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            What is the aerosol filtration efficiency of 29 kinds of medical surgical masks to prevent new coronary pneumonia?

            Investigation results: In this quality improvement study of 29 types of medical surgical masks, the expired N95 masks with intact elastic bands have been sterilized with ethylene oxide and hydrogen peroxide, and their fixed filtration efficiency (FFE) remains unreliable. However, it still exceeds 95%, while the FFE of the wrong size N95 mask is between 90% and 95%. Compared with N95 masks, medical surgical masks have a lower FFE.

            Meaning: When there is no new N95 mask, you can use the expired but disinfected second-hand N95 mask; other less common masks are also acceptable.

            Importance: Providing respiratory protection for clinicians and other medical staff has become the main challenge of the COVID-19 pandemic, and due to the lack of masks, some non-standard practices have emerged, such as the use of expired masks and various purifications Methods to protect the safety of the respiratory tract. In addition, the hospital has donated or obtained imported, non-National Institute of Occupational Safety and Health (NIOSH) approved masks to replace the limited NIOSH approved N95 masks.

            Purpose: To evaluate the proper filtration efficiency (FFE) of medical surgical masks used during the COVID-19 pandemic.

            Design, setup, and participants: For the quality improvement study conducted from April 2020 to June 2020, we used the quantitative fitting test procedure of the U.S. Occupational Safety and Health Administration to filter supplementary materials in a laboratory environment. Masks of sodium chloride particles to evaluate FFE in the laboratory. Various masks worn by male and female volunteers.

            During the new coronary pneumonia (COVID-19) pandemic, the main concern is to protect clinicians and other medical staff from respiratory aerosols and contact transmission of the severe acute respiratory syndrome coronavirus (SARS-CoV-2). infection. The universality of personal protective equipment and a serious shortage, mainly filter masks, have prompted people to take non-standard measures to meet the protective needs of medical institutions. The Centers for Disease Control and Prevention (CDC) has developed emergency and crisis strategies to provide alternatives to masks, including use, purification and reuse after the expiration date, and use without the approval of the National Institute of Occupational Safety and Health (NIOSH) Respirator.

            The comparison of the proper filtration efficiency (FFE), the combination of the inherent filtration efficiency of the material and the efficiency that fits the face, has not been fully quantified for masks before, and medical institutions are faced with prioritized selection guidance decisions for which there is no available data. In order to meet this demand, we conducted a series of FFE assessments on 29 types of masks used by medical institutions, including expired but sterilized N95 masks, CDC approved imported masks, CDC unlisted masks, and CDC approved masks. Medical surgical mask with ties and earrings.

            More detailed results: Among the 29 different masks tested on 1 male and 1 female, N95 masks with intact elastic bands that have failed and were respirators sterilized by ethylene oxide and hydrogen peroxide The FFE is unchanged (>95%). The performance of the wrong size N95 mask is slightly reduced (FFE is 90%-95%). All masks not listed in this assessment (n = 6) did not achieve 95% FFE. The two imported masks authorized by the US Centers for Disease Control and Prevention that were tested in this study without NIOSH approval did not reach 95% FFE, while the FFE of the two more effective masks was about 80%. Compared with N95 masks (98.5% of the overall FFE), the filtering performance of disposable medical surgical masks is lower.

            Conclusion and relevance: This quality improvement study evaluated 29 types of masks used by clinicians and patients during the new coronary pneumonia pandemic. It was found that when there is no new N95 mask, the expired but disinfected second-hand N95 mask can be used, and others can be used. Masks may reduce the filtering effect.

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