Summarize the following passage :
Of the many pressing problems of today, the pollution of environment is the most serious one. And it is a matter of profound concern all over the world. The ecological imbalance caused by acts of man, such as deforestation, environmental pollution, nuclear explosions and the dumping of garbage causes health hazards.
Calcutta is one such place where the contaminated air and water threaten the very existence of citizens. The waters of the Ganga are also polluted by the domestic sewerage system, waste products of various factories, carcasses and filth thrown by the people.
Garbage piling at street corners causes air pollution. Irresponsible citizens and the Calcutta Municipal Corporation are to be blamed for this. Smoke belched out by factories in and around Calcutta also pollutes the air to a great extent. The number of trees is too small in comparison to the population of Calcutta. Every year attempts are made to plant trees but for want of proper care, most of them vanish in no time. Automobiles contribute to air pollution too.
Pollution, which is caused by deforestation, environmental pollution, nuclear explosions and dumping of garbages, resulting in health hazards, is a matter of global concern. The people of Calcutta suffer from both air and water pollution. The river Ganga is getting polluted by thoughtless activities Garbages, emission of smoke from factories, fewer number of trees and automobiles are responsible for air pollution in the city. The negligence of authorities is also to be mentioned.