CPCB defends exclusion of extreme PM 2.5 spikes from AQI

Automated system excludes readings above 1,000 µg/m³

The Central Pollution Control Board said its monitoring equipment is calibrated only for ranges up to 999 µg/m³. Readings exceeding 1,000 micrograms per cubic metre are treated as out-of-range by the automated data validation system.

Consequently, these extreme concentrations are excluded from the 24-hour average calculation. An Environment Ministry source told reporters that the data is collected but not used in the calculation.

The CPCB explained in an 11-point statement on November 10 that these gaps occur because out-of-range readings are omitted.

Focus on prolonged exposure over momentary spikes

The Central Pollution Control Board said the National Air Quality Index is designed to measure prolonged exposure to pollution. The agency defended its use of a 24-hour running average for health impact assessments.

It considers momentary spikes, such as those from Diwali firecrackers, less relevant indicators of health effects. The index is computed by an automated system without human intervention, and individual pollutant concentrations remain available in the public domain.

Calls for overhaul of 2015 validation framework

Environment Ministry sources state the 2015 data validation system is outdated and requires a comprehensive review. The CPCB is currently reviewing its methodology to account for advancements in monitoring technology and international practices.

This review addresses why extreme pollution readings currently fall outside the 2015 data validation framework. Internal discussions are underway involving two or three scientists, though no official external expert group has been constituted.

Discrepancies between government and private platforms

Private applications often display higher pollution levels due to variations in measurement techniques, averaging periods, and the use of low-cost sensors. The CPCB maintains a strict AQI ceiling of 500 for its own calculations.

The board asserts that readings beyond this level remain in the severe category. It maintains that extending the index would not change the assigned health impact for residents.

CSE reports record-high pre-winter pollution levels

In the week leading up to Diwali 2026, the average PM 2.5 level reached 236 micrograms per cubic meter.

This level is the highest recorded in the last three years.

Anumita Roychowdhury of the CSE stated that elevated pollution levels before the festival indicate higher baseline pollution compared to previous years.

Sharanjit Kaur of the CSE noted that toxic pollutant levels were notably higher in the week before the festival compared to previous years.

Transport identified as primary pollution source

The study identified transport as the primary local source of pollution in Delhi-NCR. Analysis of traffic congestion confirmed that vehicular emissions are the main cause of daily toxic pollution exposure.

The CSE report claims that emergency restrictions on pre-BS-VI vehicles have failed to reduce traffic congestion.

Anumita Roychowdhury said year-round measures to control emissions from key sources have been insufficient. She added that pollution would not have reached critical levels if the air had been cleaner at the start of winter and if stubble burning and firecracker bursting were effectively curbed.

Adani's Kutch Copper has become the first Indian producer to receive the 'Copper Mark'.

Expansion of monitoring network since 2014

The index uses a 24-hour average for most pollutants, while carbon monoxide and ozone use an eight-hour average, with the highest sub-index determining the hourly air quality index.

There were 35 stations still not reporting at 2 am on Monday.