(i) Huge population depended on dung and wood as fuel in their daily life.
(ii) The industries and establishments that used steam engines were run on coal.
(iii) In 1855, the introduction of railway brought coal from Raniganj which had high content of ash. It also polluted the air.
(iv)The fog in the city combined with smoke to create thick smog.
(v) Due to mashy land, the resulting fog combined with smoke to generate thick smog.
Bengal Smoke Nuisance Commission controlled industrial pollution in Bengal.