Our human body constantly needs oxygen (O2) to maintain vital bodily functions. The external respiration transports the O2 to the lungs, where it is then transported via the internal respiration with the blood circulation to the cells. Here the gas is “burned” and energy is gained for the vital body functions. Without oxygen supply, this cycle comes to a standstill and unconsciousness and brain death occurs within a few minutes.
In many conversations I am therefore asked how long the oxygen in a panic room lasts if the family has to withdraw into it. To answer this question, we will look at what our safe rooms are designed for and how human air consumption is affected.
A panic room serves to avoid an immediate danger for a limited period of time. In practice, this period is a maximum of 30 minutes, since intervention by the police or security services is to be expected within this period.
Our oxygen consumption naturally depends on many factors. Nevertheless, we consider the idealized case of an adult without much effort. Here we know that on average 8.5 litres of air are inhaled per minute. Of these 8.5 litres, however, we only use about 5 % oxygen for the above-mentioned functions. So we have a consumption of 0.426 l/(min x person).
The volume of air in a 1.5 m x 3 m floor space and a height of 2.4 m room, is 10.8 m³. With 21 % oxygen in the air, this results in 2.268 m³ or 2268 litres of oxygen within the room. If there are four people in the panic room, our total consumption is 1.704 l/min. [persons x 0.426 l/(min x person)].
Mathematically, the 2268 litres of oxygen are sufficient for 1331 minutes. That’s over 22 hours. With the consumption of oxygen, however, the proportion of carbon dioxide (CO2) also increases as a result of exhalation. If the concentration is too high, this impedes oxygen uptake and leads to headaches and unconsciousness. With the room size mentioned, this occurs after about 8 hours. If you are staying in a room without fresh air for a longer period, it is recommended to breathe in an upright position, as the CO2 is heavier than air and accumulates on the floor.
For the designed purpose of offering a retreat possibility for 30 minutes, no fresh air supply is necessary. Even after 4 hours you will be able to leave the safe room physically undamaged.