Human Body Temperature - Measurement Devices

Measurement Devices

There is a risk of injury from cracking glass thermometers if too much force is applied by the teeth to hold them in place and the alcohol or mercury contents are poisonous. Mercury is the most toxic non-radioactive element; ingestion can thus be fatal or lead to serious health consequences. Merely possessing a mercury thermometer creates the risk that it will be broken at some stage, raising serious environmental health issues (such as mercury lodging in carpet or floorboard cracks), and requiring difficult remediation efforts. For these reasons mercury thermometers are gradually being replaced by electronic thermometers which are made from solid plastic and use a metal (thermocouple) sensor.

A plastic thermometer strip placed on the forehead gives an approximate local reading, which depends to a great extent on ambient air temperature and local circulation effects. Using a thermometer to record the temperature under the armpit is less affected by surrounding air temperature, but is still prone to diverge from true core temperature if there are alterations in blood circulation.

Since the year 2000, small ear thermometers have become available. It is thought that the eardrum closely mirrors core temperature values, and these devices work by detecting the infrared heat emission from the tympanic membrane. A measurement is quickly taken within one second, making them popular for use with children. While the electronic display of the temperature value is easier to read than interpreting the graduation marks on a thermometer, there are some concerns for the accuracy of ear thermometers in home use.