Ozone Layer Depletion -meaning and effects

The earth surface consists of three layers: atmosphere, hydrosphere and the lithosphere. The atmosphere further divided into 4 namely:

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere

The ozone layer is as the name implies an “abundance of ozone” (O₃).It is located in the lower layer of the stratosphere, and its distance is approximately 10-50 km above the earth. Its thickness depends mainly on the season and geographical location.

The ozone layer was first discovered in the year 1913 by some French physicists; Charles Fabry and Henri Buisson, but its major characteristics were examined by the British meteorologist G.M.B Dobson. During his research he developed a simple spectrophotometer or as it is sometimes called “the Dobson meter).

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This scientific equipment is known to be able to measure stratospheric ozone from the earth. Between 1928 and 1958, he was able to develop a worldwide network of ozone monitoring stations that are in function till date. The “Dobson unit”, the unit used to measure the total amount of ozone in the ozone layer, is named in his honour.

The ozone layer was formed as a result of the buildup of oxygen in the atmosphere over time, which eventually settled in the upper atmosphere or stratosphere forming the ozone layer.

The ozone layer is very vital to life form on earth as it filters out “cell-damaging” Ultraviolet rays that come directly from the sun. Such rays are very dangerous to health because exposure to such rays affects the body cells and can lead to the development of certain chronic illnesses and growth in the body like cancer.

Ozone is a form of oxygen but of distinct characteristics from the one we inhale. The normal oxygen we inhale from the atmosphere is made up of two molecules of oxygen, denoted as O₂ which according to chemistry is a colourless and odourless gas. But ozone is made up of three molecules of oxygen denoted by the chemical formula O₃, it is also colourless but has a very harsh odour.

Most ozone is produced naturally in the upper atmosphere of the earth surface. The highest concentration of ozone is found at an altitude of 19-30km above sea level. Ozone also occurs in minuscule values at lowest levels of the atmosphere known as “the troposphere”.

Depletion in reference to the ozone layer is simple, the breakdown of the stratospheric ozone in the ozone layer. Scientific researchers have discovered that as the days go by the ozone layer depletes and this continued action can endanger life forms on the earth.

In Nigeria, ozone depletion has an adverse effect on climate change. Northern areas where major food produce are grown in is said to experience sparse rainfall which could affect the growth of food produce in that part of the country.

In some countries like India scientific reports states that there has been increased in the amount of UV rays entering into their atmosphere, B.N Srivastava of the Physical Laboratory has conducted some research and says that during summer, at noon the UV radiation with a wavelength of 290 nanometer is equivalent to levels attained in Antarctica during the ozone hole period.

He equally warns that even the slightest bit of depletion of the ozone layer over India may lead to large percentage changes in UV radiation over the country.

The occurrence of skin cancer which could arise as a result of ozone depletion is low in India but still the yearly surveys conducted are fluctuating. With the use of the Dobson spectrophotometers the measure of the total ozone layer in the atmosphere is being successfully carried out in some countries like Varanasi, Pone, New deli and some others. But the report on increase or decrease of the ozone covering is still inconclusive in some countries.

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Causes of Ozone Depletion

Research has shown that the depletion of the ozone layer is as a result of certain actions of man. Overtime our world is evolving both technologically and otherwise. As we evolve some of the actions we carry out causes the depletion of the ozone layer.

However, scientists have been able to come to certain conclusions that some of man’s actions e.g. the burning of fossil fuel, bush burning, greenhouse effect and so on…could be the cause of the depletion of the ozone layer, but as earlier stated this fact is still uncertain.

The depletion on the ozone layer has various effects on life form. Below are some of the effects that could arise as a result of ozone depletion.

• It affects both human and animal: depletion of the ozone layer causes the easy penetration of ultraviolet rays from the sun to the earth. Such exposure has a profound effect on the health of human and animals alike with the potential risk of skin cancer, eye disease and other infectious diseases.

UV rays can affect our immune system exposing us to certain chronic diseases. Experiments on animals show that on exposure to UV rays the immune system of animals becomes impaired resulting in low resistance to certain diseases like skin cancer, infectious agents and other antigens.

• It affects the climatic changes in an environment: the depletion of the ozone layer and climatic changes are interlinked, though ozone depletion is not the major cause of climatic change. The atmospheric ozone has two effects on the earth’s temperature; it absorbs UV rays which heat up the stratosphere and also absorbs infrared radiation emitted by the earth surface thereby trapping heat in the troposphere. This action causes the climate of a particular area to be unstable.
• It affects aquatic ecosystems: more than 30% of human food for consumption comes from aquatic habitat. High level of exposure of aquatic bodies to UV rays can lead to the death of phytoplanktons which is one of the basic aquatic food for higher animals. The absence of food is starvation which can lead to death.
• It affects terrestrial plants: In forest and grassland, exposure to ultraviolet rays can result in mutation of plants, thereby altering the number and variety of plants. It could also cause changes to plant shape and form, secondary metabolism, etc.

Just as we have man-made technologies for security like the metal detector doors in banks and offices, the Ozone layer is an important part of our environment and natural security to keep off the danger of the sciences above, any breach in security robs of certain benefits.