Q.Write about the preventive measures of ozone depletion.

Preventing further ozone-layer depletion centres on eliminating the man-made chemicals that destroy stratospheric ozone and replacing them with safer alternatives, backed by international agreements and public awareness.

Background

• The stratospheric ozone layer absorbs harmful solar UV-B radiation; its depletion (notably the Antarctic 'ozone hole') is caused chiefly by chlorine- and bromine-containing compounds -- CFCs (used in refrigerants, air-conditioners, aerosol propellants, foam-blowing), halons (fire extinguishers), carbon tetrachloride, and methyl bromide -- which release reactive chlorine/bromine atoms that catalytically break down ozone molecules.

Preventive measures

1. Phase-out of ozone-depleting substances (ODS) -- global elimination of CFC and halon production/use as mandated by the Montreal Protocol (1987) and its subsequent amendments (London, Copenhagen, Montreal, Beijing, Kigali).
2. Use of ozone-friendly substitutes -- replacing CFCs with hydrofluorocarbons (HFCs), hydrocarbons, and other low/zero ozone-depletion-potential refrigerants and propellants.
3. Safe handling and recycling of old equipment -- proper recovery and disposal of CFCs from discarded refrigerators, air-conditioners, and foams instead of releasing them into the atmosphere.
4. Avoiding halon-based fire-extinguishing systems in favour of alternative agents.
5. Reducing nitrous oxide (N2O) emissions -- from excessive use of nitrogenous fertilisers and industrial processes, since N2O also contributes to ozone breakdown. …