Scientists are conducting tests on a 100-meter-high air purification tower in Xi'an, capital of Shaanxi province, and are expected to issue a statement about its ability to reduce air pollution within the next few months.

Construction of the tower, which is overseen by the Institute of Earth Environment at the Chinese Academy of Sciences, was completed in June 2016.

In January, media reports said the tower, which covers 2,580 square meters and was put into operation late last year, is capable of purifying more than 10 million cubic meters of air a day and has an effective range of 10 square kilometers. On average, the facility can help to reduce the concentration of PM2.5－particulate matter with a diameter of less than 2.5 micrometers that can enter the bloodstream via the lungs－by about 15 percent when heavy smog occurs.

However, the scientists are still collecting data during a trial run, so the statistics are preliminary and not official, according to Huang Yu, a researcher at the institute.

"When we have completed the test run or reach a stage where we can release solid data, we will make the findings public as soon as possible. The expected release time is April or May," he said.

Despite the apparent optimism, during a recent visit to the tower, China Daily reporters spoke with a construction worker who works in the area around the tower. He said he has not noticed any difference in air quality. "It doesn't work at all," said the man, who declined to be named.

It's not the first time an outdoor purification tower has been used to combat air pollution in China. In 2016, Daan Roosegaarde, an artist and environmentalist from the Netherlands, tested a "Smog Free Tower" in Beijing. The 7-meter-high facility, which has been used in the Netherlands since September 2015, sucks in polluted air and uses ion technology to clean it before releasing purified air through a series of vents.

An online statement released by the China Forum of Environmental Journalists, the body that invited Roosegaarde to China, said a number of tests conducted by the artist in the Netherlands indicated that the tower is capable of "completely" purifying 30,000 cubic meters of air per hour and uses just 1 kilowatt-hour of electricity－equivalent to the amount used by a small electric kettle－every 60 minutes. However, it added that tests conducted by an independent third party suggested that the facility's performance was erratic.

Chai Fahe, deputy head of the Chinese Research Academy of Environmental Sciences, expressed doubts.

"The effect is too limited in an outdoor environment," he said. "The main causes of air pollution are the emission of pollutants, and unfavorable meteorological conditions that mean they are not dispersed. The key measures to control smog are the reduction of emissions via adjustments to the industrial structure and energy use, and improvements in the management of motor vehicles."