How Thermal Scanners Can Help Detect A Fever

FLIR, the manufacturer of our thermal imaging cameras, is at pains to remind the public that thermal scanners are not medical devices.

As such, they cannot be relied upon to single-handedly detect or diagnose coronavirus (COVID-19), SARS, H1N1, or a fever.

However, they are incredibly effective at detecting small deviations in the surface temperature of objects and people. As such, they are a useful tool in screening for people that might be showing the symptoms of a viral infection, such as a fever.

Our thermal cameras are so sensitive that people often think they can see through things with them. For example, if you point one of these devices at a wall you can often 'see' the studs behind the wall. You are not actually seeing through the wall, but rather observing the minute differences in surface temperature where the wall has a support structure behind it, and where it does not.

Anyway, back to COVID-19 and scanning for fevers! Sorry, I mean 'Elevated Body Temperature.'

Thermal Scanners Detect Elevated Body Temperature

The jargon that FLIR and others use in this field is Elevated Body Temperature or EBT. Because, like I already said, this is what they most certainly can detect. After all, someone with an elevated body temperature may have coronavirus, a fever, or they may have just been for a run.

Some of FLIR's thermal scanners are even US FDA (United States Food & Drug Administration) approved for detecting elevated body temperature. This includes our higher-end FLIR Exx Series.

Which Thermal Scanners Have Fever Detection 'Screening Mode'?

Some of FLIR's thermal cameras like the E75, E85 & E95 that we sell have an inbuilt 'screening mode'. You can see this screening mode in action in the above video.

The screening mode shows:

  • The sampled average temperature.
  • The alarm temperature.
  • The measured temperature.

One of the key benefits is the audio alarm that sounds if someone passes through the detection area with an elevated temperature. This makes these cameras ideal for relatively high traffic areas such as airports, train stations, ports, and large office buildings.

FLIR Thermal Scanner Fever Detection Mode

FLIR Exx Series Screening Mode.

The FLIR Exx Series is also tripod-mountable which makes it ideal for set-up in thoroughfares. You can also transmit the data over wifi or a cable connection to a nearby computer with a larger display screen.

Other Thermal Scanning Options To Detect People Who May Have Coronavirus (COVID-19)

The above mentioned thermal scanners are relatively expensive. While they are the best tool for the job, there are some lower-cost thermal cameras which are also worth considering.

FLIR Ex Series - Above Alarm Mode for Fever Detection

The FLIR E5 XT, E6 XT and E8 XT cameras have an inbuilt 'above alarm' mode. Unlike the 'screening mode' described above, this is a visual alarm.

The colour palette remains grey - except for areas above a pre-defined temperature. If someone walks in front of the camera above your pre-defined fever temperature, an area around their tear ducts or forehead will immediately show up as bright red.

FLIR Thermal Scanner Fever Detection Above Alarm

FLIR E5 XT in above alarm mode. Note: if using the device to detect a fever, you would set the alarm to just above normal body surface temperature (say around 36˚C). In this example, we set the above alarm a bit lower (to 34.3˚C), just so you get the idea of how it works.

As such, these cameras can also be used to detect people with a coronavirus fever. They're more suited to situations where the flow of people is less than at an airport or mass transit terminal. I am thinking of applications such as scanning workers as they enter a factory. Or scanning staff and customers as they enter your workplace.

Other Options to Detect Elevated Body Temperature

As you go further down FLIR's range, many of the cameras are still accurate and useful for a wide range of applications. But their lower thermal resolution means you need to be more careful when taking readings of human body temperature.

For example, the FLIR C3 has a tripod mount and 'Area Max' temperature measurement. But with a small 80 x 60 pixel thermal detector, you would need to ensure the subject is very close to take a reliable temperature measurement.

Similarly, the FLIR One Pro can take useful images, but it lacks a precisely settable above alarm or screening mode.

In summary, thermal cameras can be more useful than other screening options like non-contact thermometers. Non-contact thermometers need the subject to be very close (15cm from forehead). Manufacturers of non-contact thermometers also suggest taking three measurements of a subject and taking the average, which is slow to check many people.

On the other hand, as you can see from the examples above, thermal cameras can provide a quicker and more detailed scan of people as they pass through an area. Unlike non-contact thermometers, thermal cameras have an array of thermal detectors constantly taking an average reading of the target area.

Want to Find Out More?

Check out our:

--> Complete range of thermal imaging cameras.

--> Free online thermal camera training resources.

--> Over 60 unique uses for infrared cameras.

By Ryan McCarthy |

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