Delhi's air quality has experienced a dramatic and unexpected improvement, marking the lowest reading for October in the past three years. This sharp drop in the Air Quality Index (AQI) comes after a concerning spike in pollution levels earlier in the week, leaving experts and residents alike surprised.
On Thursday, October 30, 2025, Delhi recorded its worst AQI for October in three years, with a reading of 373, placing it in the "very poor" category. The last time Delhi experienced a higher AQI in October was in 2022, with a reading of 392 on the last day of the month. Several factors contributed to this decline in air quality, including calm surface winds, high humidity, and a drop in night temperatures, leading to a temperature inversion that trapped pollutants near the surface. The city was blanketed in a thick haze, and visibility was significantly reduced in many areas. Data from the Decision Support System indicated that vehicular emissions contributed significantly to Delhi's PM2.5 levels.
However, the situation took an unexpected turn as air quality improved drastically, settling into the "moderate" category. The reasons behind this sudden improvement are still under investigation. While meteorological factors such as shifts in wind direction and lower humidity may have played a role, they don't fully explain the extent of the drop.
The government has credited its extensive efforts, including the deployment of enforcement teams, the use of anti-smog guns, and increased road sweeping, for the improved air quality. Delhi Environment Minister Manjinder Singh Sirsa has credited the government's initiatives for the improved AQI levels.
Data from the Commission for Air Quality Management (CAQM) shows that Delhi has registered its cleanest air quality between January and October 2025 in eight years, excluding the lockdown year of 2020. The average AQI for this period stood at 170, a notable drop from 184 in 2024 and 187 in 2022, signalling a sustained improvement trend across the National Capital Region (NCR). Delhi also did not witness a single 'severe' air quality day (AQI above 400) in the first ten months of 2025, a first since 2018. Furthermore, Delhi experienced 79 'satisfactory' air quality days (AQI between 51–100), the highest since 2018, excluding 2020. CAQM data revealed that Delhi recorded its lowest PM2.5 and PM10 concentrations during January–October 2025 compared to the same period since 2018 (excluding 2020).
While the improvement in air quality is a welcome development, authorities remain cautious, as the transition from monsoon to post-monsoon winds could lead to weaker and drier conditions that trap pollutants. The Air Quality Early Warning System has also indicated that Delhi's ventilation index remains below the favorable level.
