"Whether used daily or occasionally, a desktop mercury sphygmomanometer should be calibrated every six months to ensure its accuracy," said Li Fenglan of the Xicheng District Metrology Calibration and Testing Institute in Beijing. As a medical dedicated instrument, the sphygmomanometer is a mandatory calibration measuring instrument stipulated by China's Metrology Law. It should undergo a rigorous "physical examination" at the metrology calibration and testing institute under the technical supervision department every six months to ensure accurate measurement and safe use. In the past six months, the Xicheng District Metrology Calibration and Testing Institute in Beijing has handled more than 200 desktop mercury sphygmomanometers delivered by citizens themselves, of which more than 60% had issues such as mercury leakage or air leaks.