New Delhi: Air in Delhi this year was much cleaner before Diwali compared with 2018. But on the Diwali night, the peak level of pollution was somewhat similar to that of 2018, due to bursting of firecrackers.
From a very clean afternoon to severe pollution after 10 p.m. on the Diwali night, the change was drastic. There was 10-fold jump in PM 2.5 concentration between 5 p.m, and 1 a.m, due to bursting of firecrackers.
“During Diwali, the peak level during 1 a.m. to 3 a.m. was quite similar to 2018. It was a warmer and windier Diwali than 2018. But while in 2018, the peak pollution continued until 8 a.m., this year it showed a sharper fall after 3 a.m,” said the Centre for Science and Environment (CSE).
As per the weekly trends in PM 2.5 levels, in 2019 air was much cleaner before Diwali compared with 2018, which shows the overwhelming role of firecrackers in building the severe peak on Diwali night.
CSE said this year, there were no severe pollution days during the week preceding Diwali. In 2018, the region had experienced a couple of days of severe pollution, with many more days in the ‘very poor’ category. This year, only Ghaziabad had experienced the season’s first 24-hour average severe pollution on the Diwali day. But according to indications, the air quality in the post-Diwali days could deteriorate to ‘severe’ category.
The CSE analysis of real-time data for Delhi and the towns in the National Capital Region (NCR), including Gurugram, Faridabad, Noida and Ghaziabad, showed how the Diwali night ushered in the season’s first severe pollution peak.
It has undone the comparatively cleaner trend achieved between September 15 and October 27.
Said Anumita Roychowdhury, CSE executive director-research and advocacy, “While harsher winter conditions are yet to set in and the weather during September 15 to October 27 remained relatively favourable (including a delayed monsoon), several systemic actions and preventive measures had also contributed to blocking early onset of very poor and severe pollution in the NCR. But the scenario changed on the Diwali night.”
Ghaziabad became the first among peers in the region to experience the season’s first 24-hour average severe pollution on the day of Diwali. The air in other cities and towns is expected to follow suit post-Diwali.
The CSE also compared the levels between 2019 and 2018 Diwali days. In 2018, Diwali was on November 7, 10 days later than this year in the season, and it was colder. It also took into account the wind speed trends.
The analysis emphasised that favourable weather and action tamed the 2019 winter pollution. It has noted that overall pollution levels are comparatively lower in Delhi and NCR towns since September 15.
While favourable weather conditions have contributed to this trend, the role of ongoing action and emergency interventions have also been important. This prevented build-up of pollution to ‘very poor’ and ‘severe’ levels before Diwali and also enabled quicker dissipation of pollution post-Diwali, the CSE said.
More importantly, during 2019, there have been days with wind speed lower than in 2018, and yet pollution has not exceeded 2018 levels. Even on days with better wind conditions in 2018, leading to Diwali, the pollution level was higher compared with 2019. It shows the overall pollution load in the city in 2018 must have been higher.
The CSE has demanded stronger and continuous action in Delhi and across NCR to reduce the pollution. It stressed enforcement of emergency action on industrial pollution, waste burning and dust generators with strong deterrence and zero tolerance.
Simultaneously, it has called for stepping up longer term systemic action to eliminate dirty industrial fuels, up-scale public transport, and minimise waste burning and dust generation for sustained air quality impact.
“It is absolutely necessary that action is stepped up to ensure that Delhi and NCR don’t plunge into a prolonged smog episode this winter,” said Roychowdhury.