Depletion of the ozone layer has been traced mainly to the widespread use of industrial chlorofluorocarbon chemicals, but there might have been an additional culprit.

Depletion of the ozone layer has been traced mainly to the widespread use of industrial chlorofluorocarbon chemicals, but there might have been an additional culprit.

Ozone depletion began decades before discovery of ozone hole, MIT scientists have found. Using modern tools, they also determined that carbon tetrachloride, a common dry-cleaning…