Panchkula recorded the third-highest air pollution level in North India this evening, prompting concerns not only over deteriorating air quality but also the reliability of pollution-monitoring system amid unusually sharp fluctuations in official readings.

At 8.05 pm on December 21, the city’s air quality index (AQI) stood at 340, categorised as very poor.

Only Delhi and Ghaziabad reported worse air quality, with AQI levels of 373 and 353, respectively, at 8:05 pm on Sunday. Panchkula ranked above Baddi (328), Jind (329), Gurugram (321) and Rohtak (318), reflecting the widespread impact of winter pollution across the region.

Official data over the past four days reveals extreme variation in Panchkula’s air quality. On December 18, the AQI was 346 (very poor), before dropping sharply to 145 (moderate) on December 19 — an improvement of over 200 points within a single day. This was followed by a sudden spike to 361 (very poor) on December 20, before easing slightly to 340 on December 21 evening.

Such abrupt swings contrast with trends in neighbouring Chandigarh, where changes were more consistent. Chandigarh recorded an AQI level of 266 (poor) on December 18, 254 (poor) on December 19, 302 (very poor) on December 20 and then improved to 216 (poor) on December 21. Environmental observers noted that while both cities were affected by winter pollution, Panchkula’s volatility stood out.

Experts say that variations of this magnitude, without a corresponding change in meteorological conditions or emission sources, raise questions about local monitoring mechanisms and data generation. Some specialists point to the need for closer scrutiny of sensor calibration, station placement and data averaging methods, particularly during winter when fog and a lower boundary layer can interfere with accurate readings.

Commenting on the broader regional pattern, Dr Ravindra Khaiwal, Professor of Environmental Health at the Department of Community Medicine and School of Public Health, said in a public health advisory: “North India continues to experience unhealthy air quality with AQI remaining in poor category. Unfavourable winter meteorology, lower boundary layer and fog limit pollutant dispersion are increasing exposure risks, especially for vulnerable groups.”

Health officials have advised residents, especially children, senior citizens and those with respiratory conditions, to limit outdoor activities. With winter conditions likely to persist, experts stress the need not only for pollution control but also robust air quality monitoring.