資料來源: Dr. Peter Tsai
Here I quoted below is an excerpt from ABC nightly news on January 11th, 2022.
'According to the American Conference of Governmental Industrial Hygienists, an uninfected person can catch COVID-19 from an infected person in 15 minutes if neither is wearing a mask. That time nearly doubles if both are wearing cloth masks and quadruples if both wear surgical masks. A person wearing an N95 mask can be protected for 25 hours or more, regardless of what others wear.'
‘假如雙方都沒戴口罩，被感染的時間是 15 分鐘，假如雙方都戴布口罩，被感染的時間是 兩倍（30 分鐘），假如雙方都戴醫療口罩，被感染的時間是四倍（60 分鐘），假如你戴 的是 N95 口罩, 無論對方戴的是什麼口罩，被感染的時間會是 25 個小時以上。
Here are my picks:
A medical mask has the efficiency of 70-80%, a cloth mask 5-20%, tested using the standard to test the N95 while N95 has the efficiency of ≥ 95%. In addition, N95 has tight fit with little leakage while a medical mask has a loose fit with a leakage of 40-60% from its edge.
The crucial issue of a medical mask is it's leakage from its loose fit. A way to fix the leakage of a medical mask is double masking, i.e., to wear a cloth mask over a medical mask. The function of a cloth mask is to shield the edge leakage from a medical mask.
Here are my points:
It should be a real N95 in contrast to a counterfeit one. It should be a right size for the wearer so the respirator contour can have a tight fit on your face with little leakage.
The following are the instructions to tight fit a butterfly type N95.
Instructions to tight fit a butterfly type respirator
If the respirator does not tightly fit for a small or a child face, staple it along the welded area on the tip of the respirator chin as shown in the Picture (L). The length of the ear loops or the head straps is adjustable using a buckle as shown in the same Picture (R) to fit a small or a child head or face.
Use either the respirator with head straps or the ear loops as you prefer. It is believed that the head strap type has a tighter fit. However, the ear loop one is easier to don and to doff.
Don’t touch the inner or the outer surface of the respirator. Wash hands with soap for at least 20 seconds after doffing the respirator.
The respirator can be reused for five times or more for a total period of less than 40 hours or when it is felt that the respirator is difficult to breath. For the pandemic use, hang the respirator for five days after each use before reuse. The survival time of COVID-19 on the surface of a plastic material is three days at 70F, 50% RH according to NEJM published on March 14, 2020.
Respirator figures, a staple (L), Ring buckles (R).