delhi

Updated: Oct 30, 2019 01:01 IST

A thick, smoky haze smothered the national capital on Tuesday as air pollution breached “severe” levels for the first time this season, a sharp deterioration caused by a double whammy of toxic fumes left over from illegal Diwali fireworks and a big spike in farm fires in neighbouring states.

Two days after thousands in the national capital defied restrictions to use banned firecrackers, Delhi’s overall air quality index (AQI) was 400 in the daily 4pm bulletin by the Central Pollution Control Board (CPCB), up from Monday’s 368. An AQI between 0 and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor”, and 401 and 500 “severe”.

By 11pm, the AQI climbed to 421 as lower temperatures led heavy pollutants to sink closer to the ground.

Pollution levels in Ghaziabad (446), Noida (439) and Greater Noida (428) were much worse. Gurugram and Faridabad were in the “very poor” category at 368 and 387 respectively, as per the four 4pm bulletin.

On Diwali night, several people across the National Capital Region (NCR) flouted the Supreme Court-enforced two-hour limit for bursting crackers. The apex court had also ordered that only green firecrackers, which cause 30% less pollution, be sold. But a large number of illegal crackers could be heard going off across the region, almost non-stop from about 8pm till late into the night.

Experts said that the post-Diwali air on Monday was the cleanest in four years but the pollution remained in the “very poor” category, with the PM2.5 level rising to 18 times the safe limit.

According to scientists at pollution forecasting agencies, the air is likely to worsen over the coming days since a north-westerly wind is bringing with it smoke from Punjab and Haryana, where crop stubble burning is at its peak this week.

Satellites picked up at least 2,200 instances of fires in Punjab and Haryana on Monday, most of them cases of stubble burning. On Tuesday, the India Meteorological Department (IMD) said the figure stood at 1,602 just for Punjab, the most recorded on a single day this season. Experts have previously predicted that more crop residues are burnt around the time of Diwali since farmers can show them as incidental fires. They use the method to quickly and cheaply ready their fields for the next round of sowing.

IMD scientists said “smoke” reduced visibility in the national capital and in its neighbouring cities on Tuesday. The wind speed was low at about 7-8 kmph, not enough to disperse the pollution left behind by Diwali celebrations. “The pollution from Diwali is still accumulated near the ground. Wind direction is westerly and north-westerly. The high pollution level in Delhi is because of the smoke from stubble burning,” said Kuldeep Shrivastava, director, Regional Weather Forecasting Centre.

VK Soni, a senior scientist at IMD, said: “What you are seeing outside is smoke; because there is no moisture in the air, there is no chance of mist. The wind direction is also westerly so it seems like smoke from stubble burning is impacting air quality.”

Soni added that wind speeds are likely to pick up slightly once clouds caused by cyclonic system Kyarr clear up over the next couple of days. But that will result in only a marginal improvement. “In all the Indo-Gangetic plain cities, low wind speed has caused an accumulation of pollution.”

Delhi chief minister Arvind Kejriwal appealed “with folded hands” to Punjab and Haryana to take steps against stubble burning to prevent the national capital from becoming a “gas chamber”. “At our level, we are making all possible efforts and will continue to do so,” he tweeted.

The Aam Aadmi Party (AAP) government later said in a statement that latest Nasa images showed a drastic spurt in crop residue burning in the neighbouring states. “The effective stubble fire counts of Haryana and Punjab have increased from 1,654 to 2,577 during the past 24 hours, which is a matter of extreme concern for the residents of Delhi,” it said.

Farm fires and emissions from firecrackers result in heavy concentrations of PM2.5 ultrafine particles in the air, which can lead to major health problems since they can enter the bloodstream after penetrating deep into the lungs.

While Delhi-NCR has a Graded Response Action Plan (Grap) that is enforced by the Supreme Court-mandated Environment Pollution Control Authority (Epca), the Centre’s National Clean Air Programme (NCAP) is also in place for a year.

With Delhi’s air quality plunging to the “severe” category on Tuesday evening, the task force headed by CPCB will on Wednesday review whether additional pre-emptive measures listed under Grap will be needed to stop the situation from deteriorating further.

According to Grap, if the air quality continues to be in the “severe” category for 48 hours, measures such as traffic rationing and a ban on the entry of trucks is brought into force. Industries running on coal are also asked to cease operations.

In previous years, schools in NCR have been forced to be closed due to dramatic rise in air pollution, with people, especially the elderly and young children, being asked not to go out.

Officials at IMD said a significant increase in the wind speed is unlikely over the next two days and similar conditions are expected to prevail. The AQI takes into account five chief pollutants — particulate matter with a diameter less than 10 micrometres (PM10), PM2.5, ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO).

The spiking pollution levels in Delhi have resulted in many joggers and cyclists complaining of difficulty in breathing, itchy throat, and watery eyes. Doctors said there was an increase in the number of patients coming in with asthma and other respiratory allergies.

At the All India Institute of Medical Sciences (AIIMS), the doctors saw an increase of about 15% in patients coming in with such complaints. “We see this spike every year. People come in with their symptoms worsening as the pollution levels increase. However, what is more concerning is healthy people coming in with upper respiratory tract allergies and allergic coughing that refuses to heal. We have to treat it just like asthma,” said Dr Karan Madan, assistant professor of pulmonary medicine at the premier institute.

The World Health Organization says outdoor air pollution is a major cause of death and disease globally. Particulate matter is capable of penetrating deep into lung passageways and entering the bloodstream causing cardiovascular, cerebrovascular and respiratory impacts, it says.

“When we are addressing a broader geography like the Indo-Gangetic plains, we need a regional focus. NCAP has to figure how to take a regional approach to air quality. Currently, the focus is on hundreds of small municipalities across the country without addressing the challenges of the larger air-shed. That’s where we now need to focus and at the same time scale up localised action,” said Anumita Roy Chowdhury, executive director at Centre for Science and Environment.