Maximum Toxi-city: Delhi's pollution crisis prompts WFH orders, school closure

Delhi was smeared in a morbid grey on Monday as the air quality index (AQI) surged to 494, the city’s second-highest reading ever and just shy of the maximum of 500, as the Capital’s calamitous pollution crisis plumbed new depths, with more than 20 million people held hostage in a sea of poison by the weather and an apathetic administration.

Delhi’s AQI was this bad on November 3, 2019, when the official 4pm reading was also 494. It was only topped, marginally, on November 7, 2016, when the number was an even more grim 497.

The AQI inched up through the evening and touched 495at 11pm.

Worse still, the AQI at 15 of the city’s 36 active monitoring stations hit 500 at 4pm, when the Central Pollution Control Board (CPCB) logs its daily reading.

And even as residents across the Capital took in laboured breaths, struggled with prickly throats, irritable eyes and all the trappings of a fever, local authorities did their best to deflect blame.

All the usual excuses were thrown around. But in the deep end of the “severe” zone, none of them matter.

It doesn’t matter that the AQI turned severe later in the year than it usually does; it doesn’t matter if it lasts for just a day or two; it doesn’t matter that the reading came on the back of reportedly fewer farm fires in Punjab; it doesn’t matter that the state government has deployed ineffective gimmicks like smog guns to tackle a deep-rooted but predictable problem.

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Delhi’s hourly average concentration of PM2.5 (a microscopic pollutant with a diameter between 1 and 2.5 micron) on Monday touched a peak of 820 micrograms per cubic metre (µg/m3) at 12pm. This was around 14 times the national 24-hour standard of 60µg/m3 and 164 times the World Health Organization’s (WHO) daily limit of 5µg/m3.

At these levels of pollution, it only matters that millions have been crippled by years of administrative ineptitude and left to fend for themselves.

And the air emergency is likely to remain at this alarming level till Thursday at least, according to predictions by the Early Warning System (EWS) for Delhi.

The city’s AQI was 441 on Sunday and 417 on Saturday. An AQI between 401 and 500 is considered “severe”.

Experts said the latest chapter in the crisis was fuelled by a perfect storm of weather factors – smoke from farm fires in Punjab that gushed into Delhi and remained locked in place by slow winds and plunging temperatures.

“At the transport level (several metres above the surface), we have strong winds, but locally, winds are not strong enough to disperse pollutants,” said Mahesh Palawat, vice-president at Skymet meteorology, a private weather forecaster.

“With the winds blowing in from the northwest, stubble smoke is travelling to the Capital. We also have low temperatures, which will only dip further and slow down dispersion further,” he added.

The effects of this cocktail were seen and felt.

A soupy smog coursed through the city’s alleys, blotting buildings, roads and trees even at close range, prompting several offices to allow people to work from home, as schools and colleges shifted to online lessons.

Scientists argued that Monday may have been Delhi’s most polluted day in modern history, given that the Capital had only nine stations in 2016, when its record AQI was logged.

Monday’s AQI was calculated on the basis of 36 stations, all of which were deep in the “severe” range. Throughout the day, at least 15 stations touched 500 — Mundka, Punjabi Bagh, Dwarka Sector 8, Ashok Vihar, North Campus, Wazirpur, Rohini, Nehru Nagar, Najafgarh, Bawana, Major Dhyanchand, Sirifort, Jahangirpuri, Dr Karni Singh Shooting Range and Patparganj.

ITO recorded the city’s lowest AQI at 4pm — 413.

The smoke and smog combined to slash visibility, which dipped to 100m in some parts, hitting flight and rail operations. At least 11 diversions and over 350 delays were reported at Indira Gandhi International (IGI) Airport, while at least 28 trains to or from Delhi were delayed by over an hour.

Temperatures were a key cog in Monday’s calamity.

Delhi’s maximum temperature was 23.5°C, four below normal and the lowest so far this season. It was 27.2°C a day earlier. The minimum temperature was 16.2°C, nearly four degrees above normal.

Experts said a weather condition known as “inversion” worsened matters. Inversion is characterised by a layer of warm air sitting on top of cooler air, trapping it. The warm layer tends to lock in the smog close to the surface. This condition is called inversion because cool air normally tends to sit above warm air.

The pre-dawn fog, combined with temperature dip and calm winds has paved the way for the inversion, said experts.

“Though surface winds did pick up marginally during the day to 8 to 10km/hour, it did not do much to disperse pollutants. We had significant fog in the early hours and then smog. No change in conditions is expected over the next two or three days, unless there are strong winds that blow away the fog forming over northwest India,” said Palawat.

Sunil Dahiya, lead analyst at the think-tank Envirocatalysts, said Delhi’s baseline pollution was already high, owing to sources like construction, industries, high transport emissions and waste burning, with unfavourable conditions and stubble burning exacerbating the situation.

“We are seeing stubble smoke reach Delhi and at the same time, there has been a drop in temperature. Winds are also calm and that is creating a layer of smoke and fog over the city. Reaching such unprecedented levels shows despite claims, nothing has been done to tackle air pollution,” he said.

Delhi chief minister Atishi blamed farm fires in Haryana, Rajasthan, Uttar Pradesh, and Madhya Pradesh for the worsening air.

“North India is choking because of the Modi government’s inaction. Stubble burning incidents have escalated in BJP-ruled states like Haryana, Rajasthan, Uttar Pradesh, and Madhya Pradesh, while AAP-governed Punjab has registered a decline,” Atishi said.

“People of Delhi are struggling to breathe, with the elderly and children needing medical support due to the severe pollution. Instead of taking action, the central government is busy playing politics, pushing the entire region towards a health crisis,” she said.

However, experts pointed out that Haryana recorded 36 farm fires on Monday, Rajasthan clocked 152, Uttar Pradesh 133 and Madhya Pradesh 639, all significantly fewer than Punjab’s 1,251.

Moreover, they added, that most of these states were downwind of the national capital and therefore cannot impact its air quality.

“The deterioration in the last few days is mainly down to stubble emissions from Punjab and Haryana. DSS data shows that the contribution of stubble burning has been over 20% since November 14. Locally, Delhi also experienced dense fog on Sunday and Monday, which reduced the amount of solar radiation reaching the ground, thereby reducing the mixing layer height. This is the height at which pollutants mix vertically in the air, and a low mixing layer height leads to the accumulation of pollutants near the ground,” said Priyanka Singh, programme lead at the Council on Energy Environment and Water (CEEW).