Fig. 1. The location of CPCB stations used in this study. 1) Delhi, 2) Ambala, 3) Amritsar, 4) Jaipur, 5) Lucknow, 6) Patna 7) Jorapokhar, 8) Kolkata, 9) Ahmedabad, 10) Dewas, 11) Mumbai 12) Nagpur, 13) Amaravati, 14) Bangalore, 15) Trivandrum, 16) Chennai and 17) Hyderabad. (One station in each city).