Context: Recently, the Chief Minister of Delhi inaugurated the country's first 'smog tower’ in Connaught Place.

• Ahead of its infamous smog season, this ‘smog tower' provides a technological aid to help combat air pollution.
• This is the first experiment with a large-scale outdoor air-purification system in India. Small smog towers have been raised in the Netherlands and South Korea; larger ones have been set up in China.
• The Delhi government will study the impact of smog towers on pollution and could add more such structures across the national capital.

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. The court was hearing a matter related to air pollution in the national capital due to stubble-burning in Punjab, Haryana and Uttar Pradesh. IIT-Bombay then submitted a proposal for the towers to the CPCB.

Extent of Delhi’s pollution

• 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).
• Also, since 2009, an increase of 258% to 335% had been observed in the concentration of PM10 in Delhi, a 2016 report by the CPCB noted. But the most prominent pollutant in Delhi and neighboring areas is PM2.5

Reasons behind high pollution levels

• Construction work, industrial and vehicular pollution — in and around the city.
• The situation is aggravated at the start of winter by smoke from stubble-burning in northwestern states, coupled with unfavourable meteorological conditions, such as calm winds, low temperatures, and fewer sunny days.

About Smog Tower

• 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.

Is smog tower a viable solution?

• While smog towers might come across as a visible solution to air pollution, there is no scientific evidence -- even globally -- to support that they can filter outdoor air effectively.
• India took the decision of installing smog towers following China’s footsteps, but experts say China is implementing strong pollution control rules across sectors, which India hasn’t. 
• “Beijing fixed its problem of high pollution levels by also looking at industries, public transport and pushing bicycles. 
• Visually, the tower looks appealing, that it will engulf all the pollutants, but that is not the reality.
• Smog towers can solve problems very small areas around them, but not the whole city. Therefore, the only way to reduce air pollution is to reduce emissions at the sources.

Other Measures taken to control pollution

• Persuading farmers in Punjab and Haryana to use mechanical alternatives to stubble-burning.
• Closure of thermal power stations in Delhi.
• Making industries use piped natural gas.
• Control measures taken under the Graded Response Action Plan (GRAP) when pollution levels spike.

Road Ahead

• Our problem is so severe and we have no option but to move away from fossil fuels. We know what percentage of emission comes from which source. Be it industrial, biomass burning, paddy burning or vehicular pollution. When we know the sources, why are we continuing with these hogwash things?”