Stratospheric Ozone Depletion

Ozone at ground level has adverse health impacts on humans and animals and plant life. . However, at high altitudes (stratosphere, 60 miles+) it blocks certain wavelengths of harmful solar radiation. Stratospheric ozone protects the earth's surface from excessive ultraviolet radiation which can cause skin cancer and other harmful effects, including plant damage.

The ozone in the stratosphere is created when an oxygen molecule (O2) absorbs ultraviolet energy and breaks apart (disassociates) to form two separate oxygen (O) atoms. These oxygen atoms quickly combine with oxygen molecures (O2) to project an ozone molecule (O3).

In the early 1980s, scientific observations showed a disturbance in ozone concentrations over the Antartic. Certain man-made chlorine-containing chemicals, including refrigerant gases called chlorofluorocarbons (CFCs) were causing significant reductions in stratospheric ozone concentrations resulting in increased ultraviolet radiation intensity on the earth's surface. This "ozone hole" was increasing in size from year to year causing great alarm as it stretched toward highly populated areas of the globe. The chlorine atoms in the CFCs were causing the ozone molecule to break down to ClO and O2.

In response to this global concern, regulations were adopted world-wide requiring the phase-out of CFC use in the United States by 1996. Other nations agred to such a phase-out by 2000. As a result, the ozone destruction has been halted and the damage is being repaired. However, because of the persistence of CFCs, it is expected that it could take 15 years or more to fully repair the damage.

It is noted that if all of the harmful ozone at ground level (troposphere) could somehow be transported to the stratosphere, it would be a "drop-in-the-bucket" to what is needed to fully repair the damage done by CFCs and other man-made chemicals.