Ozone in Nature

Abstract

Ozone is naturally present in the atmosphere surrounding the earth. In the stratosphere between 20 and 30 Km from the earth’s surface, there is an ozone layer that may reach a maximal concentration of 10 ppmv (parts per million 1:10⁶) at about 22 Km. The ozone layer is extremely important because it absorbs most of the ultraviolet (UV) radiation (<290 nm) emitted by the sun and damaging biological systems: UV rays include band A (316–400 nm), mainly responsible for suntan, and bands B and C (from 100 up to 315 nm) which are far more mutagenic. If they reach the earth’s crust, they can enhance skin carcinogenesis during Summer; indeed, it has been estimated that a 10% drop in the level of stratospheric ozone could cause a 25% increase of skin carcinomas and melanomas.