We were living in hustle and bustle type of environment. All the things around us were changed drastically. We were once struggled and looked forward to getting pure and clean drinking water by paying some money which was once available as free. People have found a solution to many of our and the problems of our environment. 

But now, it looks like the increasingly uncertain air quality of the national and international capitals. To sort out this problem and to breathe pure and clean air, IIT-Delhi and IIT- Bombay in collaboration with the University of Minnesota, had planned for a design of an air purifier smog tower and was installed in China and our national capital Delhi.

Delhi's smog tower

The Smog Free Tower is essentially a giant air filter for the surrounding space. Delhi’s gigantic 20 ft tall air-purifier is established in South Delhi’s Lajpat Nagar market, which sees an average footfall of 15,000 people every day whereas China has the world’s largest smog tower of over 328 feet height which has been built in Shanghai province, Northern China.

The smog tower established at Lajpat Nagar, Delhi is capable of treating 6,00,000 cubic metres of air per day and can get more than 75 per cent of particulate matters (PM) 2.5 and 10. The tower in China has been effective in cleaning almost 75 million cubic metres of air per day. 

The effects of China’s tower are significant, with concentrations of fine smog particles falling by 15% during days with heavy pollution. The facility can serve an area of roughly 3.8 square miles (10 square kilometres).

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

Working of Smog tower

Smog towers are structures produced to work as large-scale air purifiers. They are normally fitted with several layers of air filters, which clean the air of pollutants as it passes through them. 

The working method of Delhi’s air purifier tower:

The air purifier tower is fitted with exhaust fans to pull in the air with the help of a big inlet unit.

After the cleaning, the smog tower or the large air purifiers will emit purified air which will form a bubble of fresh air around it. The air purifier will run on electricity.

The working method of China’s air purifier tower:

Around the base of the tower is a system of greenhouses that cover an area about half the size of a soccer field. It sucks polluted air in and heats it with solar energy. The heated air then rises through the tower and passes through multiple layers of cleaning filters. 

China's Smog towerAccording to Cao Junji, head of research, they have observed improvements in air quality over an area of 10 square kilometres (3.86 square miles) in the city over the past few months and the tower has managed to produce more than 10 million cubic metres (353 million cubic feet) of the clean air a day since its launch. Furthermore, on severely polluted days the tower was able to reduce smog close to moderate levels.

Wintertime in Xian experiences the heaviest amount of pollution since the majority of the city’s heating relies on coal. Because of this, the tower is designed especially apt to be fully functional through the winter months. 

The system at the base still works in the cold months as coatings on the greenhouses enable the glass to absorb solar radiation at a much higher efficiency.

Specific features of national and international smog towers:

Height of the towers:

The Delhi’s smog tower is 20-feet-tall. The giant air purifier has been erected on a 4 feet high platform on a covered drain near Veer Savarkar Marg in Lajpat Nagar. The total height of the tower from ground level is 24-feet. China has the world’s largest smog tower of over 328 feet height which has been built in Shanghai province, northern China that is said to be the largest air purifier in the world standing at over 100 meters.

Design of Delhi's Smog tower

Design of the tower:

In terms of the design, the tricolour-themed tower is shaped like a cylindrical structure chimney with four outlet units and China’s smog tower is a hexagonal tower with a big inlet and four outlet units. The tower is painted in four colours orange on the top, white in the middle, blue at the bottom and green just above the bottom.

Cost of the tower:

The estimated cost of smog tower is Rs 7 lakh and the operational and maintenance cost is 30K per month whereas the cost of China’s smog tower is to be around Rs. 10 to 12 crore which includes filtering equipment, monitoring system and construction of the tower.

What then is the difference between Delhi’s Smog Tower and the Xian Smog Tower?

Inauguration of Delhi's Smog tower

Delhi’s City Cleaner will be different from China’s Smog Tower as it wouldn’t use the ionisation technique to clean the air.

The ionisation of air does not eradicate the pollutants but works by separating the pollutants from the oxygen, which could be a part of the problem itself.

Future plan of smog tower:

Besides the tower that has installed in Lajpat Nagar, the Delhi government is planning to install a smog tower at Central Park in Connaught Place. 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.

Image Courtesy: Curlytales.com


To study more about the air purification, click


Technological Aspect of Air Purification – Part 2