The following points sum up the history of air pollution in Calcutta during the nineteenth century.
- Calcutta had a long history of air pollution. Its inhabitants inhaled grey smoke, particularly in the winter. Since the city was built on marshy land, the resulting fog combined with smoke to generate thick black smog.
- High levels of pollution were a consequence of the huge population that depended on dung and wood as fuel in their daily life. But the main polluters were the industries and establishments that used steam engines run on coal.
- Colonial authorities were at first intent on clearing the place of miasmas, or harmful vapours, but the railway line, introduced in 1855, brought a dangerous new pollutant into the picture coal from Raniganj.
- The high content of ash in Indian coal was a problem. Many pleas were made to banish the dirty mills from the city, with no effect.
- However, in 1863, Calcutta became the first Indian city to get smoke nuisance legislation.