Guidelines on wearing masks in public places like shopping malls and cinemas are to be revised by the Hong Kong health authorities. The move came as officials reported one new Sars case yesterday following a landmark zero infection day on Saturday. A further four patients died, bringing the death toll to 266. The number of infections is now 1,725. Director of Health Margaret Chan Fung Fu-chun conceded that opinions were mixed on taking masks off. 'As the outbreak is being contained, there is a need to review under what circumstances people should wear masks. My advice would be carry a mask. Sometimes you cannot predict the flow of people, the ventilation and what not,' she said. She added that masks would be a must for medics, patients and people visiting patients.