Delhi's air quality remained 'very poor' for a fourth consecutive day on Monday, with the average air quality index (AQI) recorded at 359 at 8am. It was 377 at 4pm on Sunday, making it a marginal improvement as winds picked up - touching 15 km/hr during the day on Sunday.
Forecasts show Delhi is unlikely to see any relief ahead, with the AQI set to worsen again and touch 'severe' on Monday -- till Wednesday.
"Delhi's air quality is likely to be in the severe category from November 17 till 19. The outlook for the subsequent six days shows the air quality is likely to be between 'severe' and 'very poor' category," said the Early Warning Systen for Delhi (EWS), a forecasting model under the Ministry of Earth Sciences.
Delhi's average AQI for the period November 1-15, considered as the most polluted period in the entire year -- stood at 349, marginally lower than 367 in 2024 and 376 in 2023, and only slightly higher than the 345 recorded in 2022.
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Experts said a delayed harvest season, fewer farm fires so far and an early Diwali have all helped keep the numbers from sliding further towards the 'severe' zone.
Data anomalies and missing data across the 39 active ambient air quality monitoring stations are likely to have played a part, they said.
Central Pollution Control Board (CPCB) data shows the city has seen three 'severe' days, alongside 10 'very poor' days and two in the 'poor' category in the last 15 days. In the same period last year, Delhi recorded two severe days and 13 very poor ones.
Dipping mercury is also likely to negatively impact Delhi's AQI. The minimum temperature stood at 9°C on Sunday - around 4.5°C degrees below normal and the lowest for November since 2022, when it was 8.3°C on November 30.
Forecasts show the minimum may dip even further on Monday - possibly hovering close to 8°C.
Lower the temperature, the more stable the atmosphere becomes, making dispersion of pollutants difficult.
Delhi presently is in the middle of stage 3 measures of the Graded Response Action Plan (Grap) which came into force on November 11.