Delhi recorded its cleanest July in over a decade. The Air Quality Index (AQI) for July 2025 averaged just 79, with 29 out of 31 days falling in the satisfactory range. Not a single day in July slipped into the poor or very poor categories.

TREND OF JULY OVER PAST DECADE

Back in 2015, Delhi’s average AQI for July was 138. In 2017, the average dropped to 98, showing some improvement. However, that trend didn’t last; by 2019, pollution levels had surged again, with the average AQI climbing to 134.

July 2020 saw another dip to 84, but it rose once more in 2021 to an average of 110. Since 2022, though, Delhi has managed to keep July AQI levels below 100. And in 2025, the city recorded its cleanest July yet, with an average AQI of just 79, a ten-year low.

Not only did July 2025 record the cleanest average AQI in a decade, but it also marked the highest number of satisfactory air days since 2015. That year, Delhi had only 11 satisfactory days in July, and the count dropped further in 2016. Over time, the numbers gradually improved; 2020 and 2022 each saw 25 such days.

However, July 2024 saw a dip, with only 17 days falling under the satisfactory category. In contrast, July 2025 had as many as 29 satisfactory days.

The air quality journey through 2025 has been anything but stable. The year began on a grim note. January had 13 poor and 16 very poor days, with not a single satisfactory or good day. February showed only slight relief, with 12 moderate and 2 very poor days. March was dominated by moderate days, while April had 20 poor days.

However, May brought cleaner skies with 24 moderate days and the improvement was seen more as June saw 11 satisfactory days. July broke this erratic trend with its consistently clean days. These months are usually less polluted due to monsoon rainfall — but the question remains: is July’s record-breaking clean air also primarily because of the rain?

While July 2025 recorded the cleanest average AQI in over a decade, it wasn’t the month with the highest rainfall. Delhi received 259.1 mm of rain, far less than the 507.1 mm recorded in July 2021 and 384.6 mm in July 2023, yet both those years had worse air quality.

In fact, 2021 had an average AQI of 110 despite receiving the highest rainfall between 2015 to 2025. Similarly, in 2016, when Delhi saw 292.5 mm of rain, the AQI spiked to a decade-high of 146. While the rainfall does help clear pollutants, it alone doesn’t guarantee clean air. The improvement in July 2025 likely reflects a combination of rain, favourable wind patterns, and other factors.

– Ends

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