Delhi experienced yet another day of choking haze on Monday, with air quality deteriorating to alarming levels while the city’s pollution monitoring systems went offline, leaving residents in the dark about the true severity of the crisis. Despite visible smog covering the city, the government’s key air quality monitoring platforms—including the Central Pollution Control Board (CPCB) portal and the Sameer mobile app—remained largely non-functional for much of the day, frustrating the public and raising questions about the reliability of official data during critical pollution surges.

The breakdown of the monitoring infrastructure coincided with the worsening of particulate pollution, with the AQI expected to breach the “severe” category of 400. Updates from the CPCB eventually trickled in late at night, by which point Delhi had already endured hours of visibly poor air quality. For most of Monday, the AQI was unreported, and residents had no official information to gauge the risks of exposure amid the dense haze blanketing the city.

The blackout in monitoring came on the heels of Sunday’s readings, when the AQI had touched 370 according to the CPCB’s bulletin. The absence of real-time data on Monday meant that the public and policymakers could not determine how many of Delhi’s 39 pollution monitoring stations were registering “severe” levels. On Sunday, 24 stations were already in this category, underscoring the gravity of the situation.

Throughout Monday, the Sameer app froze at 345, showing no updates even as pollution visibly worsened. An update around 10 pm finally indicated an AQI of 391—matching Sunday’s peak—followed by a reading of 398 two hours later, marking the season’s worst level and perilously close to the “severe” category. Meanwhile, the CPCB’s daily bulletin, released around 11 pm, recorded an AQI of 362, reflecting readings from the afternoon hours at 4 pm.

Efforts to access raw pollutant data revealed a troubling drop in station reporting. Early in the morning, between 34 and 37 stations were providing data on PM2.5 and PM10, the city’s most concerning pollutants. By noon, reporting had dropped to 27 stations, and after 12 pm, data from nearly all stations disappeared, except for a brief period when one station transmitted readings. This blackout occurred precisely during the afternoon when haze visibly thickened, reducing visibility across Delhi. At the airport, METAR reports indicated that visibility fell from 3,000 metres on Sunday afternoon to just 1,500 metres on Monday during comparable hours. Environmental experts noted that the persistent haze was due to pollutant accumulation rather than ordinary fog.

Officials attributed the outage to server issues affecting the nationwide network of air quality monitoring stations. By 5:30 pm, only four of India’s 562 stations were transmitting data to the CPCB portal. The number of functioning stations gradually increased over the evening, reaching 66 by 6:30 pm and roughly half by 8 pm. Despite partial restoration, Delhi’s bulletin remained unpublished past 9 pm.

“This was not limited to Delhi but affected stations across the country,” an official familiar with the situation said, clarifying that while the stations themselves were operational, the problem lay in data transmission to the central system. The Commission for Air Quality Management (CAQM) directed the CPCB to urgently resolve the technical glitches, issuing orders to ensure data from all monitoring stations was reliably shared.

However, the CAQM did not invoke Stage 3 pollution control measures despite the visible deterioration in air quality. The commission issued a statement asserting that it was “closely monitoring the overall air quality scenario in Delhi-NCR” and coordinating with relevant agencies to sustain improvement trends, but the statement did not address how such reviews could be effectively conducted when real-time data was unavailable.

The lack of timely information compounded public frustration, especially following Sunday’s protests at India Gate, where 60–80 demonstrators were detained for gathering without permission. Protesters had called attention to the dangerously high AQI reading of 391 that morning, yet official interventions remained limited. Environmental analysts criticized the absence of accurate monitoring data, arguing that it hindered immediate and effective measures to mitigate exposure risks.

Vimlendu Jha, an environmental activist detained during Sunday’s protest, remarked on the government’s failure to maintain transparency: “It is sheer brazenness to allow air quality to deteriorate while making monitoring data unavailable. Residents cannot gauge their risk or take necessary precautions when information is withheld. The authorities’ lack of accountability is why people are protesting.”

Experts at Envirocatalysts, a Delhi-based environmental research group, noted that even with partial data, the situation was visibly critical. Sunil Dahiya, the group’s founder, stated, “Without timely and accurate readings, interventions like GRAP cannot be effectively implemented. Missing data only creates confusion and delays remedial action.”

This incident marks the third extended data outage of the season. On October 26, monitoring updates ceased for 11 hours, delaying the national bulletin from 4 pm to 10:45 pm. The following day saw a 12-hour blackout before the CPCB declared the issue resolved. The recurring outages have raised concerns about the robustness of India’s air quality monitoring infrastructure, especially during periods of severe pollution when timely data is most critical for public health and regulatory measures.

Meanwhile, residents continue to experience the consequences of prolonged exposure to high pollution levels. The haze, which accumulated during daylight hours, poses heightened health risks for vulnerable populations, including children, the elderly, and those with respiratory conditions. Experts emphasize that accurate monitoring is essential not only for public awareness but also to trigger emergency response protocols and sector-specific interventions aimed at mitigating the impact of extreme pollution events.

As Delhi battles yet another air quality crisis, the combination of thick haze and the failure of monitoring systems underscores the urgent need for technical reliability, transparency, and swift government action. The city’s experience serves as a stark reminder that visible pollution is only part of the problem; effective governance requires real-time data to guide decision-making, protect public health, and maintain public trust.