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Ursprungligen postat av
Ulf-Utredaren
Jo det gör de visst.
De säger följande:
""WHO beskriver även hur munskydden bör se ut. De bör bestå utav tre lager olika material: Bomull, närmast ansiktet följt av ett lager polypropen, en typ av plast, följt av ett lager med vätskeresistent material längst ut.
– Det handlar alltså om ett munskydd i tyg, inte den typ av medicinskt munskydd som används i vården. Vi har nu belägg för att om det görs på rätt sätt så kan ett munskydd stoppa potentiellt smittsamma partiklar.""
Märk väl. OM det görs på rätt sätt så KAN ett munskydd hjälpa.
Mycket OM och MEN här alltså.
Och de disktrasor man ser på TV ifrån Europa är definitivt inte att göra det på rätt sätt. Och de saknar stöd ifrån WHO.
Som jag svarat tidigare: I princip alla munskydd som inte är fake från Kina är bra munskydd. Dom finns att köpa överalt.
Sen det här är vad WHO faktiskt skriver i sin FAQ och det har absolut inget med att avråda från att använda munskydd som inte har den här kvalité i fall man inte har möjlighet att få tag på eller göra hemma. WHO är tyst kring den saken då dom fattar att det vore idioti att säga något sådant.
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Since there are many types of fabric masks available, does WHO have any guidance on which masks to use?
WHO is actively studying and encouraging research on the science of masks. New research findings identified the following preferable types of fabrics, number of layers and the composition of a non-medical, fabric mask:
an inner layer of absorbent material such as cotton
a middle layer of non-woven material such as polypropylene
an outer layer of non-absorbent material, such as polyester or polyester blend
More information on the types of materials and their effectiveness can be found in the updated mask guidance document -
https://www.who.int/publications/i/item/advice-on-the-use-of-masks-in-the-community-during-home-care-and-in-healthcare-settings-in-the-conte xt-of-the-novel-coronavirus-(2019-ncov)-outbreak
WHO skriver:
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Non-medical mask
Non-medical (also referred to as “fabric” in this document) masks are made from a variety of woven and non-woven fabrics, such as polypropylene. Non-medical masks may be made of different combinations of fabrics, layering sequences and available in diverse shapes. Few of these combinations have been systematically evaluated and there is no single design, choice of material, layering or shape among the non- medical masks that are available. The unlimited combination of fabrics and materials results in variable filtration and breathability.
A non-medical mask is neither a medical device nor personal protective equipment. However, a non-medical mask standard has been developed by the French Standardization Association (AFNOR Group) to define minimum performance in terms of filtration (minimum 70% solid particle filtration or droplet filtration) and breathability (maximum pressure difference of 0.6 mbar/cm2 or maximum inhalation resistance of 2.4 mbar and maximum exhalation resistance of 3 mbar).(71)
The lower filtration and breathability standardized requirements, and overall expected performance, indicate that the use of non-medical masks, made of woven fabrics such as cloth, and/or non-woven fabrics, should only be considered for source control (used by infected persons) in community settings and not for prevention. They can be used ad-hoc for specific activities (e.g., while on public transport when physical distancing cannot be maintained), and their use should always be accompanied by frequent hand hygiene and physical distancing.
Decision makers advising on type of non-medical mask should take into consideration the following features of non- medical masks: filtration efficiency (FE), or filtration, breathability, number and combination of material used, shape, coating and maintenance.
a) Type of materials: filtration efficiency (FE), breathability of single layers of materials, filter quality factor
The selection of material is an important first step as the filtration (barrier) and breathability varies depending on the fabric. Filtration efficiency is dependent on the tightness of the weave, fibre or thread diameter, and, in the case of non- woven materials, the manufacturing process (spunbond, meltblown, electrostatic charging).(49, 72) The filtration of cloth fabrics and masks has been shown to vary between 0.7% and 60%.(73, 74) The higher the filtration efficiency the more of a barrier provided by the fabric.
Breathability is the ability to breathe through the material of the mask. Breathability is the difference in pressure across the mask and is reported in millibars (mbar) or Pascals (Pa) or, for an area of mask, over a square centimeter (mbar/cm2 or Pa/cm2). Acceptable breathability of a medical mask should be below 49 Pa/cm2. For non-medical masks, an acceptable pressure difference, over the whole mask, should be below 100 Pa.(73)
Depending on fabric used, filtration efficiency and breathability can complement or work against one another. Recent data indicate that two non-woven spunbond layers, the same material used for the external layers of disposable medical masks, offer adequate filtration and breathability. Commercial cotton fabric masks are in general very breathable but offer lower filtration.(75) The filter quality factor known as “Q” is a commonly used filtration quality factor; it is a function of filtration efficiency (filtration) and breathability, with higher values indicating better overall efficiency.(76) Table 3 shows FE, breathability and the filter quality factor, Q, of several fabrics and non-medial masks.(73, 77) According to expert consensus three (3) is the minimum Q factor recommended. This ranking serves as an initial guide only.
Ni har varit igång i 20 timmar nu på detta kontot, och på alla dessa timmar har du inte framfört något vettigt eller övertygad någon.