Question

In metropolitan cities, automobiles cause air pollution.
A. 80 percent
B. 60 percent
C. 50 percent
D. 100 percent

Answer 1

Hint:-Air pollution means any undesirable change in the chemical, physical, and biological conditions of the air. Air pollution causes health problems and environmental problems. Automobiles act as a major cause of air pollution as the gases emitted by them contain air pollutants. Air pollutants means the substances or agents that cause air pollution. In metropolitan cities, the number of automobiles is very high and air pollution also increases.

Complete solution:Many substances act as air pollutants like unburnt hydrocarbons, carbon monoxide, ozone, sulfur dioxide, lead, nitrogen oxides, etc. These are mainly gases that are harmful to humans and the environment. It affects the respiratory tract of humans and animals. Air pollutants reduce the yield of the crops and cause the premature death of plants. The effect of air pollution depends on the duration of exposure, the concentration of air pollutants, and the type of organism being exposed. In metro cities automobiles is the major cause of air pollution or atmospheric pollution. Metropolitan cities refer to urban areas with a high population in the range of 1 million or 10 lakhs having industrial, commercial, and economical significance. As the population size in these cities is very high the number of automobiles is also more in these cities. Automobiles release unburnt hydrocarbons, carbon monoxide, sulfur oxides, nitrogen oxides. The use of lead-containing petrol in vehicles also causes pollution. Catalytic converters are used in automobiles to reduce the number of unburnt hydrocarbons emitted by them. The use of lead-containing fuels decreases the efficiency of the catalytic converters. Noise is also considered an air pollutant. Noise is the undesired high level of sound. In cities as the population is high, the noise produced by the people also increases. So the noise produced by automobiles is also considered an air pollutant. Therefore automobiles cause approximately 80 percent of air pollution in metropolitan cities.
Thus the correct answer is option (A), 80 percent.

Note:- There are several legislative measures taken all over the world to decrease air pollution. In India, the Air ( Prevention and Control of Pollution) Act was made into action in 1981, which was amended to include noise as an air pollutant in 1987. Public transportation is preferred over personal automobiles to decrease the number of vehicles. The use of CNG – Compressed natural gas is also promoted as they burn fuels very efficiently.