Concentration of a pollution in a limited space as a room depends on the amount of polluted material spread in the room, supply of fresh air, outlets positions and construction, principles used for supply and outlet from the space

*****!!!!****!!!!*** {Provides excellent definitions of ppm in air vs. liquid, etc} [Helpful note: Molecular weight of Chlorine Dioxide is 67.45] The unit of gas concentration is converted into another unit.

When measuring gases like carbon dioxide, oxygen, or methane, the term concentration is used to describe the amount of gas by volume in the air. The 2 most common units of measurement are parts-per