What are the main pollutants of indoor air?
CO2 as a good indicator of air pollution
When people stay in an enclosed space without adequate ventilation, the content of harmful substances in the air increases, as does the concentration of CO2. For this reason, measured values of carbon dioxide are mainly used to assess the level of indoor air pollution.
Carbon dioxide is therefore primarily an indicator suitable for effective management of ventilation systems in spaces where people frequently and for extended periods (schools, kindergartens, department stores, offices, living rooms, bedrooms, children’s rooms…) stay. However, the main air pollutants are so-called volatile organic compounds.
What are volatile organic compounds or VOC?
They are various types of organic compounds that are in a gaseous state at normal temperatures. It is estimated that there are around ten thousand types of volatile organic compounds.
VOC can have a negative impact on health and well-being of people.
They can simply be divided into two groups:
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- Bio-waste substances – produced during the metabolic processes of living organisms (breath, sweat, …) or, for example, during cooking, baking, etc.
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- Fumes from building materials, furniture, carpets, cleaning agents, or cosmetic products, paints, etc.
Main manifestations include:
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- reduced ability to concentrate
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- irritation of the eyes or even dizziness
These are essentially the pollutants for which ventilation is primarily needed (odors). VOC sensor is therefore most similar to the perception of odors by the human nose. In the table on the right, take a look at the main sources of VOC.
| Indoor Air |
| Source of Pollution |
Source of Emissions |
| Human |
▶ Breath |
| ▶ Skin respiration and perspiration |
| ▶ Metabolic activity (flatulence) |
| ▶ Cosmetics |
| ▶ Household products |
| ▶ Combustion (engines, appliances, tobacco smoke) |
Building materials
Furniture
Office equipment
Consumer products |
▶ Paints, adhesives, solvents, carpets |
| ▶ PVC |
| ▶ Printers, copiers, computers |
Table of main sources of VOC
What to do in a space where there is an odor, but the concentration of CO2 may be fine?
It is always necessary to choose the type of sensor according to the predominant use of the specific space. For example, in restrooms, kitchens, changing rooms, or fitness centers, the level of CO2 is often fine despite unpleasant odors, thus necessitating ventilation.
A similar situation can also occur in new buildings, where upon entering you can smell odors from paints, furniture, … this phenomenon is called SBS = Sick Building Syndrome (more about SBS here).
*CO2 = carbon dioxide, a colorless gas without odor
*VOC = English Volatile Organic Compounds – volatile organic compounds
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