India, Dec. 24 -- If Mumbai's air quality has lingered on the "moderate" level lately, it must be known that air quality readings since December 15 have been calculated using data from a limited number of monitoring stations, raising concerns over the legitimacy of the Air Quality Index (AQI) reported.

HT has scrutinised data accessed from the Central Pollution Control Board (CPCB) between November 15 and December 23, and has found that of the 28 air quality monitoring stations in Mumbai, only 17 to 19 were functional on most days between December 15 and December 23.

During this period, the city's AQI fluctuated between 91 and 138, remaining largely in the "moderate" category. However, the averages were drawn without data from several o...