Two recent reads, and one current...

"Fifteen miles above us was a feature first discovered by the British Antarctic Survey nine years before, the hole in the ozone layer, which is also the nest where man-made pollutants called chlorofluorocarbons come to roost.

Stratospheric winds carry these compounds, long used in aerosols and coolants, south, where they mix with high-altitude clouds in the cold and dark of the Antarctic winter.

As the sun returns in spring, these frozen chemical clouds react with its rays, releasing chlorine molecules that temporarily dissolve the thin layer of ozone that protects earthbound life from harmful solar radiation.

Since we were travelling directly below this hazard, it made sense to cover our skin." From Mad, Bad and Dangerous to Know, by Sir Ranulph Fiennes, who went on (among other achievements) to run 7 marathons on 7 continents in 7 days after a heart op!