2025 had been an anomoly of sorts as far as the air quality of the Delhi-NCR region was concerned. For the January-August period, the national capital registered its best average air quality index (AQI) in the last eight years, barring the pandemic years, thanks to strong wind patterns, above-normal rainfall, and high temperatures.
Not anymore.
On Tuesday, 21 October, the morning after Diwali, Delhi once again ranked on top in the world's most polluted major cities, according to live data from IQAir, a Swiss air quality tracking company. In the same ranking, Mumbai stood at third place, while Kolkata was sixth.
"It was worse this morning. The air felt heavier, breathing was harder, and running was difficult. Last week it felt fine, but today there’s a clear difference," YS Negi, 63, who was out for a run at Lodhi Garden, told The Quint.
The night before, as India celebrated Diwali, several parts of Delhi recorded an AQI above 400, according to SAMEER, a mobile app developed by the Central Pollution Control Board (CPCB) that provides hourly air quality updates.
These reporters analysed the difference in air quality by comparing the AQI before and after Diwali. The first reading was taken on Saturday, 18 October and another on Tuesday, 21 October at four different locations. In most areas, the AQI had doubled or nearly doubled.
AQI at Connaught Place on Saturday vs Tuesday.
(Photo: Raqeeb Raza/ The Quint)
Did Green Crackers Work?
On Wednesday, 15 October, the Supreme Court allowed the use of 'green crackers', relaxing the annual blanket ban on firecrackers that aims to curb severe air pollution in the Delhi-NCR during Diwali. The court noted that the blanket ban had previously led to black marketing of conventional firecrackers and argued that permitting ‘eco-friendly’ green crackers could help curb their illegal production and sale.
Delhi Chief Minister Rekha Gupta welcomed the verdict, saying it honours the spirit of the festival while 'striking a balance' between tradition and environmental protection.
However, writing for The Quint, Shailaja Chandra, former Chief Secretary of Delhi, pointed out the loophole in the order with the unavailability of green crackers. "The red ones are easily available in the NCR cities of Noida and Faridabad (where I know people buying them), and sharing sacks full of firecrackers is going on briskly," she writes.
Moreover, while green crackers are claimed to be 30 percent less polluting than traditional firecrackers, experts have repeatedly warned of their health risks. “The pollutants may be lower, but the smoke and dust remain. You cannot eliminate that. Any firecracker that emits smoke and dust will affect people’s health,” Dr Rajesh Chawla, senior pulmonologist at Apollo Hospital, told The Quint.
As fireworks rang out across the city well into the night, the air quality took a hit, leaving the city shrouded in thin veil of smoggy haze. Delhi’s 24-hour average AQI stood at 356 at 9 AM on Tuesday, according to CPCB data, and remained high at 255 by 2 PM.
"It’s better here (Lodhi Garden) compared to other places, since there are a lot of trees," said another regular jogger at the garden in Central Delhi.
Several areas, particularly densely populated residential and industrial zones such as Bawan, Burari, Jahangirpuri, Anand Vihar, and Wazirpur, experienced “severe” air pollution, with AQI levels exceeding 400.
Just 72 hours earlier, on Friday evening, AQI levels were much lower, ranging between 180 and 200.
For reference, the CPCB classifies air quality as follows:
51–100 is “satisfactory”
101–200 is “moderate”
201–300 is “poor”
301–400 is “very poor”
401–500 is “severe”
The Impact on Health
"We do see a spike in sales of inhalers around this time of the year. It happens every year. This year, we have had a few sales so far, but we expect it will go up in the coming weeks," Girish, who works at a chemist shop in Jangpura, told The Quint.
Poor air quality can cause breathing difficulties, coughing, flu-like symptoms, and chest pain, and in severe cases, may trigger asthma, COPD, and cardiac problems. Children and the elderly are particularly vulnerable.
Speaking to The Quint for a previous article, Dr Priyanka Singh, Consultant and Eye Surgeon at Neytra Eye Centre in New Delhi, explained that air pollution can also affect eye health, causing watery eyes, itching, redness, irritation, and even pain.
"When particles from pollution, dust, and smoke enter the eyes, they disrupt the tear film that normally keeps them moist and lubricated, leaving the eyes dry and uncomfortable," she said.
Experts say the best way to protect against pollution-related illnesses is to minimise exposure as much as possible.