The ozone layer is a region in Earth’s stratosphere where a higher concentration of Ozone gas is present. It is considered “good” in the stratosphere as it absorbs some of the sun’s harmful Ultra Violet radiations and hence protects lives on Earth.
However, in recent studies, scientists have observed changes in equilibrium between the formation and destruction of Ozone due to the influx of various substances into the atmosphere which reacts with ozone and destroys it.
Ozone Layer depletion is the significant decrease in the concentration of ozone in the upper layer of the atmosphere caused due to the reaction of chemical compounds containing chlorine and bromine. It implies that the rate at which the Ozone is being destroyed is much faster than the rate at which it is being formed.
These are made up of Chlorine, Fluorine and Carbon. They are released into the atmosphere by discarded refrigerators, aerosols, solvents, etc. Molecules of CFCs when exposed to UV radiation break up, thus freeing Chlorine atoms. This free chlorine atom reacts with Ozone and depletes it.
like NO2, NO, N2O are responsible for ozone depletion. The sources of Nitrogen Oxides are mainly explosions of thermonuclear weapons, agricultural fertilizers and industrial emissions.
These are called Hydrobromo Fuorocarbons (HBFCs) and are used in fire extinguishers. Each bromine atom destroys a hundred times more ozone molecules than a chlorine atom does.
The ozone layer is depleted by a number of natural causes like the sunspot cycle, volcanic eruption. However, the percentage effect is less i.e around 1-3%.
Ozone Depleting Substances are those which deplete the Ozone layer by reacting with Ozone and thus thinning the Ozone layer. The number of substances and their sources is present in the following table:
Reduction in the quantity of Ozone implies increased penetration of solar UV-B radiations to the Earth’s surface. It has devastating effects on human health, animals, plants, microorganisms and air quality.
People become vulnerable due to the increase in the incidence of morbidity from eye diseases, skin cancer and infectious diseases.
In light skin coloured populations, UV_B radiation is the main risk factor for the development of Non-Melanoma skin cancer.
Psychological processes of plants are affected by UV-B radiation.
Response to UV-B also varies voraciously among different species. Therefore, in agriculture, it becomes necessary to use more UV-B tolerant species.
In forests and grasslands, it results in changing the composition of species.
There are several indirect changes like plant form, biomass allocation of the plant, timing of development phases triggered due to UV-B radiation.
More exposure to UV-B radiation has affected motility in phytoplanktons which results in reduced survival rates of these organisms.
UV-B radiation has been found to cause damage in the early development stages of fish, crabs, amphibians and various other animals. The more severe effect is a decrease in reproductive capacity.
Reduction of Ozone in upper layers of atmosphere and the direct increase of UV-B radiation penetrating to the lower atmosphere results in higher photodissociation rates of gases that control the chemical reactivity of the Troposphere.
Products formed due to these reactions are known to have adverse effects on human health, plants and outdoor materials.
Increase in tropospheric reactivity will lead to increased production of particulates due to oxidation and nucleation of sulfur due to anthropogenic and natural causes.
Materials like polymers, naturally occurring biopolymers and some other materials of commercial interest are affected by UV radiations.
Increase in solar UV-B content due to partial ozone depletion accelerates the photodegradation rate of these materials and therefore limits their life outdoors.
Instead of using chemicals, one should stop using pesticides and switch to natural methods to get rid of pests. A significant amount of greenhouse gases are produced by cars, contributing to global warming as well as ozone depletion. The use of vehicles should therefore be reduced as far as possible. Many of the materials used for cleaning have chemicals that damage the ozone layer. We should substitute eco-friendly goods for that. Maintain air conditioners, as CFC escapes into the atmosphere via their malfunctions.
Q1. What Depletes the Ozone Layer?
Ozone depletion: It is the depletion in ozone molecules as chlorine and bromine atoms come into contact with ozone in the stratosphere. Ozone can be lost more rapidly than naturally produced. The primary cause of ozone-layer depletion is chlorofluorocarbons or CFCs. The chlorofluorocarbon molecules in the stratosphere are broken down by ultraviolet radiation and chlorine atoms are released. Such atoms react with and kill ozone. Depletion of the ozone layer is the progressive thinning of the upper atmosphere of the earth's ozone layer due to the release of chemical compounds containing gaseous bromine or chlorine from industry or other human activities.
Q2. What is the Ozone Hole?
The word 'ozone hole' refers to the loss in the upper atmosphere (stratosphere) of the protective ozone layer over the polar regions of the Earth. The action of the sun's ultraviolet radiation on oxygen molecules continually creates stratospheric ozone (known as photochemical reactions). The annual ozone "hole" over Antarctica that has arisen during the Antarctic Spring since the early 1980s is one example of ozone depletion. This is not only a hole in the ozone layer but rather a large stratospheric region with very low ozone levels. It is necessary to know that ozone depletion is not confined to the South Pole region. As per researches, Ozone depletion occurs over latitudes that include North America, Europe, Asia, and most of Africa, Australia, and South America, etc.