Clean air is a hot topic throughout the world. India is passing through the climate emergency. India has installed its first smog tower in National Capital Delhi. Smog tower is a 40 feet high and 20 feet wide structure to clean 32 million cubic metres of air per day.
The country’s first ‘smog tower,’ an experimental set up worth Rs 20 crore to purify air in a 1-km radius around the structure, at a rate of around 1,000 cubic metres of air per second.
Trends from the pilot study to assess the reduction of particulate air pollution in urban areas through ‘air cleaning’ could be available in around a month, Arvind Kejriwal, Chief Minister of Delhi said.
Terming the tower “experimental”, Kejriwal said its data will be analysed to determine its efficacy. Smog towers can be raised in other parts of the city as well, if a pilot study conducted on the new one set up at Connaught place provides favourable results, he said.
The tower constitutes a pilot study to assess the reduction of particulate air pollution in urban areas through ‘air cleaning’. The two-year pilot study will be carried out by IIT Delhi and IIT Bombay, technical advisors for the project. The institutions will monitor the impact of the tower on PM2.5 and the functioning of the tower under different weather conditions.
Trends from the pilot study could be available in around a month, Kejriwal said. If the project is not successful, new techniques will have to be attempted, he added.
Going by the project description, the tower can filter around 1,000 cubic metres of air per second. It is expected to have an impact on a 1 km radius from the centre of the tower.
A total of 40 fans have been installed at the bottom of the tower — air will be sucked in from the top, filtered and released through the fans at the bottom. The tower comprises 5,000 filters. These are electrostatic air filters that can filter out microparticles, including those that constitute smoke, household dust and pollen, according to the project description. A Supervisory Control and Data Acquisition (SCADA) system has been installed in the tower to collect data and monitor its functioning.
Construction workers who were at the inauguration said they had been working on the tower for about a year and a half. While work had stalled during the first Covid-related lockdown, it continued through the second lockdown, they said.
A similar tower is being set up at Anand Vihar, work on which is nearly complete.
Critics of the project point out that localised impact at a high cost would not be useful in tackling Delhi’s air pollution issues. Dipankar Saha, former additional director, CPCB, who was also head of the air quality monitoring division in Delhi, said that the tower might dilute emissions generated at the ground level, though it may not be significant.
“The tower is localised. How many such installations are required for Delhi at such a high investment cost? In tropical places, it’s not possible to suck dust out of the air, since it’s such a huge task. In winter, the dust layer stands at around 800 metres from ground level,” he said. Emission control at the ground level is the only feasible way to handle air pollution.”
Gautam Gambhir, BJP’s MP from East Delhi, had set up a 20 feet tall air purifying tower in Lajpat Nagar, near the central market, in January last year, in collaboration with the traders’ association of Lajpat Nagar. It functions with air filters.
Ashwani Marwah, general secretary of the traders’ association, said that the tower is functioning and its operational cost is being borne by the association. A display board on top of the tower shows AQI to gauge its impact, he added.
The World Health Organization (WHO) says that India has 6 of the top 10 most polluted cities in the world. National capital Delhi is sitting on the top of the list.
According to a Greenpeace report published last year;1.2 million people die every year in India due to air pollution.
In the light of such severe air condition; all the institutions, corporate houses, social pressure groups, and the concerned government are striving hard to improve the condition of air quality throughout the country.
Key Points
Background
- In 2019, the Supreme Court directed the Central Pollution Control Board (CPCB) and the Delhi government to come up with a plan to install smog towers to combat air pollution.
- IIT-Bombay then submitted a proposal for the towers to the CPCB.
- In January 2020, the Supreme Court directed that two towers should be installed by April as a pilot project. The smog tower at Connaught Place (CP) is the first of these towers.
- The second tower, being constructed at Anand Vihar in east Delhi with CPCB as the nodal agency, is nearing completion.
About
- Smog towers are structures designed to work as large-scale air purifiers.
- They are usually fitted with multiple layers of air filters, which clean the air of pollutants as it passes through them.
- China has the world’s largest smog tower.
Working of the Tower
- It uses a ‘downdraft air cleaning system’ where polluted air is sucked in at a height of 24 m, and filtered air is released at the bottom of the tower, at a height of about 10 m from the ground.
- It is different from the system used in China, where a 60-metre smog tower uses an ‘updraft’ system — air is sucked in from near the ground, and is propelled upwards by heating and convection. Filtered air is released at the top of the tower.
Developed by
- Tata Projects Limited (TPL) built it with technical support from IIT-Bombay and IIT-Delhi, which will analyse its data.
- National Biofuel Coordination Committee (NBCC) India Ltd is the project management consultant.
- Delhi Pollution Control Committee was in charge of the Project.
Need
- According to a report by CPCB, an increase of 258% to 335% has been observed in the concentration of PM10 in Delhi since 2009. But the most prominent pollutant in Delhi and neighbouring areas is PM2.5
- PM2.5 refers to fine particles which penetrate deep into the body and fuel inflammation in the lungs and respiratory tract, leading to risks of cardiovascular and respiratory problems, including a weak immune system.
- Delhi was the most polluted capital city in the world in 2020 for the third consecutive year, according to a report by a Swiss group (released in March 2021) that ranked cities based on their air quality measured in terms of the levels of ultrafine particulate matter (PM 2.5).
Challenges
- It may provide immediate relief from air pollution in a small area but they are a costly quick-fix measure with no scientific evidence to back their efficacy in the long term.
- The tower could have an impact on the air quality up to 1 km from the tower.
- However, the actual impact will be assessed by IIT-Bombay and IIT-Delhi in a two-year pilot study that will also determine how the tower functions under different weather conditions, and how levels of PM2.5 vary with the flow of air.
Other Steps Taken to Tackle the Problem of Pollution in Delhi
- Subsidy to farmers for buying Turbo Happy Seeder (THS) which is a machine mounted on a tractor that cuts and uproots the stubble, in order to reduce stubble burning.
- The introduction of BS-VI vehicles, push for electric vehicles (EVs), Odd-Even as an emergency measure and construction of the Eastern and Western Peripheral Expressways to reduce vehicular pollution.
- Implementation of the Graded Response Action Plan (GRAP). It is a set of curbs triggered in phases as the air quality deteriorates, which is typical of the October-November period.
Use of Green Crackers.
Development of the National Air Quality Index (AQI) for public information under the aegis of the CPCB.
Way Forward
Since there is no scientific evidence that proves its efficiency, governments should instead address root causes and promote renewable energy to tackle air pollution and reduce emissions.
It will be really unfortunate if other cities decide to follow suit and set up these expensive, ineffective towers.
