Breath of fresh air: Delhi is building giant ‘smog towers’ to suck up pollution, but will they actually work?

Two towers will be built, and if successful, the Indian government has pledged to build more, reports Namita Singh in Delhi

An Indian man walks up stairs as Delhi’s skyline is seen enveloped in smog and dust (AP)

Delhi’s pollution season has arrived. Announcing itself with a dramatic dip in visibility and soaring numbers on the air quality index (AQI), a thick quilt of smog has wrapped itself around the capital city and there it shall remain, based on the bitter experience of recent years, until around March.

This year, the pollution crisis is being talked about with a greater sense of urgency because of the ongoing coronavirus pandemic. Covid-19, like air pollution, tends to attack the respiratory system, in what Delhi’s chief minister Arvind Kejriwal has called a “life-threatening” combination.

Ordered to take action by the Supreme Court, Delhi’s devolved government has now come up with a new idea of how to address this chronic issue – it has announced plans to construct a giant air purifier or “smog tower” that sucks up and filters bad air before releasing it back into the environment.

It’s a plan that is actually borrowed from China, which has made great strides in tackling its cities’ smog in recent years, and in 2018 built the world’s largest air purifier in the city of Xi’an.

Delhi says it will improve on the Chinese design, and it all sounds promising on paper, at least: “In China, the smog-tower sucks the polluted air from down below and releases clean air from above. Our smog tower will suck the polluted air from above, and release the clean air from the bottom,” said a government statement this month.  

Two towers are to be built, one by the Delhi government and one by the central administration of prime minister Narendra Modi. Delhi has said its tower will cost upwards of £2m – a huge outlay by the standards of Indian state coffers. Chief minister Kejriwal said these structures would be put in place on a pilot basis, and if successful, more such towers will come up in the megacity.

There’s just one small problem – experts say there is no way the towers will actually work to improve Delhi’s toxic air.

The air quality in the national capital of the country has been a cause of concern for quite some time, as Delhi and its suburbs have frequently appeared in the World Health Organisation’s  most polluted cities of the world. In fact, in 2014 Delhi topped the list.  

According to the WHO, a healthy Air Quality Index – a composite indicator of different types of particulate matter – is deemed to be 50. In 2019, the average AQI in Delhi was 195. In January, the most polluted month last year, the average was 326. In early November last year, the AQI regularly neared one thousand in several parts of the city. The Delhi government declared an emergency with schools shut for four days.    

Earlier this week, The State of Global Air 2020 report said air pollution caused the premature deaths of nearly half a million babies, and 116,000 of those were in India.

The year 2020 is an aberration in the pollution trends, with the Covid-19 lockdowns and a range of restrictions for all the sectors. Across India, ambient air pollution levels improved as much as 50 per cent compared to the annual trends for the same period in the previous year, according to a report released by the pollution control board of India in September.  

“It is obvious that the pollution ought to be cut at the source of emission,” Sunil Dahiya, an analyst at the Centre for Energy and Clean Air told The Independent.  

Though it is hard to imagine now, not so long ago, Delhi played host to a success story in cutting down the pollution at source.  

In 1998, the Supreme Court of the country had directed that all the public transport buses and auto-rickshaws should run on compressed natural gas. “The apex court’s order of CNG conversion was a very successful story for the transport sector and because of that, the city witnessed a significant reduction in its pollution level in the early 2000s,” said Aarti Khosla, the director of Climate Trends, an NGO working on environmental issues.  

She argued that the change, however, could not be sustained due to the rapid increase in the total number of vehicles on road, construction work, open burning of waste due to poor municipal systems. “The situation in winter is further aggravated by smoke from stubble-burning in northwestern states,” said Ms Khosla. According to the data from the System of Air Quality and Weather Forecasting and Research (SAFAR), the contribution of stubble burning to Delhi’s air quality depends on the speed and direction of wind and can vary from 4 per cent to 44 per cent.  

The vexing air pollution further shoots up in the winter due to the meteorological conditions of the city, Anumita Roy Chowdhury, an air pollution expert and the executive director at the New Delhi-based Centre for Science and Environment told The Independent.  

“Cold conditions do not allow the air to rise high enough to disperse, the wind is nearly gone and the calm conditions trap air close to the ground level,” Ms Chowdhury explained. “Since there is no wind to blow pollution away in this landlocked city, the pollution gets trapped creating a blanket of smog during winter,” she added.

“But how can industry adopt clean fuels for large, small and medium scale units if natural gas is more expensive than the dirtier fuels like coal?” asked Ms Chowdhury.  “How can waste burning be stopped if the municipal systems needed for proper disposal are weak; huge volume of cars and two-wheelers and growing automobile dependence cannot be curbed if adequate infrastructure for public transport is not built. Similarly, the industry sector needs access to clean and cheap fuel particularly for small and medium scale units,” she said.  

The message is clear. To sustain air quality gains, deeper systemic reforms are needed across all sectors to cut down emissions. So, when the Supreme Court of India in September issued direction for the installation of smog towers, the experts were sceptical.  

Dr Sarath Guttikunda and Puja Jawahar, the co-founders of an advocacy group, urbanemission.info wrote a research paper questioning the efficacy of smog towers as a solution to combat the pollution problem of the city. Explaining the science behind the air pollution problem, they argued that the air is a complex mixture of chemical compounds which is constantly transforming and moves at a varying speed, without a specified border.  

“With no boundaries, it is unscientific to assume that one can trap air, clean it, and release into the same atmosphere simultaneously,” they argued.  

In November 2019, an expert panel estimated that Delhi would need a total of 213 anti-smog towers to make any effective difference to its pollution crisis.  

“Nowhere in the world, at no point in history or in future will smog tower ever be a solution to air pollution, at least at the scale of a city,” said Mr Dahiya. Calling the installation of these towers as nothing but a “political stunt”, Mr Dahiya explained, “you can keep sucking the pollution out of the thin air for 8 hours a day and when you switch it off for an hour, the area will be polluted again.”

Ms Chowdhury also backed the claim and said “we have not found any global instance where air quality regulators or governments have adopted smog towers as a regulatory strategy for air pollution mitigation – at least not to our knowledge.” She added that the money invested in the project should instead be leveraged to cut emissions at the source of pollution.  

The chief minister’s announcement of the installation of its tower came on 16 October, almost a month after the Supreme Court of India stipulated a 10-month deadline directing them to act. The apex court warned that it would initiate contempt proceedings against both the centre and the state if they failed to comply.  

Reena Gupta, an adviser at the Dialogue & Development Commission of Delhi, said that the Delhi government was only following the directions of the Supreme Court, while the environment minister of Delhi Gopal Rai did not immediately respond when contacted by The Independent for comment.  

In an affidavit submitted in the top court last year, the Delhi environment department stated: “The [Delhi government] committee is of the view these smog towers may not be useful for the whole city, but they can be useful in creating ‘clean air area’ zones in different parts of the city.”