(1) Trichlorofluoromethane*, *dichlorotetrafluoroethane*, and *monochloropentafluoroethane* are refrigerants restricted by the Montreal Protocol. Restrictions on their use have led to their replacement in many consumer and industrial products, including refrigerators and air conditioners.*
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Dichlorodifluoromethane is a refrigerant and aerosol spray propellant restricted by the Montreal Protocol. Manufacturers have had to shift to using arguably more dangerous chemicals because of the ban, namely the flammable propane, n-butane, and *isobutane*. Some products like whipped cream or cooking spray used compressed nitrous oxide or carbon dioxide.*
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*Bromochlorodifluoromethane* and *bromotrifluoromethane* are both *Halons* used in fire suppression, restricted by the Montreal Protocol. They have the advantage of not reacting to electrical equipment, so they can be used in areas with computers or other equipment without fear of damage. In many cases, they are being replaced by sprinklers, leading to potential damage to equipment. In some cases, alternative chemicals are being used, some of which have global warming or other side effects.*
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*2(a).* Ozone concentrations are at their highest in July. At that point, polar vortex winds have isolated chlorine and bromine into polar stratospheric clouds, where they are converted into less-stable forms. When polar sunlight returns in August, these less-stable forms are converted into free radicals which destroy ozone. This destruction continues until October, when the polar winds die down and the chemicals can disperse. Ozone rebuilding then begins until the next polar spring.*
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*2(b).* Over the past 30 years, ozone concentrations have dropped and the ozone hole has grown. Since the implementation of the Montreal Protocol, these have leveled off. It is now expected that the residual chemicals in the atmosphere