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India: CPCB addresses stark Delhi pollution data gap on Diwali night
India’s Central Pollution Control Board (CPCB) has explained why its reported air quality in Delhi on Diwali night was far lower than figures shown by private platforms. The discrepancy drew scrutiny as fireworks filled the city with toxic smog and reports said some monitoring stations stopped reporting at the pollution peak.
The CPCB app recorded an Air Quality Index (AQI) of 400, while private services showed figures above 2,000. The board said its system measures particulate matter only up to 1,000 micrograms per cubic metre and excludes readings beyond that calibrated range from AQI calculations. Data later released by Delhi’s pollution committee showed one area reached 3,744 micrograms of PM2.5 per cubic metre in an hour, about 60 times the national average; the CPCB said it is reviewing how to process readings beyond its system’s range.
In short
- Delhi’s official AQI was far below private platform readings on Diwali night.
- CPCB says its monitors are calibrated only up to 1,000 micrograms per cubic metre.
- One released hourly PM2.5 reading reached 3,744 micrograms per cubic metre.
Steelman: both sides, in good faith
The strongest fair case each way — we don't pick a winner.
The case for
The CPCB’s AQI may be more useful when it stays within a defined measurement range and follows a consistent method, allowing comparisons across places and time. A calibrated upper limit can also make clear that readings above the instrument’s range are uncertain rather than falsely precise, provided that limitation is reported plainly and addressed.
The case against
A ceiling that excludes the most extreme pollution readings risks understating the conditions people actually faced, especially on a night when independent data suggested exceptionally high concentrations. The gap can weaken public trust and the usefulness of official warnings, so critics can reasonably argue that monitoring and reporting systems should capture extreme peaks and make any limits unmistakable.
Explained simply
Delhi’s air is monitored by the Central Pollution Control Board, a national agency, alongside other bodies and private services. They use sensors to measure pollutants such as PM2.5, tiny particles that can enter the lungs, and turn those measurements into an Air Quality Index, or AQI, to describe pollution levels.
Diwali is a Hindu festival often marked with fireworks, which can add smoke and particles to the air. The different figures matter because people use pollution readings to understand potential health risks, while gaps or limits in monitoring can make conditions harder to assess.
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