Ozone Recovery

Why in news?

As per NASA’s recent report,an international ban on chlorine-containing man-made chemicals called chlorofluorocarbons (CFCs), has resulted in about 20% less ozone depletion

Chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it.

FACTS FOR PRELIMS

OZONE DEPLETION

Ozone depletion describes two related phenomena observed since the late 1970s: a steady decline of about four percent in the total amount of ozone in Earth’s stratosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth’s polar regions

The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric phenomena

The main cause of ozone depletion and the ozone hole is man-made chemicals, especially man-made halocarbon refrigerants, solvents, propellants, and foam-blowing agents (chlorofluorocarbon (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS)

These compounds are transported into the stratosphere by the winds after being emitted at the surface

Once in the stratosphere, they release halogen atoms through photodissociation, which catalyze the breakdown of ozone (O3) into oxygen (O2). Both types of ozone depletion were observed to increase as emissions of halocarbons increased.

The ozone layer prevents most harmful UVB wavelengths of ultraviolet light (UV light) from passing through the Earth’s atmosphere

These wavelengths cause skin cancer, sunburn, and cataracts, which were projected to increase dramatically as a result of thinning ozone, as well as harming plants and animals

These concerns led to the adoption of the Montreal Protocol in 1987, which bans the production of CFCs, halons, and other ozone-depleting chemicals.

SOURCE – LIVEMINT.