Ozone Layer is Recovering (Download PDF)

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Recent study by NASA has confirmed recovery of ozone layer due to absence of chlorine from Chlorofluorocarbon (CFC) in atmosphere. Study has confirmed phenomenon by mapping chemical composition of atmosphere.

Image of Ozone Layer is Recovering

Image of Ozone Layer is Recovering

Image of Ozone Layer is Recovering

Highlights of Study

  • Study revealed that chlorine levels declined by 0.8 % each year b/w 2005 & 2016 & speculates that it could be effect of worldwide ban on use of CFC.

  • Previous research had hinted at decrease in depletion of ozone layer. Scientists believe that ozone layer would fully recover by 2080.

Ozone Layer

  • Layer of ozone envelops Earth & keeps damaging ultraviolet, or UV, radiation from reaching living things on planet’s surface.

  • Ozone layer exists mainly in stratosphere, layer of atmosphere that reaches from 10 to 50 kms (abt 6 to 30 miles) above Earth’s surface.

Ozone Hole

Ozone hole is region of depleted layers of ozone above Antarctic region, whose creation is linked to increased cases of skin cancer.

Factors responsible for depletion of ozone

  • Depletion of ozone is due to many factors, most dominant of which is release of chlorine from CFCs (Chlorofluorocarbons) which destroys ozone.

  • CFCs are released by products such as hairsprays, old refrigerators etc.

CFCs

  • Chlorofluorocarbons, or CFCs, are compounds made up of combinations of elements chlorine, fluorine & carbon; aerosols, refrigerants & foams contain CFCs.

  • When CFCs enter air, they rise up into atmosphere to meet up w/ & destroy ozone molecules.

  • 1st used in 1928, CFCs have since become more common as various other CFC compounds were created.

  • Some of better-known CFCs are Freon compounds, which were used as cooling ingredients in refrigerators & air conditioners. CFCs have lifetimes from 50 to 100 years.

CFCs Destroy Ozone

Once in atmosphere, CFCs drift slowly upward to stratosphere, where they are broken up by ultraviolet radiation, releasing chlorine that catalytically destroys ozone. Process is as follows:

  • UV radiation breaks off chlorine atom from CFC molecule.

  • Chlorine atom attacks ozone molecule (O3), breaking it apart & destroying ozone.

  • Result is ordinary oxygen molecule (O2) & chlorine monoxide molecule (ClO).

  • Chlorine monoxide molecule (ClO) is attacked by free oxygen atom releasing chlorine atom & forming ordinary oxygen molecule (O2).

  • Chlorine atom is now free to attack & destroy another ozone molecule (O3). One chlorine atom can repeat this destructive cycle thousands of times.

Applications of CFCs

  • There are plenty of uses for CFCs molecules.

  • CFCs are not flammable; so they were used as propellants that would push other molecules out of aerosol sprays.

  • CFCs were used to form foamed plastics.

  • Low flammability enabled people to use these molecules to dry clean hot electronic components of devices such as air conditioning.

- Published/Last Modified on: January 21, 2019

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