atmospheric science - Pressure inside a closed room

I am sitting inside a closed room with a cement ceiling just above my head. The pressure of the atmosphere is exerted on the ceiling from above(outside). But solid cement not being a fluid does not transport that pressure into my room. But i still feel the atm pressure which has no way to be transported into the room.I do not boil to death or anything. How does this happen?

Answer

We'll assume all the rooms and other containers are airtight, and that temperature is constant, for sake of simplicity.

If you put a mass of air in a bottle and seal it, it exerts pressure on the inside of the bottle. The pressure is dependent only on the amount of air, the volume of the bottle and the temperature. Since the bottle is rigid the volume does not change, and we're assuming constant temperature, so there's really no difference between that bottle of air in space than at sea level. The pressure inside is the same.

The same goes for a closed room. The air pressure on your body doesn't change when you close the door, because the air inside the room is the same amount at the same volume and temperature as before. At this point you could use a ridiculously large crane to lift the whole room into space and you still wouldn't boil away, because you're in a sealed room and the air pressure stays the same around you as you go from the ground into space. The air pressure outside the room changes, but luckily your concrete room is inelastic, so it "holds in" the pressure.