In July 2025, Delhi achieved a remarkable milestone in its ongoing battle against air pollution by recording its cleanest air in more than ten years. The Air Quality Index (AQI) for the entire month averaged just 79, the lowest figure recorded in the past decade. What makes this achievement even more significant is that 29 out of the 31 days in July fell under the “satisfactory” category for air quality. There wasn’t a single day during the entire month that entered the “poor” or “very poor” ranges, which are typically a common concern in Delhi’s air quality reports. This improvement represents not just a statistical change but a hopeful sign that consistent efforts, whether through policy, climate support, or urban changes, may finally be starting to yield tangible results.
Looking back at the trend over the past ten years reveals how much progress has been made. In July 2015, Delhi’s AQI was alarmingly high at 138, and though a dip was seen in 2017 when the AQI dropped to 98, pollution levels quickly rose again by 2019, with an average of 134. In July 2020, there was another drop in AQI to 84, which many attributed to reduced industrial and vehicular activity during the pandemic lockdowns. However, this was not sustained, as July 2021 saw the AQI climb once again to an average of 110. It was only from 2022 onwards that Delhi managed to consistently keep its July air quality below the 100 mark. By 2025, the efforts appear to have culminated in a landmark success, with the AQI dropping to an all-time low of 79 for the month.
Beyond the improved AQI, July 2025 also recorded the highest number of satisfactory air quality days in more than a decade. For comparison, July 2015 had just 11 satisfactory days, and that number dropped even lower in 2016. There was a slow upward trajectory in later years, with 2020 and 2022 each recording 25 satisfactory days. Although July 2024 saw a decline with only 17 such days, July 2025 rebounded impressively with 29 satisfactory days, nearly the entire month. This not only highlights a significant turnaround from previous years but also reinforces the notion that sustained improvements in air quality are possible even in a densely populated and polluted city like Delhi.
The broader air quality pattern throughout 2025 had been quite erratic until July. The year began with January witnessing 13 days in the “poor” category and 16 in the “very poor,” without a single day of good or satisfactory air. February brought a minor relief with 12 moderate and 2 very poor days, while March was dominated by moderate conditions. April saw another decline with 20 poor air days. However, in May and June, things started to improve. May had 24 moderate days, and June followed with 11 satisfactory ones. July, in contrast to the earlier unpredictability, stood out for its consistently clean air, offering a rare period of clarity and improved health conditions for residents.
While July is typically associated with better air due to the monsoon rains, rainfall alone doesn’t explain the cleaner skies of 2025. This July, Delhi received 259.1 mm of rainfall, which is significantly less than the 507.1 mm seen in July 2021 or the 384.6 mm in July 2023. Yet, those months did not record equally clean air. For instance, July 2021 had an AQI of 110 despite the heavy rainfall. Likewise, in 2016, when Delhi received 292.5 mm of rainfall, it saw the worst July air with an AQI of 146. These figures strongly indicate that while rainfall plays a role in washing pollutants out of the atmosphere, it is not the only determining factor for clean air.
The dramatic improvement in July 2025’s air quality likely results from a combination of multiple contributing elements. These may include not only the cleansing effect of monsoon showers but also improved wind patterns, stricter emissions controls, reduction in construction dust, greener transportation methods, and possibly heightened awareness and behavioural changes among citizens. As Delhi continues to explore solutions to its chronic air pollution problem, July 2025 may serve as a case study in what can go right when both nature and human efforts work together toward a cleaner environment.
