In China, questions raised over efficacy of smog towers

Beijing: China’s experiment with installing giant outdoor “smog-free towers” in its polluted cities haven’t had the desired results despite generating interest when first talked about in 2016.

Instead, emission control remains the only effective way to control pollution, experts told HT.

A seven metre high anti-smog tower, designed by Dutch designer Daan Roosegaarde, was the first to be put up in an art district in Beijing in 2016.

It was the last.

Within months, China’s state-controlled media had trashed the tower, calling it an “eyewash” and ineffective in a megacity with more than 20 million people like Beijing.

A larger, skyscraper-sized smog-tower was also built in Xi’an, the capital of northwest China’s Shaanxi province, another heavily polluted city, the same year.

Two years later, in 2018, the evidence of its effectiveness was questioned by a research institute.

“A skyscraper-sized air purifier curbed pollution by about 15% in a 10-square kilometer area over two years in one of China’s most polluted cities,” the state-controlled tabloid, Global Times said in a report.

“It would take about 1,000 to do the same for the entire city of Xi’an,” the tabloid quoted Cao Junji, from the Institute of Earth Environment at the Chinese Academy of Sciences as saying.

The 60-meter-high air purifier cost 12 million yuan ($1.91 million) when it was installed in 2016.

About 1,000 such structures could handle 10,000 square kilometers, Cao said.

“It is costly and works for a limited area like 100 metres, and the pollutants can be easily transported to clean air (area) again. It is not practical to use these (smog-towers) to control air pollution,” Hongliang Zhang from the Department of Environmental Science and Engineering from Shanghai’s Fudan University told HT.

“People build it for reasons but no one academia thinks it is effective,” Hongliang added.

“The haze towers in Chinese cities have not been used much; their effectiveness is limited to 100 metres (in the immediate surrounding areas). It has a limited effect on the environment,” a Liping Zhang, a consultant on pollution based in eastern China’s Hangzhou said.

“The economic feasibility of such towers is relatively poor for improving the environment on a large scale. They could have an impact on the environment at a very local level,” Liping added.

“Emission is the only way to control pollution,” Hongliang, the first expert, said.

In March, Beijing announced that it will allocate 25 billion yuan or $3.73 billion to prevent and control air pollution, an increase by 25% year on year.

As for the towers, they could probably work as anti-pollution symbols but the cost involved in building such structures in the first place puts a question mark on the projects.

The one already put up in Beijing, for example, has since been renamed as “smog reminder” instead of the more ambitious “smog tower”, state media reported, adding that the structure was retained for educational purposes.