The Central Pollution Control Board (CPCB) has dismissed allegations of under-reporting of air pollution data, clarifying that discrepancies between its official figures and private air quality apps stem from scientific methodology and hardware limitations. The clarification, posted on X on Tuesday, came in response to media reports questioning the CPCB’s Air Quality Index (AQI) reporting during and after Diwali. Concerns were being raised over apparent data gaps at certain Delhi monitoring stations, a perceived AQI “cap” of 500, and glaring differences between official values and those shown by private platforms. Also Read | What was Delhi air quality on Deepavali night? Check Diwali AQI data Why did official monitors show ‘data gaps’ during Diwali? Quick answers to key questions •5 QUESTIONS Some older particulate-matter analysers were calibrated to measure up to 1,000 micrograms per cubic metre. The automated system treats readings above that range as errors, so those hours are excluded from the station’s 24-hour average. CPCB said the apparent gaps were caused by older instruments’ measurement limits and data validation—not deliberate under-reporting. When readings exceed the analysers’ calibrated range, the system treats them as errors. Private apps may react to sharp hourly pollution spikes, while CPCB’s National Air Quality Index reflects exposure over the preceding 24 hours. As concentrations change, the two readings may differ. The NAQI converts pollutant data into a single, colour-coded value intended to indicate the health impact of sustained exposure. It reflects the preceding 24 hours rather than only a short-lived hourly peak. Yes. CPCB said older instruments are being replaced and the monitoring network is being expanded continuously to help prevent data dropouts during extreme pollution events. Addressing the missing data during peak firecracker bursting, the pollution watchdog explained that older particulate matter analysers—deployed when the National Air Quality Index (NAQI) was introduced in 2015—were calibrated for a measurement range of 0-1,000 micrograms per cubic metre. Because of this hardware constraint, the automated data validation system treats any hourly reading exceeding this calibrated range as an error. Consequently, these extreme readings are not used in the final computation. “During extreme episodes, which are occasional, like Diwali firecracker bursting, this may appear as a data gap at the particular station concerned, and those hours do not contribute to the 24-hour average of relevant pollutant for the concerned station,” said the board. Also Read | Heavy rain, snowfall alerts across India till Nov 16; Delhi’s AQI improves CPCB vs private apps: The 24-hour exposure rule Addressing why private apps often flash alarming, higher AQI numbers compared to the official NAQI platform, the CPCB said the private apps react instantly to hourly spikes, while the official NAQI is designed to measure sustained health risks. “It is generally perceived that private apps show higher AQI. This may hold during short peaks, when hourly values rise sharply. However, when concentrations fall, such apps show lower AQI than the NAQI (National Air Quality Index), since NAQI continues to reflect the exposure of the preceding 24 hours,” said the CPCB. The board emphasised that the NAQI converts complex pollutant data into a single, colour-coded index value to effectively communicate long-term health risks to the public. “The NAQI provides a consistent and reliable indication of the likely health impacts of sustained exposure to pollutants, which is the scientifically relevant measure for public health advisories,” the CPCB said. Upgrading the monitoring network To prevent future data dropouts during extreme pollution events, the board noted that monitoring instruments have advanced considerably since 2015. The replacement of older instruments and the expansion of the monitoring network are currently being carried out continuously. “CPCB remains committed to transparent, scientific and reliable reporting of air quality and to continuous improvement of the monitoring network and methodology in consultation with experts,” said the board. Also Read | Panchgaon tops pollution chart with AQI of 365; Delhi ranks eleventh Delhi Diwali AQI CPCB classified the citywide average AQI as ‘very poor’ on Diwali night, with numerous monitoring stations already recording ‘severe’ levels above 400. Meanwhile, independent monitoring platform AQI.in reported a staggering peak AQI of 2,283 immediately after Diwali, then settled to a “hazardous” 637 by Monday morning. Source link Post navigation Who is John Harrison? Meet British author who won Booker Prize 2026; here’s what he said on ‘The End of Everything’ Sirsa records highest air quality index of 403, Delhi logs 299
