Disposable masks should be free of chemical carcinogens if they are produced by regular manufacturers. Disposable masks produced by formal manufacturers are free of carcinogens, but some disposable masks produced by informal manufacturers may have carcinogens. The raw material for producing disposable masks is mainly non-woven fabric, which is divided into flat masks, three-dimensional masks and so on. Generally speaking, no carcinogens are added or remain in the formal production process of disposable masks, but there may be hidden dangers in the production process of informal manufacturers. This is because there is an ethylene oxide sterilization process in the production of masks, and ethylene oxide is a carcinogen. If not handled properly, it can lead to residual ethylene oxide, resulting in the presence of carcinogens in the mask. Therefore, it is recommended that medical supplies such as disposable masks should be purchased from a regular pharmacy or local hospital.