The Commission for Air Quality Management on Saturday imposed Stage 4 restrictions under the Graded Response Action Plan to control pollution in Delhi and the National Capital Region, as the air quality slipped to the “severe” category.
A day earlier, the commission had invoked Stage 3 measures.
GRAP is a set of incremental anti-pollution measures that are triggered to prevent further worsening of air quality once it reaches a certain threshold in the Delhi-NCR region. The commission is a statutory body formed in 2020 to address pollution in the NCR and adjoining areas.
It stated on Saturday that the Air Quality Index of Delhi was 400 at 4 pm and deteriorated to 428 by 8 pm due to “calm winds, stable atmosphere and unfavourable meteorological conditions resulting into trapping of the pollutants”.
The India Meteorological Department and the Indian Institute of Technology-Madras have forecast further deterioration of air quality, the commission added.
“Accordingly, in an effort to prevent further deterioration of the air quality, the sub-committee on GRAP hereby decide to proactively invoke all actions under Stage 4,” it stated.
An AQI in the “severe” category signifies hazardous pollution levels that can pose serious risks even to healthy individuals.
Stage 4 restrictions under GRAP include a ban on trucks entering the region and halting construction activities for public and private projects. All schools, except for classes 10 and 12, also shift to hybrid mode.
Stage 3 measures, which were already in place, include a ban on non-essential construction work and the closure of stone crushers and mining activities.
Additionally, the use of BS-III petrol and BS-IV diesel cars is restricted in Delhi and the NCR.
BS norms, or Bharat Stage Emission Standards, are regulations set by the Indian government to control air pollutants from motor vehicles. The higher the BS norm, the stricter the standard and the lower the permissible emissions.
The commission’s decision on Saturday came as the overall AQI in Delhi rested at 400, according to the Sameer application, which provides hourly updates from the Central Pollution Control Board.
On Sunday, the AQI in the national capital was 439 at 7.05 am.
Watch: Delhi’s pollution crisis needs drastic action
An index value between 0 and 50 indicates “good” air quality, between 51 and 100 indicates “satisfactory” air quality and between 101 and 200 indicates “moderate” air quality. As the index value increases further, air quality deteriorates. A value of 201 and 300 means “poor” air quality, while between 301 and 400 indicates “very poor” air.
Between 401 and 450 indicates “severe” air pollution, while anything above the 450 threshold is termed “severe plus”.
Delhi and the neighbouring cities have recorded air quality in the “poor” or worse categories since mid-October.
Air quality deteriorates sharply in the winter months in Delhi, which is often ranked the world’s most polluted capital. Stubble burning in Punjab and Haryana, vehicular pollution, along with the lighting of firecrackers during Diwali, falling temperatures, decreased wind speeds and emissions from industries and coal-fired plants contribute to the problem.
On December 24, the commission revoked Stage 4 restrictions that had come into force on December 13 after the air quality slipped into the “severe plus” category.
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