Are mercury thermometers accurate?
Disease description:
My son is 8 years old. I touched his forehead and it felt a bit warm. We only have a mercury thermometer at home. I would like to ask whether this type of thermometer provides accurate measurements.
Doctor's answer (1)
Dr. Zhou Xiaofeng
Mercury thermometers are relatively accurate. Their accuracy mainly stems from the thermal expansion and contraction properties of mercury; this physical characteristic allows mercury to precisely reflect subtle fluctuations in body temperature when temperature changes occur. Compared to other types of thermometers, mercury thermometers do not suffer from battery failure or electronic component malfunctions, so they can provide stable and reliable measurement results when used correctly. However, care should be taken to avoid breaking the mercury thermometer, as mercury is toxic and may cause harm to human health and the environment if it leaks.
When using a mercury thermometer, to ensure measurement accuracy, it is necessary to shake the mercury column down to below 35°C before use, as this is the starting point for measurement. The usual measuring site is under the armpit. During measurement, place the thermometer in close contact with the skin and hold it tightly, ensuring that the mercury end is fully placed under the armpit. The typical measurement time is 5 to 10 minutes. After measurement, carefully read the scale indicated by the mercury column, keeping the eyes level with the top of the concave surface of the mercury column to ensure an accurate reading. In addition, after use, the thermometer should be stored properly to avoid dropping or exposure to high temperatures, in order to prolong its service life and maintain measurement accuracy.
