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Chapter 24 
Ozone Depletion 
 

LEARNING OBJECTIVES       Ozone depletion in the stratosphere is now recognized as a major environmental problem with potential catastrophic effects.  This section should foster your understanding of the material covered in the book regarding the following:    How chemical and physical processes and reactions link emissions of chlorofluorocarbons to stratospheric ozone depletion; What options are available to minimize ozone depletion; Issues surrounding the debate about the primary source of ozone depleting chemicals (natural vs. man-made chemicals. ENVIRONMENTAL ISSUE - Are Natural or Man-Made Chemicals Causing the Ozone Hole?       By 1993 scientists had accumulated enough evidence to support earlier predictions that stratospheric ozone was being depleted over the Antarctic.  Most of them blamed the damage on organic chlorine compounds (those containing both carbon and chlorine) manufactured by humans, such as CFCs.  But consensus among most of the scientists in the filed did not prevent a continuing storm of controversy over these findings.  Critics from a variety of professions charged that natural sources of chlorine, not those generated by humans, were responsible for ozone depletion and that the environmental and health threats of ozone depletion were greatly exaggerated.  Although scientific uncertainties about the cause of the ozone hole were and are still cited, continuing research has added to the evidence that man-made chemicals and other pollutants are a direct contributor to ozone depletion.      FAQs . Photo Credit: EPA Office of Air and Radiation*  (This is a graphic that represents total ozone levels above the Antarctic and high latitudes during the Fall of 1995. Although it is not visible on August 1, the Antarctic  ozone hole is the red and purple area that appears near the center around September 15. It is defined as having less than 220 dobson units (DU) of ozone in the overhead  column).