Because the body temperature fluctuates every moment, it is not fixed and will also change with changes in the ambient temperature. Moreover, the mercury thermometer is close to the actual body temperature in 5 minutes, but in 10 minutes, the energy of the body's pulsation will be superimposed, which will increase the measurement error, resulting in different readings in 5-minute and 10-minute measurements.
Many countries have banned mercury thermometers due to their harmful effects. As early as 1992, Sweden banned the sale of all medical equipment containing mercury. Mercury pollution has attracted global attention. After several rounds of intergovernmental negotiations, a legally binding international mercury pollution control convention is likely to be promulgated in June 2013.
Notes on the use of mercury thermometers:
A mercury thermometer contains about 1 gram of mercury. After being smashed, all the leaked mercury will evaporate, and the air mercury concentration in a 15-square-meter, 3-meter-high room can reach 22.2 mg/cubic meter. China stipulates that the maximum allowable concentration of mercury in indoor air is 0.01 mg/cubic meter. It is generally believed that people will soon suffer from mercury poisoning in an environment with a mercury concentration of 1.2-8.5 mg/cubic meter.
However, the use of mercury thermometers is not prohibited in China. Mercury thermometers are widely used in the medical field and ordinary households. They can be purchased in some pharmacies. Data from the China Medical Device Industry Association shows that the national production of mercury thermometers consumed 109.25 tons of mercury in 2008, which is equivalent to the amount of mercury used in 21.85 billion standard mercury-containing energy-saving lamps.