Question

why is delhi poluted

Answer 1

various reasons:
rich people tends to use a single car for each member . this tends to increase air pollution.
you want to go somewhere  you take your car and travel rather then using public transport.
huge amount of use of acs.

Answer 2

Delhi is polluted because of its excessive air wastes & water wastes even the loud noise somehow ; Its air pollution increases because the people tends to use more vehicles even one for one person & have more dependence on them. There are more factories which mostly increases polluted gases like carbon dioxide, carbon monoxide, etc. & excessive polluted water in rivers, etc. Hence, its most polluted.