Delhi’s air quality slips back to ‘very poor’ after brief respite

A day after a slight improvement, the air quality in the capital slipped back to the ‘very poor’ category at 304 on Monday, marking a return to the prolonged pollution spell Delhi has been battling this winter.

Following 24 days of ‘very poor’ air, often edging towards the ‘severe’ zone, Delhi’s Air Quality Index (AQI) improved to ‘poor’ on Sunday with a reading of 279.

However, by 4 pm on Monday, the 24-hour average AQI climbed to 304, according to Central Pollution Control Board (CPCB) data.

The CPCB classifies an AQI between 0 and 50 as ‘good’, 51 and 100 ‘satisfactory’, 101 and 200 ‘moderate’, 201 and 300 ‘poor’, 301 and 400 ‘very poor’, and 401 and 500 as ‘severe’.

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Transport emissions accounted for 20 per cent of Delhi’s pollution on Monday, and it is projected to contribute 19.8 per cent on Tuesday, according to the Decision Support System of the Indian Institute of Tropical Meteorology, Pune.

Before Sunday, Delhi last recorded AQI in the ‘poor’ category this season on November 5, when the reading stood at 202.

Monday’s AQI followed a week-long trend – 279 on Sunday, 305 on Saturday, 369 on Friday, 377 on Thursday, 327 on Wednesday, 352 on Tuesday and 382 on Monday.

According to the Sameer app developed by the CPCB, no monitoring station in Delhi recorded ‘severe’ air quality on Monday, similar to the trend seen over the weekend, in contrast to eight stations falling in the ‘severe’ zone on Friday.

November’s average AQI stood at 357 – in the ‘very poor’ range but slightly better than 374 in 2024 and 366 in 2023. The city saw no ‘good’, ‘satisfactory’, or ‘moderate’ air quality days last month. Instead, it recorded three ‘poor’, 24 ‘very poor’, and three ‘severe’ days.

Meanwhile, winter conditions tightened in the capital, with the minimum temperature dropping to 5.7 degrees Celsius on Monday, 4.6 notches below the season’s normal.

The maximum temperature settled at 26.1 degrees Celsius, marginally above the season’s average, while humidity levels fluctuated between 63 per cent and 100 per cent during the day.

The India Meteorological Department (IMD) has predicted a cold wave with no warning for Tuesday, with the maximum and minimum temperatures expected to hover around 26 degrees Celsius and 9 degrees Celsius, respectively.