The System of Air Quality and Weather Forecasting and Research (SAFAR) examined the quality of air in Delhi, Mumbai, and Pune from February 27 and March 13, 2017.

The study found that 20% of the days in Mumbai had ‘very poor’ air quality, while Delhi and Pune did not have any ‘very poor’ air quality days.

It was also noted that Delhi and Pune had 40% and 47% ‘satisfactory’ air quality days respectively, but Mumbai only had 13%.

“Between February and March, Mumbai had more ‘poor’ and ‘very poor’ days and less ‘satisfactory’ air quality days. Delhi and Pune did not have any ‘very poor’ days with cleaner air than Mumbai,” said the study.

The data also revealed that the air quality index (AQI) in Mumbai was 312, whereas Delhi recorded an overall AQI of 105.

The study by SAFAR showed that the levels of particulate matter in Mumbai were well above the permissible limits. These microscopic pollutants in the air can easily enter the lungs and cause ailments.

Experts said that Delhi, which is considered as one of the most polluted cities in the world by the World Health Organisation, recorded an improvement in air quality, which comes as good news to its residents.