Context

• In November, the Supreme Court had directed the Centre and the Delhi government to prepare a plan to install ‘smog towers’ across the capital to deal with air pollution.

What is a ‘smog tower’, how does the one at Delhi’s Lajpat Nagar work?

• 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.
• The smog tower installed at Lajpat Nagar is capable of treating 6,00,000 cubic metres of air per day and can collect more than 75 per cent of particulate matters (PM) 2.5 and 10, PTI reported. After the cleaning, the tower releases clean air.
• The 20-metre (65 feet) high tower will trap particulate matter of all sizes suspended in the air. Large-scale air filters shall draw in the air through fans installed at the top before passing it through the filters and releasing it near the ground.
• The filters installed in the tower will use carbon nanofibres as a major component and will be fitted along its peripheries. The tower will focus on reducing particulate matter load.
• The project is a collaboration between the Indian Institute of Technology (IIT) Bombay, IIT-Delhi and the University of Minnesota, the latter having helped design a similar tower of over 100 metres in China’s Xi’an city. The Central Pollution Control Board (CPCB) will also be involved with the project.

Other examples in the world

• China, which has been battling air pollution for years, has two smog towers — in its capital Beijing and in the northern city of Xi’an.
• The Xi’an tower is dubbed the world’s largest, and has reportedly brought down PM 2.5 by 19% in an area of around 6 sq km in its vicinity. The 100-metre (328 feet) high tower has produced 10 million cubic metres of clean air every day since its launch, and on severely polluted days, is able to bring down smog close to moderate levels, according to the South China Morning Post.
• The tower in Beijing, built by Dutch artist Daan Roosegaarde, has been able to compress the carbon waste generated during purification to produce gemstones, according to the TED Conferences website. Upon compression for 30 minutes, the smog particles turn into dark gems, which are used for rings and cufflinks.

Source:IE