Updated on 26-09-2025
When we consider the factors that influence our children’s education, we place importance on the quality of teachers, teaching methods and teaching materials.
However, a critical and often overlooked factor is the air they breathe every day in the classroom: indoor air quality (IAQ).
A poorly ventilated classroom is not only an uncomfortable environment, but also a direct obstacle to learning, health, and concentration. This is why understanding why ventilation is important in schools and nurseries should be a priority for educational institutions.
Why is it important to ventilate classrooms properly? Effects of air quality on pupils’ health
Both school-age and pre-school children spend much of their time indoors at school.
This means that if the indoor air quality is poor due to the presence of pollutants—mainly due to a lack of ventilation or incorrect ventilation—children will be exposed to polluted environments for long periods of time.
In a closed environment with 25 people, pollutant levels can skyrocket in less than an hour, causing significant effects on pupils’ health, such as fatigue, drowsiness, headaches, eye and throat irritation, etc., which can affect both their general well-being and academic performance.
Conditions such as asthma, bronchitis and respiratory allergies can also be exacerbated, directly contributing to increased school absenteeism.
That is why it is essential to ensure that the air they breathe is clean and safe.
Why does indoor air pollution affect young children more?
In the case of preschool-aged children, controlling the air they breathe is even more important.
The respiratory and immune systems in young children are still developing, with narrower airways and smaller lungs compared to adults, and defences that are less capable of fighting disease and allergies.
These characteristics facilitate the penetration of harmful particles into the lungs, causing lung damage and breathing difficulties.
In addition, children’s metabolic rate is higher than that of adults, which means that they inhale more air and therefore receive a greater amount of pollutants in relation to their body size.
Main air pollutants in educational centres
Some of the key parameters that can worsen indoor air quality in nurseries and schools are:
- Carbon dioxide (CO2): high levels of this gas can indicate poor ventilation and, consequently, the accumulation of other pollutants.
- Particulate matter (PM10 and PM 2.5): fine suspended particles can enter the respiratory system and even reach the alveolar level, causing serious health problems.
- Volatile organic compounds (VOCs): emissions of chemicals with a high degree of volatility at room temperature from building materials, furniture, cleaning products, etc. can cause respiratory and skin problems.
- Biological pollutants: indoor environments in schools and nurseries are a constant source of viruses and bacteria, as poor air quality caused by a lack of ventilation and the underdeveloped immune systems of children encourage them to spread in an almost continuous cycle.
These pollutant parameters are also influenced by temperature and relative humidity: temperature, for example, increases the volatilisation of VOCs and promotes the proliferation of allergens and bacteria in indoor air, as does relative humidity; all of which leads to a deterioration in air quality.
How does ventilation affect academic performance?
The relationship between CO2 concentration and cognitive function is not an assumption; it has been scientifically proven. When CO2 levels in a classroom exceed 1,000 parts per million (ppm), a threshold that is alarmingly easy to exceed, students’ ability to concentrate, process information and solve problems is drastically reduced.
A global benchmark study was conducted by Joseph G Allen et al for the Harvard T.H. Chan School of Public Health. Their research on the impact of air quality on cognitive function revealed that in tasks measuring crisis response and strategy, participants in well-ventilated environments scored 131% and 288% higher, respectively, than those in environments with high levels of CO2 and volatile organic compounds (VOCs).
But this is not an isolated document. Researchers at the Lawrence Berkeley National Laboratory reached the following conclusions regarding indoor air pollution and performance:
- A 20% increase in the risk of subjective mental deterioration for every 10 µg/m³ increase in total VOCs.
- For every 100 µg/m³ increase in PM10 particles, there is a 40% increase in school absenteeism.
- High CO2 (>1000 ppm) is significantly related to slower reaction times in cognitive tests.
- Temperatures above 25.4°C are associated with a 15% reduction in task performance.
- Each 1°C increase within the comfort range (22.2-25.6°C) is associated with:
- +7.9% mental confusion
- +7.7% fatigue
- -4.1% productivity
Air pollution also increases the risk of infectious diseases such as colds and flu due to exposure to airborne pathogens, leading to school absences that affect continuity of learning.
If the indoor environment also has unpleasant odours and a lack of freshness, this creates a feeling of discomfort that can distract students and make it difficult for them to concentrate.
How can we improve air quality in classrooms? The importance of monitoring
It is therefore clear that indoor air quality in schools is crucial to the well-being and health of both students and teaching staff.
To improve air quality in classrooms, it is important to have effective ventilation and air conditioning strategies in place, as stipulated in the Regulation on Thermal Installations in Buildings (RITE), which includes classrooms in schools and nurseries.
In this other article, we explain in more detail when to ventilate classrooms in schools and nurseries.
So, how can we know if ventilation and air conditioning are effective in improving indoor air quality?
The importance of this issue is such that even the United States Environmental Protection Agency (EPA) has created a guide to managing indoor air quality in schools, which includes:
- Control of airborne pollutants.
- Introduction and distribution of adequate outdoor air.
- Maintaining an acceptable temperature and reasonable humidity.
Acting without data is like navigating in fog, so it is clear that the only way to improve air quality is to identify and control pollutant parameters by using devices to measure IAQ.
The use of indoor air quality meters such as Nanoenvi IAQ facilitates the detection of atmospheric pollutants and the implementation of effective ventilation strategies to provide clean, oxygenated air in educational centres.
