In order to live a healthy life in Delhi or any other city for that matter, you need to do the following
1) Adequate Exercise - at least 45 mins daily. Walk at least 10,000 steps daily. In doors or outdoors basis level of pollution.
2) Complete Medical check up at least once every year.
3) Adequate rest - at least 6hrs of sleep daily.
4) Consume Balance diet
5) Don’t skip meals
6) Meditate 10 mins daily and read positive material.
7) Plant more trees to help improve air quality. Indoor and outdoor.
8) Use certified & specialized Air purifier in home as well as cars.
9) Don't Smoke.
10) Avoid Alcohol
11) For strengthening of lungs do pranayam.
12) Include ginger, turmeric, garlic , green tea, calciferous vegetables and vitamin C rich foods in your diet.