A "Smog Free Tower" by Dutch designer Daan Roosegaarde undergoes tests in Beijing, Oct. 20, 2016. The seven-meter-high metal structure is said to be the world's largest air purifier with the capacity to scrub 30,000 cubic meters of air an hour. (Photo/CFP)

The smog-filtering tower created by Dutch artist and innovator Daan Roosegaarde has been renamed a "smog warning tower" by the China Forum of Environmental Journalists (CFEJ), after the tower's 50-day trial performance failed to live up to expectations.

On Nov. 20, CFEJ released the results of the tower's performance assessment, confirming that the device does possess a filtering effect, but that it is unstable and only covers a limited area. Three sets of data showed that even the tower's best record didn't pass WHO air standards for PM2.5, which is lower than 75 micrograms per cubic meter.

According to Roosegaarde's studio, the tower runs on a limited amount of green energy and uses patented ozone ion-free technology. It is designed to capture PM2.5 and PM10, purifying 30,000 cubic meters of air per hour. However, some Chinese experts claim that the weight of the machine's captured particulate matter per hour is less than that of a spoonful of salt.

Roosegaarde noted that a smog-filtering tower cannot act as a panacea. He hoped that his project would be a reminder to the Chinese government, students and citizens to protect their environment and raise awareness of environmental protection.

Liu Guozheng, secretary general of CFEJ, commented, "To introduce the tower to China is to live in a future without need for it."