Once I had a discussion with someone as to what
happens if the doors of room are kept closed for a long time with a person
inside it. How long would it be able to sustain his breathing? When I enquired
on that I found the following facts.
A room can be of different sizes and can contain
different quantities of Oxygen. Let us take a room of 10*10*10 (length 10 feet,
width 10 feet & height 10 feet) with an area of 1000 cubic feet or 28.31
Cubic Mtrs.
The density of air is 1.225 Kg/m 3. So a room of 1000 ft3 would have 28.31*1.225 or 34.68 Kgs of air. Now we think that air is weightless, so this weights of surprises us.
Air contains 21% Oxygen, so a room of 1000 ft3 would have 34.68*21/100 or 7.28 Kgs of Oxygen.
A person consumes about 700 gms of Oxygen in 24 hours’ time or thereabouts. So if he sleeps in a completely closed room (air conditioned) with an area of 1000 ft3 without opening the doors then the Oxygen in the room would be sufficient for 7280/700 or 10 days. But there are other factors that have to be taken into consideration.
Humans consume only 5% of Oxygen per breath and of the 21% we breathe in 16% is exhaled out as the human body does not require it. So as long as the concentration of Oxygen in the air does not drop below one fourth there would not be any discomfort for a person in a completely sealed room that is airtight.
However, there is another important factor to be considered and that is Carbon Dioxide because we give out CO2 while breathing out. Atmosphere contains .043% of CO2. 4% CO2 in the air is dangerous for humans and 10% is fatal. Each inhalation of ours gives out .04 gms of CO2. An adult inhales 0.5 ltrs of air per breath while at rest. Exhaled air consists of 4% CO2.
It has been estimated that in a closed room of
1000 cubic feet a person can remain safe for 2-3 days. So if 6 people sleep in such
a room that is air conditioned which is airtight for a night (8 hrs) they would
have no problem. Since the area of the room is so small, no way more than that
number can sleep in it. An air conditioner does not make any difference to the equation
as it only compresses the air in the room and merely circulates it and does not
bring in any fresh air. But even if the door of the room is opened once air
from outside the room flows in and extends the safe time.
