Division of Nephrology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada; St Joseph's Healthcare Hamilton, Hamilton, Canada; Centre of Excellence in Protective Equipment and Materials.
Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
Mayo Clin Proc. 2020 Oct;95(10):2204-2224. doi: 10.1016/j.mayocp.2020.07.020. Epub 2020 Jul 31.
Management of the global crisis of the coronavirus disease 2019 pandemic requires detailed appraisal of evidence to support clear, actionable, and consistent public health messaging. The use of cloth masks for general public use is being debated, and is in flux. We searched the MEDLINE and EMBASE databases and Google for articles reporting the filtration properties of flat cloth or cloth masks. We reviewed the reference lists of relevant articles to identify further articles and identified articles through social and conventional news media. We found 25 articles. Study of protection for the wearer used healthy volunteers, or used a manikin wearing a mask, with airflow to simulate different breathing rates. Studies of protection of the environment, also known as source control, used convenience samples of healthy volunteers. The design and execution of the studies was generally rigorously described. Many descriptions of cloth lacked the detail required for reproducibility; no study provided all the expected details of material, thread count, weave, and weight. Some of the homemade mask designs were reproducible. Successful masks were made of muslin at 100 threads per inch (TPI) in 3 to 4 layers (4-layer muslin or a muslin-flannel-muslin sandwich), tea towels (also known as dish towels), made using 1 layer (2 layers would be expected to be better), and good-quality cotton T-shirts in 2 layers (with a stitched edge to prevent stretching). In flat-cloth experiments, linen tea towels, 600-TPI cotton in 2 layers, and 600-TPI cotton with 90-TPI flannel performed well but 80-TPI cotton in 2 layers did not. We therefore recommend cotton or flannel at least 100 TPI, at least 2 layers. More layers, 3 or 4, will provide increased filtration but there is a trade-off in that more layers increases the resistance to breathing. Although this is not a systematic review, we included all the articles that we identified in an unbiased way. We did not include gray literature or preprints. A plain language summary of these data and recommendations, as well as information on making, wearing and cleaning cloth masks is available at www.clothmasks.ca.
管理 2019 年冠状病毒病全球大流行危机需要详细评估证据，以支持明确、可操作和一致的公共卫生信息传递。普通公众使用布制口罩的问题正在讨论中，并且不断变化。我们检索了 MEDLINE 和 EMBASE 数据库以及 Google 上报道平面布制或布制口罩过滤性能的文章。我们查阅了相关文章的参考文献，以确定其他文章，并通过社交和传统新闻媒体确定了文章。我们找到了 25 篇文章。对佩戴者的保护研究使用了健康志愿者，或使用戴口罩的人体模型，用气流模拟不同的呼吸速率。对环境的保护，也称为源头控制的研究，使用健康志愿者的便利样本。研究的设计和执行通常都有严格的描述。许多对布的描述缺乏可复制性所需的细节；没有一项研究提供了材料、线数、织物和重量的所有预期细节。一些自制口罩设计是可复制的。成功的口罩由每英寸 100 线的平纹细布（MUSLIN）制成，有 3 到 4 层（4 层平纹细布或平纹细布-毛毡-平纹细布三明治）、茶巾（也称为洗碗巾），使用 1 层（预计 2 层会更好），以及高质量的 2 层纯棉 T 恤（边缘缝合以防止拉伸）。在平面布实验中，亚麻茶巾、2 层 600 线的棉和 2 层 600 线的棉加 90 线毛毡表现良好，但 2 层 80 线的棉则不然。因此，我们建议使用至少 100 线的棉或毛毡，至少 2 层。更多的层，3 或 4 层，将提供更高的过滤效果，但呼吸阻力也会增加，这是一个权衡。尽管这不是系统评价，但我们以无偏见的方式纳入了所有我们确定的文章。我们没有包括灰色文献或预印本。有关这些数据和建议的通俗语言摘要，以及有关制作、佩戴和清洁布制口罩的信息，可在 www.clothmasks.ca 上获得。
