Visitors arriving in Kathmandu should receive a pleasant surprise as a government ban against a big polluter of city's Himalayan air takes effect. The ban is the latest in a series of initiatives to battle air pollution - a serious health hazard and threat to the country's small but steadily growing tourism industry. Roughly 640 diesel-run smoke belching three-wheelers, locally known as Vikram Tempos, are to be forced off the streets of Kathmandu Valley from 18th of September.