Did you know that the air quality in a classroom affects how well children are able to concentrate and learn? Many studies show that carbon dioxide (CO₂) concentration in particular is an important indicator of indoor air quality – not only for health, but for learning too.
Why does CO₂ matter?
Children spend a large part of the day at school and are more sensitive to poor indoor air than adults. A high CO₂ concentration is a sign of poor ventilation and has been linked to, among other things:
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Increased absences
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Poorer concentration and disruptive behaviour
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Lower learning outcomes
For example, a Scottish study found that an increase of just 100 ppm (parts per million) in CO₂ levels increased pupil absences by 0.2% a year. On average, this amounts to half a school day more absence per year.
CO₂ and school performance
A longitudinal study in California found that better ventilation (i.e. lower CO₂) was associated with higher scores in English tests. When ventilation was improved by 10%, test scores rose by an average of 0.6 points. Maths results followed the same trend.
Studies in Finland and Estonia have also found that concentration becomes more difficult once CO₂ levels exceed 1,000 ppm. In a Latvian study, pupils' test performance declined when the indoor air was classified as "poor".
What are schools doing?
In many countries, including Finland, it is recommended that the CO₂ concentration in classrooms be kept below 1,000 ppm. This is not a matter of opinion, but is based on research and official recommendations. For example, according to the UK's BB101 guidance on air quality in schools (2018), in mechanically ventilated teaching spaces the daily average CO₂ concentration during occupied hours should be below 1,000 ppm, and the concentration should not exceed 1,500 ppm for more than 20 consecutive minutes a day. With natural ventilation, the corresponding limits are 1,500 ppm (daily average) and 2,000 ppm.
During exams or in full classrooms, however, CO₂ can quickly rise above 2,000 ppm if rooms are not properly aired.
What can be done in practice?
Fortunately, the solutions are often simple and inexpensive:
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Airing during lessons and breaks: Opening the windows regularly helps quickly. Refreshing the air is especially important after exams.
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CO₂ measurement in classrooms: Measurements tell the teacher straight away when it is time to air the room.
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Mechanical ventilation: School buildings should make sure that mechanical ventilation works on every floor.
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Guidelines and monitoring: The school could adopt a CO₂ limit as an internal indicator (KPI) that is monitored regularly, for example by moving a measuring device from classroom to classroom each week, and so ensure that all classrooms are adequately ventilated.
Finally
Good indoor air won't turn anyone into a super-learner, but it can reduce absences, improve alertness and help with concentration – and in turn improve learning outcomes. Even small steps can make school days easier and learning more effective.
Good ventilation is also a good investment in the future.
Indoor CO₂ is an important parameter to monitor in all kinds of buildings. In addition to sensory observations and user experiences, it is worth keeping track of it by measuring.