Smog tower’s current efficiency ‘half’ of Delhi Government claim

Authorities say if needed they will enhance the entire system to achieve set goals

Published - December 09, 2021 02:20 am IST - New Delhi

On October 1 this year, the Delhi Government said that a smog tower can clean up to 80% of polluted air, citing a preliminary report. However, two months later, the percentage of pollution being reduced is only 34%-43%, according to six readings between November 30 and December 1 accessed by The Hindu .

The smog tower at Connaught Place, a pilot project installed at a cost of ₹20 crore, was inaugurated on August 23 by Chief Minister Arvind Kejriwal, who had said similar towers will be built in other parts of the city if the results are satisfactory.

A few weeks later, Environment Minister Gopal Rai’s office released a statement that read: “The preliminary report of the smog tower installed by the Kejriwal Government was released today (October 1). The report has revealed that the smog tower is cleaning up to 80% of the air.”

This statement has been challenged by the readings at the same tower on December 1, where at 10 a.m, the level of PM2.5 — a chief pollutant — at the inlet of the tower was 460.06 ug/m3 and the value at outlet after purification was 299.22 ug/m3 — a reduction of only 34.9%. The reduction in the level of pollutants at a distance from the tower will be even lesser.

At 9 a.m. on November 30, the level of PM2.5 at the inlet of the tower was 314.62 ug/m3 and at the outlet of the tower was 179.1 ug/m3, a reduction of 43.07%. This is the highest reduction in pollution levels among the six readings between November 30 and December 1.

IIT studying project

When contacted, a Delhi Government spokesperson said, “Studies are being done by IIT-Bombay at all levels. This is a pilot project and final conclusion of efficiency is yet to be arrived at. If needed we will enhance the entire system to achieve our goals.”

The smog tower is a 24 metre-high structure fitted with fans and air filters which draw in polluted air from the top and release purified air near the ground through fans fitted on the sides. The tower has 40 big fans and 5,000 filters to clean the air.

When asked about the efficiency of the tower being “only half” of what the Government had announced in October, Karthik Ganesan, a fellow at Council on Energy, Environment and Water, a think-tank, said, “It may be because filters of the tower have been clogged with pollutants and need to be changed. Also, now the tower is operating at a higher pollution load compared to October.”

“Smog tower is a terrible idea. Yo u cannot vacuum clean air. You just cannot do it. It has to be addressed at the source of pollution appropriate technologies,” he added. The Government has not made these reading public till now.

A team from IIT-Bombay is currently studying the impact of the tower at Connaught Place at different distances away from it and is expected to submit a report to the Delhi Government.

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