Ozone depletion, a harbinger of
health
Dr. Dwijesh Kumar Panda, M.D., Ph.D, Senior Scientist.
What
is Ozone: -
The element oxygen exists
naturally in two forms. The more abundant form has two atoms of oxygen joined
together to form a molecule. This is the oxygen breathe. Sunlight keeps
breaking the O2 molecule into two oxygen atoms. These atoms can rejoin to form
oxygen or join another oxygen molecule and make O3 or Ozone. Almost 90% of
Ozone in the atmosphere is concentrated in the stratosphere – the layer of the
atmosphere between about 10 and 50 km altitude. It acts like Sunscreen lotion
and absorbs a large proportion of the Sun’s ultraviolet (UV) radiation which
would otherwise sterilize earth and eliminate life from the planet. It absorbs
the most energetic UV-c and UV-b radiation and filters about half of the UV-a
radiation. Exposure to these can cause sunburn, lead to Cancer and damage eyes.
Why
is it getting depleted?
There are many naturally
occurring substances that can destroy ozone. For instance, ozone gets destroyed
when it comes in contact with molecules that contain nitrogen, hydrogen,
chlorine, bromine and so on. In the atmosphere, oxygen and ozone molecules are
continuously converting into each other and a balance is maintained. But of increasing
man made pollution and the release of gases like CFCs (chlorofluorocarbons) the
natural balance is broken and the amount of ozone destroyed is far higher than
the amount naturally formed.
What
is the ozone hole?
There is nothing like a
continuous layer of ozone in the atmosphere and a hole in that coating. Ozone
does not form any layer. It is dispersed in the atmosphere like other gases.
But the zone of atmosphere where ozone has maximum density is called the ozone
layer. The density of ozone is measured by Dobson units. The average amount of
ozone in the atmosphere is about 300 Dobson units. If all this ozone is
compressed at zero degrees Celsius at one atmospheric pressure it would form a
3 mm thick layer around the earth. What we call ozone holes are the areas where
the concentration drops to an average of about 100 Dobson units. 100 chemicals
are being phased out for ozone.
Initiatives
to check the depletion:
A 1986 NASA study found the
depletion of ozone over Antarctica. Human pollution results in ozone depletion
It was also established that CFCs (chlorofluoro carbons) were the main catalyst
in ozone’s destruction. The first measure global initiative to restrict CFCs
was taken when the Montreal Protocol was signed in 1987. The protocol requires
the control of nearly 100 chemicals. For instance, hydro chlorofluorocarbons
(HCFCs) are to be phased out by 2030 in the developed world and 2040 in the
developing world. By these initiatives the depletion which had stretched up to
an area of 26 million square km in 1998 was reduced to 22 million square km in
2009. The presence of harmful chemicals around the clouds accelerates the
degradation of ozone. West polluted and we are paying. The developed countries
that have overused the atmospheric carbon sink help developing nations build
infrastructure for alternate sources of fuel that do not result in carbon
emissions.
Health
hazards:-
The Sun can nourish or
destroy our body by UV radiation. The sun’s ultraviolet rays are torpedoed down
to earth. The UVC rays are blocked by the atmosphere, so they have little
effect on us. The rays that are constantly being played into our body are the
UVA rays and the UVB rays. If the UVB rays are stopped at the level of the
skin, they can still cause burning and cancer of the skin and tanning as well.
Moreover, if the UVA rays penetrate deep in to the skin they cause burns,
wrinkles, and skin cancer. To top it up, sunlight also destroys the reserves of
folic acid, also known as folate or vitamin B9. Folate is needed so our body
can replicate DNA properly (that is why it helps protect against birth defects).
Also the rays can damage our eyes.
How
do UV rays cause damage?
One of the ways that the
rays cause damage is through the connective tissue breakdown. UV radiation
causes the structural protein of our skin, collagen to break down and disable
our ability to repair damage. Another way the sun ages our skin is through the
formation of free radicals- those aggressive charged compounds that damage
cells break down collagen as well. Free radicals can cause cancer by changing
our DNA and preventing our body from repairing it. How? UV destroys the rungs
of the DNA ladder so that the DNA ladder posts bind with one another. This
makes a bulge so that the DNA does not form or function correctly. Still
another way that the UV rays cause damage is by thinning the walls of surface of
blood vessels, leading to bruising, bleeding, and showing the appearance of
blood vessels through the skin. The Major Ager of UV radiation has a great impact
on our eyes by oxidizing the pigments in the retina and decreasing the
antioxidants in the thin, yellowish film that protects it: meaning that these
delicate cells are always at the risk of being damaged through another Major
Ager, free radicals. Sunlight damage to the eye is cumulative-particularly in
conditions like macular degeneration, where the cells die from oxidative
damage. Radiation from the Sun that passes through the ozone stimulates our
eyes (Visible rays) and our skin (UV rays). The UV wavelengths either bounce
off the dermis or penetrate deeply into our tissues like the depletion of
folate.
Protection against Ultra
Violet Radiation:
The Environmental Protection Agency (EPA) has
cautioned people to protect themselves against UV light 'whenever you can see
your shadow'. Some of the common preventive measures that need to be followed
are to avoid overexposure to sunlight especially between 10 am to 4 pm when the
UV rays are at their strongest. It is advisable to make sure to be adequately
protected by wearing the appropriate clothing and protective covering like hats whenever exposed to
the sun. Make sure to carry an
umbrella when going out. One must ensure to apply a generous coating of appropriate
sunscreen suitable for the skin type after consulting a dermatologist.
Sunscreen Lotions are available in different SPFs like 15, 30, etc. One should
always avoid artificial means of tanning, such as the use of sun-tan beds. In
case of blisters due to overexposure, the neighborhood GP or dermatologist
should be consulted for right diagnosis and treatment so that the condition
does not worsen.
The
End.
Dr. Dwijesh Kumar Panda, M.D, PhD.
Senior Scientist, Govt. Of Orissa.
M5/12,
Acharya Vihar,
Bhubaneswar-751 013
Contact- +919438470777.
Submitted to the Director,
NISER, Bhubaneswar, Orissa, Institute of Physics Campus, Bhubaneswar, 751005.
Email: tkc@niser.ac.in for
favour of publication in Souvenir, UNESCO Kalinga Prize for popularization of
science.