3.2.1 Motor Vehicles
It is quite obvious that by far the largest amount of pollutants were emitted by motor vehicles. Also the amount of air pollution due to motor vehicles is increasing day by day. This means that there will be more polluted highways, and roads, and more congestion. Hydrocarbons and Nitrogen oxides emanating mainly from motor vechiles are the ingredients of photochemical smog. This photochemical smog problem can be clearly seen in the downtown areas of our cities.
A major amount of air pollution in United States is contributed by industries. The major contributors of industrial pollution are metallurgical plants, smelters, chemical plants, pertroleum refineries, fertilizer and synthetic rubber manufacturers, pulp and paper mills etc. Industrailization has helped in technological progress and it helped in raising the standard of living. But certain price has been paid with respect to the environment quality and especially with respect to air pollution.
3.2.3 Power Plants
In United States more than 90% of the electrical energy is generated by burning coal and oil. As sulfur is the major ingredients of these fuels power plants are the greatest contributors to sulfur dioxide pollution. Power consumption increases twice as fast as the population. The use of low sulfur fuel, which is rather scarce, is one of the methods used to reduce sulfur emissions. Other methods of power production such as hydroelectric power, energy from gas turbines, magneto hydrodynamics, garbage burning, and nuclear reactor, should be investigated for their economic feasibility and potential hazards.
3.2.4 Space heating
Emissions from area sources constitute the fourth largest source of air pollution. These include single and
multiple houses, apartment houses, offices, stores, restaurants, hotels, clubs, hospitals, laundries, dry cleaners
etc. The major pollution from residential areas which are constructed far away from industries and
seperated from heavy traffic are fireplaces in the cold months and barbecues in the warm summer months.
3.2.5 Refuse Disposal
Most of waste material is burned in municipal, industrial and commericial incinerators, in appartment
house incinerators, or in open dumps. An ordinary apartment house incinerator emits about 25 pounds of
pollutants for every ton of refuse burned.
3.2.6 Transportation Services
Ships are considerable contributors of smoke and SO2 to the pollution in port cities. Automobiles are
naturally the biggest pollutors, but emissions from jet aircarft are coming very close in quantity to those
from power plants.
3.2.7 Commercial and agricutural activites
Demolition, construction, and spray painting are the most common sources of pollution within this category.
Field burning and dusting and spraying of the fields with pesticides are some of the methods farmers use to
contribute their share to the general pollution problem.