Thanks for the links, Dom, but they seem to disprove the statement that the harm done by the shuttle is significant.
From the first link:
"...studies have shown that the amount of chlorine produced by the Space Shuttle and other rockets using similar solid propellants is actually quite small and has a miniscule effect on the ozone layer."
and,
" In an average year, industry generates an estimated 300 million kilograms of stratospheric chlorine while natural sources like volcanoes produce about 75 million kilograms. Assuming nine Space Shuttle launches and six launches of Titan rockets per year results in a total of 725,000 kilograms of chlorine released into the upper atmosphere. The actual launch rate of the Shuttle has only been this high once, in 1985, and is generally much lower with an historic average of less than five launches per year. "
From the NASA link:
"The report concludes that Space Shuttle launches at the current rate pose no significant threat to the ozone layer and will have no lasting effect on the atmosphere. The exhaust plume from the Shuttle represents a trivial fraction of the atmosphere, and even if ozone destruction occurred within the initial plume, its global impact would be inconsequential."
If the information from the first link is correct (it probably is, since there are similar numbers on the NASA site), then ALL of the shuttle/Titan launches during the busiest year in history (1985) amounted to less than one average DAY of industry output. This seems reasonable, because in spite of what Walt Disney says, it's a really big world afterall.