There is a mechanism for operating and controlling health regulations. Only the closed control area can't get in. If the scan code enters the middle and high risk area, on the one hand, it can't get out, on the other hand, the health code will be activated and turned red. The function of health code is not to prove that you are healthy, otherwise you are not allowed to declare your physical condition yourself. Its function is not only to report your personal health, but also to record your action track. You have been to the middle and high risk area, and your health code will change color.