Ask A Scientist© Environmental Science Archive

Author:     virginia reid
Text:       What gases are harmful to the ozone layer?

Response #: 1 of 1
Author:     Ronald Winther
Text:       Some gases that harm the ozone layer are nitric oxide, nitrogen 
dioxide, nitrous oxide, chlorofluorocarbons (CFC's), and other chlorine-
containing compounds such as chlorine monoxide (ClO), which can be produced by 
relatively nonreactive chlorine nitrate. In essence what these gases do is 
break the ozone O molecule into 03 and 02, then aid in the conversion of two 
03 atoms to 02. CFC's themselves are chemically unreactive (one property that 
made them attractive for use as propellants and refrigerants, but which also 
allows them to survive in the atmosphere for a long time), but when they get 
up in the upper atmosphere where they are exposed to ultraviolet radiation, 
the W causes the CFC molecule to lose an atom of chlorine. This atomic 
chlorine is very reactive. What is worse, when NO and Cl destroy ozone, they 
are not used up or changed in the reactions so they are free to destroy more 
ozone. (Substances that enhance chemical reactions but are not themselves 
changed are referred to as catalysts for the reactions.)