Air, which is the material that composes the atmosphere, is a mixture of invisible gases. The atmospheric air consists of approximately 78% nitrogen and 21% oxygen. The remainder is made up of argon, carbon dioxide, several other gases, and water vapor. The combustion of fossil fuels is the greatest source of atmospheric pollution. A convenient way to develop quantitative theory on the critical oxygen levels has been dependent on the diffusion process. The average diffusion rates (ADRs) depend on the diffusion process. The diffusion of fuel combustion gases might be affected from local atmospheric pressure, gas flow pattern, process, and height from the earth surface. The ADRs of the gases depend on height and the ADRs reach maximum values at 25 m height.