A short visit to the store before they close and you can already see a line forming as you pull up. Crowds used to only be a time-consuming problem, but with the spread of COVID-19, they are also a health hazard. However, this is not only a problem in supermarkets, but also in public transports, elevators, and even hospitals - crowds are unavoidable, and also problematic. They have been looked down on since the start of the pandemic, but what if there was a way to make them less risky? Can thermal cameras do the job?
Thermal Temperature Screening Technology
The concept of temperature screening technology is that they can seek out who has an elevated temperature in a crowd of people. In crowd-based temperature screening the infrared device searches for exceptions of people who might have a fever. This can be extremely beneficial for COVID-19, as one of the symptoms can be a high body temperature, and thermal cameras have an accuracy up to ±0.3℃.
Elevating Body Temperature in Crowds
However, Markus Tarin is of the opinion this cannot work. He says that “scanning a crowd means that some people are closer in and some people are further away from the camera, which means that nobody is in the ideal focus position of the camera”. It is true that in a crowd people will stand at different distances, which can change the projected pixel size, as well as pixels in focus.
Indeed, no cameras are produced only for the intention of scanning the crowd, but this does not mean thermal temperature screening is not helpful when taking people's temperatures in crowds - the temperature is accurate if people follow the instructions. For example, The World Health Organization states that a person must take their glasses and head coverings off and stand a certain distance for a few seconds before they have their temperature taken.
For buildings like small offices or clinics, of course, the crowd is also small, thus people can be checked individually as they enter, so their temperatures can be measured with LCD thermal cameras or smartphone USB thermal cameras. The LCD camera can also be set up on a tripod, and its function of an automatic alarm turned on.
For areas with bigger crowds like airports or places of public transport, intelligent thermal cameras with measurements for multiple targets should be used. These devices are better options since the temperature can be measured more quickly, and they can detect faces instead of other objects with a high temperature like, for example, coffee cups.
Due to the slow easing of lockdowns and, in some places, people swarming around packed like sardines, wearing a mask might not prevent catching the virus. Do you feel sick? No. Do you have a headache? Again, no. However, there is always the risk of unintentionally spreading an infection. Even though Tarin stated that taking people's temperature in crowds equals to a nurse putting a hand to someone’s forehead and taking a guess, it can still, if used correctly, provide accurate results and make the world a slightly safer place.