Answer: China
Notes: In an attempt to fight air pollution, China has constructed an experimental air purifying tower, touted to be the "world’s biggest air purifier" at a height of over 100 meters (328 feet). The tower has been built in Xian in Shaanxi province and is being tested by researchers at the Institute of Earth Environment at the Chinese Academy of Sciences. As per reports, the air purifier has produced more than 10 million cubic meters of clean air since it was launched. The air purification system works through greenhouses covering about half the size of a soccer field around the base of the tower.
