Surviving 3 days in one of China's most polluted cities

There to see the world's tallest air purifier, the writer regrets not wearing a mask, as her lungs felt as though they were burning.

- Ang Qing

Miles away from the famed terracotta warriors and walls of ancient city Xi'an, a tower with a forgotten global reputation stands on its outskirts.

Unlike others drawn to the splendour of China's capital of 13 imperial dynasties, I was in town for this 20-storey tower - the world's tallest air purifier, once hyped as a solution to the thick smog plaguing the country.

It was built in 2016 by scientists, firms and the Xi'an authorities at a cost of US$2 million (S$2.7 million), according to an NBC News report. Researchers behind the project had said then that they hoped to build an even taller tower in Xi'an and similar structures in other cities.

Upon arriving at the foot of the tower, I discovered it was barricaded by a stained wall, part of which had graffiti on it. Seven of the eight people I asked did not have the foggiest idea about its existence.

A 65-year-old who gave his name only as Mr Hu was the only one who knew about the tower.

"It was an experiment. I think the costs were too high because you don't see any of such towers being built around town," he said.

The authorities and researchers behind the air purifier did not respond to my requests for comment. It is therefore unclear whether the tower is still in operation.

The giant air purifier is just one example of the lengths that the Chinese authorities have gone to since 2013 in their efforts to bring back blue skies.

That year, smog in China hit record highs and Xi'an was in the same year named one of its 10 cities with the worst air pollution.

It triggered public frustration and plans to counter the "airpocalypse".