Delhi: When rain failed to wash away city’s pollution pain

NEW DELHI:: Despite receiving excess rainfall of 33%, Jan, this year was more polluted than last year. The average AQI in Jan 2026 was 307, compared to 305 in Jan last year, according to an analysis of Central Pollution Control Boards data.

Jan 2025 did not witness a single ‘severe day (an AQI above 400 on a scale of 500), this month saw a spell of severe days from Jan 17 to 19. The AQI stood at 400 on Jan 17, at the extreme end of the ‘very poor category, but it rose to 440 on Jan 18 and 410 on Jan 19. Most days in the first three weeks of Jan this year recorded high levels of pollution, while the last week was relatively better due to rain.

Gufran Beig, founder of System of Air Quality and Weather Forecasting and Research (SAFAR) and chair professor at National Institute of Advanced Studies (NIAS), said earlier studies showed La Nina conditions were associated with relatively faster winds in Nov-Dec.

If it had come, AQI would have been better, as strong winds help in the dispersion of pollutants. However, ENSO-neutral conditions continued till Jan, due to which winds were not fast. Due to ENSO neutral conditions, the western disturbances were not intense in the beginning of Jan, which did not help in the dispersion of pollutants. If there was no rain in the last week of Jan, this Jan may have seen a record high average AQI. Rain caused a dip in AQI in the last week of Jan, leading to an improved average AQI, said Beig.

India Meteorological Departments data shows that the city saw very light rainfall of just 0.01 mm on Jan 9. However, the city logged 21 mm of rainfall on Jan 23 and 24, and another 4 mm of rainfall on Jan 28. This Jan was the wettest in four years, but the first three weeks were dry. Due to high emissions, adverse meteorology could not provide any respite, said an expert.

However, the city is likely to receive rain during the weekend. IMD issued a yellow alert for rain accompanied by thunderstorms, lightning and gusty winds up to 40 kmph for Saturday and Sunday.

Dec last year, was the most polluted since 2018, with an average AQI of 349. The average AQI in Nov stood at 357, marginally better than the 375 recorded in Nov 2024, though it remained in the ‘very poor category.

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