1、Unit 4Text:Environmental Protection（环境保护）1.Key words2.Externality3.Forms of environmental pollution4.Causes for environmental pollution5.Controls of environmental pollution6.Questionsenvironmental pollutionone-way externalityuncompensated damageindustrial establishmentmarginal utilityorganic sewages
2、elf-purification.atmospheric pollutionpollution controlnoxious dischargesbody of waterpollution abatementwater purificationwater cleanlinessmarginal benefitmarginal costinternalizing the externalitiesbiochemical oxygen demandA situation in which action by one consumer or producer confers benefit or
3、inflicts damage on another consumer or producer is said to involve externalities.Environmental pollution typically involves one-way externality,in which the actions of one producer or consumer inflict uncompensated damage on other producers and consumers.3.1 Air pollution3.2 Water pollution3.3 Accum
4、ulation of solid wastes3.4 Noise pollutionThis is the discharge of noxious gases and solid particles into the atmosphere,leading to“smog”conditions in many metropolitan areas.This type of pollution arises from discharge of organic and inorganic wastes into streams and lakes.The automobile junkyard i
5、s the most conspicuous example.This is a level of background noise that can range from mildly unpleasant to literally deafening.With the growth of population and production,clean air and pure water have become scarce goods,particularly in the metropolitan areas where most of the population resides.N
6、atural processes can no longer cope unaided with the flow of waste materials,and the environment can become overloaded to a degree that produces permanent deterioration.Discharge of plant nutrients into a lake can stimulate the growth of weeds and algae to the point where the lake fills up with soli
7、d matter.Heavy discharge of organic sewage into a river can reduce the oxygen content of the water to the point where it becomes a dead stream,incapable of supporting fish or other life and incapable of selfpurification.Atmospheric pollution in our larger cities could reach the point at which life i
8、n these areas would become impossible.5.1 Damage created by water pollution5.2 Social benefits from pollution reduction5.3 Social costs from pollution reduction5.4 ConclusionCommunities located downstream have to spend more on water purification to make the water safe and palatable.Industries locate
9、d downstream may also have to spend money on raising water quality to the level needed for their operations.Fish life may be damaged.Boating and swimming may be prevented.Debris and odors may reduce the attractiveness of recreational areas.The marginal benefit of a 1 percent improvement in cleanline
10、ss declines as the cleanliness level rises.Rising cleanliness from 20 to 21 percent will yield more benefit than raising it from 85 to 86 percent.Pollution abatement also requires use of economic resources.Either production processes have to be changed,equipment must be installed to reduce waste dis
11、charges,or water purification systems must be constructed to clean up after the fact.This takes labor and capital;and this is a social cost,regardless of who pays the money cost.It is reasonable to expect that the cost of an additional unit of cleanliness will rise as more and more cleanliness is pr
12、oduced.The level of water quality should be raised so long as the marginal benefit from further improvement exceeds the marginal cost of achieving it.The gap between private and social cost is eliminated.This is called“internalizing the externalities.”(1)What is pollution?Which form of pollution do
13、you find the most serious around you?(2)Why does such pollution around you occur?(3)An important issue in developing environmental control is how pure we want the air or water to be.Explain how economic analysis can be applied to this issue.(4)You have a friend who argues that pollution is an absolute bad,and that complete air and water cleanliness is an absolute good that should be pursued without compromise.What would you reply?
