This video gives a brief overview of Earth's ozone layer. Satellite measurements provide consistent, daily, global maps of column-integrated ozone around the world, most of which is found in the stratosphere.
The ozone layer is a layer in Earth's atmosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains relatively high concentrations of ozone, although it is still very small with regard to ordinary oxygen. Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in small amounts in the upper atmosphere, between about 10 and 50 kilometers altitude. The ozone layer in the stratosphere absorbs the most harmful UV rays from the sun before they reach Earth's surface.
For living creatures on Earth, there is good ozone and bad ozone. About 90% of ozone is found in the stratosphere, where it absorbs and scatters incoming harmful UV radiation from the sun, particularly the most dangerous UV-B and UV-C forms. This is ozone protects life on Earth from the sun's UV radiation.
About 10% of ozone in the atmosphere is found in the troposphere, the layer we live in, created by chemical reactions between air pollutants from vehicle exhaust, gasoline vapors (VOC), and other emissions. At high concentrations, ground-level ozone is toxic to people and plants and is one of the six pollutants that the EPA monitors and regulates. Good up high; bad nearby.
The ozone hole is a thinning of stratospheric ozone over Antarctica, defined as total ozone below 220 Dobson units. The hole has been proven to be a result of ozone depleting chemicals manufactured by humans and not observed before 1979.