Many businesses related to critical activities continue to operate as the Covid-19 pandemic caused by the SARS-CoV-2 coronavirus continues. It has been raging around the world for several months now and has been very severely affecting European countries in recent weeks. The monitoring of the body temperature of employees on arrival at the company is increasingly being practiced as in many Asian countries that have managed to control this pandemic, the thermal camera is an interesting option.

Febrile state during a Covid-19 infection

CoV-2-SARS disease begins after 2 to 14 days incubation (average 3 to 7 days) with non-specific clinical signs: headache, cough, fever ≥ 38° or a feeling of fever, dyspnea (difficulty breathing), anorexia, rhinorrhea (runny nose), myalgia, headache, pharyngitis, odynophagia (difficulty swallowing), loss of taste, loss of smell, sometimes digestive disorders (vomiting, diarrhea), conjunctivitis, skin rash;
At the beginning of the infection the fever is not very high and the person is not always aware of it, that is why it makes sense to control the body temperature.

Infrared technology, IR, to control body temperature

Of course, all devices used must be non-contact to avoid transmission of infectious agents; therefore, infrared (IR) technology is used, since infrared thermometers allow the temperature to be measured quickly, remotely and without touching the person to be tested.

We are all familiar with infrared: it is when we feel the heat from a warm object at a distance. We also know that this radiation is invisible because heat is also felt in total darkness.
It was in 1800 that the British scientist Herschel discovered the existence of this radiation. He also found the first evidence that light and infrared are two aspects of the same phenomenon, today called electromagnetic radiation.

The infrared (IR) thermometer measures temperature by quantifying the radiative energy emitted in the infrared spectral band.

Depending on the device (conventional thermometer) or tablet or thermal camera, the size of the infrared sensor is different: a thermometer has a small sensor and can analyze only part of the reflected IR radiation a device such as a camera or thermal tablet has a larger sensor and therefore analyzes a larger part of the body, provides a more reliable measurement.

Equipment available to monitor the body temperature of people arriving at a site

These devices are non-contact to prevent transmission of infectious agents, including Covid-19, SARS-CoV-2

Handheld infrared thermometer, Gun type
These non-contact thermometers are used by an operator who, for example, checks each person on arrival at the company.

Most portable infrared thermometers have laser pointers that show the approximate centre of the measuring area. This laser is only a pointer and is not used for actual temperature measurement.
Also contrary to a common misconception, the thermometer does not strictly measure the area illuminated by the laser beam, the measuring point is always wider.

You have to aim at the forehead and stay in position until a measurement is displayed on the screen: the device measures the temperature several times over a short period of time and then displays the value it believes to be closest to reality.

In order to have an accurate and reliable measurement it is necessary to observe strict enough conditions to use it :

In particular, leave the thermometer for about 20 minutes to reach the temperature of its environment when you take it to a place significantly warmer or colder than where it was stored,
observe a latency of at least 1 minute between 2 measurements,
Remember that steam or dust can affect the accuracy of IR thermometers,
Remember to maintain the thermometer lens to keep it clean and scratch-free.

Thermal camera to monitor body temperature
These devices, which are available as tablet or thermal camera, are more reliable because they analyze a much larger part of the body.

A camera requires a fixed position because the person must be placed in the skeleton displayed by the camera. This standardised posture allows a more reliable result to be obtained for the measurement of the body temperature of the person being tested.

Which equipment to choose?

With the Covid-19 pandemic the Covid-19 thermal cameras and tablets flooded the market.
It is strongly advised to contact suppliers who are familiar with this type of equipment and sell thermal cameras and tablets.