'Only 9 Delhi AQI Posts Worked On Diwali': Top Court Told Of 'Missing Data'

Only nine of Delhi's 37 air quality monitoring stations were functioning on Diwali – when the city was smothered by a toxic smog of chemicals from 'green' firecrackers, dust and vehicular pollution, and hazardous particulate matter from farm fires – the Supreme Court was told Monday, in another round of the now-annual bickering over air pollution in the city.

The court's amicus curiae, Aparjita Singh, demanded to know how the Commission for Air Quality Management, a statutory body tasked with improving Delhi's AQI, could fulfil its mandate without critical data on air pollution levels in various parts of the city.

"We don't even know when to implement GRAP (Graded Response Action Plan). That is the severe situation," Singh said, "… let them (i.e., the CAQM) answer this question – 'what is the situation of monitoring stations?' Because on Diwali, out of 37, only nine were working."

"Why is the CAQM shrinking from filing a report?"

In response, the bench led by outgoing Chief Justice BR Gavai directed the CAQM and CPCB, the Central Pollution Control Board, to submit a detailed report on its battle to improve AQI.

Research by NDTV on October 21, a day after Diwali, showed AQI dropped to a five-year post-Diwali low despite a 77.5 per cent drop in farm fires - normally a key reason for air pollution.

READ | 'Green' Crackers Failed. Delhi Suffers Worst Post-Diwali Air In 5 Years

Average PM2.5 levels reached shocking averages of 488 micrograms per cubic metre - nearly 100 times the exposure limit advised by the World Health Organization - and, perhaps worse, represented a catastrophic 212 per cent increase from pre-Diwali levels.

Air pollution levels, in fact, reached a three-year high.

This after the Supreme Court permitted bursting of 'green' firecrackers within specified hours.

READ | "Since Crackers Smuggled In...": Why Supreme Court Gave Big Go-Ahead

However, both orders, it seemed, looking at the deadly grey blanket over the city on the morning after Diwali, were ignored, with the familiar acrid smell of chemicals lingering in the air.

Air quality readings pre-, on, and post-Diwali for 2021-2025. Data: CPCB

Today's exchange in the top court came as Delhi continues to gasp for breath and air pollution levels soar to alarming levels, again. The AQI, or air quality index, in most parts of the city today was well above the danger mark; it was 335 in RK Puram, 350 in Sonia Vihar, 352 in Rohini, and 377 in Wazirpur. In others, including Siri Fort in the posh South Delhi area, it was over 330.

CPCB data showed PM2.5 concentrations at 189.6 micrograms per cubic metre and PM10 at 316 – both well above safe limits. These particles, invisible to the eye, silently invade the lungs and bloodstream, posing often fatal health risks, especially to children and elderly people.

The overall air quality in the city – one of the worst polluted in the world - remains in the 'very poor' category at 316. This was a marginal relief from the 366 measured Sunday, when data from three (of the functioning) AQI monitors showed readouts of 400+, or in the 'severe' category.

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