Question

you are put into a room where the air pressure is very low? what effect will this have on your body?

Answer 1

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.