777. What happens to gas in a gas mask? — TF, Auburn, WA
Most gas masks remove toxic molecules from the air by allowing those molecules to react with or stick to a surface inside the mask. Molecules are generally too small to remove from the air with simple filters, so they must be removed by chemical processes. Highly reactive molecules, such as chlorine, fluorine, and ozone, naturally attack and bind with many chemicals and are easily removed by a mask containing those chemicals. Other molecules aren't so reactive and must be collected in a more complicated manner. Sometimes the gas mask will contain a reactive chemical that seeks out specific toxic molecules in the air and binds chemically to those molecules. But some mask simply use activated carbon, which just sticks molecules to its surface. The molecules don't stick very tightly to the carbon surface, so they can be driven off by baking the carbon. But the carbon is finely divided so that it has an enormous amount of surface area and can accumulate a great many molecules before it becomes "full." Finally, some gas masks contain catalysts that decompose certain toxic molecules, chopping them up before they enter your lungs.