[CTO Talk] Elevated Temperature Detection AI for Workplace Safety

Elevated Temperature Detection AI for Workplace Safety

As we plan to return to work safely, the Equal Employment Opportunity Commission (EEOC) is allowing employers to take the employers temperature to mitigate the spread of COVID-19. In a statement updated on March 17, the EEOC states, "Generally, measuring an employee's body temperature is a medical examination. Because the CDC and state/local health authorities have acknowledged community spread of COVID-19 and issued attendant precautions, employers may measure employees' body temperature. However, employers should be aware that some people with COVID-19 do not have a fever." (Source: EEOC )

There are many ways to measure an employee's temperature: The most optimal way is to measure using a Non-contact Infrared Thermometer (NCITs) or to use a Thermal Imaging System.

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Source: FDA Thermal Imaging Systems

In this article, we will focus on thermal imaging systems and especially its use in a workplace like an office, factories, warehouses, etc. We will also only focus on intent-based screening for individuals and not mass screening like airports, stadiums, etc. as it is another topic by itself. 

If used correctly, thermal imaging systems generally are an effective and scientifically supported method in measuring human skin temperature. The advantage of using such a system is that you can determine if someone is experiencing an elevated skin temperature without being physically close to the person being evaluated. The U.S. Food and Drug Administration (FDA) provides a detailed overview and recommendation for Thermal Imaging Systems. (Infrared Thermographic Systems / Thermal Imaging Cameras)

What are thermal imaging systems?

Thermal imaging systems are different from non-contact infrared thermometers (NCITs), Thermal Camera detects heat radiation and can be used to identify the surface temperature of objects and people.

 

IR200
Extech IR200:  Non-Contact Forehead InfraRed Thermometer

Source: http://www.extech.com/

FLIR A400/A700 Smart Sensor - Thermal Camera

Source: http://www.flir.com/

What types of thermal cameras can be used for this purpose?

Not all thermal cameras are fit to measure elevated skin temperature; as they don't meet the minimum specifications needed to determine EST, the reliability depends on the camera resolution, stability, and measurement accuracy / sensitivity (NETD ), etc.

As a thumb rule, the camera should have a Noise Equivalent Temperature Difference (NETD) value less than 50.

FLIR (https://www.flir.com/) is one of the top manufacturers of thermal cameras and has the suite of Thermal Cameras that are suited to measure Elevated Skin Temperature ( EST ), Oloid uses FLIR cameras combined with our platform to offer a complete solution for employers planning to bring employees safely back to work.

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FLIR Lepton - Example type of camera used by Oloid. (Source: https://lepton.flir.com/)
What are some essential things to consider before choosing a solution?

Elevated Skin Temperature DOES NOT Equal to Fever:  Elevated Skin Temperature in individuals can vary due to weather, ambient temperature, clothing, perspiration etc. even with best solution in the market expect some false positives, which makes secondary screening very important.

Thermal Screening CANNOT detect COVID-19 :  This is obvious but needs to be said.

Thermal Camera Resolution is Important:  In the sections below, we have detailed the methods to detect EST, it has been scientifically confirmed that Inner Canthus of the eye (tear duct) is demonstrated to be the most reliable and robust location as the blood is supplied by internal carotid artery. (Source: ISO/TR 13154:2017)

Hence it would help if you had a camera with enough resolution to get sufficient pixels from the Inner Canthus area. Forehead temperature is not a reliable source to determine EST due to high variability from person to person.

Forehead Temperature:  < 2 C variability from person to person
Inner Canthus:   0.5 C variability from person to person
(Source: FLIR)

Atashi_Face_Thermal

How does it work?

Most systems in the market today generally follow one of the following approaches.

1. Take the temperature of Inner Canthus: Given the camera resolution, the temperature readings from the pixels near Inner Canthus and with some basic normalization, and resulting temperature value is displayed.

Pros
Less compute required, reasonably fast

Cons
Requires constant calibration
Temperatures fluctuate a lot
Lower resolution/sensitivity cameras have very high error rates
Reliable cameras are costly $10K +

2. Detect only elevated skin temperature: This method does not attempt to measure accurate absolute temperature instead of it takes few reference temperatures of normal individuals, and it measures average and standard deviation, and the subsequent measurements are categorized based on how much difference there is from the references, the result is a binary determination of Positive or Negative Elevated Skin Temperature

Pros
More reliable than measuring Absolute temperature

Cons
Requires constant reference temperature settings ( in some cases every 15 mins ) 
False-positive rates can be high depending on the type of references set
False-negative rates can be high depending on the type of references set

3. Using Black Body: This method uses a reference temperature object also known as black body, this object maintains a set temperature, hence if it is in the camera view, the camera can adjust and correct itself based on the difference of values.

Pros
Accurate results if there is a desire to measure absolute temperature

Cons
Extra Hardware that needs to be to mounted at a specific place
Black body’s are expensive
Error prone if moved

ThermalCameraSetup copy

How is Oloid's Solution different?

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Oloid Thermal - Multi-Modal Fusion Analysis

Oloid uses temperature from the Inner Canthus, measures reference temperatures, also analyzes the distribution of temperature on the face, as Febrile face usually has a relatively more uniform distribution. Our system also combines other factors such as Ambient Temperature, Time of the day, Calibration effect, etc. to normalize the data. The result is a highly accurate and fast determination of Elevation Skin Temperature. These results can be achieved without using High-End Thermal Cameras. Oloid uses FLIR Lepton based devices and depending on the setup. The device can cost anywhere between $300 - $1000, compared to a $5,000+ device to achieve a similar outcome.

Benefits of Oloid Thermal

  Highly Accurate and Fast EST detection
√   Uses Inexpensive FLIR Lepton based devices
  Purchase off the shelf recommended hardware
  Quick and Easy Setup
  Integrated with Wellness Attestation ( Oloid Certify )
  Facial Auth & QR Code Support using Face Vault
  Enterprise App Integrations

 

References

EEOC: https://www.eeoc.gov/wysk/what-you-should-know-about-covid-19-and-ada-rehabilitation-act-and-other-eeo-laws
FDA: Infrared Thermographic Systems / Thermal Imaging Cameras
ISO/TR 13154:2017: https://www.iso.org/standard/69347.html  
FLIR: www.flir.com

 

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