At the South China Morning Post office in the World Trade Centre complex, lifts are disinfected every 15 minutes. The building managers are doing as good a job as they can. But that is small comfort for tenants cooped up in an enclosed environment long enough for them to catch Sars from an infected colleague. So when the Nihon Keizai newspaper correspondent, whose office is in an annex of a five-star hotel, said staff were checking the temperature of all guests and tenants before they were allowed in the lifts, I felt envious. Last week, that envy for the hotel's apparently exemplary efforts to fight Sars evaporated. At a seminar on Sars organised by the British Chamber of Commerce at the hotel, about 100 diplomats, foreign health-care workers and businesspeople had to pass gloved attendants who pointed infrared thermal scanners at their foreheads. Everybody was allowed in. Quite a number asked for their readings: they were all a uniform - and obviously incorrect - 33 degrees Celsius. Clearly, anyone with a fever would escape detection. Further, that reading meant most people in the room were suffering hypothermia, medical souces at the seminar said. Guests criticised the readings privately, but nobody thought of asking health department spokesman Feng Shaomin, who was on the panel of speakers, if the government should look into banning the use of such inaccurate scanners. Doctors said the handheld scanners should only be used in a small, enclosed space, where the room temperature is constant. The Guangdong government and businesses are working hard to get off the World Health Organisation's travel advisory, which has been damaging for the economy. That five-star hotel is trying to put guests and tenants at ease. But it could do better by replacing the scanners with something more accurate, like ear thermometers. The provincial government may also want to look into the thermal imaging equipment installed elsewhere. Those installed at the border checkpoints in Shenzhen are thought to be only 90 per cent accurate. Another good measure is to make sure all work units, companies and schools issue thermometers to staff. One of the WHO's conditions for lifting the warning on Guangdong is good border control to ensure Sars cases are not imported or exported. Guangdong is doing such a good job of keeping down the number of new daily cases that it would be a shame to slip up on something as simple as reading temperatures.