Choose chemical resistant medical masks for preparation: determine all components of chemical mixtures in the workplace; the condition and characteristics of chemicals; contact with chemicals; evaluate the medical masks that are waterproof, acid and alkali resistant, chemical resistant and oil resistant. Carefully check whether there is any damage and aging before use. Medical mask rubber, latex, plastic and other protective medical masks should be cleaned, stored, avoid high temperature, and spread talcum powder on the product to prevent adhesion. Insulating medical masks should be used in strict accordance with the instructions, and the electrical insulation performance should be checked regularly. If not, they should not be used. Injury prevention is a particularly complex issue due to the diversity of chemicals encountered. Acids, disinfectants, hydrocarbons, solvents, oils, lipids and acetate have different chemical properties. As a result, each material has different characteristics and specific uses, which depends on the type of chemicals in contact with medical masks. 1) filtration efficiency: under the condition of air flow rate (85 ± 2) l / min, the filtration efficiency of sodium chloride aerosol with aerodynamic median diameter of (0.24 ± 0.06) μ m is not less than 95%, that is, it meets the grade of N95 (or FFP2) or above. It can block the air borne infectious factors with diameter less than 5 μ m or contact with the infectious factors transmitted by droplets in close contact. 2) Inspiratory resistance: under the above flow conditions, the inspiratory resistance does not exceed 343.2pa (35mmh2o). 3) When the sample is sprayed to the mask under the pressure of 10.9kpa (80mmHg), the inner side of the mask should not show any technical indicators such as penetration. 4) The mask must be equipped with a nose clip, which is made of bendable plastic material with a length of more than 8.5cm. 5) The synthetic blood was sprayed to the mask sample at the pressure of 10.7kpa (80mmHg), and the inner side of the mask should not be penetrated.