Ozone depletion

• O,O2 and O3 are present in the stratosphere in a dynamic equilibrium of chemical reactions caused by absorbance of UV
• Stratospheric ozone is located above earth's surface 12-24km
• Ozone prevents most High energy UV solar radiation reaching earth's surface
• UV is short wavelength electromagnetic energy
• If UV is not absorbed in the atmosphere it reaches earth and living cells may absorb it, this can break up biolomogical molecules causing skin damage, dna damage, cancer and affected photosynthesis rates
• Climate change affects the ozone layer: an increase in temperature changes in wind, changes in atmospheric composition all influence chemical and physical processes in the ozone layer
• Chloroflourocarbons are used in air conditioning units, refrigerators, aerosol cans and is also a greenhouse gas
• Ozone layer depletion causes increased UV radiation to reach the surface, causing living organisms harm
• Ozone depletion is caused by release of man-made chemicals containing chlorine, bromine such as chloroflourocarbons
• Substances such as chloroflourocarbons are stable and do not dissolve in rain hence remain in the atmosphere for years
• When these stable chemicals are carried into the ozone, solar UV radiations breaks it down releasing chlorine and bromine atoms which can destroy ozone molecules
• Some gases that cause ozone depletion are also greenhouse gases contributing to global warming
• Measuring ozone using the dobson unit, this estimates the thickness of all ozone in the atmosphere
• An ozone hole refers to levels below 220 du this has only been measured after increased pollution
• Ground based data collection at antarctica is evidence of ozone depletion, detection of higher levels of UV at ground level was evidence of ozone loss in the stratosphere
• Satellite surveys are evidence of ozone depletion
• Air samples can be taken in the stratosphere as eveidence for ozone depletion, they showed high UV levels
• Air samples collected by helium balloons confirmed chemicals were causing ozone depletion
• Ozone depletion over antarctica, atmospheric conditions over antarctica are unique, and hence ozone depletion is more severe here
• Restoration of ozone layer involved Vienna convention for protection of ozone, this was an agreement between every country in UN to protect ozone layer but it was not legally binding
• Montreal protocol (1987) is a method of ozone restoration: manufacture and use of cfcs were phased out and banned, there is a fund to help countries implement Montreal protocol
• Montreal protocol has been implemented by use of alternative process of materials, such as stick on or roll on deoderants, hydrochlorofluorocarbons replaced chloroflourocarbons, chloroflourocarbon solvents replaced by alcohol