Smog chokes Delhi; crackers, farm fires lead to worst post-Diwali AQI in 5 years

Delhi's 24-hour average AQI, which entered the 'severe' zone on Thursday night, stood at 462 at 4 pm on Friday.

Published: 05th November 2021 09:42 PM  |   Last Updated: 06th November 2021 07:59 AM   |  A+A-

Low visibility due to smog after Diwali celebrations, in New Delhi. (Photo | Parveen Negi, EPS)

Low visibility due to smog after Diwali celebrations, in New Delhi. (Photo | Parveen Negi, EPS)

Express News Service

NEW DELHI:  Delhi woke up to a thick layer of haze and smoke-filled skies on Friday, registering the worst post-Diwali pollution spike in five years. A combination of factors — firecracker emissions despite a blanket ban; first winter fog and calm winds; and peak stubble burning  — pushed the air quality into the severe zone, an analysis by government agencies said.

Poor enforcement of cracker ban in Delhi and the absence of any bar in the satellite towns allowed large-scale burning of firecrackers overnight, resulting in a midnight spike in pollution levels.  As per the Central Pollution Control Board (CPCB), Delhi’s overall air quality index (AQI) on Friday was 462, a sharp rise from 382 the previous day.

The PM 2.5 levels — the most prominent pollutant that can enter the blood stream and pose a serious health risk — shot up five times the permissible limit at midnight. Besides, the wind direction changed on Thursday night, bringing in smoke from peak stubble burning in neighbouring Punjab and Haryana. 

Delhi environment minister Gopal Rai on Friday said NASA images show stubble burning instances shot up from 1,000 last week to over 3,500 on Thursday. “A large population of Delhi did not burst crackers, but the BJP-ruled Union government did not enforce or place a blanket ban in satellite towns resulting in people bursting firecrackers,” Rai said. 

The Delhi government had launched an anti-firecracker campaign last month — Patakhe Nahi, Diye Jalao to discourage people from burning crackers. This year, it had placed a blanket ban on sale and purchase of firecrackers early on while no licenses were issued to traders. Police officials said that it is mainly the NCR towns from where people have been buying crackers, as sale was not restricted there. 

A senior police official who did not wish to be named, said, “Crackers were not available anywhere in Delhi. People bought them from Noida and Ghaziabad. The only solution is to put a complete ban on selling and bursting crackers in NCR regions too.”  According to an analysis by the Delhi Pollution Control Committee, this was the sharpest rise in pollution levels in the city on the morning after Diwali since 2016 when the AQI was 445.   

Fireworks, stubble burning pushed AQI to ‘severe’

“A gradual increase in concentration of particulate matter was observed on Diwali and the highest value was observed at midnight, which then slowly started decreasing. The sudden deterioration this year is attributed to extremely calm conditions, change of wind direction and use of firecrackers. Though the increase in trend in the concentration of pollutants — PM2.5 and PM10 — was observed since the evening of November 3, the major changes were observed after 8pm on Diwali when the fireworks started,” the analysis said.

On Diwali day, the 24-hour city average concentration of PM2.5 was 607 and PM10 on the day of Diwali was 748. Most monitoring stations in Delhi recorded PM2.5 levels ranging from 800 to 1,700 ug/m3 during 8 pm to 5 am, peaking around midnight. The PM 2.5 levels soared to 309ug/m3 at 12 am on the intervening night between Thursday and Friday. In India, the permissible levels for PM 2.5 are 60ug/m3. At 6 am on Friday, the PM 10 levels (coarse particles) — another major pollutant in city air — soared to 511ug/m3.

The permissible limit for PM 10 is 100ug/m3. As per the Ministry of Earth Sciences (MoES), air quality forecasting system, firework emissions on Diwali evening combined with peak stubble burning (36% share to overall PM 2.5 levels) pushed the air quality to ‘severe’ zone. “However, local winds have picked up since Friday morning and now fast dispersion is expected. Without any more firecracker emissions, the AQI will improve to ‘very poor’ zone on Friday night itself although stubble contribution is expected to remain almost the same as due to continuous burning.

Relief is expected only from the evening of November 7, but AQI is likely to remain in ‘very poor’ zone,” it said. According to the India Meteorological Department (IMD), Delhi saw its first fog episode on November 4. On Friday also there was fog early morning g with the visibility remaining around 200 metres till 8.30 am. In the absence of enough sunlight and fog, which allows settling of pollutants in the atmosphere, the concentration of pollutants was too high and close to the earth’s surface resulting in the pollution-mixed haze.

“The contribution from firecrackers, biomass burning and unfavourable weather conditions brought AQI in the severe category. The air quality is likely to improve marginally on November 6-7 owing to strong winds,” said R K Jenamani, senior scientist, IMD. The Delhi Police, meanwhile, registered as many as 210 cases and arrested 143 persons for bursting crackers in the city. Also, 138 people were arrested for illegal supply of firecrackers from September 29 to November 4. A total of 1143 calls were made to the Police Control Room (PCR) regarding bursting crackers on Diwali.


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