CO2 in closed rooms: Harmful?
What is CO2 actually?
CO2 (carbon dioxide) is an odourless invisible gas. It is a natural component of our breathing air and important for control processes in our bodies. It cannot therefore be considered poisonous per se. But as is usually the case, concentration also plays a major role here.
Our breathing air
The normal breathing air consists of 78.8% nitrogen and 20.9% oxygen. The rest is divided between noble gases and carbon dioxide. However, its concentration is only 0.04 vol% or 400 ppm. The oxygen from the air is needed in the body for the combustion of food components and thus for energy generation. This process produces CO2, which is transported via the blood to the alveoli. This is where the gas exchange takes place. Oxygen enters the blood and is distributed to the body cells. CO2 passes into the lungs and is exhaled. The gases always move in the direction of the lower concentration. In this way, a certain balance between oxygen and carbon dioxide in the body is maintained.
If the CO2 concentration in the breathing air is higher than normal, the CO2 cannot pass from the blood into the lungs in the necessary quantity and thus the blood cannot absorb enough oxygen. The problem is therefore not a lack of oxygen, but an excess of carbon dioxide in the breathing air.
The air in closed rooms
The human body continuously “produces” CO2 and releases it into the ambient air. As a result, its concentration in the room inevitably increases over time. This is all the more true when several people stay in the room for a longer period of time. Added to this are the natural vapours from the human body, clothing and even furniture, floor coverings and building materials. The air gets worse and worse over time and the gas exchange in the lungs described above is hindered. This has several negative effects on human health and well-being. Roughly speaking, increasing CO2 concentrations result in the following physical symptoms:
- 1 to 1.5 % … low impact, but growing lack of concentration
- 3 % … fatigue, deep breathing, headache, high blood pressure and pulse, loss of hearing
- 4 to 5 % … deeper and faster breathing, clear symptoms of poisoning
- 5 to 10 % … laborious breathing, headache and loss of judgment
- over 10 % … unconsciousness within 1 min., acute danger to life
Of course, even in the presence of many people in a room, no values of CO2 concentration are reached that pose an acute danger to life. However, values of 2% and above have a very strong impact on well-being and ability to work. However, the symptoms disappear quite quickly when you leave the affected room. But what if you are repeatedly exposed to such conditions in the long term?
Long-term effects of bad indoor air
People who spend hours and hours in rooms with poor air quality and excessive CO2 concentrations as a result of their activities will of course also show the above symptoms again and again during this time. However, this also means that they cannot call up their true performance during this time. This often applies to pupils, students and teachers, for example. But such phenomena can also be found in open-plan offices and meeting rooms.
If bad air becomes a permanent burden for several hours a day, these complaints can become chronic. Headache, for example, does not disappear after leaving the room. The constant indisposition can also lead to really permanent tiredness during the day and to sleep disturbances during the night. The people affected feel a constant feeling of illness over time, as the metabolism no longer functions properly due to the excess CO2 in the body and waste products can no longer be excreted to a sufficient extent. Often an increased sensitivity to allergens develops.
The problem of bad indoor air has only come to light in recent decades. The reason for this is that building envelopes are becoming increasingly airtight due to legal regulations on energy efficiency. The air exchange between the interior and the environment outside the buildings, which used to take place completely on its own, practically no longer exists. In principle, regular and thorough ventilation of the affected rooms would be sufficient to reduce the CO2 concentration to normal levels and remove other air pollutants. But this is not always possible, because e.g. street noise would disturb the lessons or meetings. A ventilation regime would have to be introduced and enforced which would shift ventilation to off-peak times and breaks. However, this is often not the case because those responsible do not (want to) see the problem.
An elegant option is the installation of a ventilation system that meets your requirements. Felderer offers a variety of energy-efficient solutions for this purpose.