Question raised in Lok Sabha on Increase in Level of Particulate Matter, 21/06/2019. Ambient air quality data of Delhi monitored under Continuous Ambient Air Quality Monitoring Stations (CAAQMS (real time)) during 2016-2018 is enclosed at Annexure-II. The ambient air quality data for metropolitan cities / million plus urban agglomerations during 2016- 2018 is given in Annexure-I. Analysis of data revealed that SO2 levels were within the National Ambient Air Quality Standard (NAAQS) in all 50 cities during 2016-18.