Delhi sees worst December AQI in seven years, stubble burning contribution at 3.5 per cent

New Delhi: Delhi recorded its worst air quality for December this year since 2018 with an average AQI of 349, even as farm fires accounted for just 3.5 per cent of the PM2.5 pollution, according to official data.

In December 2018, the capital logged an average Air Quality Index (AQI) of 360, an official told PTI.

The December average stood at 294 in 2024, 348 in 2023, 319 in 2022, 336 in 2021, 332 in 2020, 337 in 2019, and 301 in 2015, Central Pollution Control Board (CPCB) data showed.

This month, the city recorded 'severe' air quality on five days. Last year, Delhi saw six such days in December.

On Monday, too, Delhi's air quality slipped into the 'severe' category with an AQI of 401 at 4 pm as against 390, in the 'very poor' category, on Sunday.

According to the CPCB, an AQI between 0 and 50 is considered 'good', 51 to 100 'satisfactory', 101 to 200 'moderate', 201 to 300 'poor', 301 to 400 'very poor', and 401 to 500 'severe'.

Stubble burning accounted for only 3.5 per cent of Delhi's PM2.5 pollution till December 5 this year, even as Delhi-NCR remained among the most polluted regions in the country, according to information provided by the CPCB in response to an RTI application filed by Noida-based environmentalist Amit Gupta.

The CPCB said it continues to rely on the TERI-ARAI Source Apportionment Study of 2018 to assess the contribution of various sources to PM2.5 and PM10 pollution in Delhi-NCR. No comprehensive source apportionment study has been conducted since then, it said.

However, daily mean data generated by the Decision Support System (DSS) of IITM Pune under the Ministry of Earth Sciences shows a steady decline in the contribution of stubble burning to PM2.5 levels during the October-December period over the years.

The share of stubble burning stood at 13 per cent in 2020 and 2021, fell to 9 per cent in 2022, rose marginally to 11 per cent in 2023, and was 10.6 per cent in 2024 before dropping to 3.5 per cent in 2025.