india

Updated: Oct 27, 2019 06:28 IST

Air quality across the national capital in the run-up to Diwali this year has been much cleaner in comparison to the days preceding the festival since 2016, but experts warn that the real test will come on Sunday, the day of the celebration, and its immediate aftermath.

The relatively cleaner air breathed by Capital’s residents in recent days was because of multiple factors, including meteorological conditions that carried away from Delhi the emissions from farm fires in neighbouring states of Punjab and Haryana where farmers have been offered incentives against post-harvest stubble burning, shutting down of coal-based power plants, building of peripheral roads to avoid the entry of polluting trucks and measures to check burning of waste. A longer monsoon this year also helped.

Last year, in the five days before Diwali, the Air Quality Index was in the “very poor” category for four days, and “moderate” for one. While this year, the AQI has remained in the “poor” category for four out of five days before Diwali. It it was in the “very poor” category on Thursday.

A day before Diwali, AQI was 287 (poor) on Saturday, compared to 338 (very poor) on the festival’s eve last year. In 2017, AQI on Diwali eve was “very poor” at 302.

In 2018, AQI was “very poor” the day after Diwali while it entered the “severe” category the day after that. In 2017, AQI post-Diwali was “severe”.

On Saturday, after sounding a “high alert” on air pollution, the authorities enforced a ban on overnight construction work and shut down coal-based industries until Wednesday. The Prime Minister’s Office on Friday asked Punjab and Haryana to use “every resource available so that stubble burning could be brought down.”

Even so, government agencies warned that the city’s air quality may plunge into the “severe” zone even if Delhi burns even half the crackers it did last year. Pollution could hit its peak between 1am and 6am (October 27-28) – the most crucial hours to watch out this year, according to the System of Air Quality and Weather Forecasting and Research (Safar), the weather and air pollution forecast wing of the Union ministry of earth sciences.

“The highest impact of firecracker emissions (if any) is expected post-Diwali in the early morning of October 28 between 1am and 6am. The forecast shows that most of hot spots would be residential areas, as these are the areas where bursting of crackers is maximum. In industrial areas it would be comparatively less,” said Gufran Beig, programme director at Safar.

To be sure, restrictions have been put in place on fireworks this Diwali. Only so-called green crackers — with 30% fewer emissions than traditional ones — are being allowed for the first time; these do not contain harmful chemicals such as barium nitrate. In line with Supreme Court guidelines, on Diwali, crackers can be burst only between 8pm and 10pm. Flouting of the rules, including the time window, could land one in jail.

One fallout is that only two kinds of fireworks — phuljhari (sparklers) and anar (flower pots) — are available in the market; manufacturers of green crackers didn’t have sufficient time to get other samples tested and cleared.

Delhi Police have said that, in multiple raids in the fortnight leading to Diwali, they have seized over 26,000 kilograms of illegal firecrackers and have arrested eight people for running manufacturing units, hoarding crackers to sell and use. Two police officials who did not wish to be named said they suspect people may have stored banned crackers weeks before Diwali in order to sell them illegally in the black market.

Safar has predicted that AQI will plummet and enter the “severe” category on Monday. However, weather conditions like wind speed direction may help disperse the pollutants by the next day.

“The wind speed is expected to remain good. The effect of stubble burning is also moderate this year. The wind blowing over Delhi will be easterly (not from northwestern parts of Punjab and Haryana). All this coupled with bursting of less crackers this year may see a cleaner post-Diwali air this time,” said Safar in a statement released on Saturday.

But the experts warned that the forecast could be upset by residents burning more firecrackers than they did in previous years around the time the city transitions from the monsoon to winter, a critical period for Delhi when it comes to the battle against pollution.

The period between October 25 and November 12 is critical because of a multiplicity of factors, one expert said.

“At this time of the year, stubble burning is at its peak. Winds slow down and there is a dip in temperature. If Diwali falls within this period and if crackers are burnt then chances remain high that Delhi would get engulfed in a thick layer of pollution that may not disperse for the next two to three days. Hopefully the easterly winds and its speed will help dispel pollutants this year,” said D Saha, a former head of the Central Pollution Control Board’s air quality laboratory.

Other experts asserted the importance of the larger role of the community in controlling emissions from firecrackers in giving Delhi residents breathable air over the next few weeks.

“This year when Delhi-NCR has already enforced the emergency action plan as well as additional measures such as construction ban etc in anticipation that crackers will contribute to high pollution levels, it is crucial that the overall quantum of bursting of firecrackers is minimised if not eliminated, as they result in a toxic spike. Delhi has taken tough preventive measures ahead of Diwali to curb air quality from plunging. At such time, community support is required for less and less bursting of crackers. At the end it is a health issue for everyone,” said Anumita Roychowdhury, executive director, research and advocacy, Centre for Science and Environment (CSE).