Ozone as concentrations in μg/m. The study of ozone concentration in the atmosphere started in the 1920s. The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 km and 50 km above the surface (or between about 6 and 31 miles). However, even in this "layer", the ozone concentrations are only two to eight parts per million, so most of the oxygen there is dioxygen, O, at about 210,000 parts per million by volume. Ozone in the stratosphere is mostly produced from short-wave ultraviolet rays between 240
Ozone depletion warming as a subset of the "ozone hole". In the beginning, classical green NGOs refrained from using CFC depletion for campaigning, as they assumed the topic was too complicated. They became active much later, e.g. in Greenpeace's support for a CFC-free fridge produced by the former East German company VEB dkk Scharfenstein. The metaphors used in the CFC discussion (ozone shield, ozone hole) are not "exact" in the scientific sense. The "ozone hole" is more of a "depression", less "a hole in the windshield". The ozone does not disappear through the layer, nor is there a uniform "thinning" of the