Q.The Ozone Day is observed every year on September 16 as on this day in 1987 the ___________was signed for launching efforts to arrest the depletion of the fragile ozone layer in the stratosphere that prevents the harmful ultra-violet rays of the sun from reaching the earth. Fill the correct word in blank.

Stratospheric ozone — "good" ozone, distinct from the harmful "bad" ozone found near ground level — forms a protective layer in the upper atmosphere that absorbs dangerous ultraviolet (UV) radiation from the Sun before it can reach the surface, since UV radiation readily damages the DNA and proteins of living organisms. The total ozone in a vertical air column is measured in Dobson units.

Ozone is continuously formed and broken down in the stratosphere, normally in a stable balance; this balance is disrupted by chlorofluorocarbons (CFCs), widely used as refrigerants, which drift up into the stratosphere where UV radiation splits them apart, releasing chlorine atoms that catalytically destroy ozone without themselves being consumed — so a single chlorine atom can degrade many ozone molecules, giving CFCs long-lasting effects on ozone levels. Depletion is most severe over Antarc …