Examine the effects of air pollution on Calcutta

Calcutta suffered from air pollution. Its inhabitants inhaled grey smoke, particularly in winter.
Since the city was built on marshy land, the resulting fog combined with smoke produced thick black smog.
High level of pollution was the result of the huge population that depended on dung and wood as fuel in their daily life.
Smoke from the chimneys of industrial units in addition to smoke from steam engines of trains polluted the city even further.