雙層30%口罩隻能阻擋51%，要達到95%阻擋率要8個。

來源: 周老大於 2021-11-13 09:41:31 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

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雙層30%口罩隻能阻擋51%， 要達到95%阻擋率要8個。