Delhi NCR in a chokehold of its own emissions
The air quality in the National Capital Region plunged back into the “severe” pollution zone and inched towards emergency levels on Wednesday, shrouding the region in a haze of its own emissions that have now been trapped by a cocktail of metrological factors: low winds, a blanket of clouds, and cold temperatures.
The 24-hour air quality index in Delhi was 413 according to the 4pm bulletin by the Central Pollution Control Board (CPCB), and the concentration of fine PM10 particles and ultra-fine PM2.5 particles were close breaching the emergency thresholds. The deterioration comes after a brief respite from an early November spell of pollution largely caused by farm fires in Punjab and Haryana.
Weather agency officials said the problem now is because local emissions – tailpipe gases, road dust, smoke from garbage burning and industrial emissions – are not being blown away by wind. It is made worse by cloud cover, which drives up moisture and reduces the room for pollutants to lift higher into the sky.
“Both mixing height and ventilation index are very low now, which leads to accumulation of pollutants very close to the surface. This is mainly due to lack of winds which would otherwise disperse these pollutants,” said VK Soni, senior scientist at IMD.
Experts also saw this as a reminder of how much of the problem that Capital itself is responsible for.
“Today (Wednesday) a fire raged on at the Ghazipur landfill, that too on a day when pollution levels were already in the critical levels. It is such instances that we need to control. Can we say that there are no garbage fires happening in Delhi now? Or no vehicular emissions or we have been able to control road dust completely,” said Anumita Roychowdhury, executive director (research and advocacy), Centre for Science and Environment (CSE).
Roychowdhury added that Delhi’s air quality also depends on the polluting sources in the NCR towns such as Ghaziabad, Gurugram, Faridabad and Noida -- they recorded AQIs of 444, 299, 348, 414 respectively.
Delhi largely goes through several cycles of bad air days in winter, which relent only when the region has favourable weather conditions. After the October-end, early-November peak seen every year for at least the past decade, the second peak arrives sometime in December. This year, however, it seems to have happened sooner than usual.
A 2019 analysis by Council on Energy, Environment and Water showed tailpipe emissions from vehicles contribute as much as 39.2% of the city’s PM 2.5 levels. Roadsides dust adds up to 37.8% to this. In PM10 levels (particulate matter with diameter less than 10 micrometres), the contribution of road dust goes up to 65.9%.
Delhi does not have an emissions inventory showing contribution of local sources to overall pollution levels on a daily basis – the above numbers reflect how it is typically in winter. Experts point out that addressing these is crucial for a long-term solution.
“If local emissions are reduced by a large fraction (at least by 25%-30%), the peak in pollution levels reaching in the ‘severe’ zone could definitely be lowered to ‘very poor’ and even ‘poor’ levels. While the number of ‘severe’ days recorded during winter has come down over the past few years, specific action and long-term planning is required,” said Sagnik Dey, associate professor, Centre for Atmospheric Sciences, IIT-Delhi.
Dey also said emissions from the neighbouring regions including Gurugram, Faridabad and Ghaziabad are a problem for the Capital. “Gurugram and Faridabad are upwind of Delhi, the emissions directly have an impact on the city’s air. Besides, a number of industries, both conforming and not conforming to regulations, are located at Delhi’s border and in areas such as Ghaziabad, which also contribute to pollution in the capital,” said Dey.
According to Union government’s air quality forecasting wing, the share of farm fires in Delhi’s pollution levels was as low as 2% (the number of fire counts was 63.
Delhi environment minister Gopal Rai, however, said most of the problem is still due to farm fires that neighbouring states need to address. “Even over the last fortnight, when Delhi’s air quality started deteriorating, the contribution of stubble fires was high. This can be clearly seen through the satellite images of NASA,” said Rai.
MM Kutty, the chairperson of the newly-formed Commission for Air Quality Management (CAQM) in the National Capital Region and Adjoining Areas, said long-term solutions are being worked upon.
“We have a forward looking approach. We are working on identifying long term solutions to this problem (stubble burning). A workable solution will be attempted by the Commission in consultation with all stakeholders so that the problem does not arise in future. Now stubble burning is over. We are also trying to establish the wherewithal to implement various measures to control spike in winter pollution. CPCB should continue to do its job,” said Kutty.
A senior official in the Delhi Pollution Control Committee (DPCC) said action on hot spots is being taken. “The patrolling teams have been issuing fines wherever garbage burning has been observed. Besides, all efforts are being taken to prevent dust emissions,” the official said.
Soni said slight improvement is likely in air quality from Thursday onwards when light rain is expected and the wind speed is predicted to pick up to 10-12kmph. “The air quality is expected to improve tomorrow onwards. Also, no major deterioration is likely till November 30. It will remain in the lower end of ‘very poor’ to ‘poor’ zone,” he said.
But even these few days of severe air quality can be more dangerous than typical years. Exposure to high levels of pollution has been linked to an increase in the likelihood that a person can develop a serious grade of Covid-19, raising the risk of fatalities.
Over the next few days, people should expect winter to take hold more strongly. “Due to likely fall in minimum temperatures over northwest India, cold wave condition is expected to prevail at isolated places over Punjab, Haryana, Chandigarh and Delhi, north Rajasthan and west Uttar Pradesh between November 27 and November 29,” the India Meteorological Department said on Wednesday.
The minimum temperatures in Delhi on November 23 dipped to 6.3 degree Celsius, lowest for the month in the last 17 years.
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