Air quality swung back to pre-Diwali levels with most monitoring stations in the NCR registering “very poor” on the index. This was primarily due to elevated concentrations of particulate matter 2.5, a class of pollutants implicated in aggravating respiratory diseases.
Data from 15 stations on Sunday said that AQI stood at 329 or the “red zone”, but several points below the “maroon zone” or 400, when air quality is deemed to be “severely” bad. The day after Diwali, the AQI had dropped to “severe”.
Experts said this was due to stagnant air that had partly resulted from a depression in the Bay of Bengal. The effect of this, however, wasn’t specific to Delhi and air quality was “very poor” in several parts of north India including Agra, Moradabad and as far as Amritsar.
Despite a ban on the sale of crackers, the evening after Diwali saw Delhi record its sharpest dip in air quality this year.
This Diwali, the CPCB said, the concentration of pollutants was significantly lower than last year, when cracker-burning and unfavourable weather saw pollution levels spike above the maximum readings at several monitoring stations.
The Supreme Court has already directed a phase-down strategy in its directive of September 12 that asked for regulation of chemicals, reduced quantum of crackers, and controlled bursting through community events, among others.
Experts say that bringing down pollution requires much more than a cracker ban. These include steps to control emissions from continuous sources of pollution, including vehicles and industry, while placing curbs on episodic pollution such as from firecrackers and farm fires.
A comprehensive action plan must be drawn up on priority, which will combine short and long-term strategies for vehicles, industry, waste burning and construction activities, experts added.
The Supreme-Court mandated Environmental Pollution (Prevention and Control) Authority has, in the light of poor air quality in Delhi, directed that the Badarpur Thermal Power plant be shut and diesel gensets banned in the city. It will review these decisions next week.