What is ozone? An ozone molecule is a temporary association of three oxygen atoms. Energy from lightning or ultraviolet radiation from the sun breaks apart O2 molecules. The single atoms can combine with O2 molecules to form O3.

Ozone Layer The ozone layer is a slight concentration of ozone gas in the upper atmosphere (stratosphere). It shields us from the harmful effects of the Sun’s ultraviolet (UV) radiation, such as melanoma and cataracts. Without the ozone layer, life would be restricted to the oceans.

Ozone in the Lower Atmosphere In the lower atmosphere (troposphere), ozone functions as a greenhouse gas (although not a very powerful one), and is a component of smog. It is considered poisonous, and can interfere with lung function and the immune system. Automobile exhaust produces the majority of ozone in the lower atmosphere. IN THE UPPER ATMOSPHERE OZONE IS GOOD. IN THE LOWER ATMOSPHERE IT IS BAD!

Human Activities and Ozone In the 1980s, scientists found that chlorofluorocarbons (CFCs) produced by the chemical industry made its way into the upper atmosphere where it has been destroying the ozone layer. CFCs come from refrigerators and air conditioners – there is no natural source of CFCs. It takes 50 to 100 years for CFCs to break down.

What is the ozone hole? The thinning (40-70%) of the ozone layer over Antarctica. In the Antarctic winter, the formation of icy clouds provides sites for CFCs to react and produce chlorine atoms. These atoms then stay attached to the clouds until spring. In spring, the ice crystals melt, releasing the Cl atoms to the air which react to remove ozone. So, the hole is greatest during the Antarctic spring.

The Good News! CFC production fell 77% between 1988 and 1995. Chlorine levels should be back to safe levels by 2045. Good example that the world can act quickly and effectively when needed.

Keep it Straight! Even though ozone acts as a greenhouse gas in the LOWER atmosphere, it is not a big player in the greenhouse effect. The hole in the ozone layer (UPPER atmosphere) has NOTHING TO DO WITH GLOBAL WARMING!