No consistent improvement in Delhi’s winter air quality over four years: CREA

There has been no consistent improvement in Delhi’s winter air quality over the past four years, despite the imposition of the Graded Response Action Plan (GRAP), according to an analysis of government data by the Centre for Research on Energy and Clean Air (CREA), a Finland-based non-profit research organisation.

Delhi’s winter AQI (Air Quality Index) has fluctuated over the past four years, with no consistent improvement. The mean AQI rose from 280 in winter 2022–23 to 304 in 2023–24, fell to 285 in 2024–25 and increased again to 295 in 2025–26. The median AQI followed a similar pattern, rising from 294 to 324, falling to 289 and then increasing to 305,” CREA said in a statement.

A higher AQI indicates poorer air quality. Delhi’s winter air quality has not followed a consistent downward trend since the 2022 revision of GRAP, and the mean and median AQI for the latest winter were both higher than in 2022–23, said Manoj Kumar, an analyst at CREA.

The mean and median of the AQI are statistical measures used to summarize air quality data over a specific period. Because AQI levels can fluctuate wildly due to weather changes or pollution spikes, these two metrics tell different stories about the air you breathe.