Poor air quality across 41 cities in 2015, says CPCB survey

While the worsening air pollution in the country's metro cities has been under scrutiny of courts and Centre, the air quality across tier-II or million plus cities is equally bad. People in 41 Indian cities with a million plus cities breathed bad quality air during 58% of the days monitoring was carried out in 2015, a Central Pollution Control Board (CPCB) study said. CPCB monitored air quality at a total of 205 monitoring stations. Days when the air quality exceeded pollution norms were categorized as 'bad days' as per the study.

The air quality stations monitor sulphur dioxide, nitrogen dioxoide and particulate matter smaller than or equal to 10 micrometers. As per the Air quality index calculated for 41 million plus cities based on available air quality data, 48% of AQI values can be categorised as moderate category, 32% as satisfactory and 1% as severe. Coimbatore, Ahmedabad and Rajkot recorded the highest number of good air quality days while Gwalior and Allahabad had the highest number of bad air quality days.

As has been seen during various other studies too, air quality has been good during monsoon while the quality dipped across cities during winter. "Most cities have recorded high percentage of good says during monsoon season and low percentage of good days during winter season. Coastal cities have recorded higher percentage of good days compared to the land locked cities," the study said.

Southern and western cities have recorded higher percentage of good air quality, which according to the report can be due to variation in the local meteorological and geographical land conditions, including topography, type of soil and vehicular density.

On water quality, CPCB did a long-term assessment of water quality data and identified 275 rivers out of 445 as polluted. It found that the maximum percentage of polluted river stretches were found in Maharashtra, followed by Assam and Madhya Pradesh.