Plato poses this immortal question in political science: who guards the guardians? The Food and Environmental Hygiene Department should try to answer it. Yesterday it admitted that several of its air conditioners at one of its main offices in Mong Kok had been dripping water like mad. This was known for a long time but nothing had been done about it. The ironic thing is that the faulty machines are all next to the environmental hygiene unit responsible for going after owners who have dripping air conditioners - which the department says on its website cause diseases and create a nuisance. But apparently no staff members have complained, and the unit never bothered to fix them. A department spokeswoman said different rules applied for units operated by government offices. Guidelines say problems experienced by such offices are handled by the Electrical and Mechanical Services Department. She said penalties only applied to private premises. 'Usually one department contacts another department to rectify the situation - penalty and threats don't apply in such cases,' she said. Naturally, there's one rule for officials, another for everyone else!