Also....a PDF file (small) :
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1.3 Conclusions
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Humankind is having a considerable influence on the condition in the atmo- sphere, even in areas that are very far removed from the pollution sources.
Most surpris- ingly and unexpectedly, over Antarctica during September–October, enormous damage is done to the ozone layer due to a remarkable combination of feedbacks: radiative cool- ing, giving very low winter and springtime temperatures, and the presence of chlorine gases in the stratosphere at concentrations about six times greater than that of the nat- ural background provided by CH3 Cl. The cold temperatures promote the formation of solid or supercooled liquid polar stratospheric cloud particles consisting of a mix- ture of H2 SO4 , HNO3 , and H2 O, on whose surfaces, or within which, reactions take place that convert HCl and ClONO2 (which do not react with ozone) to highly reactive radicals Cl and ClO. The latter rapidly remove ozone from the lower stratosphere by catalytic reactions. Nobody predicted this course of events.
(9-13 November 1998)