The Causes of Ozone Depletion
Scientific evidence indicates that stratospheric ozone is being destroyed by a group of manufactured chemicals, containing chlorine and/or bromine. These chemicals are called "ozone-depleting substances" (ODS). ODS are very stable, nontoxic and environmentally safe in the lower atmosphere, which is why they became so popular in the first place. However, their very stability allows them to float up, intact, to the stratosphere. Once there, they are broken apart by the intense ultraviolet light, releasing chlorine and bromine. Chlorine and bromine demolish ozone at an alarming rate, by stripping an atom from the ozone molecule. A single molecule of chlorine can break apart thousands of molecules of ozone. What's more, ODS have a long lifetime in our atmosphere — up to several centuries. This means most of the ODS we've released over the last 80 years are still making their way to the stratosphere, where they will add to the ozone destruction. The main ODS are chlorofluorocarbons (CFCs), hydrochlorofluorcarbons (HCFCs), carbon tetrachloride and methyl chloroform. Halons (brominated fluorocarbons) also play a large role. Their application is quite limited: they're used in specialized fire extinguishers. But the problem with halons is they can destroy up to 10 times as much ozone as CFCs can. For this reason, halons are the most serious ozone-depleting group of chemicals emitted in British Columbia. Hydrofluorocarbons (HFCs) are being developed to replace CFCs and HCFCs, for uses such as vehicle air conditioning. HFCs do not deplete ozone, but they are strong greenhouse gases. CFCs are even more powerful contributors to global climate change, though, so HFCs are still the better option until even safer substitutes are discovered. The Main Ozone-Depleting Substances (ODS)
The most widely used ODS, accounting for over 80% of total stratospheric ozone depletion. Used as coolants in refrigerators, freezers and air conditioners in buildings and cars manufactured before 1995. Found in industrial solvents, dry-cleaning agents and hospital sterilants. Also used in foam products — such as soft-foam padding (e.g. cushions and mattresses) and rigid foam (e.g. home insulation). Halons
Used in some fire extinguishers, in cases where materials and equipment would be destroyed by water or other fire extinguisher chemicals. In B.C., halons cause greater damage to the ozone layer than do CFCs from automobile air conditioners. Methyl Chloroform
Used mainly in industry — for vapour degreasing, some aerosols, cold cleaning, adhesives and chemical processing. Carbon Tetrachloride
Used in solvents and some fire extinguishers.
HCFCs have become major, “transitional” substitutes for CFCs. They are much less harmful to stratospheric ozone than CFCs are. But HCFCs they still cause some ozone destruction and are potent greenhouse gases. What You Can Do about Ozone Depletion
Help Prevent Further Ozone Depletion
The nations of the world have taken a crucial step in joining together to halt the production and use of ozone-destroying chemicals. But the work can't stop there. Here's what you can do: Know the rules: It is illegal to recharge refrigerators, freezers and home/vehicle air conditioners with CFCs. If you have an older vehicle with an air conditioner*, have it serviced by a qualified technician, and make sure the CFC is recaptured and recycled by technician who is specifically certified to do this work. If you don't use your air conditioner — or if the vehicle is about to be scrapped — make sure a qualified technician recaptures and recycles the CFC. *Vehicles of model year 1995 or newer do not use CFCs.
The same rules apply to older refrigerators freezers and home air conditioners, which may contain CFCs. Don't buy or use portable fire extinguishers that contain halons. Protect Yourself from Ultraviolet (UV) Radiation...
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