Can Thermal Imaging Technology Identify People With Fevers?
As we begin to round the corner of the COVID-19 pandemic and people start to return to workplaces, many organizations are looking for ways to help promote safety and CDC compliance. One of the categories of products that has gathered growing interest during this time are the various thermal imaging devices that can be used to potentially identify individuals with an elevated body temperature. With increased interest comes increased scrutiny regarding the true capabilities of this technology.
To understand what this technology can and cannot do, it’s helpful to understand how it works. Unlike optical or visible light cameras, which use reflected light from the environment to view an object, thermal cameras detect electromagnetic radiation generated by the object itself. With careful application, sensor data can be used to estimate temperature. As the temperature of an object increases, the intensity of electromagnetic radiation increases, and the peak wavelength becomes shorter.
However, when it comes to whether this technology can detect a fever in an individual, the answer is “maybe.” While thermal cameras may be an effective tool in a process to quickly screen individuals for the presence of a fever, customers considering this technology should be aware of its limitations:
- Thermal cameras measure skin surface temperature, but there may not be a strong correlation to body temperature. Also, a high body temperature may not always indicate the presence of a viral disease.
- Most thermal imaging technology marketed to identify fevers during the COVID-19 crisis are not medical-grade devices and are not FDA cleared or approved.
- Environmental factors, such as wind or sweat, can limit accuracy.
- Use cases today are focused on standalone solutions that are manually operated with a single operator, which poses various scalability challenges.
Careful system setup can help maximize accuracy of measurement and should always be set up according to the manufacturer’s specifications. To provide the best results, a system should follow these best practices:
- Use a camera mounted level with the subject’s face and positioned closely, typically five to 15 feet away.
- Within the field of view of a camera, a reference temperature source should be positioned the same distance away as the subject. This device, known as a black body, is maintained at a temperature close to normal human skin surface temperature.
- The thermal camera should have a sufficient resolution so that at least nine pixels measure near the tear-duct of the eye. Studies have shown skin temperature near the tear duct has the best correlation with body temperature.
- The measurement passageway should be located indoors to reduce the influence of the environment.
- For accuracy, glasses must be removed to see the tear duct. Glass may be transparent to visible light, but it is opaque to thermal wavelengths. Face coverings and hats may need to be removed, as most systems rely on face detection to work properly.
- Systems should be tested and have a measurement uncertainty of less than half of a degree Celsius, used in accordance with manufacturer instructions, and paired with a secondary temperature measurement process.
Ask an expert
The Anixter Technology & Support Services team is an important resource for guidance on thermal cameras and other potential solutions as you build your comprehensive safety programs. We encourage you to work with your local Anixter sales representative to engage our technical resources if you would like to explore options regarding thermal imaging.