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October usually translates mainly to the festival season, but for Delhi locals, there’s another seasonal tradition creeping in: the annual winter smog, and this year, it's already showed up. Rather early.
In fact, on Sunday, October 4, the national capital recorded its worst AQI of the season at 190 and above. By 10am on Sunday, the AQI had touched 196: the highest in more than 82 days, since July 13, when it stood at 246.
Experts say this is less a standalone blip and more of an opening for a run of increasingly polluted days. The forecast for this week, unfortunately, says that pollution is expected to stick around, with 22 monitoring stations predicting ‘poor’ air and no rain to wash the atmosphere clean. Weaker winds throughout are only going to make the pollution hang around rather than disperse.
Delhi recorded an AQI of 166 on Thursday, 174 on Friday and 171 on Saturday, with PM10 as the dominant pollutant. The average index was sitting at the higher end of the ‘moderate’ category throughout last week, until it dropped to worrisome ‘poor’ levels on Sunday.
Which areas were the most polluted in Delhi?
Mundka recorded the highest reading at 273 among all Delhi stations, followed by Narela at 257. Neighbouring parts of the National Capital Region weren’t breathing easy either. Noida reported an AQI of 281, while Ghaziabad recorded 248. Delhi Cantonment had the lowest AQI in the city at 115.
What AQI reading falls in the 'poor' category?
According to Central Pollution Control Board (CPCB) standards:
0–50: Good
51–100: Satisfactory
101–200: Moderate
201–300: Poor
301–400: Very poor
401–500: Severe
That’s how the pollution board calculates how lethal the air becomes. For the government and its transport departments, the same air is graded on a separate, yet similar-ish, scale. The Graded Response Action Plan, or GRAP, is a set of emergency measures implemented in the Delhi-NCR to prevent and control air pollution. The plan escalates the number of restrictions as per the smog situation’s grimness. Stage 1 is triggered when the AQI is in the 201–300 range, Stage 2 at 301–400, Stage 3 at 401–450, and Stage 4 above 450.
What’s Delhi’s winter plan?
Delhi does has a winter plan – but we're yet to see if it'll work.
Statistically, since most pollution inside Delhi is caused by vehicles operating within the city and those entering from outside, the motor side of the story is getting plenty of attention in the Delhi winter pollution plan.
Transport and commute
All petrol, diesel and CNG stations will sell fuel only to vehicles with a valid Pollution Under Control Certificate (PUCC) throughout the year. The government has separately announced an enforcement drive against vehicles with invalid PUCCs from October 1 across 500 petrol pumps using Automatic Number Plate Recognition (ANPR) systems. The system will will flag any vehicle via its number plate in case there’s no valid pollution certificate for it. Similar restrictions are on the way against end-of-life vehicles.
Delhi generates around 30% of its pollution, out of which roughly 60% to 65% comes from or is influenced by surrounding NCR areas. That necessitates coordination with regional states like Haryana and Uttar Pradesh. Between November 1 and January 31, no non-BS6 vehicle registered outside Delhi will be able to enter the capital. These restrictions will not apply to CNG and electric vehicles and emergency services vehicles.
To discourage the use of private vehicles, parking charges at authorised parking sites, barring those maintained by DMRC, will be doubled between November 1 and February 28. The government’s target is to raise daily ridership to 72 lakh on the Metro and 42 lakh on DTC buses, supported by a fleet of 5,088 electric buses.
Please leave the car at home, if you can.
Work from home
Between November 1 and January 31, private entities have been advised to adopt staggered working hours and measures such as car-pooling, ride-sharing and common buses to reduce vehicles on the road. For the same period, government and private offices are required to ensure no more than 50% physical attendance, with the remaining employees working from home or following a two-day-per-week work-from-home model.
Construction
Construction gets a winter timeout from November 1 to January 31. All dust-generating demolition and open civil construction activities will be prohibited, except for essential public infrastructure projects. The ban will be all out between December 10 and January 20, barring urgent government and emergency works. Large commercial buildings and construction sites will have to deploy anti-smog guns or mist systems.
Vehicles carrying construction material such as sand, stones, bricks and cement cannot enter the city during this period, barring exemptions for projects of national importance, essential public infrastructure and emergency works.
Why does Delhi cry for help every winter?
The smog situation gets considerably worse every winter without fail because of two things: no rain and weaker winds. While low wind speeds prevent emissions from dispersing effectively, an increase in farm-fire activity in the surrounding areas makes Delhi air stuffed with toxins. While the polluted cold winter air stays dense and heavy near the ground, warmer air settles above it, effectively putting a lid over the city and stopping pollution from rising and dispersing. And when winter winds are calm, pollutants remain trapped even horizontally.
Delhi’s geography doesn’t make matters easier, either. The city sits in the Indo-Gangetic Plain, bordered by regional mountain ranges that restrict air movement. That is why the blinding winter smog, composed of moisture mixed with tiny particles of dust and smoke, has become an annual Delhi feature.
Why was this not the case two decades ago? Well, Delhi, like other cities, was actually suffering from rising air pollution even two decades back. That was the time when the government took the whole matter seriously for the first time. The CNG bus fleet started swelling up, and people were asked to avoid crackers during festivals. Then, pollution remained a matter for a countable number of days. Over time, urbanisation and construction for it, and also more vehicles and less green space to filter air, made Delhi a burning furnace even during summers.
Now, Delhi’s pollution problem isn’t simply switched on when winter arrives. Overall emission loads generally remain broadly similar through the year, barring exceptional events such as stubble burning, firecrackers, and dust storms. Just that during winters, as stated above, the filthy air gets more space to play, and hence more footage.
Which is why, when a Delhiite says ‘winter is coming’, there’s usually a very specific mix of excitement and dread, both in equal parts.