Derrick J L, Gomersall C D
Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
J Hosp Infect. 2005 Apr;59(4):365-8. doi: 10.1016/j.jhin.2004.10.013.
Guidelines issued by the Centers for Disease Control and Prevention and the World Health Organisation state that healthcare workers should wear N95 masks or higher-level protection during all contact with suspected severe acute respiratory syndrome (SARS). In areas where N95 masks are not available, multiple layers of surgical masks have been tried to prevent transmission of SARS. The in vivo filtration capacity of a single surgical mask is known to be poor. However, the filtration capacity of a combination of masks is unknown. This was a crossover trial of one, two, three and five surgical masks in six volunteers to determine the in vivo filtration efficiency of wearing more than one surgical mask. We used a Portacount to measure the difference in ambient particle counts inside and outside the masks. The best combination of five surgical masks scored a fit factor of 13.7, which is well below the minimum level of 100 required for a half face respirator. Multiple surgical masks filter ambient particles poorly. They should not be used as a substitute for N95 masks unless there is no alternative.
美国疾病控制与预防中心及世界卫生组织发布的指南指出，医护人员在与疑似严重急性呼吸综合征（SARS）患者进行所有接触时，应佩戴N95口罩或更高级别的防护装备。在无法获取N95口罩的地区，人们尝试使用多层外科口罩来预防SARS传播。已知单个外科口罩的体内过滤能力较差。然而，多个口罩组合的过滤能力尚不清楚。这是一项针对六名志愿者，使用一、二、三及五个外科口罩的交叉试验，以确定佩戴多个外科口罩的体内过滤效率。我们使用Portacount来测量口罩内外环境颗粒计数的差异。五个外科口罩的最佳组合的适合因数为13.7，远低于半面罩呼吸器所需的最低水平100。多个外科口罩对环境颗粒的过滤效果不佳。除非别无选择，否则它们不应被用作N95口罩的替代品。
