Direct answer: in a classroom, CO2 levels rise quickly because many students are breathing in a relatively small space, and high CO2 levels can contribute to feeling tired or less alert. A CO2 monitor makes this visible, so that ventilation can take place at the right time. Only ventilation with fresh outdoor air actually lowers the CO2 level; other devices such as an air purifier do not.
Why CO2 levels rise quickly in a classroom
A classroom often houses twenty to thirty students in a limited number of square meters. Everyone exhales CO2, and in an enclosed space without sufficient ventilation, it accumulates quickly during a lesson hour. Over time, the CO2 level can rise far above the level that is considered comfortable for an indoor space.
What high CO2 levels do to concentration
High CO2 levels in the classroom are often experienced by students and teachers as a stuffy or drowsy feeling, and can contribute to reduced alertness towards the end of a lesson hour. This is not a direct health claim, but a signal that the air quality in the room is lacking and that ventilation is needed.
Why a CO2 monitor is so useful
Without measurement, CO2 cannot be smelled or seen, making it easy to go unnoticed until the classroom already feels clearly stuffy. A CO2 monitor gives a concrete value in ppm, so that a teacher can objectively see when it is time to open a window or door, instead of relying on a vague feeling.
Why only ventilation helps, and an air purifier does not
It is important to be honest about this: an air purifier filters fine dust, pollen, and some odors from the air, but does not remove CO2. Only letting in fresh outdoor air, through a window, door, or mechanical ventilation system, actually lowers the CO2 level. An air purifier and ventilation therefore complement each other, but do not replace each other.
Practical tips for a fresher classroom
Preferably ventilate during the break between two lessons, so that the classroom does not cool down in the middle of a lesson, and where possible, crack open a window as soon as the CO2 monitor indicates a higher value. A combination of short but frequent ventilation often works better than opening all the windows wide once a day.
Dynter mainly focuses on air purification, dehumidification, fans, and heating for the home, and does not sell CO2 monitors or ventilation systems. If you do want to improve the air quality at home or in a smaller space in terms of fine dust, odor, or moisture, check out the options on dynter.eu.