New Delhi: Despite Delhi recording a rare ‘good’ air quality day two weeks ago, this month has been the most polluted July in six years.The average air quality index (AQI) this July was 119. A higher average July AQI was recorded only thrice since Central Pollution Control Board (CPCB) started calculating AQI in 2015: 2019 (134), 2016 (138) and 2015 (146).Though the city experienced two days of heavy rainfall this July, a prolonged dry spell for the rest of the month led to elevated pollution levels, experts said.An analysis of CPCB data shows this July had two consecutive ‘poor’ air days, 15 ‘moderate’ days and 12 ‘satisfactory’ days. In contrast, July 2025 witnessed 29 ‘satisfactory’ days and two ‘moderate’ days.The city recorded the lone ‘good’ air day with an AQI of just 48 this July 9 when heavy rain settled down pollutants. However, a dry spell from July 11 to 19 led to a rise in pollution. There were two ‘poor’ air days on July 12 (261) and July 13 (246) when dust from Iran, Afghanistan and Pakistan worsened Delhi’s air quality.Sunil Dahiya, founder of think tank Envirocatalyst, said the fewer number of rainy days meant a reduction in washing down of pollutants. Hence, the PM2.5 levels remained in the same range as in past years. “However, PM10 levels were much higher compared to the last few years, highlighting the impact of dry dust re-suspension in the city,” he said.Anumita Roychowdhury, executive director, research and advocacy, Centre for Science and Environment, said, “There is an interplay between monsoon and Delhi’s air quality. While heavy rains cleanse the air dramatically, high humidity coupled with dry breaks causes pollutants to linger and resuspend, keeping the air quality elevated in the ‘moderate’ to ‘poor’ ranges on non-rainy days.““While the emission load from transport has dropped over the past years due to the introduction of BS VI-compliant vehicles and tighter regulations on industries in Delhi-NCR, the result of other sources like power plants and new industrial units stepping up their operations has reduced the gains Delhi needs to make in its air quality,” said Dahiya.Aggressive action on emission load reduction at source within the city as well as in the larger airshed is the only solution, he said, adding, “The fact that even monsoons aren’t able to wash down its pollution levels is an urgent alarm for us to start acting fast.”Meanwhile, the mean maximum and minimum temperatures this July were higher than last year. The first was recorded at 35.4 degrees Celsius compared with 34.5°C in July 2025. The mean minimum stood at 27.7°C, up from 26.1°C last July.
