What's more, these devices are supposed to be used with a disposable hood that covers the lens. This is not a problem for home use, but neither efficient nor cost effective if you're taking the temperature of everyone entering city hall.
Taipei City Hall has a different solution. Everyone entering the lobby of the building walks past a camera that measures heat instead of light.
The camera is connected to a computer and passersby appear on a monitor as images colored in relation to normal body temperature; anything hotter than 37.5℃ and possibly running a fever appears in bright red while ambient temperatures are blue and green. Anything cooler than 34℃ doesn't show up at all.
Should anyone's forehead light up the screen, they'll be pulled aside for closer examination. Some of these thermal imaging systems are actually more accurate than ear thermometers, with plus or minus 0.25℃ of accuracy. But their greatest utility is for screening large groups of people, such as at Taipei City Hall or Singapore's Changi Airport, where the system was first put into public use.
It's the same technology first used in the military to see at night and later to guide surface-to-air missiles into enemy jets. It was also overused in 1987's Predator, starring Arnold Schwarzenegger.
The problem with all of these devices, of course, is that people's body temperatures change naturally in the course of a day. When you first awaken, your body is at basal temperature and a measurement taken with most any of these thermometers will register an accurate reading.
But the more active you become, the higher your temperature rises: Light exercise or prolonged periods in the sun can raise your core temperature a half a degree or more, as can smoking a cigarette or becoming embarrassed.
A half a degree isn't much, you say, but there is another problem with accurate thermometry that has nothing to do with thermometers: the 37℃ normal body temperature that Wunderlich came up with was rounded up.
The Journal of the American Medical Association reported in 1992 that 36.8℃, rather than 37℃ was, in fact, the normal body temperature of the average adult and well below the upper ranges of normal temperature.
Thirty-seven degrees centigrade(98.6°F) should be abandoned as a concept relevant to clinical thermometry, JAMA reported.
So, 37.2℃ (98.9°F) in the early morning and 37.7℃ (99.9°F) overall should be regarded as the upper limit of the normal temperature range in healthy adults aged 40 years or younger.
Anyone with a temperature of 37.7℃ would have a hard time getting into most buildings in Taipei and that can be a pain in the butt.
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