During an epidemic, the main means of protection is to wear a mask, wash hands regularly, and change the mask diligently after infection. The general principle of using masks is that the outside layer is a waterproof layer, the middle layer has a non-woven fabric, which contains static electricity and has an adsorption effect on viruses, and the inside belongs to the comfort layer, which has a protective effect on the human skin. This role is based on its quality and quality, to ensure that the mask has the ability to disinfect. Our laws provide for the shelf life of the product mainly quality assurance and quality assurance, if the mask expires, the non-woven fabric electrostatic ions will be lost, the adsorption capacity of the virus will fade, and its quality can not be guaranteed. Absorbing virus ability and quality cannot be guaranteed, it will affect the function of the mask to prevent virus, so it is better not to use the mask after the shelf life. Content source: Dr. You Lai