Local authorities in Bangkok have installed a giant air purifier in front of a shopping mall in the city centre in a bid to improve air quality. The 4-metre tall air tower is said to be able to process some 17,000 cubic meters of air per hour over a range of 1,000 square metres. The device will operate over a 3-month trial period, and was developed by Thailand's Kasetsart University and the air-con company Mastercool Inc.