How useful are thermal cameras to protect from COVID-19 infection?
Opinions are divided on the subject of thermal imaging cameras. They are often marketed as the “must-have for the new normal” to protect customers and employees from the Corona virus. That sounds great, but is it worth investing in?
We were excited by the idea of being able to reduce the COVID infection rate by selling thermal cameras. Measuring fever reliably from a distance, even on several people at the same time, could alleviate the situation of the current pandemic, we were convinced of that.
Covid-19 as a business opportunity?
At the beginning of the pandemic, we were intensively involved in the topic of thermal cameras. The demand for prevention and protection measures against the virus was enormous and it looked like it would be a real win-win situation to include thermal cameras in easypsim’s product range. We quickly got in touch with a large manufacturer of surveillance cameras. We thought maybe there are already first delivery bottlenecks, but we were told that thermal imaging cameras are quickly available and can also be tested for free. It seemed almost too perfect, as if we could still get something good out of the nasty pandemic.
Thermal imaging cameras with “blackbody unit”
Specifically, we were interested in the top model, which includes a blackbody unit in addition to the thermal camera.
The blackbody unit serves as a reference sensor for the thermal camera in order to be able to calculate the surface temperature in combination with AI. Such a setup corresponded to our idea of a precise temperature measurement.
According to the manufacturer, the possible deviation of the temperature measurement is ± 0.54° F, which corresponds to about 0.3 °C. But precision has its price, as is well known, more than 10’000 CHF is the price for a complete setup including Blackbody, mounts etc..
Are the high prices justified?
The prices communicated by dealers seemed very high to us, so we took a closer look and searched for neutral test reports in order to justify the high purchase costs to our customers and to be able to verify the measurement accuracy. If you search on google for “fever camera test + manufacturer X”, you will quickly get to the website of IPVM. According to the website, IPVM tests surveillance cameras, video analytics, VMS software and other products in the context of security and surveillance. There are no paid advertisements or contributions, but you pay for a subscription and receive neutral test reports. Even the US Congress has already relied on IPVM’s expertise. According to the terms and conditions of IPVM it is forbidden to advertise with information from test reports. However, since this topic is so important, you have made publicly available videos, which allows us to share the information with you.
Can fever be reliably detected with thermal cameras?
Fever cameras” are also a hot topic for IPVM. They have conducted extensive tests with most of the well-known products in the fever-measuring cameras and tablets category. Most tests have shown that the promised measurement accuracy could not be met.
An algorithm that adjusts readings
It was possible to identify an algorithm in Dahua’s thermal camera that adjusts the measured temperature to the average temperature of a person, thus manipulating the measurement. Normalizing the values results in measurements being taken very quickly. Since the majority of people do not have a fever, the system then appears to work reliably. However, the algorithm used also means that people with fever are not reliably detected. An example for the adjustment of the temperature is a photo stuck on a cardboard, which shows with 33°C (91.5 F° = ), an almost human body temperature. Passing persons on skateboards can also be “measured”.
Fast measurements in the entrance area
The great strength of the newly deployed thermal cameras is that temperature measurements can be taken particularly quickly. Normally, “temperature screenings” are carried out in the entrance area. However, because the outside temperature often does not correspond to the inside temperature of the building, it is fundamentally problematic to measure the surface temperature of the skin of people who have just entered. For example, people who have warmed up in the sun or exerted themselves may have an increased skin surface temperature and immediately set off the “fever alarm”. The opposite is true in winter, when the surface of the visible skin area cools down quickly. Glasses, headgear or masks make precise measurement of the surface temperature even more difficult.
Our recommendation on thermal cameras and Covid-19
Thermal cameras are a great thing, but we don’t think you can do much to help contain the corona pandemic today. There are too many factors that can skew measurement results. This could also lead to the suggestion of false certainty, even if temperatures cannot be reliably determined. Furthermore, we are of the opinion that thermal cameras used to measure fever in humans should also meet the same approval conditions as other fever measuring devices. In accordance with the conformity assessment, it would then have to be checked whether the product meets the requirements and fulfills the advertised effectiveness or performance (Art. 9 Para. 2 MepV). We would very much welcome a test of efficacy; this would also clarify the question of the accuracy of measurements.
References:
IPVM about:
IPVM Video “Dahua Rigs Fever Cameras, Covers Up”:
https://www.youtube.com/watch?v=gyPRXcjmkN4
Fiebermesser sind medizinische Geräte:
https://www.swissmedic.ch/swissmedic/de/home/ueber-uns/publikationen/video.html
Medizinprodukteverordnung:
https://www.admin.ch/opc/de/classified-compilation/19995459/index.html
