Industrialisation leads to coming up of factories and industries..
(i) The harmful smoke that comes out of the factory through the chimney contributes to air pollution.
(ii) For industrialization deforestation has to be done to clear land .. Now when no trees are there there is no one to take CO2 and give O2 and content of harmful gases in the atmosphere rises.
(iii) When industrialisation takes place, ultimately economic development is there. So standard of living enhances .. More vehicles will be used by the people. and they will also release harmful smoke as exhaust gases.