How it began
One of the largest outbreaks of severe acute respiratory syndrome, or SARS, began in Singapore in March 2003. During the outbreak, Singapore's Defence Science and Technology Agency joined forces with Singapore Technologies Electronics to conceive and build the Infrared Fever Screening System. Its developers described it in a 2004 engineering paper as the first infrared-based system in the world to be used for fever screening of large groups of people.
Before it existed
Checking for fever meant taking each person's temperature with a clinical thermometer, one at a time. That was too slow for the large flows of people that had to be checked during an epidemic. Infrared thermography already existed and had been used in medicine to detect inflammation and nerve problems, but not for screening crowds.
How it works
The system does not measure skin temperature as such. It uses a two-point detection concept. At the first decision point, thermal imagers view people and sieve out those who are probably febrile. At the second decision point, those people have their body temperature confirmed with a conventional clinical thermometer. The system cannot diagnose an illness; it shows in a moment who should be checked further.
What lasted
Time magazine included the system, under the name Fever Finder, among its best inventions of 2003. The developers published the design in the proceedings of an international thermal sensing conference in April 2004, which made the two-point screening concept available to others. Later medical researchers have questioned how well thermal scanners perform in mass screening for fever.
