As air pollution once again tightens its grip over Delhi and the National Capital Region, social media platforms are flooded with sensational claims that the Air Quality Index (AQI) has breached the maximum measurable level of 999. Several posts circulating online since Diwali show screenshots and short video clips allegedly proving that pollution levels touched or exceeded the upper limit of handheld measuring devices. However, an examination of official air monitoring data reveals a different picture. No government-recognised monitoring station has reported AQI readings close to 999 this season, even though the air quality remains firmly in the “poor” and “very poor” categories across large parts of the capital.

The current wave of posts began soon after Diwali celebrations, during which firecrackers are believed to cause a sharp spike in PM2.5 concentrations across Delhi. One widely shared post on X claimed: “AQI jumps to 999 from 194 in Delhi due to Diwali firecrackers. It’s more than 999 but this meter could measure up to 999 only.” The user also posted a handheld reading device, which appeared to rapidly climb before displaying its maximum limit while the background showed people lighting crackers.

The video triggered alarm on social media, leading many to believe that Delhi’s air quality had crossed into the uppermost levels of toxicity, typically associated with severe industrial pollution or wildfire conditions. Arvind Kejriwal’s AAP leaders amplified this perception. AAP MLA Saurabh Bharadwaj reposted the clip, accusing the BJP-led Delhi government of concealing the severity of pollution levels. “The government is hiding AQI data, but people’s own monitoring devices are showing the truth. Why does the government want people to fall ill?” he wrote on X, prompting further online debate about the reliability of official readings versus handheld devices.

In another instance, AAP leader Sanjay Singh circulated a screenshot earlier in October that purportedly showed an AQI of 1991 in Naraina Village, an implausibly high figure that nonetheless spread rapidly among users already anxious about deteriorating winter air. These incidents contributed to widespread confusion about the actual air quality levels in the capital, as well as questions about how air quality data should be interpreted during peak pollution episodes.

However, despite the viral images and accusatory claims, none of the major air quality monitoring systems corroborate the assertion that AQI has crossed 999 this season. The widely used global portal aqicn.org, which aggregates real-time AQI data from official monitoring stations, showed no such extreme values upon detailed examination on Thursday morning. When HT.com cross-checked the specific readings shared online — which displayed 9 am AQI levels — the data available on the portal did not show any location in Delhi-NCR recording a measurement even close to 999.

Similarly, the most authoritative source of air quality data in India, the Central Pollution Control Board (CPCB), reported a citywide AQI of 278 at 8 am on Thursday — well within the “poor” category but far from the catastrophic levels suggested on social media. Several prominent monitoring stations, including Jahangirpuri (284), ITO (295), and Rohini (296), remained in the “poor” category, with isolated pockets such as Mundka (305) and Narela (302) slipping into “very poor” levels. While these readings signal unhealthy environmental conditions requiring caution, they do not approach the purported levels of 999 that have captured public attention online.

Neighbouring NCR regions showed similarly elevated but not extreme pollution levels: Noida’s Sector 62 posted a 5 am AQI of 215 and Ghaziabad’s Sanjay Nagar recorded 265. All of these remain within the poor-to-moderate range of winter norms in Delhi, but again none matched the sensational high readings of the handheld devices populating social media feeds.

Global air monitoring service IQAir also presented a much more moderate picture of Delhi’s pollution levels. The platform ranked Delhi as the world’s fifth-most polluted city for the day, with an AQI of 166 — significantly above safe limits but nowhere near the unattainable 999 being circulated online. This discrepancy highlights an important distinction: professional, calibrated AQI monitors measure a range of pollutants and convert them into a composite index, whereas portable handheld devices commonly measure only particulate matter concentration at a hyperlocal level and can be triggered by immediate pollutants such as smoke from nearby crackers, incense, cigarettes, or vehicle exhaust.

Environmental experts have repeatedly cautioned that low-cost or consumer-grade sensors often lack calibration, have limited pollutant detection capabilities, and can show wildly fluctuating or inaccurate readings depending on placement and exposure. For instance, taking a handheld sensor directly into a cloud of cracker smoke, cooking smoke, or a dusty room can produce an instantaneous reading above 999, even though ambient outdoor air quality is significantly lower. This makes such devices useful for personal exposure tracking but unreliable as indicators of citywide AQI trends.

Still, public suspicion has risen in recent years due to delays, occasional server outages, or lapses in real-time reporting on government systems. This environment of scepticism allows unverifiable or misleading data—including screenshots, viral clips, and uncalibrated air quality readings—to fill the information vacuum during high-pollution periods.

Despite the online noise, meteorological and environmental agencies have warned that the capital’s air quality is expected to deteriorate further over the coming days. According to forecasts from the Air Quality Early Warning System, pollution levels across Delhi are likely to remain in the “very poor” category between November 6 and 8, driven by low wind speeds, falling temperatures, and increased seasonal emissions. This aligns broadly with CPCB’s assessment that air quality has been on a decline since November 5, when Delhi reported an AQI of 202 at 4 pm. Key areas have shown a consistent downward trend, with Burari Crossing reporting 280, Dwarka Sector 8 hitting 296, and Bawana reaching 337.

Although the numerical values may be lower than the alarm-inducing viral claims, the health implications remain serious. Medical professionals have reported an uptick in respiratory illnesses, including asthma, bronchitis, and sinusitis. Vulnerable populations such as children, the elderly, and those with chronic respiratory or cardiac conditions are particularly at risk.

For residents trying to make sense of the conflicting data, experts advise relying on official monitoring systems rather than handheld or crowd-sourced readings. Even though government systems may not always reflect hyperlocal spikes, they remain the most consistent and scientifically calibrated indicators of broader atmospheric conditions.

The social media frenzy around “999 AQI” underscores a larger challenge: in a city accustomed to winter pollution and political blame games, misinformation spreads easily, often overshadowing scientifically grounded updates. As Delhi braces for another polluted winter, accurate information — especially during crises — becomes just as vital as measures to reduce emissions and protect public health.

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