New Delhi, Feb. 7 -- Delhi's air quality improved on Thursday - partly due to favourable meteorological conditions, but also a malfunctioning air quality monitoring system as real-time data from 34 of 39 air quality monitoring systems in the Capital went "missing".

This was the third time in the past 30 days that AQI data was not available for hours and was only made available at night.

The Central Pollution Control Board (CPCB) released its daily air quality index (AQI) bulletin - the national bulletin was still not available, but a Delhi-NCR AQI bulletin was made available - around 9pm, instead of around 4pm -- while only partial data, that too for only three cities, was available on the Sameer phone app till 8pm.

The CPCB daily bull...