September 16th : 'International Ozone Day'

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September 16th every year is observed as the “International Ozone Day” to commemorate signing of the “Montreal Protocol” in 1987 which aims stopping the usage of ozone layer depleting substances. Even though Ozone Depletion as an environmental concern has become a commonly discussed topic, most often it is discussed along with “Global Warming” which has totally different source.

OZONE LAYER

  • Ozone comprises of ozone molecules (O3) i.e. three atoms of oxygen.
  • It is present in the stratosphere layer of atmosphere.

Formation:

  • Firstly, when short-wavelength UV(ultraviolet) light strikes oxygen molecule / ozone molecule, it splits it into two oxygen atoms or one oxygen molecule and one oxygen atom.
  • Each single oxygen atom will then attach itself to other oxygen molecule creating ozone.
  • Short wavelength UV light is absorbed by ozone layer.
  • After that, short wavelength UV splits ozone molecule, creating one oxygen atom and one oxygen molecule.
  • This process continues on and on. 

WHAT ARE ULTRAVIOLET RAYS ?

 

  • Ultraviolet rays are the cosmic rays coming from sun.
  • They are categorized into UV-A, UV-B and UV-C types.
UV TYPE STATE Transparency to Ozone Layer  
UV-A

Very harmful 

Completely Stopped by ozone layer

UV-B

Less harmful than UV-A but main source of skin cancer

stopped by ozone layer but some pass through

UV-C

Least harmful

Most of it pass through ozone layer

WHAT IS OZONE HOLE ?

  • Myth: Ozone hole means there is a hole in the ozone layer.
  • Reality: In reality it is not actually the ozone hole.
  • Ozone hole means thinning of ozone layer at a particular place.
  • Largest ozone hole can be seen only in the atmosphere over Antarctica region.

REASONS FOR OZONE LAYER DEPLETION

Natural

  • Seasons
  • Weather conditions
  • Solar cycles

Man-made

  • Manufactured chemicals : Substances which are responsible for destruction of ozone layer are called as Ozone-Depleting Substances (ODS).

Main ODS are as follows :

  • CFC (Chlorofluorocarbons) : small molecules that contain chlorine, fluorine and carbon atoms. They are also called as Freons (commercial name)
  • Methyl Bromide
  • Halons
  • Carbon Tetrachloride
  • Hydrocloroluorocarbons

CFC’S Vs HCFC’S : HCFC’s are CFC’s with hydrogen. They have low lifetime than CFC’s in troposphere. So if used instead of CFC can prove helpful as less fraction of HCFC’s are able to reach stratosphere and there will be less depletion of ozone layer.

EFFECTS OF OZONE LAYER DEPLETION :

There are various effects of the UV rays which will pass through ozone layer if it depletes. UV rays will not only affect humans, but the whole life system on earth, and have adverse effects on agriculture, ecology and will lead to global warming at a higher rate.

CATARACT – A MEASURE ISSUE IN OZONE LAYER AFTER EFFECTS : phenomenon in which eye vision decreases due to clouding in the eyes. It can be treated by surgery but with increasing time it can lead to permanent blindness.

  • Though various causes have been given for it, but the prominent among them are the Ultra Violet (UV) rays.

WHAT IS GREEN BUILDING ?

  • Myth – Green building is the one which has green plants planted in abundance on it.
  • Green building is the one which is resource efficient and environmentally responsible.
  • It means efficient at using water, electricity, etc., and reduces waste

MONTREAL PROTOCOL – A QUICK REVIEW

  • It was on stop usage of substances that deplete ozone layer.
  • It was signed in the year 1987.
  • It was only due to this protocol that today ozone layer is recovering itself.

Refrigerant Type           Phase Out Dates
CFC’s                                 By 1995
HCFC’s                              By 2020
HFC’s                                 Not Applicable

SUCCESSORS TO MONTREAL PROTOCOL : These are also referred as amendments to montreal protocol :

London Amendment (1990) :

  • a. ODS be phase out by 2000 (developed countries) and 2010 (developing countries)
  • b. Methyl chloroform added to the list of ODSs with phase out in 2005 (developed countries) and 2010 (developing countries).

Copenhagen Amendment (1992):

  • significantly accelerated the phaseout of ODSs and incorporated an HCFC phaseout for developed countries, beginning in 2004.
  • Under this agreement, CFCs, halons, carbon tetrachloride, and methyl chloroform were targeted for complete phaseout in 1996 in developed countries.
  • In addition, methyl bromide consumption of methyl bromide was capped at 1991 levels.

Montreal Amendment (1997):

included the phase-out of HCFCs in developing countries, as well as the phaseout of methyl bromide in developed and developing countries in 2005 and 2015, respectively.

Beijing Amendment (1999):

  • Included tightened controls on the production and trade of HCFCs.
  • Bromochloromethane was also added to the list of controlled substances with phaseout targeted for 2004.

ISSUE OF HFC’S

  • HFC’s are not harmful to ozone layer and hence are not covered under montreal protocol.
  • But they act as super-green house gases trapping a lot of heat as compared to carbon dioxide.
  • Developed countries have already found substitutes for HFC’s and are using it which they term it as green technology.
  • Developing countries want HFC’s to be phased out through Montreal protocol while developed countries want it be phased out under United Nations Framework Convention on Climate Change (UNFCCC).
  • Developing countries want it to be part of Montreal protocol because parties in Montreal protocol don’t have legal obligation.
  • Developed countries want it to be part of UNFCCC as it will have legal binding and they can sell their green technology at a higher price to developing world.

DIFFERENCE BETWEEN GROUND LAYER OZONE AND STRATOSPHERE OZONE

  • Ground level or “bad” ozone is not emitted directly into the atmosphere, but is created by chemical reactions of oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight.
  • Ground layer ozone acts as a green house gas which traps heat and accounts to global warming.
  • Ground layer ozone is extremely harmful to human respiratory system which continues to damage it even when symptoms have disappeared.
  • Also damages trees and in turn decreases their food producing and storage capacity.
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