Day after Diwali, Delhi's air quality at season's worst but better than last year

A hazy cocktail of emissions from fireworks, stubble burning and vehicles hung over the national capital a day after Diwali on Monday when the air quality index plummeted to "very poor", the worst-recorded level this season.

The city's air quality index (AQI) stood at 368 on Monday, a huge improvement over last year when it touched as high as 642, according to data from the Central Pollution Control Board (CPCB) and Delhi Pollution Control Authority (DPCC).

AQI at 4pm on Sunday was 337.

After last year's Diwali, Delhi's AQI reached as high as 642, which is more than three times the safe limit. The AQI post-Diwali was 367 in 2017 and 425 in 2016.

V.K. Shukla, in-charge of air quality management at CPCB, said stubble burning, higher vehicular emissions due to the festive season and unfavourable meteorological conditions were the prime reasons for the dip in air quality.

The satellite towns of Ghaziabad (396), Greater Noida (375), Gurgaon (372) and Noida (397) also recorded their AQI in the "very poor" category, according to the CPCB data.

Ambala, Hisar and Kurukshetra in Haryana recorded their AQI at 385, 370, and 392, respectively. In Uttar Pradesh, Muzaffarnagar, Moradbabad and Meerut recorded AQI at 426, 398 and 352.

The AQI in Punjab's Patiala, Ludhiana, Jalandhar and Khanna stood at 349, 353, 377 and 328, respectively.

An AQI between 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor", and 401-500 "severe". Above 500 is "severe-plus emergency" category.

The DPCC said less fireworks, rigorous night patrolling and enforcement measures to curb instigators reduced the PM2.5 and PM10 levels by 30 per cent on Diwali night this year when compared to 2018.

With Delhi's air quality plummeting to dangerous levels around Diwali every year, the Supreme Court had in 2018 banned polluting firecrackers and ordered that only green firecrackers, which is said to cause 30 per cent less pollution, can be manufactured and sold and enforced a two-hour limit for setting them off.

The Arvind Kejriwal government also organised a mega laser show in an effort to dissuade people from bursting crackers.

However, a large number of revellers brazenly flouted the Supreme Court-enforced two-hour limit for bursting crackers this year too.

According to Dr Arvind Kumar, lung surgeon at the Sir Ganga Ram Hospital in New Delhi, there has only been a "relative fall" in the pollution level but it is still a serious hazard for health.

"The intake of every 22 micrograms per cubic metre of polluted air is equivalent to smoking a cigarette. So whether the PM2.5 level is 700 or 300 units, the impact is still as bad. People should not get complacent that the air quality has improved, as the improvement is not absolute but only relative," he told PTI.

Kumar said people flouted norms and restrictions imposed on bursting of crackers at several places in Delhi, and at no place the AQI stood less than 300.

"I would say, pollution level has come down with concomitant good effects on health when the level reaches 60 or even 100. But has it fallen to that level anywhere? Telling that pollution had come down by a certain percentage is slipping into sense of complacency," he said.

According to data released by the Delhi Police, it received 940 calls about various violations on Diwali. It also seized nearly 3,765 kg firecrackers.

A total of 371 cases were registered on Diwali night, of which 56 cases were for storing and selling illegal firecrackers. Forty-four people were arrested in the 56 cases.

The rest 315 cases have been registered for use of unauthorised firecrackers and violating the two-hour time-frame set by the Supreme Court. As many as 166 people were arrested for these two violations.

According to the ministry of earth sciences' air quality monitor, SAFAR, levels of PM2.5 tiny particulate matter of diameter 2.5 or less than 2.5 microns that can enter deep into the lungs reached as high as 740 at Delhi University.

Delhi's overall air quality index (AQI) stood at 506 at 6.30 pm, according to the System of Air Quality and Weather Forecasting and Research (SAFAR).

The AQI at Pusa, Lodhi Road, Airport Terminal T3, Noida, Mathura Road, Ayanagar, IIT Delhi, Dhirpur, and Chandni Chowk was 491, 432, 464, 674, 428, 482, 460, 555 and 677, respectively, according to SAFAR data.

SAFAR said an increase in the wind speed will help disperse pollutants and the pollution levels are expected to come down by Tuesday.

It had earlier predicted that Delhi's overall AQI would enter the "severe" category between 1 am and 6 am on Monday, primarily due to firecracker emissions, unfavourable weather and a significant spike in stubble burning.

Kuldeep Srivastava, a senior scientist at India Meteorological Department (IMD), said the spike in pollution levels was a result of unfavourable weather trapping pollutants.

"The wind speed is around 7-8 kilometers per hour and the direction is northwesterly, which is unfavourable. The visibility levels have dropped to around 1,200 metres. Similar weather is likely to prevail over the next two to three days. Only a marginal improvement in air quality is expected," he said.

Last night, people reported violation of the Supreme Court-enforced two-hour window in Malviya Nagar, Lajpat Nagar, Kailash Hills, Burari, Jangpura, Shahdara, Laxmi Nagar, Mayur Vihar, Sarita Vihar, Dwarka among others places.

People could also be seen bursting crackers before 8pm, however, the intensity remained low.