‘World’s biggest air purifier’ test results revealed in Xi’an

Experts in Xi’an, northern China have revealed the test results of a 100-metertall “anti-smog tower,” which has been dubbed the “world’s biggest air purifier.”

The results were announced during the project’s status briefing on April 24, reports Chinese news portal Guancha.

The air filtering efficiency of the tower reached 80 percent, according to Cao Junji from the Institute of Earth Environment at the Chinese Academy of Sciences, who is also the project leader.

It can purify air at an average of 16 million cubic meters per day in the summer and eight million cubic meters during the winter. During days of severe air pollution, the tower can clean a volume of five million cubic meters.

Furthermore, the number of PM2.5 — the fine particles in smog deemed most harmful to health — per cubic meter in the air has fallen to between 11 and 19 percent in the 10 square-kilometer radius around the tower.

To clean the air, polluted smog is drawn in through a series of greenhouses surrounding the base of the tower and heated using solar energy. Then, the hot air rises up through the tower via multiple scrubbing filters before being released back into the atmosphere.

The tower is entirely powered by electricity, which in China is provided mainly by coal-powered plants.

The project is still in its trial phase at present. If the system were to be put into practical use, around 1,000 towers would be needed to cover the city of Xi’an, which boasts an area of 10,100 kilometers, according to Cao.

The project was launched in 2015 and construction was completed last year. The tower cost the provincial government around 12m yuan (approximately $2m) to build and it requires 200,000 yuan ($31,820) per year to operate.