New Delhi: That Capital on Friday woke up to the worst post-Diwali air in five years, with the air quality nose diving into the "severe" category and a hazardous amount of pollutants as the Delhi government's ban on firecrackers went up in smoke - with residents defying the ban openly in almost all parts of the city, bursting crackers in some parts throughout the night.
A thick layer of acrid smog hung over NCR accumulated due to firecrackers and farm fire emissions from neighbouring states, which also reached a season peak on Friday. The capital's 24-hour average air quality index for the day after Diwali was recorded at 462, the highest in five years - with many monitoring stations recording "hazardous" air throughout the day.
In neighbouring Noida, the 24-hour AQI was 475, the highest in the country. The neighbouring cities of Faridabad (469), Greater Noida (464), Ghaziabad (470), Gurgaon (472) also recorded 'severe' air pollution levels.
The smog partially blotted out the sun in Delhi on Friday and residents complained of itchy throats and watery eyes.
The Diwali night pollution was at such a peak that even the 24-metre high smog tower recently inaugurated by Chief Minister Arvind Kejriwal at Connaught Place failed to deliver breathable air on Diwali night, according to government data.
There was no immediate reaction from the office of Delhi Environment Minister Gopal Rai to queries related to the smog tower data.
Official sources, however, said smog towers can "reduce pollution only to a certain extent and one cannot expect the large air purifiers to provide clean air on hazardous air quality days like Friday".
Sunil Dahiya of the Centre for Research on Energy and Clean Air said all environmentalists and scientists have been saying there is no proven record or data globally that establishes that smog towers are effective.
"This experiment at Connaught Place has shown that smog towers can never be a solution to the problem of air pollution. Any further wastage of money on such structures should be stopped immediately. The money should be utilised to reduce pollution at source," he said.
But even as Delhi defied the firecracker ban with impunity, the Delhi Police said that they had received over 1,000 PCR calls related to the bursting of firecrackers on Diwali night and added that they had arrested 143 people for bursting firecrackers between September 28 and November 4. During this time, they said they had registered 125 cases for selling and manufacturing firecrackers, arrested 138 people in these cases and seized over 19,000 kg of firecrackers.
However, according to locals in areas in such as Chhatrapur, Fatehpur Beri, Kailash Colony, Burari, Shahdara, Paschim Vihar and even in Old Delhi several places, firecrackers were burst throughout Thursday night - indicating that there were far more people in the city with access to the banned crackers and those who had burst them.
But this was not for lack of efforts from agencies such as the police with Delhi Police saying that in October they had reached out to nearly 700 schools to spread awareness about not bursting crackers and had over 1,300 meetings with RWAs on the issue. But the ban was defied spectacularly nevertheless.
The 24-hour average concentration of lung-damaging fine particles known as PM2.5 in Delhi-NCR shot up from 243 micrograms per cubic metre at 6 pm on Thursday (Diwali day) to 430 micrograms per cubic metre at 2 pm on Friday, around seven times the safe limit of 60 micrograms per cubic metre.
The PM10 levels crossed the 500 micrograms per cubic metre mark around 5 am on Friday and stood at 558 micrograms per cubic metre at 2 pm.
In fact, a report prepared by the Delhi Pollution Control Committee showed that fireworks after 8 pm led to major changes in PM10 and PM2.5 concentrations in Delhi on Diwali night.
The sudden deterioration in Delhi's air quality this year can be attributed to extremely calm conditions, change in wind direction and low ventilation coefficient, and use of firecrackers, according to the DPCC's Diwali day air pollution analysis. This year, the 24-hour city average concentration of PM10 on the day of Diwali is 748 and PM2.5 is 607, the report read.
Though the increase in the concentration of pollutants was observed since Wednesday evening, the major changes were observed after 8 pm on Diwali when the fireworks started, the DPCC said.
A gradual increase in the concentration of particulate matter was observed on the day of Diwali and the highest value was observed at midnight and then slowly started decreasing, the report said.
According to the Graded Response Action Plan (GRAP), the air quality is considered to be in the 'emergency' category if PM2.5 and PM10 levels continue to be above 300 micrograms per cubic metre and 500 micrograms per cubic metre respectively for 48 hours or more.
Low temperatures and fog in the morning allowed the accumulation of pollutants - in addition to lowering visibility at the Indira Gandhi International Airport and the Safdarjung Airport to the range of 200 to 500 metres at 5.30 am. Visibility in parts of the city dropped to 200 metres, said R K Jenamani, a senior scientist at the India Meteorological Department (IMD).