And we can easily imagine a scenario in which someone is contagious with COVID and is taking anti-fever medicine like acetaminophen, which will bring their temperature down. On the other hand, the device might tell you you are feverish even though you’re not because of stress, physical activity, nicotine, a hot beverage, hormonal treatments, pregnancy, hot air currents or even a sunburn. There is actually a significant list of reasons why these infrared thermometers can miss a fever: circulatory problems, previous injuries, heavy makeup, certain drugs. Sweat on your brow can artificially lower the temperature that is measured, essentially disguising a fever. They are not meant to be used in the direct sunlight, because the Sun will warm up your forehead and bias the reading.
And they are quick to take and retake a temperature.īut if we focus for a minute on forehead infrared thermometers-also sometimes referred to as “thermometer guns”-much can theoretically affect their accuracy.
The lack of contact should lower the spread of disease. Thermal imagers have their advantages, especially for the mass screening of people during a pandemic. And because forehead temperature is lower than the temperature underneath our tongue, it has to be converted by the device into an “oral temperature equivalent.” The laser you see on some devices does not detect temperature it exists to make sure the user is pointing the device correctly.
An NCIT has a lens that focuses this heat onto a detector, which transforms it into electricity. Our forehead emits heat in the form of infrared radiation. All of these thermal imagers function under the principle that heat is emitted by any object above absolute zero (-273.15☌ or -459.67☏). There is a class of devices called thermal imagers which includes both thermal cameras seen in some airports as well as non-contact infrared thermometers (NCITs). And now, contact with the body is no longer needed. More recently, liquid was done away with in electronic thermometers, many working under the principle that electric resistance changes due to temperature. Johannis Hasler of Berne, a theologian and physician, thought body temperature went up in tropical latitudes and published a table with presumed body temperatures around the world to guide his mixing of “medicines.” Thermometers were initially based on the expansion of water as it warmed up this water was later replaced by mercury, which responded much more quickly to changes in temperature, then to alcohol due to mercury’s toxicity. Thermometers go way back to the early 1600s, but even before their existence, physicians understood that there were degrees of heat and cold. The only question is, do these temperature-sensing technologies actually work? Thermal cameras and non-contact infrared thermometers will get deployed in an effort to prevent people with a fever from entering into an area where they may infect others. In the age of COVID, our forehead will become the target of fever spot checks. Is it greasy? You may want to wipe that sweat off. Your forehead is about to get a lot of action.