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International Day for the Preservation of the Ozone layer

International Day for the preservation of the Ozone layer by Dr. Dotun Bobadoye; COO, GET Consortium

September 16 was designated by the United Nations General Assembly as the International Day for the Preservation of the Ozone Layer. This designation had been made on December 19, 2000, in commemoration of the date, in 1987, on which nations signed the Montreal Protocol on Substances that Deplete the Ozone Layer.

The ozone layer is a region of  Earth‘s stratosphere that absorbs most of  the Sun‘s ultraviolet radiation. It contains high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth’s atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 15 to 35 kilometres above Earth, although its thickness varies seasonally and geographically.

The ozone layer acts like sunscreen, protecting the Earth from harmful ultraviolet rays. In 1974, scientists first found that chlorine from chemicals used in refrigerators, aerosol cans and other products can destroy ozone molecules. These chemicals, chlorofluorocarbons and hydrochlorofluorocarbons were thinning the ozone layer around the world, it was later found that it’s creating a hole in it, the size of the continental U.S. above the Antarctic. The 1989 Montreal Protocol limited the production and use of these gases

Effect of Ozone layer Depletion Human Health

Stratospheric ozone depletion has a range of possible health impacts on your skin. Epidemiological studies implicate solar radiation as a cause of skin cancer including squamous cell carcinoma, basal cell carcinoma, and melanoma with a higher risk in individuals with fair skin. In fact, the International Agency for Research on Cancer concluded, in 1992, that solar radiation is a cause of skin cancer. And the highest risk for skin cancer is related to UVB exposure. Obviously, this is an ominous sign, with ozone depletion leading to greater ground levels of UVB.

UV-B radiation can damage several parts of the eye, including the lens, the cornea, and the membrane covering the eye (conjunctiva). “Snow blindness” is the result of over exposure to UV-B and occurs in areas of the world with high levels of UV exposure, including snowy regions at high altitudes. Snow blindness is not unlike a sun burn, and if repeated, can cause damage to eye over the long term. Cataracts are a clouding of the eye’s lens and are the leading cause of permanent blindness worldwide. They are a result of over exposure to UV. A sustained 10% thinning of the ozone layer is expected to result in nearly two million new cases of cataracts per year globally.

Effects on Marine Ecosystems

Phytoplankton forms the foundation of aquatic food webs. Phytoplankton productivity is limited to the euphotic zone, the upper layer of the water column in which there is sufficient sunlight to support net productivity. Exposure to solar UVB radiation has been shown to affect both orientation and motility in phytoplankton, resulting in reduced survival rates for these organisms. Scientists have demonstrated a direct reduction in phytoplankton production due to ozone depletion-related increases in UVB.

UVB radiation has been found to cause damage to early developmental stages of fish, shrimp, crab, amphibians, and other marine animals. The most severe effects are decreased reproductive capacity and impaired larval development. Small increases in UVB exposure could result in population reductions for small marine organisms with implications for the whole marine food chain.

Effects on Biogeochemical Cycles

Increases in UVB radiation could affect terrestrial and aquatic biogeochemical cycles, thus altering both sources and sinks of greenhouse and chemically important trace gases (e.g., carbon dioxide, carbon monoxide, carbonyl sulfide, ozone, and possibly other gases). These potential changes would contribute to biosphere-atmosphere feedbacks that mitigate or amplify the atmospheric concentrations of these gases.






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