FUNCTION OF THE OZONE LAYER
Overexposure to UV Rays
For people, overexposure to UV rays can lead to skin cancer, cataracts, and weakened immune systems. Increased UV can also lead to reduced crop yield and disruptions in the marine food chain. UV also has other harmful effects.
Whenever outdoors for lengthy periods, always apply sunscreen with proper Sun Protection Factor (SPF) rating, and be sure sunglasses you purchase provide 100% UVA and UVB protection. The ozone layer protects the earth and its inhabitants from the harmful ultra violet rays by converting the UV rays.
CAUSES
Chlorofluorocarbons (CFCs), along with other chlorine- and bromine-containing compounds, have been implicated in the accelerated depletion of ozone in the Earth's stratosphere. CFCs were developed in the early 1930s and are used in a variety of industrial, commercial, and household applications. These substances are non-toxic, non-flammable, and non-reactive with other chemical compounds. These desirable safety characteristics, along with their stable thermodynamic properties, make them ideal for many applications--as coolants for commercial and home refrigeration units, aerosol propellants, electronic cleaning solvents, and blowing agents.
EFFECTS
UV RAYS
Stratospheric ozone protects the biosphere from potentially damaging doses of ultraviolet-B radiation (UV-B). Recent depletion of stratospheric ozone could lead to significant increases in UV-B reaching the Earth's surface. UV-B radiation is responsible for a wide range of potentially damaging human and animal health effects, primarily related to the skin, eyes, and immune system. Human exposure to UV-B depends upon an individual's location (latitude and altitude), the duration and timing of outdoor activities (time of day, season of the year), and precautionary behavior (use of sunscreen, sunglasses, or protective clothing). An individual's skin color and age can influence the occurrence and severity of some of the health effects from exposure to UV-B.
ENVIRONMENT
Effects of increased ultraviolet radiation on biological systems had been investigated even before the ozone-depletion issue came to prominence. Effects such as alterations in tropospheric chemistry and potential global warming due to chlorofluorocarbons (CFCs) did not present themselves, however, until depletion and the rise in CFC levels were thought to be possible.
RESPONSES TOWARDS OZONE DEPLETION
Protecting the stratospheric ozone layer by controlling the production and use of ozone-depleting compounds has been an environmental concern since the mid-1970s, when it was discovered that chlorine could potentially deplete the ozone layer. Not until significant losses of ozone were reported in 1985, however, did ozone depletion become an important international issue. The principal international policy instrument for protecting the stratospheric ozone layer is the
HYPERLINK "http://www.ciesin.org/TG/PI/POLICY/montpro.html"
Montreal Protocol on Substances That Deplete the Ozone Layer
. Many countries, and even some cities and other sub national authorities, have taken action to control production and use of chlorofluorocarbons (CFCs) and other ozone-depleting substances. Much of the National/Sub national Ozone Policy Formulation is in response to the Montreal Protocol, although several countries had taken steps to control CFCs prior to the international agreements set forth in the Protocol.
In response to these policy and regulatory developments, industrial organizations directly affected have been actively engaged in developing alternative substances to CFCs and other ozone-depleting compounds. Several environmental and economic factors need to be considered in
HYPERLINK "http://www.ciesin.org/TG/OZ/cfcphs.html"
Chlorofluorocarbon Phase out
, such as safety characteristics, efficiency, and ozone-depletion potential, and economic impacts on industry of phase out schedules for existing CFCs.
REDUCTION OF OZONE DEPLETION
Hydrochlorofluorocarbons (HCFCs) still contain chlorine atoms, but the presence of hydrogen makes them reactive with chemical species in the troposphere. This greatly reduces the prospects of the chlorine reaching the stratosphere, as chlorine will be removed by chemical processes in the lower atmosphere. Hydrofluorocarbons (HFCs), potential replacements for CFCs that contain no chlorine, have been evaluated for potential effects of fluorine compounds on ozone destruction.
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