A day of "O-Zone"

The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone (O3). This layer absorbs 97–99% of the sun's high frequency ultraviolet light, which is harmful to the life on earth. Ozone layer is mainly located in the lower portion of the stratosphere from approximately 13 km to 20 km above Earth, though the thickness varies seasonally and geographically.

The ozone layer can be depleted by free radical catalysts, including nitric oxide (NO), nitrous oxide (N2O), hydroxyl (OH), atomic chlorine (Cl), and atomic bromine (Br). While there are natural sources for all of these species, the concentrations of chlorine and bromine have increased markedly in recent years due to the release of large quantities of man-made organohalogen compounds, especially chlorofluorocarbons (CFCs) and bromofluorocarbons.

These highly stable compounds are capable of surviving the rise to the stratosphere, where Cl and Br radicals are liberated by the action of ultraviolet light. Each radical is then free to initiate and catalyze a chain reaction capable of breaking down over 100,000 ozone molecules. The breakdown of ozone in the stratosphere results in the ozone molecules being unable to absorb ultraviolet radiation. Consequently, unabsorbed and dangerous ultraviolet-B radiation is able to reach the Earth’s surface.Ozone levels, over the northern hemisphere, have been dropping by 4% per decade. Over approximately 5% of the Earth's surface, around the north and south poles, much larger (but seasonal) declines have been seen; these are the ozone holes.
In 2009, nitrous oxide (N2O) was the largest ozone-depleting substance emitted through human activities.

But unfortunately during the last 20 years the ozone layer over many world regions, was too ”thin”. As a result, the probability of skin cancer and eye cataracts increased, immunity weakened, agricultural crops and fishery catch decreased, etc.
Results of some researches state that the ozone layer thinning has practically stopped at the present moment, while others researchers say that the "ozone hole” is growing, i.e. in the year 2005 was almost a record big size.

"Now, its time to take action!!"

source: wikipedia

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