口罩有效防疫的定義
Definition of effective anti-epidemic mask
病毒的空氣傳播，包括了以下的兩種方式。
Viruses spread in the air with two methods.
第一種方式：是已經被具體證實的廣泛傳染方式，那是透過飛沫傳染。所謂的飛沫是透過空氣傳播與飄落處的表面污染的傳播，按照飛沫的大小，我們可以簡單的分成以下三種情況：
First method: It is a widespread method of transmission that has been confirmed, and it’s transmitted through droplets. The so-called droplet is through airborne and the spread of pollution on the surface where it falls. According to the size of the droplet, we can simply divide it into the following three situations.
● 比較大的飛沫: 是指大約5μm的微粒，在人類說話、打噴嚏或是咳嗽的過程之中，大約可以在空氣中飛行大約一公尺左右。
Larger droplets: refers to particles about 5μm, which can fly about a meter in the air when we talk, sneeze, or cough.
● 比較小的飛沫: 是指大約1μm~5μm微粒，屬於前述的較大型飛沫在乾燥環境中失去外部水分後，所形成的小型飛沫。這些飛沫將會在空氣中停留更長的時間，感染的風險更大。
Smaller droplets: refers to particles about 1μm~5μm, which are formed after the larger droplets lose their external moisture in a dry environment. These droplets will stay in the air longer, and cause a greater infection risk.
● 大型飛沫(>10μm微粒): 以上兩種飛沬，都和大型飛沫(>10μm微粒)一樣，最終會落到地面上或是物體上，汙染飄落處的表面。這時需要做到經常擦拭與消毒才可以達到防疫的目的。
Large droplets (over 10μm): The above two types of droplets are both like the large droplets, they will eventually fall on the ground or on objects, contaminating the surface where they fall. At this time, frequent wiping and disinfection are required to achieve the purpose of epidemic prevention.
第二種方式：是透過可以長期或是相對長時間漂浮於空氣中的更小微粒(<1μm微粒)去傳染。醫學界尚未證實，這是傳染的途徑之一，但是值得我們重視透過這種方式傳播的可能性。一般來說，>3μm微粒在空氣中的運動，我們假設是可以用牛頓力學中的慣性運動來說明，也就是說，微粒的運動可以假設成直線，而過濾的效果則可以假設成為過篩式的慣性阻隔效果。然而，1μm~3μm微粒的空氣中運動開始受到少許的空氣分子碰撞所產生的布朗運動所影響，會在原本的運動之中，呈現隨機的擾動，而在空氣中產生比較長時間的停留。
Second method: It is transmitted through smaller particles (under 1μm) that can float in the air for a long time or relatively long time. The medical profession has not confirmed that this is one of the ways of transmission, but it is worthy of our attention to the possibility of transmission through this method. Generally speaking, the motion of particles over 3μm in the air can be explained by the inertial motion in Newtonian mechanics. That is to say, the motion of the particles can be assumed to be a straight line, and the filtering effect can be assumed to be a sieve type of inertial blocking effect. However, the movement of 1μm~3μm particles is starting to be affected by the Brownian motion by the collision of a few air molecules, and will exhibit random disturbances in the movement, and cause a longer stay in the air.
當微粒直徑小於1μm時，布朗運動的效益愈來愈大，於是我們可以將這種粒淨的氣懸膠分成以下兩種運動的方式：
When the particle diameter is less than 1μm, the benefit of Brownian motion becomes greater and greater, so we can divide this clean aerosol into the following two motion modes:
● 0.3μm~1μm微粒大小: 屬於相對長時間懸浮於空氣中的氣懸膠微粒。
Particle size between 0.3μm~1μm: It belongs to aerosol colloidal particles suspended in the air for a relatively long time.
● <0.3μm微粒大小: 屬於永久懸浮於空氣中的氣懸膠粒子
Particle size under 0.3μm: It belongs to aerosol particles that are permanently suspended in the air.
沒有醫學證據目前證實以上兩種懸浮在空氣中的細小微粒，可以傳染CoV-19病毒。但是在病毒在空氣中存活的時間變長，以及無症狀感染者的人數不斷增加的客觀風險之下，按照邏輯去推測後續的發展，這些細小微粒所可能造成的潛在傳染風險，值得重視。幸好這些微粒經過空氣碰撞而產生的隨機運動，大幅提升了這些微粒被口罩織物所捕捉的機率，也因此，讓口罩設計者，根據此一現象，做出了提前佈署的規劃。
There is no medical evidence that the above two kinds of fine particles suspended in the air can infect the CoV-19 virus. However, under the objective risk that the virus survives longer in the air and the number of asymptomatic infections continues to increase, according to logic to speculate the subsequent development, the potential risk of infection caused by these fine particles is worthy of our attention. Fortunately, the random movement of these particles caused by air collision has greatly increased the probability of these particles being captured by the mask fabric. Therefore, mask designers are allowed to make advance plans based on this phenomenon.
口罩設計的提前佈署
Advance plan of mask design
好的口罩設計，在微粒過濾上，必須考量以下三種情況:
For a good mask design, the following three situations must be considered in terms of particle filtration.
● 直徑>5μm大小微粒的過濾效果
Filtering effect of particles with diameters over 5μm.
● 直徑介於1μm到5μm微粒的過濾加阻擋的綜合效果
The combined effect of filtering and blocking particles with a diameter between 1μm and 5μm.
● 直徑小於1μm微粒的阻擋效果
The barrier effect of particles with diameter under 1μm.
在設計上，要產生足夠的過濾效果，就是透過口罩表面織物的空隙大小來做規範。如果要有效的過濾5μm直徑的微粒，口罩表面織物的空隙就要控制在比5μm小一點即可，無需太密造成透氣性的問題，造成過度的呼吸阻礙。對於更小的微粒(<1μm直徑)，我們必須考量如何阻攔與”沾附”這些以布朗運動隨機飄浮在空氣中的微粒。而沾附的兩個基本的辦法，其一是透過靜電吸附，其二則是透過纖維本身的吸附能力。
In the design, to produce sufficient filtering effect, is through the pore size of the fabric on the surface of the mask to make specifications. If you want to effectively filter 5μm particles, the pore of the fabric on the mask surface should be controlled to be smaller than 5μm, there is no need to be too dense to cause air permeability problems and excessive breathing obstruction. For smaller particles (under 1μm), we must consider how to block and adhere these particles that are randomly floating in the air with Brownian motion. There are two basic methods of adhesion, one is through electrostatic adsorption, and the other is through the adsorption capacity of the fiber itself.
認識飛沫和飛沫核
Understand the droplets and droplet nuclei
當人說話、打噴嚏或咳嗽等過程中產生大粒徑（大於5微米）的飛沫，一般來說，可飛行的距離約為1公尺（3英呎）；當飛沫中含有病毒等病原體時，近距離的接觸可增加人體感染的機會，稱為「飛沫傳染」。因此對於患有呼吸道感染的病人而言，除了建議配戴一般醫用口罩，以避免咳嗽等症狀造成病原體傳播給他人之外，也建議呼吸道感染病人和他人交談時保持至少1公尺以上的距離，以降低飛沫傳染的風險。此外，人在說話或打噴嚏時產生的大粒徑飛沫會沉降於地面或物體表面，所以正確的洗手動作、經常清潔與消毒各種物品表面（如桌面、地板、儀器設備、玩具等），以及採取妥善食物覆蓋等措施，均可避免飛沫污染，這些都是民眾應該養成的重要生活習慣。When people talk, sneeze, or cough, they generate droplets of large particle size (greater than 5 microns). Generally speaking, the flying distance is about 1 meter (3 feet), when the droplets contain pathogens such as viruses, then close contact can increase the chance of human infection, which is called “droplet infection.” Therefore, for patients with respiratory tract infections, apart from wearing medical masks to avoid symptoms such as coughing from spreading pathogens to others, it is also recommended that patients keep a distance of at least 1 meter when talking with others, in order to reduce the risk of droplets infection. In addition, the large-particle droplets generated when people speak or sneeze will settle on the ground or the surface of objects, so correct hand washing procedures, frequent cleaning and disinfection of various surfaces (such as floors, desktops, equipment, toys, etc.), and proper food coverage can prevent droplet pollution. These are important living habits that people should develop.
上述提及人體會產生大粒徑的飛沫，其實也會產生細小飛沫。當含有病原體的飛沫直徑≤ 5微米時，就有空氣傳染的風險。前面內容提到含有病原體的大粒徑飛沫，一旦在濕度較低的室內環境中，飛沫外部的水分蒸發將會形成細小的「飛沫核」，便可在空氣中懸浮較長的時間，若病原體本身特性又可適應該環境，也就是可以安全存活下來，此時，就有空氣傳染之虞，例如：人體吸入空氣中含有1～5微米的結核桿菌飛沫核，就可能導致肺結核病。
As mentioned above, the human body can produce droplets of large particle size, but in fact, it also produces fine droplets. When the droplets containing pathogens are smaller than 5 microns in diameter, there is a risk of airborne infection, The previous content mentioned that large-size droplets containing pathogens, once in a low-humidity indoor environment, the moisture outside the droplets will evaporate to form tiny “droplet nuclei” that can be suspended in that air for a long time. If the pathogen itself can adapt to the environment, that is to say, it can survive safely. At this time, there is a risk of airborne infection. For example, if the human body inhales the air containing 1 to 5 microns of tubercle bacillus droplet nucleus, it may cause tuberculosis.
至目前為止，現有的科學證據初步顯示COVID-19主要是以近距離的飛沫及接觸傳染，仍未有充足證據指出COVID-19會以空氣傳播方式造成人類感染，至於COVID-19是否會造成空氣傳染，此待未來更多的研究證明。
Up to present, the existing scientific evidence has preliminarily shown that COVID-19 is mainly transmitted by close-range droplets and contact. There is still insufficient evidence to indicate that COVID-19 will cause human infections by air transmission. As for whether COVID-19 will cause airborne infection or not, this is to be proved by more research in the future.
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資料參考：
[摘錄自長庚醫訊 第四十一卷第八期 109年8月1日發刊 急診新時代]
Reference: Chang Gung Medical News
