Such vitally important questions as acceptable standards of water and air quality have received some attention recently.
In the United States, the Public Health Service and the Environmental Protection Agency (EPA) have laid down certain standards to which drinking water and water for other uses must conform. These standards set mandatory limits on the levels of coliform bacteria, arsenic barium, cadmium, chromium, cyanide, lead, fluoride, selenium, and silver and recommendatory limits on the taste, smell and colour of drinking water.
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EPA has published effluent limitation guidelines, performance standards and pretreatment standards for some 23 industrial categories of water pollution; these performance standards reflect the greatest degree of effluent reduction which can be achieved by available means.
Some industries covered by performance standards for new facilities include: pulp and paper, meat products, dairy products, fruit preservation and canning, seafood processing, sugar processing, textile mills, cement manufacturing, electroplating, organic and inorganic chemicals manufacturing, soaps and detergents, fertilizers, nonferrous metals, plastic and synthetic materials, petroleum and oil refineries, iron and steel plants, leather tanning, asbestos and glass manufacturing, rubber processing, and timber products processing.
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The EPA has also prescribed certain effluent limitation standards, such a standard implying the maximum amount of a pollutant that a polluter is permitted to discharge into a water body. Such limitation standard is zero for any radiological, chemical or biological warfare materials or high-level radioactive wastes (i.e., such wastes are not permitted to be discharged into water).
Municipalities and regional sanitary authorities are legally required to provide secondary treatment facilities of their effluents. The minimum level of effluent quality to be achieved is expressed in terms of BOD, suspended solids, faecal coliform counts, bacteria and pH (see Train, 1974).
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The EPA possesses a wide variety of enforcement tools that can be used to tackle water pollution. These include imposition of heavy fines and imprisonments. In 1973 alone, more than 500 Federal enforcement actions were initiated or pursued, and most of these concerned oil and hazardous liability.
On the basis of a study of the 22 largest and most highly polluted waterways in America, the EPA has concluded that the poorest quality of water and worsening trends are associated with nitrogen and phosphorus. In contrast, those pollutants which have received the most widespread control, including oxygen-demanding loads, and bacteria, show general improvement.
The air quality standard is a limit on the amount of a given pollutant permitted in the air around us. Another kind of standard is the emission standard which signifies the maximum amount of the pollutant that may be discharged from a specified point source. So far the EPA has prescribed emission standards for three hazardous air pollutants, viz., asbestos, beryllium and mercury.
Then there are the performance standards for fossil-fueled steam-generating plants, sulphuric and nitric acid plants, cement manufacturing plants, and large incinerators. These performance standards specify emission limits for particulates, SO2, nitrogen oxides, sulphuric acid fumes, as well as limits on visible emissions. Emission standards for motor vehicles pertain to CO, hydrocarbons and nitrogen oxides all of which constitute the main ingredients of photochemical smog.