AQI data missing since noon on a smoggy, hazy day in Delhi

The Central Pollution Control Board stopped issuing AQI readings on its Sameer app and website after 12.15pm, when the AQI stood at 345.

A grey haze hung heavy over Delhi on Monday — the air thick, the skyline blurred, and the city gasping for updates that never came. On one of the visually worst days of the pollution season, the air quality monitoring system in the national capital went silent, leaving residents guessing just how bad things were.

Vehicles move along NH-9 near Dasna in Ghaziabad amid low visibility caused by smog on Monday. (Sakib Ali/ HT Photo)

The Central Pollution Control Board (CPCB) stopped issuing Air Quality Index (AQI) readings on its Sameer app and website after 12.15pm, when the AQI stood at 345. Officials blamed a technical glitch for the lapse, assuring that the system would likely be restored by evening.

The Commission for Air Quality Management (CAQM) convened a meeting of its sub-committee on the Graded Response Action Plan (GRAP), stating that it was “closely monitoring the situation”.

A CAQM official said the CPCB had been asked to fix the issue at the earliest, as hourly AQI updates had not been shared post-noon. “We have been told it is likely to be fixed by the evening. There should be no problem with the daily bulletin,” the official said.

Only a day earlier, Delhi’s AQI had touched 391 around 10am on Sunday, the highest recorded so far this season.

This is not the first time such a disruption has occurred this season. On October 26, AQI data was not updated for nearly 11 hours — between noon and 11pm. The CPCB also failed to release its daily national bulletin at 4pm, eventually publishing it at 10.45pm. Updates went missing again for 12 hours the next day, with the CPCB stating on October 27 that the issue had finally been resolved.

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On Sunday, the CAQM had held a review meeting at 4pm to assess the air quality situation but decided not to invoke GRAP Stage 3 measures across the National Capital Region (NCR), citing a declining trend in the 24-hour average and no forecasts of “severe” air ahead. It said that Stages 1 and 2 of the plan would continue to remain in force.