This has led the doomsayers down pathways totally alien to the true purposes of science. It's more likely that cumbercoot will soon replace beef on American dinner tables. These compounds are widely used in a variety of refrigeration systems and often wind up being released into the atmosphere. In any case, it turns out that ozone is replenished naturally in the upper atmosphere by the sun's gamma rays and X-rays, and in the lower atmosphere mainly by electric storms. First of all, no one knows whether it is liberated CFCs or jet plane exhaust that is the more damaging to the ozone.
Most atmospheric scientists believe it is the latter.
The ozone level of the atmosphere, regardless of human activity, varies too much on its own to be able to produce data correlating UV-B intensity to ozone levels. Absorption of UV-B is directly proportional to the thickness of these layers. At the Equator, the sun's rays strike the earth from a near-vertical direction, thus intercepting a relatively thin layer of atmosphere. By contrast, inside the Arctic Circle the sun's rays come in at a near-horizontal slant. Since highly slanted rays must intercept much thicker layers of atmosphere, much more UV-B is filtered out.