A wonderful example of myth perpetuation occurred in Winter term 97 in an anonymous sociology class on the UO campus. At that time a student who was enrolled in 202 was also in this sociology class in which the professor insisted that the Space Shuttle was a major source of chlorine deposition in the stratosphere and that the Government is covering this up. And I don't mean the nonsense of some professors, but the general student attitude of assigning ultimate credibility to authority figures. Always ask them for data or evidence of back up what they are espousing.
Good data is the most effective manner to suppress mythology.
A hypothesis is not the same as the Truth. This is because the shuttle spends only a couple of minutes in transit through the stratosphere. The residence time of HCL deposited in this manner is about three years. A full year's US schedule of shuttle and solid rocket launches injects 725 tons of chlorine into the stratosphere. The European Space Agency's Ariane rocket makes a similar contribution, with 57 tons of HCL deposited in the stratosphere for each launch.