a gas with a vapor density less than 1.0 would be tested for and found to be at all levels of a confind space.

Answer 1

Different gas has different weights and in a confined space they tend to layer out. In a room 10 by 10 ft. u release 70 cf. CO2 as long as u stand up you are safe. If u bend toward the floor the oxygen will decrease . When it drops below 19.5 u are unconscious.