Question

Give an account of pollutants which are harmful to ozone layer.

Answer 1

1. Pollutants that are harmful to the ozone layer primarily include chlorofluorocarbons (CFCs). CFCs, once released into the lower atmosphere, gradually move upwards to the stratosphere. There, ultraviolet (UV) rays break down CFC molecules, releasing chlorine (Cl) atoms. These chlorine atoms then catalytically degrade ozone molecules, converting ozone into molecular oxygen and thus depleting the ozone layer.
2. Notably, one molecule of CFC can destroy about 100,000 ozone molecules. The CFCs come from sources such as aerosol spray cans, polyurethane foams, air conditioners, and refrigerators.
3. Other related pollutants include hydrochlorofluorocarbons (HCFCs), which were introduced as interim replacements for CFCs but still have some ozone-depleting effects, though less severe. Hydrofluorocarbons (HFCs), which do not contain chlorine, do not harm the ozone layer but are potent greenhouse gases.
4. The depletion of the ozone layer due to these substances has led to serious concerns, including the appearance of the “ozone hole” over Antarctica, allowing more harmful UV radiation to reach the Earth’s surface. This has detrimental effects on human health (such as skin cancer and eye cataracts), ecosystems, and materials.
5. International efforts to control these pollutants include the Montreal Protocol, an agreement signed in 1987 to phase out the production and use of ozone-depleting substances like CFCs and HCFCs, promoting the shift to safer alternatives like HFCs.