• India’s National Air Quality Index does not provide a reliable picture of pollution in the cities. 
  • The index uses colours to show how polluted the air in the area is at any time. 
  • However, this is unreliable because most cities don’t have enough monitoring stations.

NEW DELHI: Two years after it was started, India's National Air Quality Index (NAQI) does not provide a reliable picture of pollution in cities. The index uses colours ranging from dark green to dark red to show users at a glance how polluted the air in their area is at any time. However, it is unreliable because most cities don't have enough monitoring stations, and the existing stations do not monitor for all important pollutants.

Not enough stations

The entire metropolis of Mumbai—home to more than 2.2 crore people—has only one air quality monitor in Bandra for NAQI. When former environment minister Prakash Javadekar launched NAQI under the Swachh Bharat campaign in April 2015, the goal was to cover 46 cities with a population of more than 10 lakh each, but only 29 are on the network so far. Of these, 20 cities, including some severely polluted ones like Varanasi, Patna and Kanpur, have only one NAQI monitoring station each.

The northeast has virtually no monitoring station. Large states like Chhattisgarh, Jharkhand and Odisha also don't have any. Asansol, Coimbatore, Bhiwadi, Ghaziabad, Noida, Ludhiana and Vapi are some of the critically-polluted areas that may be connected to NAQI this year.

Delhi is the only city with eight monitoring stations and it is likely to get 20 more this year. Compare that with Beijing that already has more than 35, and London, which has 100, according to a recent Greenpeace India report. Entire China has 1,500 government-run monitoring stations.

Central Pollution Control Board (CPCB), which runs the NAQI programme, had prescribed at least three stations each in Class 1 cities, nine each in mega cities like Bengaluru, and six each in all other cities that are either state capitals or major industrial areas.