As a result, it is the main naturally occurring regulator of stratospheric ozone.

However, he failed to include a role for stratospheric ozone.

But in the 1970's the chemicals were found to damage stratospheric ozone.

"We found stratospheric ozone that was coming down."

"This is stratospheric ozone being redistributed by the winds," he said.

But while the findings are encouraging, he pointed out, stratospheric ozone "will not return to normal levels for several generations."

The protection of stratospheric ozone is clearly a global task.

Studies indicate that between 1980 and 2000, stratospheric ozone decreased 3 percent globally.

Halocarbons have an indirect effect because they destroy stratospheric ozone.

Is that decrease due to too much stratospheric ozone, the calibration or local pollution?