The ozone layer is a region of the earth’s upper atmosphere lying mostly in the stratosphere that is characterized by high ozone content, it blocks most of the sun’s ultraviolet radiation from entering the lower atmosphere.
Ozone layer depletion refers to the damage of this protective layer. It is damaged by substances that contain, bromine, fluorine, carbon, hydrogen and chlorine in varying quantities.
Chlorofluorocarbons, carbon tetrachloride, and methyl chloroform are human-produced ozone-depleting gases.
The depletion of the ozone layer has varying implications on human health, agriculture, marine ecosystems, and materials.
Effects on human health.
Excessive exposure to ultraviolet radiation can cause sunburn. They can be mild or severe. Severe sunburns are marked by bright pink or scarlet-colored skin, swelling, and blistering. Sunburns can also lead to dehydration because of water lost through the skin.
Three kinds of skin cancer have been associated with ultraviolet radiation exposure basal cell carcinoma squamous cell carcinoma and melanoma. By far the most common form of Skin cancer basal cell carcinoma which makes up 75 to 90 percent of all skin cancers is strongly linked with sun exposure.
Keratoconjunctivitis or snow blindness occurs as a result of acute overexposure of the eyes.
It is essentially a sunburn on the surface of the eye around the cornea and conjunctiva
Symptoms include redness of the eyes and a gritty feeling which progresses to pain and an inability to tolerate any kind of light. Fortunately this condition is temporary.
Among the ocular diseases associated with solar exposure, cataracts is by far the most important from a public health perspective. Characterized by a gradual loss in the transparency of the lens due to the accumulation of oxidized lens proteins, the end-effect is often blindness.
Effects on the human immune system
In humans, the skin is the principal barrier to external factors, and thus the first line of defense against foreign agents that may threaten health. Inflammatory response as a result of exposure to ultraviolet radiation might compromise other important skin functions.
Effects on agriculture
According to the Environmental Effects Assessment Panel Report for 2010 by United Nations Environment Programme.
â€œIn areas where substantial ozone depletion has occurred, results from a wide range of field studies suggest that increased ultraviolet radiation -B reduces terrestrial plant productivity by about 6%â€.
This reduction results from direct damage and increased diversion of plant resources towards protection and acclimation. Long-term effects of reduced plant growth could be important, particularly for potential carbon sequestration.
Ultraviolet radiation directly causes alterations in protein synthesis and DNA through absorption of high-energy photons and can indirectly generate reactive oxygen species, which cause diverse damage to proteins, nucleic acids, and lipids.
Effects on Marine Ecosystems
The rise in atmospheric CO concentrations increases the acidity of the water, making calcified organisms more vulnerable to solar ultraviolet radiation.
The persistent acidification of marine waters impairs carbonate integration in calcified organisms, such as phytoplankton, seaweeds and corals.
Solar ultraviolet radiation has also been found to cause damage to early developmental stages of fish, shrimp, crab, amphibians and other animals. The most severe effects are decreased reproductive capacity and impaired larval development
Effect on materials.
Increase in Solar ultraviolet radiation levels accelerates the breakdown of Synthetic polymers, naturally occurring biopolymers which are materials of commercial interest limiting the length of time for which they are useful outdoors.
The Montreal Protocol was adopted in 1987, as a result of the growing concern for ozone depletion in order to reduce and control industrial emission of chlorofluorocarbons (CFCs). This international agreement has succeeded to a great extent in reducing the emission of these compounds. Continued reduction in release of greenhouse gases in the atmosphere will go a long way in mitigating the effects of ozone depletion.