Delhi’s new smog tower

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Recently, Delhi got a ‘smog tower’, a technological aid to help combat air pollution.

GS-III: Environment and Ecology (Environmental Pollution, Environmental Conservation)

Smog towers are structures designed to work as large-scale air purifiers and they are usually fitted with multiple layers of air filters, which clean the air of pollutants as it passes through them.
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
China has the world’s largest smog tower.

According to a report by CPCB, an increase of 258% to 335% has been observed in the concentration of PM10 in Delhi since 2009.
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).
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 and in 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.

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.
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.

-Source: The Hindu