Ozone & Its Effects

-------------------------------------------------
The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone (O3). The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson. It is mainly located in the lower portion of the stratosphere from approximately 30 to 40 kilometres (19 to 25 mi) above Earth, though the thickness varies seasonally and geographically. 
-------------------------------------------------
Origin of ozone
-------------------------------------------------
Ozone in the Earth's stratosphere is created by ultraviolet light striking oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O2 to create ozone, O3. The ozone molecule is also unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O2 and an atom of atomic oxygen, a continuing process called the ozone-oxygen cycle, thus creating an ozone layer in the stratosphere, the region from about 10 to 50 kilometres (33,000 to 160,000 ft) above Earth's surface. About 90% of the ozone in our atmosphere is contained in the stratosphere.
-------------------------------------------------
Ultraviolet light and ozone
Although the concentration of the ozone in the ozone layer is very small, it is vitally important to life because it absorbs biologically harmful ultraviolet (UV) radiation coming from the sun. UV radiation is divided into three categories, based on its wavelength; these are referred to as UV-A (400–315 nm), UV-B (315–280 nm), and UV-C (280–100 nm). UV-C, which would be very harmful to all living things, is entirely screened out by ozone at around 35 kilometres (115,000 ft) altitude. UV-B radiation can be harmful to the skin and is the main cause of sunburn; excessive exposure can also cause genetic damage, resulting in problems such...