Supreme Court Seeks Clarity on Delhi Air Monitoring Equipment as AQI Accuracy Concerns Grow
New Delhi, Nov 24 — The Supreme Court has asked authorities to clarify the type of equipment used at Delhi’s air-quality monitoring stations and whether it is suitable for the Capital’s meteorological conditions. The direction comes at a time when the city depends heavily on Air Quality Index (AQI) readings to assess daily pollution exposure, triggering fresh discussion on how accurate and reliable these measurements truly are.
Delhi currently operates 40 Continuous Ambient Air Quality Monitoring Stations, designed to function as automated laboratories that continuously analyse air samples. These stations track eight pollutants across the city, including PM2.5, PM10, nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia and lead. The system was created to provide representative data, operating under Central Pollution Control Board guidelines that outline calibration, testing methods and quality-control standards.
Inside each temperature-controlled cabin, instruments collect and analyse air samples through specialised methods. Particulate matter is measured through beta attenuation, while gaseous pollutants such as sulphur dioxide, ozone and carbon monoxide are monitored through optical and infrared techniques. These tools are recognised under national air-quality standards intended to ensure consistency across Indian cities.
However, questions around accuracy have surfaced due to factors such as humidity, calibration frequency, equipment placement and data continuity. Beta attenuation monitors can show higher particulate readings when moisture attaches to airborne particles, which can occur frequently in Delhi during winter and post-monsoon periods. Power fluctuations and maintenance interruptions can further limit data availability, reducing the number of valid hours required to calculate daily AQI values.
A recent performance assessment found that particulate measurements could be significantly overestimated during periods of high humidity and dense pollution, with readings rising sharply when filter loading and atmospheric moisture increased. The findings recommended site-specific correction methods to improve reliability and reduce measurement deviations.
Institutional audits have also identified gaps, including stations not recording lead levels and others failing to produce sufficient valid data days per month. Inadequate placement near buildings, traffic emissions or obstructed airflow has also been cited as a contributing factor to skewed readings. Recommendations have emphasised equipment upgrades, station relocation and regular third-party assessment to ensure monitoring consistency.
As Delhi continues to rely on AQI readings for public health guidance, school policies, construction restrictions and emergency response, the Supreme Court’s attention on monitoring accuracy has placed renewed focus on data quality, infrastructure upkeep and scientific calibration. The issue remains central to the Capital’s pollution-management framework as winter intensifies and smog levels fluctuate sharply across the region.
Final Thoughts from TheTrendingPeople
Delhi’s struggle with air pollution has made accurate monitoring a critical public necessity. The Supreme Court’s intervention highlights how essential reliable data is for health advisories, policy decisions and public confidence. Strengthening calibration practices, improving equipment, and ensuring uninterrupted data capture will be vital steps in building a clearer and more trustworthy understanding of the Capital’s air-quality conditions in the months ahead.