As the temperature of a gas is increased, the volume of a gas increases and conversely, as the temperature of a gas is decreased, the volume of that gas decreases. One can see this law take effect in the need to pressurize the tires of your car more often in the winter months. Charles' Law describes this relationship. Although this law does not greatly influence the health of a diver or aviator, it becomes a very important factor if rapid pressurization or depressurization is encountered. A diver, equipped with a cylinder of compressed gas, must keep in mind that the gas cylinder will decrease or increase in pressure with cooling or heating of that cylinder during extremes in diving temperatures.
Air is made up of a mixture of gases including oxygen, nitrogen, helium, and others.
Each individual gas contributes its pressure to the overall pressure of the gaseous mixture in accordance to Dalton's Law . Furthermore, each of these individual gases dissolves in a particular liquid, such as our blood, at different rates that are particular to that gas. At increased ambient pressure, these gases dissolve at a faster rate, but the relative rate compared to the other gases remains the same. As the ambient pressure is decreased, these dissolved gases come out of solution in the liquid at the same relative rate that it went into solution. Therefore, some gases will come out of solution faster than others.