Delhi’s air-quality monitoring network recorded extensive data gaps during the peak Diwali pollution period, with 36 of the city’s 59 stations not reporting readings at 1 am on Monday, according to an analysis by the Centre for Research on Energy and Clean Air (CREA) cited by Millennium Post. The disruption has raised questions about the reliability of official Delhi AQI data at a time when residents faced severe pollution across the capital and the wider Delhi-NCR region.
The number of stations with missing readings increased sharply as Diwali night progressed. CREA’s analysis showed that one station was not reporting data at 7 pm on Sunday, while the number rose to seven by 10 pm and 23 by 11 pm. By midnight, 29 stations had missing readings. The figure reached 36 at 1 am, leaving only 23 of the 59 stations reporting data.
The gap remained substantial at 2 am, when 35 stations were not reporting. It then declined gradually, with 30 stations still missing readings at 3 am, 20 at 4 am, 19 at 5 am and 16 at 6 am. The missing data coincided with the period when firecracker use and pollution levels were reported to be at their highest.
Delhi recorded its most polluted Diwali in five years, according to the report. However, readings released by private agencies presented a more severe picture than the official figures. Experts tracking air-quality data in real time also pointed to significant variations between government and private monitoring networks across Delhi-NCR.
Anumita Roychowdhury, executive director of the Centre for Science and Environment, questioned why the monitoring network failed to provide real-time readings during the most critical period. She said Delhi-NCR has the densest air-quality monitoring network in the country and that it is supported by public investment and operation and maintenance contracts.
“When substantial public funds have been invested in establishing Delhi-NCR’s air quality monitoring network — the densest in the country — backed by active operation and maintenance contracts, a data eclipse precisely during peak Diwali pollution is inexplicable,” Roychowdhury said, according to the report.
She added that real-time data should have supported targeted public-health advisories and calibrated emergency responses. “While the severity of exposure is evident on the ground, credible official data is needed for institutional accountability, public awareness and mitigation. Losing data does not reduce the public health emergency,” she said.
The data interruptions have also triggered political allegations. The Aam Aadmi Party alleged manipulation, while experts called for greater transparency, accountability and accuracy in pollution monitoring. The report did not establish the cause of the station outages or confirm that the missing readings resulted from deliberate interference.
Delhi cabinet minister Kapil Mishra, responding to questions at a press conference, asked reporters to share details of the stations reported to be non-functional. He said he would seek action on the issue. The next step is expected to involve identifying the affected stations and determining why readings were unavailable during the peak pollution hours.
