CPCB Considers Raising PM Measurement Cap after Delhi AQI Data Gaps on Deepavali 2026

Delhi’s Air‑Quality Data Gap and the Push to Raise PM Measurement Limits On 10 November 2026 , the CPCB announced that it is reviewing the way it records extreme spikes in PM concentrations. The move comes after several government monitoring stations in Delhi failed to report data during the massive pollution surge that followed Deepavali (Diwali) on 9 November 2026 . Key Developments Existing PM analysers are calibrated only up to 1,000 µg/m³ . Readings beyond this range are automatically discarded, creating a data gap. The CPCB’s internal deliberations are now focused on extending the measurement cap so that peak values are captured. Delhi’s 24‑hour average AQI fell to 299 on 10 November, just below the “very poor” threshold of 300. Experts say higher wind speeds helped dilute pollutants, and further improvement is expected in the coming days. Important Facts The NAQI methodology, adopted in 2015, requires data from at least three pollutants, one of which must be PM2.5 or PM10 . The cap of 1,000 µg/m³ was set because the instruments then available were only accurate up to that level. Delhi has 59 monitoring stations; 46 are run by the DPCC . While the DPCC recorded PM2.5 and PM10 values exceeding 1,000 µg/m³ on Deepavali night, the CPCB, which aggregates data for the national AQI, could not use those extreme readings. Relevance for UPSC Understanding the technical limits of pollution monitoring is crucial for answering questions on environmental governance, public health, and policy implementation (GS3: Environment). The episode highlights the gap between on‑ground data collection and national reporting mechanisms, a common theme in questions about institutional effectiveness. It also underscores the role of central agencies like the CPCB in setting standards, and the coordination challenges with state bodies such as the DPCC . Aspirants should note how technical upgrades (better analysers) may outpace regulatory revisions, creating policy lag. Way Forward Update the NAQI methodology to accommodate readings above 1,000 µg/m³. Standardise calibration ranges across all monitoring stations to avoid future data gaps. Strengthen real‑time data sharing between the CPCB and state agencies for quicker public alerts. Promote public awareness about the health impacts of extreme PM spikes, especially during festivals. These steps would improve the reliability of air‑quality reporting and help policymakers design timely interventions to protect public health.