Chandigarh, Oct. 22 -- The city's air quality index (AQI) slipped into the 'very poor' category in half of Chandigarh's monitoring stations on Diwali night, but improved rapidly within hours - a marked improvement from previous years, according to data from the Chandigarh Pollution Control Committee (CPCC). The reason, experts say, was the relatively warm weather which helped disperse the pollutants quickly. As per the CPCC data, the AQI crossed 300 at three stations - IMTech, Sector 39 (318); Punjab Engineering College, Sector 12 (312); and CAAQMS, Sector 53 (304), all in the 'very poor' category, during the peak celebrations. Sector 25 and Sector 22 recorded poor air quality with AQI levels of 296 and 234, respectively, while Sector 17 remained moderate at 183. By 6 pm on Tuesday, the AQI of two of the three CAAQMS was in the moderate category, while at Sector 53, the AQI was 95, which is considered satisfactory. UT director environment and member secretary, CPCC, Saurabh Kumar explained, "If one station has a higher AQI, it doesn't mean people in that area burst more crackers. Multiple factors affect the AQI while weather conditions and winds also play a role in this. This year, Diwali was scheduled earlier than previous years. The relatively higher temperature due to this played a role in stopping temperature inversion - a phenomenon where warm air sits above a colder, denser layer near the surface, acting like a lid that prevents pollutants from rising and dissipating." In 2024, Diwali was celebrated on October 31 while in 2023, it fell on November 12. In 2022, it was celebrated on October 24. Four of the six stations saw a drop in AQI, which means the air here was cleaner. Sector 22 saw the highest drop in AQI, which was the lowest since 2022. The Sector 39 and Sector 12 stations, however, recorded a rise in AQI. AQI in moderate category can cause breathing discomfort to people with asthma or heart and lung diseases. AQI in poor category can cause breathing discomfort to most people on prolonged exposure while in the very poor category, it can cause respiratory illness on prolonged exposure. Noise levels, meanwhile, remained consistently higher than a normal day. The loudest was Sector 22 where noise levels over 80 decibels were recorded between 9 pm and 10 pm. In Sector 39, it went up to 75.3 decibels between 10 pm to 11 pm. PEC went up to 70.6 decibels between 9 pm to 10 pm. Sector 17 went up to 72.9 decibels, Sector 25 up to 68.4 decibels and Sector 53 went up to 69.6decibels....