How Poor Indoor Air Quality Affects Students

Better Air, Better Learning: Why Indoor Air Quality Matters in Schools

Every school is designed with learning in mind. Classrooms are equipped with digital tools, flexible furniture, teaching materials and spaces that support both education and wellbeing.

But one of the most important factors affecting student performance is often invisible.

It is the air students breathe.

Across Europe, millions of children spend six to eight hours each day in classrooms where ventilation does not provide enough fresh air. The effects are not always obvious at first, but research increasingly links poor indoor air quality in schools to reduced concentration, higher absenteeism and lower academic performance.

As schools invest in healthier, more sustainable buildings, indoor air quality is becoming a much bigger part of the conversation. It is no longer just a technical issue for facility managers. It is now recognised as an essential part of creating classrooms where students and teachers can perform at their best.

Key Findings

A growing body of research shows that many European classrooms are not receiving enough fresh air during the school day.

81% of European classrooms exceed the recommended indoor CO₂ concentration of 1,000 ppm.

1,487 ppm is the median CO₂ level measured across more than 2,400 classrooms.

Most students spend 6–8 hours indoors every school day.

Mechanical ventilation provides the most reliable way to maintain healthy indoor air quality throughout the year.

Most European Classrooms Do Not Get Enough Fresh Air

Indoor air quality cannot be judged by sight or smell alone. A classroom may look clean and feel comfortable, but still have insufficient ventilation. To understand whether students are receiving enough fresh air, indoor air quality needs to be measured.

A comprehensive 2024 review analysed 125 scientific studies and data from 2,444 classrooms across Europe. It found that 81% of classrooms exceeded the recommended indoor CO₂ concentration of 1,000 ppm. The median concentration reached 1,487 ppm, almost 50% above the recommended level.

CO₂ at these levels is not considered harmful on its own. However, it is widely used as an indicator of how well a space is ventilated. When carbon dioxide builds up indoors, it usually means that not enough fresh outdoor air is entering the classroom.

This matters because CO₂ is not the only thing that accumulates in poorly ventilated spaces. Fine particulate matter, volatile organic compounds, allergens, biological contaminants, airborne viruses and bacteria can also build up when ventilation is inadequate.

In other words, high CO₂ levels are an early warning sign that the overall indoor environment is becoming less healthy.

How Poor Indoor Air Quality Affects Students

Students rely on concentration, memory and decision-making throughout the school day. These cognitive functions are directly influenced by the environment around them.

When classroom air quality is poor, students are more likely to feel tired, drowsy or distracted. They may experience headaches or physical discomfort. Research has also associated inadequate ventilation with slower information processing, reduced attention and increased absenteeism due to illness.

Many of these symptoms are linked to Sick Building Syndrome, where people experience headaches, eye irritation, fatigue and difficulty concentrating while spending time inside poorly ventilated buildings. These symptoms may disappear after leaving the building, but during the school day they can have a real impact on learning.

Healthy classrooms support learning. Poor indoor environments make learning more difficult.

A Europe-Wide Ventilation Challenge

Poor classroom ventilation is not limited to ageing school buildings or one specific country. Studies across Europe show a consistent pattern.

In the Netherlands, more than 80% of classrooms exceeded recommended CO₂ levels during occupied hours. In France, 41% of schools recorded at least one classroom above 1,700 ppm. In Germany, CO₂ concentrations exceeded 1,000 ppm during nearly one quarter of teaching time.

The issue is not limited to moderate exceedances. In the United Kingdom, peak classroom CO₂ levels have approached 6,000 ppm. In Lithuania, winter measurements recorded classroom CO₂ concentrations above 5,100 ppm.

Despite differences in climate, building age and national regulations, the conclusion is the same: many European classrooms do not receive enough fresh air during the school day.

Why Opening Windows Is Not Enough

Natural ventilation is still common in many schools. Opening windows can improve air quality for short periods, but it rarely provides consistent results throughout the full school day.

In winter, opening windows can quickly make classrooms cold and uncomfortable. It can also increase heating demand, creating a conflict between energy efficiency and indoor air quality. In warmer seasons, outdoor allergens, pollution and noise can enter the classroom.

Natural ventilation also depends heavily on weather conditions, wind direction, temperature differences and occupant behaviour. This makes it difficult for schools to control or measure ventilation performance reliably.
Opening windows may help, but it is not a dependable long-term strategy for maintaining healthy indoor air in classrooms.

Sweden Shows What Good Ventilation Looks Like

Sweden demonstrates that healthy classroom air is achievable.

Around 90% of Swedish buildings are equipped with mechanical ventilation systems that provide a controlled supply of fresh air throughout the year. Studies in Swedish schools consistently report lower concentrations of CO₂ and airborne pollutants than those measured in many other European countries.

Research has also linked better ventilation with fewer respiratory symptoms among students.

The Swedish example shows that good indoor air quality is not determined by climate alone. It depends on how buildings are designed, ventilated and operated.

Mechanical Ventilation Delivers Consistent Results

Mechanical ventilation provides a reliable and measurable way to maintain healthy classroom air, regardless of outdoor conditions.

Unlike natural ventilation, mechanical systems can provide a continuous supply of fresh air during occupied hours. They can deliver controlled ventilation rates across different seasons, filter incoming air and help maintain stable indoor conditions.

Demand-controlled ventilation can also improve energy efficiency by adjusting airflow according to actual classroom occupancy and air quality levels. This allows schools to protect indoor air quality without wasting unnecessary energy.
Research from Germany found that installing mechanical ventilation reduced students’ exposure to elevated CO₂ levels by more than 50%. This shows how much impact a well-designed ventilation strategy can have on the classroom environment.

Air Distribution Matters Too

Ventilation is not only about how much fresh air enters a classroom. It is also about how that air is distributed.
Poor air distribution can create draughts, uneven temperatures, excessive noise and stagnant areas where fresh air does not reach students effectively. When ventilation systems create discomfort, airflow is often reduced or systems are switched off. This compromises indoor air quality.

That is why air distribution should be considered alongside ventilation capacity.

Fabric-based air distribution systems are increasingly used in educational buildings because they deliver fresh air evenly at low velocity. This helps create a quiet, draught-free learning environment while supporting effective ventilation performance.

Their lightweight construction also makes them suitable for both new school buildings and renovation projects.

Better Air Is Becoming Part of Better School Design

Across Europe, school design is placing more emphasis on occupant health as well as energy efficiency.

More attention is now being given to continuous indoor air quality monitoring, healthy building certifications, smart building technologies, deep renovation programmes and stronger indoor air quality standards for schools.

This shift reflects a broader understanding of what a good learning environment should provide. A school building should not only be energy efficient and functional. It should also support the health, comfort and performance of the people inside it.

Indoor air quality is becoming an essential part of that goal.

Better Air Supports Better Learning

Schools cannot control every factor that influences educational outcomes. They can, however, control the environment where learning takes place.

The evidence is clear. Healthier indoor air supports healthier students, better concentration and more productive classrooms.

Improving school indoor air quality is about more than meeting ventilation standards. It is about creating learning environments where students and teachers can perform at their best every day.

The air students breathe may be invisible. Its impact on learning is not.

Download the Full White Paper

Want to explore the research, data and practical recommendations in more detail?

Download the full white paper here: The Air Students Breathe | FabricAir