There is a lot of hype at the moment about the ability to use Thermal cameras to monitor body temperature (and thereby COVID-19 infection) of people allowing organisations to quickly screen workers or clients entering their premises.
It is easy to see the attraction, the risk to an organisation in having someone infect other staff or clients in both financial terms and Health & Safety issues can be huge. Unfortunately, a lot of companies are making claims about the abilities of the cameras and they way in which they can operate which do not stack up in the real world.
Cameras are measuring skin temperature rather than body temperature which can make errors much more likely especially if the camera is using the forehead to make the measurement. Most companies are doing this as it makes for a nice-looking video showing people walking down a corridor and the camera measuring the temperature on multiple people at the same time.
Unfortunately, if you look at the factors that influence skin / body temperature such as
- Hot or cold ambient temperature
- Strenuous work or exercise
- Prolonged exposure to the sun
- Alcohol consumption
- Age / Gender
The forehead is an unreliable area to focus on. Experts agree that the most reliable area to measure temperature is the Inner Canthus (corner of the eye by the nose). This is because it is far less vulnerable to the environmental factors and major arteries pass by it giving a more accurate measurement of the internal body temperature. In fact, the Global IEC standard calls for Inner Canthus measurements saying others are unreliable.
What does this mean, Thermal cameras provide lower resolution (Pixel numbers) than most modern IP cameras. This means to screen a person they need to
- Stop and look at the camera for 4-5 seconds
- Be 1 -1.5 metres from the camera
- Remove any eye covering (such as glasses)
- Be able to calibrate their temperature to the surrounding environment
As well it is important to remember that despite what others are saying we are not screening for COVID-19 we are screening for elevated temperature. People may have the virus and not a temperature conversely, they may have a temperature but not be infected with COVID-19.
This does not mean that used properly the right camera can’t be a valuable tool, but it should not be your only one.