Delhi’s air quality drops to alarming low in a day, Centre bans non-essential construction work

As Delhi’s air quality dropped to the current season’s “worst level”, the Centre’s pollution control panel on Thursday banned non-essential construction work in the National Capital Region (NCR) and prohibited entry of diesel trucks into the city. These curbs are aimed to bring down level of pollution in the Delhi-NCR. .

The measures are part of Stage III of the Graded Response Action Plan (GRAP), the Centre’s air pollution control plan that is implemented in the region during the winter season.

Dry forecast worries

After a meeting to review the air quality situation in Delhi-NCR, the Commission for Air Quality Management (CAQM) said that the pollution levels are “expected to increase further”, owing to unfavourable meteorological and climatic conditions.

GRAP categorises actions into four stages: Stage I - ‘Poor’ (AQI 201-300); Stage II - ‘Very Poor’ (AQI 301-400); Stage III - ‘Severe’ (AQI 401-450); and Stage IV - ‘Severe Plus’ (AQI >450). Stage III of GRAP involves a complete halt on construction and demolition work except for essential government projects, mining and stone crushing.

It also includes a ban on the entry of Light Commercial Vehicles (LCVs) registered outside Delhi and diesel-guzzling trucks, and medium and heavy goods vehicles (except those involved in essential services).

The Air Quality Index (AQI) in many areas has breached the 400-mark to enter the “severe” category in Delhi and it reached 575 by 7.23 pm on Thursday, according to AQI dashboard. The previous high in the season was 412 AQI on October 30.

The PM2.5 concentration in Delhi reached 282 microgramme per cubic metre, higher than limit fixed by the World Health Organisation’s (WHO’s) air quality guidelines. PM2.5 is fine particulate matter that can penetrate deep into the respiratory system and trigger respiratory problems and its safe limit is 60 microgramme per cubic metre.

Hazy days ahead

Scientists have warned of a spike in pollution levels in Delhi-NCR over the next two weeks. India Meteorological Department has reported that visibility got reduced to just 500 metres at the Safdarjung Observatory around 7 am and gradually improved to 800 metres in the day as temperatures increased.

“Cold temperatures create stable atmospheric conditions, known as temperature inversions, where a layer of warm air traps cooler air near the ground, allowing the accumulation of pollutants,” the IMD said.

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’.

One of the major reasons behind the accumulation of pollutants in recent days is the lack of rainfall during this post-monsoon season, though recent spurt of stubble burning incidents is also adding to the pollution.

According to government data, Delhi’s air quality in October 2023 was the worst since 2020, with meteorologists attributing it to the absence of rainfall. The capital recorded an AQI of 210 in October, 2023 compared to 210 in October last year and 173 in October 2021, according to the Central Pollution Control Board (CPCB). In contrast to October 2022 (129 mm) and October 2021 (123 mm), Delhi experienced only one rainy day (5.4 mm of precipitation) in October 2023.

According to the Indian Institute of Tropical Meteorology (IITM), vehicular emissions (11-16 per cent) and stubble burning (7-16 per cent) are the two major contributors to worsen Delhi’s air quality.

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