CPCB considers raising pollutant monitoring cap after Delhi data gaps
The Central Pollution Control Board is discussing ways to record peak particulate matter levels that currently exceed the existing measurement limit.
The Central Pollution Control Board (CPCB) is considering measures to capture peak levels of particulate matter (PM) that exceed current monitoring limits, according to The Hindu. This follows instances where air quality data from several government monitoring stations in Delhi disappeared for hours during a pollution spike after Deepavali on Sunday.
The CPCB stated on Tuesday that PM levels are only measured up to 1,000 micrograms per cubic metre (µg/m³) for Air Quality Index (AQI) calculations. This explains why data went missing on Deepavali night when actual concentrations surpassed this limit. The automated data validation system treats hourly readings beyond the calibrated range as outside the range and does not use them in computations.
An official told The Hindu that while equipment and instruments in Delhi have been updated, the 2015 AQI calculation methodology was never updated to reflect these changes. Discussions are now underway to raise the cap so that peak values above 1,000 µg/m³ can be measured.
Of the 59 air quality monitoring stations in Delhi, 46 are operated by the Delhi Pollution Control Committee (DPCC). The DPCC recorded PM2.5 and PM10 levels exceeding 1,000 µg/m³ on Deepavali night. The CPCB uses data from these stations, along with others, to calculate the AQI.
Delhi's air quality improved to the 'poor' category on Tuesday, with a 24-hour average AQI of 299. Experts noted that increased wind speeds contributed to this improvement and suggested air quality might continue to improve over the coming days.