There was light, lamps and cheer. And later, there also came smoke and smog. But as compared with the last few years, the Diwali after-effects across the country this year were not that bad. 

According to Central Pollution Control Board data, no city in the country recorded a ‘severe’ Air Quality Index (AQI), as on the evening of Diwali, that fell on October 24 this year. . The air quality of a locality is termed severe when AQI value falls between 401 and 500.

On Diwali days of 2020 and 2021, air quality, in nine and four cities respectively, fell in the severe category. ‘Severe’ quality air is capable of causing respiratory impact even on healthy people. 

Of interest is the fact that 80 per cent of the cities, for which air quality data is available, recorded ‘moderate’ to ‘good’ air quality. During previous three Diwalis, 59 to 61 per cent of cities recorded clean air  All the cities that recorded ‘severe’ AQI in the previous year are in the northern part of the country.

What changed

So, what changed this year? Dr Sachchida Nand Tripathi, a professor of IIT Kanpur and member of the Steering Committee and Monitoring Committee, the National Clean Air Programme, says the air was cleaner mostly dueto faster winds this Diwali in the north. “The amount of PM 2.5 pollutant also saw reduction due to these winds. The fire intensity was overall lesser in Punjab and Haryana, as compared with previous years,” he says. 

What happened in Delhi? 

The capital city is always in the news, in and around Diwali, owing to smog and heavy air pollution in those days. This year, too, it was the same situation, but with a difference.

Delhi’s AQI on the evening of October 24 was 312, the lowest that capital has ever recorded on a Diwali day in seven years, according to experts. The city’s AQI values on Diwali were 337 in 2019, 414 in 2020 and 382 in 2021. 

Other factors

On October 19, Delhi Environment Minister Gopal Rai announced a jail term of up to six months and a fine of ₹200 for those bursting crackers. However, Dr Gufran Baig, Founder Project Director, System of Air Quality and Weather Forecasting And Research (SAFAR), said there could be other factors that made for a comparatively better AQI this year.

“Diwali came much earlier this year and winter is yet to begin. Accumulation of pollutants takes place faster in colder temperatures. This time, in the early hours, temperature was much higher,” says Baig, adding, “The wind direction over the stubble fires, which is north-westerly during this period, changed to south-westerly on Diwali. This region doesn’t have fires, and hence the contribution of farm fires to pollution at 5-8 per cent is minimal.” 

Of other large cities, Chennai noted an AQI of 192, while it was 136 in Mumbai, 100 in Bengaluru and 55 in Kolkata. 

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