The thermometer with mercury or without mercury

5 min read
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Le thermomètre avec mercure ou sans mercure

When we think of “thermometer” we often imagine this small transparent glass tube containing an often red or silver liquid; well this thermometer that you imagine is a thermometer with mercury. A real professional temperature taking tool, it quickly took up residence in our private bathrooms to take the temperature of family members and control fever. This mechanical thermometer has long been used as a medical thermometer for taking body temperatures of patients before being completely withdrawn from the market. How does the thermometer with mercury ? Why has it disappeared from medicine cabinets? What mercury free thermometers have become good alternatives? The temperature taking experts at come back with you on all these questions to help you see more clearly.

The thermometer with mercury 🧪

At first glance, you might think you need choose between thermometer with mercury and thermometer without mercury, like the red pill and the blue pill in the movie Matrix. What no! Let us tell you more about the mercury thermometer and its removal from the body temperature measuring instruments market…

The history of the thermometer with mercury

The thermometer with mercury was created in 1724 by the German physicist Gabriel Fahrenheit. It is composed of a glass bulb as a tip, itself surmounted by a long glass tube graduated in degrees Fahrenheit or in degrees Celsius a few years later (depending on the country). The bulb then contains mercury, a liquid metal at room temperature whose coefficient of thermal expansion is high. When the mercury heats up thanks to the temperature of a body, it expands rapidly and its volume increases in the glass tube, until it gives an accurate measurement via the scale.

The dangers of the thermometer with mercury

Mercury is part of what are called, with calcium and lead for example, heavy metals. These are highly toxic metals that can cause damage to human health. Beyond the dangers of local traumatic lesions (perforations, etc.) and skin wounds that could be caused by the breakage of the bulb when taking the temperature, the greatest indirect risks are through mercury vapours.

And a thermometer with mercury is broken, the vapors are immediately inhaled by the occupants of the room, which could especially happen in a hospital environment. It was then imperative to redouble vigilance in the rooms where the children evolve (the most vulnerable to this neurotoxic) and in the rooms of the sick, that is to say in closed, poorly ventilated, heated environments.

The phasing out of the thermometer with mercury

In France, the sale of thermometers with mercury thus ended thanks to the decree of December 24, 1998 and was quickly reinforced by a ministerial circular also prohibiting the use of these mercury medical thermometers in French hospitals from September 1999. Our European neighbors, with a little delay, banned the marketing of mercury thermometers on July 10, 2007.

Mercury-free thermometers 📲

Of course, today there are different alternatives to these medical thermometers ; underarm or rectal thermometers, the thermometer without ear contact ideal for taking the temperature of babies and other infrared temperature sensors whose measurement ranges are perfect for taking body temperature.

The axillary thermometer

The most obvious with its stainless steel tip and which strongly resembles our thermometer with mercury, is the one called the axillary thermometer to take the temperature rectally or under the armpit. Its digital screen directly displays the precise temperature thanks to the internal temperature sensor.

The infrared thermometer

forehead thermometer or ear thermometer, these non-contact medical electronic thermometers are reliable and accurate measuring devices. Infrared/laser thermometer technology gives you comfort and ease of use. No need to clean it, change the tip, insert the probe, etc. They also allow measurement of the ambient temperature. In addition, they are particularly fast and display the exact temperature within seconds on their LCD screen.

The different types of thermometers

There are therefore many alternatives to the thermometer with mercury. However, if your needs go beyond what these mercury-free thermometers can give you, do not hesitate to continue your research on different types of thermometers existing:

  • The mechanical thermometer
  • The electronic/digital thermometer
  • The IR/Laser Thermometer
  • Thermometer vs anemometer
  • Thermometer vs recorder
  • Thermometer vs hygrometer
  • Thermometer vs ph meter
  • Thermometer vs Thermocouple
  • Thermometer vs Thermostat
  • thermometer with probe
  • The gallium thermometer
  • Bubble/Galileo Thermometer
  • The multifunction thermometer


*The contents in italics are under development and will be available soon.