Happy polluted Diwali! Get ready for severe air pollution as AQI monitoring agency sounds warning this year

Delhi residents could be heading towards another polluted Diwali, with the national capital's air quality expected to enter the severe category just ahead of the festival. The warning comes as pollution levels continue to climb, farm fires gather pace in neighbouring states and unfavourable weather conditions threaten to trap pollutants close to the ground. The Air Quality Index (AQI) stood at 369 on Thursday, already placing Delhi in the very poor category. However, the situation could deteriorate further. According to the Air Quality Early Warning System for Delhi, the AQI is likely to cross 400 and remain in the severe category from Friday through Sunday. The forecast suggests little immediate relief. Delhi's air quality could fluctuate between severe and very poor levels over the following six days, raising concerns about the health impact of pollution during the festive period.

Why could Delhi face severe air pollution this Diwali?

Several factors are coming together to worsen the pollution situation in Delhi-NCR. These include crop residue burning in Punjab and Haryana, emissions from firecrackers, falling temperatures and weather conditions that could prevent pollutants from dispersing. Farm fires have already started contributing significantly to Delhi's pollution. Data showed that stubble burning accounted for 16.3% of the capital's PM2.5 pollution on Wednesday, marking the highest seasonal contribution so far.

The contribution is expected to remain substantial. According to the Decision Support System, farm fires could account for around 15.6% of Delhi's PM2.5 pollution on Thursday and rise to 19.2% on Friday. The timing is another concern. Crop residue burning has started later than usual in Punjab and Haryana, potentially shifting the peak period into November.

Super El Niño could make pollution worse

Weather conditions could add another layer to Delhi's pollution problem this year. Gufran Beig, founder of the System of Air Quality and Weather Forecasting and Research (SAFAR) and chair professor at the National Institute of Advanced Studies (NIAS), told TOI that delayed stubble burning could push the peak farm-fire period into the second week of November. He also flagged the possible impact of Super El Niño conditions.

According to Beig, weaker winds and a possible fall in temperatures could make it harder for pollutants to disperse. Although El Niño is generally associated with the possibility of a milder winter, temperatures could still decline from the second week of November. North-northwesterly winds are another concern. These winds, expected between November 7 and 10, could carry emissions from agricultural fires towards Delhi.

Firecrackers could trigger another pollution spike

The use of firecrackers during Diwali could further worsen an already difficult situation. Beig warned that conventional firecrackers could cause a sharp increase in pollution levels. The impact could be particularly noticeable around midnight on November 8 and during the early hours of November 9.

He also cautioned against Chinese firecrackers, saying certain products could expose people to carcinogenic heavy metals. The concern is not limited to fireworks, however. Even without firecracker emissions, the combination of farm fires and unfavourable meteorological conditions could push pollution levels higher in the coming days.

What happened to Delhi's AQI on Diwali in previous years?

Delhi's pollution record over the past few Diwalis offers a clear indication of how dramatically air quality can change around the festival. In several years, the AQI increased sharply on Diwali or the following day. The extent of the deterioration depended on the timing of the festival, weather conditions, farm fires and firecracker emissions. Here is how Delhi's AQI changed during recent Diwali celebrations:

Year	AQI on Diwali eve	AQI on Diwali	AQI the next day
2025	296	345	351
2024	273	328	339
2023	220	218	358
2022	259	312	303
2021	314	382	462
2020	339	414	435

In 2025, Delhi's AQI increased from 296 on October 19, the eve of Diwali, to 345 on the festival day. It climbed further to 351 on October 21. Although green crackers were permitted for limited hours over two days, restrictions were widely violated. The festival falling in mid-October meant that winter weather conditions and stubble burning had a relatively smaller influence on pollution levels.

The 2023 figures were also concerning. AQI jumped from 218 on Diwali, celebrated on November 12, to 358 the following day. Not every year followed the same pattern. In 2022, favourable meteorological conditions helped Delhi's AQI improve from 312 on Diwali to 303 the next day.

The situation was considerably worse in 2021 and 2020. In 2021, the AQI rose from 314 on Diwali eve to 382 on the festival day before reaching 462 on November 5. In 2020, it climbed from 339 before Diwali to 414 on the festival day and 435 the next day.

Will Delhi get relief after Diwali?

The immediate outlook does not offer much reason for optimism. With farm fires expected to intensify, north-northwesterly winds potentially carrying pollutants into the capital and firecracker emissions adding to the existing pollution load, Delhi could face another difficult spell.

The coming days will be particularly important. Even if firecracker use is limited, the combined impact of agricultural emissions and weather conditions could keep the capital's air quality in the very poor or severe categories.

For residents, this means the pollution problem may not end with Diwali celebrations. The post-festival period could prove equally challenging as winter conditions gradually set in.

(Inputs from TOI)