The National Health Commission website released on March 18 the “Notice on the issuance of guidelines for the public to wear masks scientifically”, putting forward scientific recommendations for wearing masks in different scenarios, the full text is as follows. The State Council issued a circular on the prevention and control of the New Coronary Pneumonia epidemic on February 5, 2019. The Joint Prevention and Control Mechanism issued technical guidelines for the selection and use of masks for the prevention of New Coronary Pneumonia in different populations. In the case of a shortage of mask resources, scientific guidance on the selection and use of masks, good protection premise, a reasonable reduction in overprotection. According to the current prevention and control situation and the need to resume work and production, in accordance with the spirit of the instructions of the central steering group, the prevention and control group organized experts on the selection and use of technical guidelines for the prevention of neoconiosis masks for different groups of people was revised and improved, forming the “Guidelines for the public to wear masks scientifically”. This guideline classifies the general public, people in specific places, occupationally exposed people and key people, and proposes scientific guidelines for wearing masks in different scenarios. I. General public (a) At home, outdoors, no gathering of people, good ventilation. It is recommended not to wear a mask. (ii) In crowded places, such as offices, shopping, restaurants, meeting rooms, workshops, etc.; or riding in compartment elevators, public transportation, etc. In medium and low risk areas, it is recommended that a spare mask (single-use medical mask or medical surgical mask) should be kept with you and worn when in close contact (less than or equal to 1 meter) with other people. In high-risk areas, it is recommended to wear a single-use medical mask. (iii) For people with cold symptoms such as coughing or sneezing. It is recommended to wear a single-use medical mask or a medical surgical mask. (d) For people living with home isolation and discharged rehabilitation personnel. It is recommended to wear single-use medical masks or medical surgical masks. Second, specific places personnel (a) in the crowded hospitals, bus stations, train stations, subway stations, airports, supermarkets, restaurants, public transport, as well as communities and units import and export and other places. In medium and low-risk areas, it is recommended that staff wear single-use medical masks or medical surgical masks. In high-risk areas, it is recommended that staff wear medical surgical masks or protective masks that meet the KN95/N95 and above levels. (ii) In prisons, nursing homes, orphanages, mental health medical institutions, and densely populated places such as classrooms and construction site dormitories in schools. In medium and low risk areas, it is recommended that daily spare masks (single-use medical masks or medical surgical masks) should be carried around, and masks should be worn when people gather or come into close contact (less than or equal to 1 meter) with other people. In high-risk areas, it is recommended that staff wear medical surgical masks or protective masks that meet KN95/N95 and above; other personnel wear single-use medical masks. C. Key personnel Suspected cases of novel coronavirus pneumonia, confirmed cases and asymptomatic infected persons; close contacts of novel coronavirus pneumonia; incoming personnel (from the beginning of entry to the end of quarantine). It is recommended to wear medical surgical masks or protective masks without exhalation valves conforming to KN95/N95 and above. IV. Occupationally exposed personnel (a) Medical personnel in general outpatient clinics and wards; emergency medical personnel in medical institutions in low-risk areas; administrative personnel, police, security guards, cleaning, etc. engaged in epidemic prevention and control-related activities. It is recommended to wear medical surgical masks. (B) Staff working in wards and ICUs of patients with confirmed and suspected cases of novel coronavirus pneumonia; medical staff in fever clinics of designated medical institutions; medical staff in emergency departments of medical institutions in medium- and high-risk areas; epidemiological investigation, laboratory testing, and environmental disinfection staff; and personnel transferring confirmed and suspected cases. It is recommended to wear medical protective masks. (iii) Operators engaged in respiratory specimen collection; staff performing tracheotomy, tracheal intubation, bronchoscopy, suctioning, cardiopulmonary resuscitation operations in patients with novel coronavirus pneumonia, or lung transplant surgery, pathological anatomy. Suggestions: hood-type (or full-face type) power-fed filtered respiratory protection, or half-face type power-fed filtered respiratory protection with goggles or full-face screen; both respiratory protectors need to choose P100 anti-particulate filter elements, filter elements are not reusable, and protective apparatus is used after disinfection. V. Precautions for use (a) Respiratory protection equipment, including masks and masks, should wash hands before wearing and after removal. (B) when wearing the mask, pay attention to the front and back and up and down, the mask should cover the mouth and nose, adjust the nose clip to fit the face. (C) Avoid touching the inside and outside of the mask with your hands during the wearing process, and take off the mask by removing the cord at both ends. (D) Wearing more than one mask can not effectively increase the protective effect, but increase the breathing resistance and may destroy the tightness. (E) a variety of mask cleaning, disinfection and other measures are no evidence of its effectiveness. (F) Single-use medical masks and medical surgical masks are limited to use, and the cumulative use does not exceed 8 hours. Occupationally exposed personnel use masks for no more than 4 hours and may not be reused. Content source: People’s Daily Online