1.- Carbon dioxide ( CO2)

a) Combustion of fossil fuels ( solid, gaseous liquids ) for energy purposes.

2.- Methane ( CH4)

a) Anachronistic fermentation on landfills.

b ) Aerobic treatment of wastewater.

c ) Animal poop.

3.- Nitrous oxide ( N2O )

a) Raw material in production of chemical industry.

b ) Digestion of animal poop.

4.- Hydrofluorocarbon (HFCs)

a) Production of HCFC -22.

b ) Leakage of insulating material.

5.-Perfluocarbono (PFCs )

a) Using fluid materials in cleaning process.

b)Using etching agent in production.

6.- Sulfur hexafluoride (SF6 )

a) Used as cover gas for magnesium casting process.

b) Used as an insulating gas for electricity.

c) Using etchant in production of semi conductors .