Question

what do you mean by polluted air ?mention the cause for the same

Answer 1

polluted air means air which is contained i.e. air which is not pure and full of pollutants.
CAUSES:
1- untreated smoke from factories
2- carbon dioxide emissions

Answer 2

Polluted air is contamination of air by harmful pollutants. It is called air pollution.
Causes :
1) burning of fossil fuels.
2) indoor air pollution
3) mining operations
4) pollution from factories