Forehead gun is not accurate for body temperature measurement? How to detect it correctly? See what experts say


Zhejiang News

  "The first measurement was 37.5 ° C. After blowing a few seconds of cold air, the measurement immediately became 35.5 ° C."

  "When driving, the car is air-conditioned. Be sure to get out of the car to cool down, otherwise every time you detect a fever!"

  "I've measured my temperature several times, and it's not even 35 ℃. Is this my temperature too low?" ...

  Recently, "body temperature" has become a hot word that many people pay close attention to. Every day when they enter or leave a residential area, an office building, or a supermarket, they will be shot with a gentle "beep" by the staff at the door. However, the body temperature measured by the forehead gun is often unstable, making people uncertain about their true body temperature. Why does the temperature measured by the forehead gun appear inaccurate?

  Why is the temperature inaccurate?

  Eliminate interfering factors before temperature measurement

  Qin Shuwei of Ningbo Metrology and Testing Research Institute introduced that the infrared forehead thermometer is a type of non-contact thermometer, which uses the relationship between the thermal radiation of the object and the temperature of the object to measure the temperature.

  Why is the temperature inaccurate? Experts say that if you do n’t master the measurement principles and methods, the measured temperature results will have a large error.

  First of all, accurate temperature measurement needs to exclude interference factors. The air, water vapor, and other obstructions in the measurement environment will also change the radiation curve of the object, resulting in inaccurate temperature measurement. Ensure that the optical system of the thermometer is clean and free of dust, water vapor and other influences, and that the subject's forehead and ear canal are not covered by sweat, hair, dust, hats and other debris. At the same time, the measurement of body temperature requires an indoor wind-free environment. It is also necessary to ensure that the use of the instrument can not have a large temperature difference, to ensure the normal working environment of the instrument (higher than 16 ℃). The temperature is not indicative and belongs to abnormal operation.

  Second, the mode and measurement unit of the thermometer, some thermometers have two functions of surface temperature and body temperature. You cannot choose the wrong mode when selecting the mode. The measurement unit should be Celsius ℃ instead of Fahrenheit ℃. Both are reflected in the number. The difference is striking.

  How to ensure accurate temperature measurement? He Tianfeng, Ningbo Center for Disease Control and Prevention, said that 20-30 minutes before taking body temperature, avoid strenuous exercise, eating, drinking cold or hot water, not cold and hot compresses, to maintain emotional stability, and not to be nervous.

  It can be measured several times. If the temperature is suspected to be inaccurate, you can repeat the measurement several times, or take a measurement on a person with normal temperature and then measure the person.

  Periodically trace the value of the thermometer. Calibrate according to the technical specifications of China's existing JJF 1107 "Infrared Thermometer Calibration Standard for Measuring Human Body Temperature" to the nearest legal metrological technical institution. If the calibration finds that the meter has a large error, poor measurement repeatability, and unstable performance, it is recommended to stop .

  At the entrance and exit of the expressway, when waiting in line for temperature measurement, the personnel inside the car should drive the window at least five to ten minutes in advance to keep the human body and the external environment temperature in thermal equilibrium before measuring.

  Measure the wrists covered by clothing

  Relatively more accurate temperature

  Just entered from the outside, the measured forehead temperature is affected by cold outdoor air and cannot reflect the true body temperature. For example, when a person rides a bicycle against the wind, the thermometer shows 34 ℃ or the value cannot be displayed. The manual of the forehead gun also reminds that the user and the infrared forehead thermometer should be kept at stable room temperature for at least 30 minutes before use.

  But the problem is that during the extraordinary period, at high-speed, high-traffic supermarkets, office buildings, and other entrances, we can't keep the temperature at a stable room temperature for at least 30 minutes before using the body temperature.

  After repeated tests, the staff of the Medical Engineering Department of Ningbo First Hospital developed a little trick for measuring the amount of thermometer. Ask the person under test to expose part of the skin of the wrist that is covered by clothing and not exposed to the air (either left or right), and measure from 6-8 cm away from the wrist, so that the measured temperature is closer to the real temperature of the human body.


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