The ozone hole is a loss of stratospheric ozone over Antarctica. The ozone hole area is defined as the size of the region with total ozone below 220 Dobson units (DU). Dobson Units are a unit of measurement that refer to the thickness of the ozone layer in a vertical column from the surface to the top of the atmosphere, a quantity called the "total column ozone amount." Prior to 1979, total column ozone values over Antarctica never fell below 220 DU. The hole has been proven to be a result of human activities--the release of huge quantities of chlorofluorocarbons (CFCs) and other ozone depleting substances into the atmosphere.
For living creatures on Earth, there is good ozone and bad ozone. Good ozone is found in the stratosphere, far above the Earth's surface. At that height, it absorbs and scatters ultraviolet (UV) radiation from the Sun, particularly the most dangerous UV-B and UV-C forms. Ozone is the planet's natural sunscreen. Plants, animals, and all forms of life developed under a sky that shielded them from damaging and mutating radiation.
Whether the molecule is helpful or harmful has nothing to do with the chemical makeup and everything to do with location. About 10% of the ozone in the atmosphere is found in the troposphere, the layer we live in. This ozone is created by chemical reactions between air pollutants from vehicle exhaust, gasoline vapors, and other emissions. At ground level, high concentrations of ozone are toxic to people and plants.
NASA Ozone Study May Benefit Air Standards, Climate
01.16.13 - A new NASA-led study finds that when it comes to combating global warming caused by emissions of ozone-forming chemicals, location matters.
Sharp Decline in Pollution from U.S. Coal Power Plants
12.01.11 - A team of scientists have used the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite to confirm major reductions in the levels of a key air pollutant generated by coal power plants in the eastern United States. The pollutant, sulfur dioxide, contributes to the formation of acid rain and can cause serious health problems.
Long Cold Spell Leads to Arctic Ozone Hole
10.06.11 - In March 2011, the Earth Observatory published images of a rare, deep depletion in the ozone layer over the Arctic. The images came from daily observations made by Aura's OMI instrument.
Study of Unprecedented Arctic Ozone Loss
10.02.11 - A NASA-led study has documented an unprecedented depletion of Earth's protective ozone layer above the Arctic last winter and spring caused by an unusually prolonged period of extremely low temperatures in the stratosphere.