Smog towers ineffective, at least 40,000 needed in Delhi to combat toxic air: DPCC tells NGT

Smog towers are ineffective at controlling air pollution, Delhi Pollution Control Committee (DPCC) has told the National Green Tribunal (NGT). Delhi is still dependent on seasonal factors to reduce air pollution and the two towers at Connaught Place and Anand Vihar in the national capital have had little effect on the air quality in the surrounding areas, it said. 

Based on data from air quality monitoring stations  near the smog towers and a report by the Indian Institute of Technology, Bombay (IIT-B), it was determined that the smog towers are ineffective at reducing air pollution, Nannida Motrai, senior scientist at DPCC, said in an affidavit filed on November 8, 2023.

The tower at Anand Vihar — one of the most polluted locations in Delhi — was not even operational, as its effect was too miniscule to make a difference, the affidavit said. 

It costs around Rs 15 lakh per month to run each smog tower, which can only reduce pollution by 17 per cent within a 100 metre radius, the affidavit said. As the total area of the national capital is 1,483 square kilometres, a total of 47,229 smog towers will be required at a total cost of Rs 11,80,725 crore. 

While it costs Rs 25 crore for each tower to be built, there will be a recurring cost of Rs 15 lakh per tower every month to operate it, DPCC pointed out, concluding that continuing the use of smog towers is not justified. 

The smog towers were installed by the Centre under the orders of the Supreme Court of India on January 13, 2020 and are being monitored by the Union Ministry of Environment, Forest and Climate Change, the DPCC said. They were installed on an experimental basis and the results were not encouraging considering the heavy expenditure. 

If smog towers were to be used  reduce air pollution in Delhi by 17 per cent, at least 40,000 of them will be required, the affidavit stated. However, the buildings can be turned into museums to disseminate technical information about air pollution control, DPCC suggested.

A smog tower reduces air pollution by 48-56 per cent in a 20 metre radius, 34-30 per cent in 21-99 metre radius, 12-13 per cent in 109 to 199 metre radius and around 16 per cent in 300-500 metre radius, the IIT-B report said. 

The smog tower has had no positive impact in the Anand Vihar area and has already become a pollution hotspot this winter, the affidavit stated. The Continuous Ambient Air Quality Monitoring Station just 30 metres away from the smog tower has noted no significant difference in the levels of Air Quality Index (AQI) recorded. Anand Vihar’s AQI remained at ‘severe’ category between October 2022 and January 2023. 

A report by IIT Delhi found smog towers reduce air pollution only by 13 to 15 per cent in a 200 metre radius, which is not significant. This reduction in air pollution also occurs through seasonal factors. 

Providing clean air within a kilometre radius is not possible through smog towers, as they have a limited range of up to 200 metres, DPCC said. The annual operation and maintenance of a smog tower also costs about Rs 1.5 crore and the annual electricity bill comes to around Rs 90 lakh, taking the operation and maintenance charge to around Rs 20 lakh per month.  

IIT-B suggested some changes to improve the effectiveness of this smog tower, for example, changing filters, lowering the height, and using smaller fans. 

According to DPCC, even after the installation of smog towers, there has been a 37 per cent increase in fine particulate matter PM 10 concentrations in Mandir Marg and Anand Vihar since 2019-20. The concentration of ultrafine particles (PM 2.5) has also increased by 2 per cent. 

DPCC stated the Delhi government was informed about the inoperability of the smog tower on May 31, 2023, but no decision has been taken till now. The towers were operationalised following a Supreme Court directive on November 7 and are still running, it added.

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