Delhi’s air quality has shown a marginal deterioration this January compared to last year, though it still ranks as the second-best January for pollution levels since 2022, according to an analysis by the Centre for Research on Energy and Clean Air (CREA).

The average Air Quality Index (AQI) in the capital till January 30 stood at 307, slightly higher than the average of 306 recorded during the same period in January 2025, the analysis showed.

CREA noted that January 2025, with an average AQI of 306, was the cleanest January since 2022, when the monthly average AQI stood at 279.

January 2026 now ranks second-best among the past four years.

So far this month, Delhi has recorded two “moderate” air quality days, 12 “poor” days, 14 “very poor” days and two “severe” days, the analysis said.

By comparison, January 2025 had two “moderate” days, 13 “poor” days and 16 “very poor” days, with no “severe” days reported during the month.

The analysis indicated that the absence of "severe" days in January 2025 and the presence of two "severe" days in January this year may have contributed to the slightly higher average AQI in 2026.

The air quality early warning system has predicted "very poor" air quality for January 31.

According to the Central Pollution Control Board, an AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".