme adjusted for a socioeconomic reference index. Pupils in schools with balanced mechanical ventilation had significantly higher achievement indicators than pupils in schools with natural ventilation, where airing took place mostly by manual window opening. Also, the carbon dioxide concentration was lower in classrooms with balanced mechanical ventilation. There was no consistent association between the achievement indicators and the person specific room volume, construction/renovation year, or the occupancy. Measurements of carbon dioxide concentrations and temperatures in 820 classrooms in 389 schools were available. In 56% and 66% of the classrooms included in the two studies, the measured CO2 concentration was higher than 1000 ppm. The findings of this study add to the growing evidence that insufficient classroom ventilation have impacts on learning outcomes. •Scores from a Danish test scheme were compared in schools with mechanical and natural ventilation.•Pupils in schools with mechanical ventilation had the highest test score.•The CO2 concentration was lowest in classrooms with balanced mechanical ventilation.