1.Fortaleza, Joji Bryan Manongdo, Marc JulianMercado, Chino Karmelo Pilotin, Pamela Anne

2. Ozone Layer It is a layer in Earths atmosphere whichcontains relatively high concentrationsof ozone (O3). The ozone layer resides in the stratosphereand surrounds the entire Earth. It was discovered in 1913 by the Frenchphysicists Charles Fabry and Henri Buisson. 3. Ozone is constantly produced from O2molecules because of its reaction with UVlight. O2 molecules are more scattered becausethe stratosphere has less air. Stratospheric ozone protects us from excessUV but ozone in the lower atmosphere isan air pollutant with harmful effects on therespiratory systems of animals and will burnsensitive plants. 4. UV-B radiation (280- to 315- nanometer (nm)wavelength) from the Sun is partially absorbedin this layer. As a result, the amount of UV-Breaching Earths surface is greatly reduced. UV-A (315- to 400-nm wavelength) and othersolar radiation are not strongly absorbed by theozone layer. 5. Ozone Depletion The ozone layer can be depleted by free radical catalysts: nitric oxide (NO) nitrous oxide (N2O) hydroxyl (OH) atomic chlorine(Cl) atomic bromine (Br) 6. Concentrations of chlorine and brominehave increased in recent years due to therelease of large quantities of man-madeorganohalogencompounds,especiallychlorofluorocarbons(CFCs) andbromofluorocarbons (BFCs). CFCs and BFCs are capable of surviving therise to the stratosphere due to theirstability, where Cl and Br radicals areliberated by the action of ultraviolet light. 7. The Chlorofluorocarbons are expelled into the atmosphere by: Refrigeration Aerosol spray cans Air conditioning Foam insulation Cleaning agents Packing material CFCs were used in consumer products because they were chemically stable and non-toxic, thus it took decades before it was known to destroy the ozone layer. 8. Each radical is then free to initiate andcatalyze a chain reaction capable ofbreaking down over 100,000 ozonemolecules. The breakdown of ozone in the stratosphereresults in the ozone molecules being unableto absorb ultraviolet radiation. Consequently, unabsorbed and dangerousUVB radiation is able to reach the Earthssurface. 9. Though it is known that ozone is naturally decomposed to O2, the presence of Cl atoms in the stratosphere serves as a catalyst to the breakdown of ozone thus making the rate of decomposition faster. 10. The Ozone Hole The ozone "hole" is really a reduction inconcentrations of ozone high above theearth in the stratosphere. It is defined geographically as the areawherein the total ozone amount is less than220 Dobson Units. The ozone hole has steadily grown in size(up to 27 million sq. km.) and length ofexistence (from August through earlyDecember) over the past two decades. 11. Each spring in the stratosphere over Antarctica(Spring in the southern hemisphere is fromSeptember through November.), atmosphericozone is rapidly destroyed by chemical processes. As winter arrives, a vortex of winds developsaround the pole and isolates the polarstratosphere. When temperatures drop below -78C (-109F), thin clouds form of ice, nitricacid, and sulphuric acid mixtures. Chemicalreactions on the surfaces of ice crystals in theclouds release active forms of CFCs. Ozonedepletion begins, and the ozone hole appears. 12. Over the course of two to threemonths, approximately 50% of the totalcolumn amount of ozone in the atmospheredisappears. At some levels, the losses approach 90%.This has come to be called the Antarcticozone hole. In spring, temperatures begin to rise, the iceevaporates, and the ozone layer starts torecover. 13. Consequences of Ozone Depletion Everytime 1% of the ozone layer isdepleted, 2% more UV-B is able to reach thesurface of the planet Human exposure to UV-B increases the risk ofthe following diseases: Skin cancer particularly in Caucasians Cataracts Increased rates of malaria and other infectious diseases. Suppressed immune system 14. The environment will also be negativelyaffected by ozone depletion. Physiological and developmental processesof plants are affected by UVB radiation. Effects on animals will also be severe, andare very difficult to foresee. Exposure to solar UVB radiation has beenshown to affect both orientationmechanisms and motility inphytoplankton, resulting in reduced survivalrates for these organisms. 15. Solar UVB radiation has been found to causedamage to early developmental stages offish, shrimp, crab, amphibians and otheranimals. The most severe effects aredecreased reproductive capacity andimpaired larval development. Other ecosystems such as forests anddeserts will also be harmed Wind patterns could change, resulting inclimatic changes throughout the world. 16. Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles, thus altering both sources and sinks of greenhouse and chemically-important trace gasese.g., carbondioxide (CO2), carbon monoxide (CO), carbonyl sulfide(COS) andpossibly other gases, including ozone. These potential changes would contribute to biosphere- atmosphere feedbacks that attenuate or reinforce the atmospheric buildup of these gases. 17. Synthetic polymers, naturally occurringbiopolymers, as well as some other materialsof commercial interest are adversely affectedby solar UV radiation. Any increase in solarUVB levels will therefore accelerate theirbreakdown, limiting the length of time forwhich they are useful outdoors. Ozone depletion will also magnify theeffects of global warming. 18. The Montreal Protocol In 1985, the Vienna Convention establishedmechanisms for international co-operation inresearch into the ozone layer and the effectsof ozone depleting chemicals (ODCs). The first discovery of the Antarctic ozone holehappened in 1985. The Montreal Protocol on Substances thatDeplete the Ozone Layer was negotiated andsigned by 24 countries and by the EuropeanEconomic Community in September 1987. 19. The Protocol called for the Parties to phasedown the use of CFCs, halons and otherman-made ODCs. After a series of rigorous meetings andnegotiations, the Montreal Protocol onSubstances that Deplete the Ozone Layerwas finally agreed upon on 16 September1987 at the Headquarters of theInternational Civil Aviation Organization inMontreal. 20. The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere-- chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2000 (2005 for methyl chloroform). Scientific theory and evidence suggest that, once emitted to the atmosphere, these compounds could significantly deplete the stratospheric ozone layer that shields the planet from damaging UV-B radiation. 21. The Montreal Protocol on Substances that Deplete the Ozone Layer is one of the first international environmental agreements that includes trade sanctions to achieve the stated goals of a treaty. It also offers major incentives for non-signatory nations to sign the agreement. The treaty negotiators justified the sanctions because depletion of the ozone layer is an environmental problem most effectively addressed on the global level. 22. Furthermore, withoutthe tradesanctions, there would be economicincentives for non-signatories to increaseproduction, damaging the competitivenessof the industries in the signatory nations aswell as decreasing the search for lessdamaging CFC alternatives. At meetings in London (1990), Copenhagen(1992), Vienna (1995), Montreal (1997) andBeijing (1999) amendments were adoptedthat were designed to speed up the phasingout of ozone-depleting substances. 23. Summary of Montreal Protocol Control Measures ODS Developed Countries Developing Countries CFCsPhased out end of 1995 a Total phase out by 2010 HalonsPhased out end of 1993 Total phase out by 2010 CCl4Phased out end of 1995 a Total phase out by 2010 Methyl chloroform Phased out end of 1995 a Total phase out by 2015 HCFCs Freeze from 1996 bFreeze in 201635% reduction by 2004 Total phase out by 204065% reduction by 201090% reduction by 2015Total phase out by 2020 c 24. HBFCsPhased out end of 1995 Phased out end of 1995 Methyl bromide Freeze in 1995 Freeze in 2002 at average at 1991 base level d 1995-1998 base level 25% reduction by 199920% reduction by 2005 e 50% reduction by 2000Total phase out by 2015 70% reduction by 2001 Total phase out by 2005 a With the exception of a very small number of internationally agreed essential usesthat are considered critical to human health and/or laboratory and analyticalprocedures.b Based on 1989 HCFC consumption with an extra allowance (ODP weighted) equal to2.8% of 1989 CFC consumption.c Up to 0.5% of base level consumption can be used until 2030 for servicing existingequipment.d All reductions include an exemption for pre-shipment and quarantine uses.e Review in 2003 to decide on interim further reductions beyond 2005. 25. Becoming Ozone Friendly All parts of our daily lives have been touched byozone-depleting substances. Prior to the 1980s, CFCs and other ozone-depleting substances were pervasive in modern life. But thanks to the work of individuals, businesses, organizations, and governments around the world, substitutes that are safer for the ozone layer continue to be developed for many ozone-depleting substances. The phase out of ozone-depleting substances has also made a substantial contribution toward the reduction in greenhouse gas emissions since their global warming potential is very high. 26. Then: Ozone-depleting substances were all around us.Now:More ozone-friendlyproducts, better processes, and new equipment are in use.Computers Then: Solvents containing CFCs and methylchloroform were used to clean circuit boardsduring their production. Now: Some companies have eliminated the needto clean circuit boards during their production.Others use water or have temporarily switched toHCFCs. 27. Polystyrene Cups and Packing Peanuts Then: Some polystyrene cups and foam packingpeanuts were made using CFCs. Now: These products are made with materialsthat do not deplete the ozone layer.Aerosol Cans Then: CFCs were the propellant used in variousspray cans. Now: Pumps and alternative propellants usinghydrocarbons are being used. 28. Central Air Conditioners Then: CFCs were used as the coolant inhousehold air conditioners. Now: HCFCs and HFCs have replaced CFCs.Degreasers Then: CFCs or methyl chloroform were used inmany solvents for degreasing. Now: Water-soluble compounds and hydrocar-bon degreasers that do not deplete the ozonelayer are available for many applications. 29. Refrigerators Then: CFCs were used in refrigerator coolants andfoam insulation. Now: HFCs have replaced CFCs, and substitutesare on the horizon that will have reducedgreenhouse gas impacts.Car Air Conditioners Then: CFCs were used as the coolant inautomobile air conditioners. Now: HFCs have replaced CFCs.Fire Extinguishers 30. Fire Extinguishers Then: Halons were commonly used in hand-heldfire extinguishers. Now: Conventional dry chemicals, which dontdeplete the ozone layer, and water have replacedhalons. HFCs are also used.Furniture Then: Foam-blowing agents containing CFCswere used in furniture making. Now: Water-blown foam is being used. 31. Safety against UV Ultra-violet light (UV) is defined as electromagnetic radiation in the spectral region between 180 and 400 nanometers (nm). Immediate or prolonged exposure to UV light can result in painful eye injury, skin burn, premature skin aging, or skin cancer. Individuals who work with or in areas where UV sources are used are at risk for UV exposure if the appropriate shielding and protective equipment are not used. 32. Some Sources Welding operations Biological laboratories where gels are visualized Areas in which germicidal UV lights areused, including biological safety cabinets Libraries where UV light may be used toexamine documents Science laboratories where Mineralights areused to cause fluorescence Mercury vapour lamps with broken or missingenvelopes 33. The symptoms of UV overexposure to the skin are well known and characteristically called sunburn. However, the symptoms of overexposure to the eyes are not widely known. Symptoms are: a burning and painful sensation in the eye a sensitivity to light the sensation of a foreign object in theeye, sometimes described as sand in the eye tearing 34. Protection The purpose of the UV Light Safety Programis to ensure that the safeguards necessary tolimit exposure have been implemented. The key to effectively reducing UV exposureis to properly shield the source and torequire that users wear the appropriatepersonal protection. Personal protectionthat is appropriate includes weldersmasks, goggles and face shields. 35. Protection from ultraviolet (UV) radiation isimportant all year round, not just during thesummer or at the beach. UV rays from the suncan reach you on cloudy and hazy days, aswell as bright and sunny days. UV rays alsoreflect offof surfaceslikewater, cement, sand, and snow. Indoortanning (using a tanning bed, booth, orsunlamp to get tan) exposes users to UVradiation. The hours between 10 a.m. and 4 p.m.daylight savings time are the most hazardous 36. Safety Measures Seek shade, especially during middayhours. Wear clothing to protect exposed skin. Wear a hat with a wide brim to shade theface, head, ears, and neck. Wear sunglasses that wrap around andblock as close to 100% of both UVA and UVBrays as possible. Avoid indoor tanning. 37. Use sunscreen with sun protective factor(SPF) 15 or higher, and both UVA and UVBprotection. Some make-up and lip balms contain someof the same chemicals used in sunscreens. Ifthey do not have at least SPF 15, dont usethem by themselves. To reduce the harm from UV radiation, themost important thing is to minimize directexposure of the skin and the eyes tosunlight.