Since the beginning of the fighting against Iran as part of Operation "Roaring Lion", many families in Israel choose to sleep at night in the safe room. The reason is clear: Proximity to a protected space provides a sense of security and makes it possible to reach it quickly in case of a siren.
But this habit has created a common mistake that many people are not aware of.
Closing the safe room door for the entire night may harm the air quality in the room, and in some cases even lead to a health risk.
The reason is not a lack of oxygen, as some people think, but the accumulation of another gas that we produce ourselves while breathing.
The real problem: Carbon dioxide
When we breathe we take in oxygen and release carbon dioxide. In an open space this gas disperses in the air, but in a sealed room it gradually accumulates.
During sleep the body continues to breathe continuously and therefore the concentration of carbon dioxide in the room gradually increases.
Studies on air quality in enclosed spaces show that the concentration of this gas can reach relatively high levels within hours, especially when several people are together in a small room.
In an average space of about 21 cubic meters, one person can raise during an entire night the concentration of carbon dioxide from about 400 particles per million to levels several times higher.
When several people sleep together in the room, the increase in the concentration of the gas occurs faster.
How it affects the body
An increase in the concentration of carbon dioxide in the air does not usually cause immediate suffocation, but it may affect the body in other ways.
Relatively high concentrations have been linked in studies to a decrease in concentration, a feeling of fatigue, headaches, and changes in blood pressure and breathing rate.
In poorly ventilated rooms such phenomena are also known in crowded offices or classrooms, a phenomenon sometimes called "Sick building syndrome".
When it comes to sleep, the problem is that we are not always aware of the change in air quality.
Why the safe room is especially problematic
The safe room was designed from the outset to be a relatively sealed room. The goal is to protect against blast, shrapnel, and sometimes also against hazardous materials. Therefore its door and window are built so that they can be sealed היטב during an emergency. But this very sealing is the reason the room is less ventilated than regular rooms in the house.
When several family members sleep together in a closed safe room for hours, the air quality may deteriorate faster than in a regular bedroom.
So how should the safe room be used at night
The recommendation of experts in the field of safety and air quality is relatively simple. If you choose to sleep in the safe room, it is better to leave the door open or partially open in order to allow air exchange.
The sealed door should be closed only during a siren or when an instruction is given to enter a protected space. This way the room remains ventilated during the night, but it can still be sealed quickly if necessary.
Another option is to operate the ventilation system in the safe room when it exists.
It is important to emphasize that staying for a short time in a closed safe room during a siren is not dangerous. The room was designed exactly for such situations and it is completely safe when staying in it for short periods of time. The problem begins when people remain there for many hours without ventilation.
Therefore the solution is not to avoid the safe room but to use it correctly. In the end the safe room is meant to protect us during an emergency. In order for it to do so in the best possible way, it is also important to follow one very simple rule: Seal it only when necessary, and not for the entire night.