It appears that scientists are claiming that nitrous oxide is the biggest threat to the ozone layer.
"A study published in the Aug. 28 Science found that N2O - a by-product of agricultural fertilizer and a number of other industrial processes - is now the biggest ozone-depleting gas in the air, and could present a real threat to the ozone layer in coming decades."
The article then goes on to claim: ""Pretty soon human-caused N2O emissions will be greater than all other ozone-depleting substances combined," says John Daniel, an atmospheric scientist with the National Oceanic and Atmospheric Administration
-Source TIME Magazine
http://news.yahoo.com/s/time/20090828/hl_time/08599191913900Just wait til the tree huggers get ahold of this one!