Describe in brief any one case study as success story addressing environmental issues.

Explanation

Controlling Vehicular Air (Case Study of Delhi). Delhi has the maximum number of vehicles in India. In 1990 the total number of cars in Delhi were more than the combined number for the states of West Bengal and Gujrat. Since 80% of air pollution in urban areas is due to automobiles, Delhi used to rank fourth amongst the 41 most polluted cities of the world. The problem of air pollution was so serious that most Delhites began to complain of burning eyes and respiratory discomforts. A public interest litigation (PIL) was filed in Supreme Court: The Supreme Court directed the government to take appropriate measures for reducing pollution caused by automobiles through (i) Switch over of public transport from diesel/petrol to CNG. (ii) Phasing out of old vehicles. (iii) Compulsory use of unleaded petrol and reduced sulphur content of diesel. (iv) Compulsory regular check up of pollution emission of vehicles and enforcement of euro II norms. (v) Fitting the vehicles with catalytic converters. Delhi became the first city of the world to use CNG for its public transport system and autorickshaws by the end of 2002. CNG (compressed natural gas) is a better fuel than petrol or diesel because it is (a) Cheaper, (6) Burns more efficiently, (c) Does not produce much pollution, (d) Cannot be siphoned off by thieves, (e) Cannot be adulterated like petrol and diesel.
Because of the above mentioned measures adopted by the Government, the air quality of Delhi has improved with a substantial fall in `SO_2`, CO, NOX level between 1997-2005. However, the number of vehicles is rising rapidly in Delhi. Further, vehicles coming from other states, especially buses and trucks are not fitted with CNG. Therefore, there is every likelihood that Delhi may face high pollution level once again.