header

NASA's Aura Satellite, the Ozone Layer, and You




Ozone Layer / Ozone Hole : What's the difference?


The ozone layer is a layer in Earth's atmosphere that absorbs most of the Sun's 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 (the stratosphere). Ozone protects life on Earth from the Sun's ultraviolet (UV) radiation. Ninety percent of the ozone in the atmosphere sits in the stratosphere, the layer of atmosphere between about 10 and 50 kilometers altitude.

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.

But I thought that ozone is "bad"?!

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.

Wear your sunscreen! Wear your hat!

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.

stratospheric ozone diagram

The Ozone Layer: Our Global Sunscreen

Miles above the surface of the Earth, a thin layer of ozone gas acts as a shield that protects us from harmful ultraviolet light. But chemicals released in the atmosphere have caused a huge hole in the ozone layer above Antarctica.

Ozone In the News

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.

+ Go to Newsroom


Is the ozone hole getting worse? See the data yourself!


Ozone Hole Poster

30 Years of Observations

Aura introduces its latest poster which illustrates data from five different missions that tracked the development of the ozone hole from space. The back of the poster provides information about stratospheric ozone. There are additional resources for educators, students, and scientists. The lesson which will introduce students to the use of color maps to visualize data about stratospheric ozone.

The Ozone hole, animated

Ozone Hole Watch

View the latest status of the ozone layer over the Antarctic, with a focus on the ozone hole. Satellite instruments monitor the ozone layer, and we use their data to create the images that depict the amount of ozone.

"The World We Avoided"

The world we avoided
This study predicts ozone losses as if nothing had been done to stop them. These "world avoided" maps show computer model predictions of the state of the ozone layer in 2064 without and with the effects of international agreements to curb ozone-destroying chemicals.


Science Features



NASA logo
Goddard Space Flight Center
privacy