Despite reports of health benefits and the energising effects of oxygen bars, which have become the latest craze in China, David Valacer, pulmonary specialist at New York Hospital contends that there is much hype associated with the use of these bars and prolonged inhalation could be toxic to certain cells in the body. More than 100 oxygen bars offering concentrated oxygen to the smog-saturated citizens have popped up recently in major Chinese cities. Six bucks buy you a half hour with a face mask or nasal tube in Beijing, where the population level is higher than the maximum considered safe by the World Health Organization.