2.2. Atmospheric Pollution Over Cities

Generally any substance that people introduce into the atmosphere that has damaging effects on living things and the environment is considered air pollution. A city atmosphere is affected by soot, ash, gases, fumes, smoke and oxides of sulphur, carbon, nitrogen. Carbon dioxide and other greenhouse gases such as Methane are the main pollutant that is warming Earth. Sulfur dioxide and closely related chemicals are known primarily as a cause of acid rain. These have effect of blanketing the radiation over a city, increasing the city’s albedo. These also act as a condensation nuclei. Under normal conditions, much of this polluted part is diffused upwards

by turbulence and removed by stronger winds at height. However, high rise buildings of cities act as obstruction in free movement of these particles. The greatest concentrations of smoke occur with low wind speeds, temperature inversion and high relative humidities.

It requires multifold strategies with the active participation of civil society and individual city people. On a larger scale, governments are taking measures to curb the air pollution through legislation, tax benefits and other schemes. Civil society can play its part by spreading environmental awareness among people and helping people in urban forestry etc.