Large-scale CO₂ measurement campaigns in Danish schools

In two large measurement campaigns performed in 2009 and 2014 more than 1500 spot measurements of CO2 were made by pupils in Danish primary school classes. In 2009 56% of the measurements exceeded the recommended value of 1000 ppm CO2. This percentage had increased to 60% in 2014. Changing the behaviour of the pupils had a positive effect, as the proportion of classrooms exceeding 1000 ppm CO2 in separate measurement (students outside and airing in the break preceding the measurement lesson in which the measurement was made) was 39%.

The principle of ventilation had a substantial impact on the measured CO2 concentrations. In 80% of the classrooms with natural ventilation the concentration of CO2 exceeded 1000 ppm, while the fraction was 40% in classrooms with balanced mechanical ventilation.