PHLT612: Special Issues in Public Health – II
Unit 04: Development and The Environment: Climate Change – Ozone Depletion
Global Warming, Green House Effect, from Unsustainable to Sustainable development
– Urban Problems Related to Energy – Water Conservation, Rain Harvesting, and
Watershed Management – Resettlement and Rehabilitation of People – its Problems
and Concern.
“The ozone layer is a region in the earth’s stratosphere that contains high concentrations of ozone and
protects the earth from the harmful ultraviolet radiations of the sun.” The ozone layer is mainly found in the
lower portion of the earth’s atmosphere. It has the potential to absorb around 97-99% of the harmful
ultraviolet radiations coming from the sun that can damage life on earth. If the ozone layer was absent,
millions of people would develop skin diseases and may have weakened immune systems.
Ozone Layer Depletion
“Ozone layer depletion is the gradual thinning of the earth’s ozone layer in the upper atmosphere caused due
to the release of chemical compounds containing gaseous bromine or chlorine from industries or other
human activities.”
Ozone layer depletion is the thinning of the ozone layer present in the upper atmosphere. This happens when
the chlorine and bromine atoms in the atmosphere come in contact with ozone and destroy the ozone
molecules. One chlorine can destroy 100,000 molecules of ozone. It is destroyed more quickly than it is
created.
Some compounds release chlorine and bromine on exposure to high ultraviolet light, which then contributes
to ozone layer depletion. Such compounds are known as Ozone Depleting Substances (ODS).
The ozone-depleting substances that contain chlorine include chlorofluorocarbon, carbon tetrachloride,
hydrochlorofluorocarbons, and methyl chloroform. Whereas, the ozone-depleting substances that contain
bromine are halons, methyl bromide, and hydro bromofluorocarbons.
Chlorofluorocarbons are the most abundant ozone-depleting substance. It is only when the chlorine atom
reacts with some other molecule, it does not react with ozone.
Montreal Protocol was proposed in 1987 to stop the use, production and import of ozone-depleting
substances and minimise their concentration in the atmosphere to protect the ozone layer of the earth.
Causes of Ozone Layer Depletion
Ozone layer depletion is a major concern and is associated with a number of factors. The main causes
responsible for the depletion of the ozone layer are listed below:
1. Chlorofluorocarbons
Chlorofluorocarbons or CFCs are the main cause of ozone layer depletion. These are released by solvents,
spray aerosols, refrigerators, air-conditioners, etc.
The molecules of chlorofluorocarbons in the stratosphere are broken down by ultraviolet radiations and
release chlorine atoms. These atoms react with ozone and destroy it.
, Unregulated Rocket Launches
Researches say that the unregulated launching of rockets results in much more depletion of the ozone layer
than the CFCs do. If not controlled, this might result in a huge loss of the ozone layer by the year 2050.
2. Nitrogenous Compounds
The nitrogenous compounds such as NO2, NO, N2O are highly responsible for the depletion of the ozone
layer.
3. Natural Causes
The ozone layer has been found to be depleted by certain natural processes such as Sun-spots and
stratospheric winds. But it does not cause more than 1-2% of the ozone layer depletion.
The volcanic eruptions are also responsible for the depletion of the ozone layer.
Effects Of Ozone Layer Depletion
The depletion of the ozone layer has harmful effects on the environment. Let us see the major effects of
ozone layer depletion on man and environment.
1. Effects on Human Health
Humans will be directly exposed to the harmful ultraviolet radiation of the sun due to the depletion of the
ozone layer. This might result in serious health issues among humans, such as skin diseases, cancer,
sunburns, cataract, quick ageing and weak immune system.
2. Effects on Animals
Direct exposure to ultraviolet radiations leads to skin and eye cancer in animals.
3. Effects on the Environment
Strong ultraviolet rays may lead to minimal growth, flowering and photosynthesis in plants. The forests also
have to bear the harmful effects of the ultraviolet rays.
4. Effects on Marine Life
Planktons are greatly affected by the exposure to harmful ultraviolet rays. These are higher in the aquatic
food chain. If the planktons are destroyed, the organisms present in the food chain are also affected.
5. Solutions to Ozone Layer Depletion
The depletion of the ozone layer is a serious issue and various programmes have been launched by the
government of various countries to prevent it. However, steps should be taken at the individual level as well
to prevent the depletion of the ozone layer.
Following are some points that would help in preventing this problem at a global level:
1. Minimise the Use of Vehicles
The vehicles emit a large amount of greenhouse gases that lead to global warming as well as ozone
depletion. Therefore, the use of vehicles should be minimised as much as possible.
Unit 04: Development and The Environment: Climate Change – Ozone Depletion
Global Warming, Green House Effect, from Unsustainable to Sustainable development
– Urban Problems Related to Energy – Water Conservation, Rain Harvesting, and
Watershed Management – Resettlement and Rehabilitation of People – its Problems
and Concern.
“The ozone layer is a region in the earth’s stratosphere that contains high concentrations of ozone and
protects the earth from the harmful ultraviolet radiations of the sun.” The ozone layer is mainly found in the
lower portion of the earth’s atmosphere. It has the potential to absorb around 97-99% of the harmful
ultraviolet radiations coming from the sun that can damage life on earth. If the ozone layer was absent,
millions of people would develop skin diseases and may have weakened immune systems.
Ozone Layer Depletion
“Ozone layer depletion is the gradual thinning of the earth’s ozone layer in the upper atmosphere caused due
to the release of chemical compounds containing gaseous bromine or chlorine from industries or other
human activities.”
Ozone layer depletion is the thinning of the ozone layer present in the upper atmosphere. This happens when
the chlorine and bromine atoms in the atmosphere come in contact with ozone and destroy the ozone
molecules. One chlorine can destroy 100,000 molecules of ozone. It is destroyed more quickly than it is
created.
Some compounds release chlorine and bromine on exposure to high ultraviolet light, which then contributes
to ozone layer depletion. Such compounds are known as Ozone Depleting Substances (ODS).
The ozone-depleting substances that contain chlorine include chlorofluorocarbon, carbon tetrachloride,
hydrochlorofluorocarbons, and methyl chloroform. Whereas, the ozone-depleting substances that contain
bromine are halons, methyl bromide, and hydro bromofluorocarbons.
Chlorofluorocarbons are the most abundant ozone-depleting substance. It is only when the chlorine atom
reacts with some other molecule, it does not react with ozone.
Montreal Protocol was proposed in 1987 to stop the use, production and import of ozone-depleting
substances and minimise their concentration in the atmosphere to protect the ozone layer of the earth.
Causes of Ozone Layer Depletion
Ozone layer depletion is a major concern and is associated with a number of factors. The main causes
responsible for the depletion of the ozone layer are listed below:
1. Chlorofluorocarbons
Chlorofluorocarbons or CFCs are the main cause of ozone layer depletion. These are released by solvents,
spray aerosols, refrigerators, air-conditioners, etc.
The molecules of chlorofluorocarbons in the stratosphere are broken down by ultraviolet radiations and
release chlorine atoms. These atoms react with ozone and destroy it.
, Unregulated Rocket Launches
Researches say that the unregulated launching of rockets results in much more depletion of the ozone layer
than the CFCs do. If not controlled, this might result in a huge loss of the ozone layer by the year 2050.
2. Nitrogenous Compounds
The nitrogenous compounds such as NO2, NO, N2O are highly responsible for the depletion of the ozone
layer.
3. Natural Causes
The ozone layer has been found to be depleted by certain natural processes such as Sun-spots and
stratospheric winds. But it does not cause more than 1-2% of the ozone layer depletion.
The volcanic eruptions are also responsible for the depletion of the ozone layer.
Effects Of Ozone Layer Depletion
The depletion of the ozone layer has harmful effects on the environment. Let us see the major effects of
ozone layer depletion on man and environment.
1. Effects on Human Health
Humans will be directly exposed to the harmful ultraviolet radiation of the sun due to the depletion of the
ozone layer. This might result in serious health issues among humans, such as skin diseases, cancer,
sunburns, cataract, quick ageing and weak immune system.
2. Effects on Animals
Direct exposure to ultraviolet radiations leads to skin and eye cancer in animals.
3. Effects on the Environment
Strong ultraviolet rays may lead to minimal growth, flowering and photosynthesis in plants. The forests also
have to bear the harmful effects of the ultraviolet rays.
4. Effects on Marine Life
Planktons are greatly affected by the exposure to harmful ultraviolet rays. These are higher in the aquatic
food chain. If the planktons are destroyed, the organisms present in the food chain are also affected.
5. Solutions to Ozone Layer Depletion
The depletion of the ozone layer is a serious issue and various programmes have been launched by the
government of various countries to prevent it. However, steps should be taken at the individual level as well
to prevent the depletion of the ozone layer.
Following are some points that would help in preventing this problem at a global level:
1. Minimise the Use of Vehicles
The vehicles emit a large amount of greenhouse gases that lead to global warming as well as ozone
depletion. Therefore, the use of vehicles should be minimised as much as possible.
