I wish India would ban two-stroke engines (phase them out, not ban them outright obviously), that would make a huuuuggeee difference in the air pollution of the large cities.
Other bigger factors to pollution are industries and electricity production. Curbing pollution is not possible if country/states are not very concerned about it, be it regulating the industries, making better public transport or focusing on renewable energy. Problem is, some of the leaders are focused on politics and others care only about growth and economics. They don't even think that pollution is a real issue. And those who care and think about it, are not allowed to live and do their work!