In modern cities complete silence is a most unusual experience. Solutions in noise pollution come from a combination of quieting the sources of noise and soundproofing homes and places of work. Man uses more water than he does any other natural resource. Although supplies of water from precipitation are indefinitely renewable, in using them, man contaminates the water with an increasing burden of dissolved and suspended refuse. As a result, he not only drastically reduces the value of his water resources but eventually poisons the seas and oceans, destroying all marine life. The solution to water pollution is clear; effluent water must be purified before it is discharged into rivers. Conservation, the rational and well-managed exploitation of the earth’s natural resources, is the other side of the pollution coin. The recycling of waste products, particularly of used paper and metallic products, not only reduces the problem of pollution but also conserves supplies of timber and metal ores.
As the world runs short of energy producing minerals and conservationists become increasingly concerned at the disturbing of the ecological balance in rivers into which water, warm with the waste heat of industry, is discharged, more efficient insulation of homes and the beneficial employment of thermal waste, thus offer relief to problems, both of thermal pollution and of energy conservation. With water itself becoming daily more precious, the elimination of pollution and the desirability of re-use come to be seen as identical causes. Conservation of a second kind is concerned with the protection and preservation of as wide a range of living species as possible. Every animal and plant represents an irreplaceable reservoir of genetic material available to be used for the benefit of mankind; the extinction of any one of them would be a serious loss, not only to science, but also to the world at large. The very success of mankind has destroyed the natural habitats of many species, so careful management of the local environment is necessary if such species are to be preserved.