自制口罩能预防冠状病毒吗?

Can DIY masks filter out viruses and coronavirus

戴上自己DIY的口罩来抵御冠状病毒听起来是个疯狂的主意。

因为数据显示很多口罩的效果都非常好,一些性能最好的口罩也是最便宜的

比如一个外科口罩只需要几美分,它可以过滤掉80%的大小只有0.007微米(比冠状病毒小14倍)的微粒。

但是,2019年爆发的冠状病毒(Covid-19)带来了一个新问题:口罩都卖光了。

 

冠状病毒期间 买不到口罩

 

买不到口罩,人们都开始开始自制口罩,但自制的口罩真的能保护你远离冠状病毒吗?

 

自制的空气污染防毒、防病毒口罩

一名用户自制“杀毒”面具

 

自制口罩测试 —— 能过滤微小颗粒吗?

 

2009H1N1流感爆发之后,剑桥大学的科学家提出了这个问题。他们认为,在全球流感爆发的情况下,我们可能会用完N95口罩。在冠状病毒爆发期间,他们的预言成真了。

 

 

研究人员让志愿者们用棉质t恤和缝纫机自制一个设计简单的口罩。然后,研究人员在口罩上他们比较了棉质DIY口罩和外科口罩过滤微粒的效果。

研究人员让志愿者们用棉质t恤和缝纫机制作自己的面具,使用的是他们设计的简单程序。然后,研究人员在口罩上注射了1微米大小的细菌(称为“阿托菲菌”),并测量自制口罩能够过滤的细菌百分比,这些颗粒的大小和炭疽、瘟疫病毒的颗粒大小差不多。

 

自制口罩和外科口罩过滤颗粒效果对比

 

自制口罩捕捉到的颗粒物比外科口罩少,但仍能捕获69%的1微米颗粒物。

但这就是自制口罩能过滤的最小的颗粒吗?研究人员在口罩上注射了0.2微米的“噬菌体MS2”粒子,提高了这个标准。它们甚至比冠状病毒颗粒还要小。

 

自制口罩和外科口罩过滤颗粒效果对比

同样,外科口罩捕捉了更多的颗粒,但是自制的棉口罩捕捉了51%的微米颗粒。

 

好的,但是它们会漏的,对吧?

 

在这一点上,聪明的怀疑论读者可能会想,“当然,布可以捕捉粒子,但它们可能不会很好的贴合在脸上,所以它们是没用的。”

幸运的是,研究人员也对自制口罩进行了测试。在佩戴测试中,有人戴好口罩,科学家测量口罩内和口罩外的颗粒物数量。

 

口罩佩戴,密封性测试

 

这台用于机器的测量,可以检测到的颗粒大小在0.02到1微米之间,冠状病毒的大小就在这个范围内。

 

自制口罩和外科口罩贴合测试

 

在21名志愿者中,自制的棉口罩捕捉了50%的0.02-1微米颗粒,而外科口罩捕获了80%的颗粒。所以DIY口罩是可以在人们佩戴着的时候捕获颗粒的。根据这些数据,研究人员得出结论,自制口罩总比什么都不戴要好。

 

自制的DIY口罩只能作为捕捉冠状病毒的最后手段

 

 

只有一个自制口罩的测试吗?

 

剑桥大学的数据显示,棉质口罩可以过滤掉一些0.02-1微米大小的微粒。这很好,但是其他材料呢?荷兰的一组研究人员测试了用桌布(在英国称为“茶布”)自制的口罩。

 

用桌布自制预防冠状病毒的口罩

 

他们也用一个合适的机器来测试人们实际带着口罩时的效果。

 

测试自制口罩的过滤颗粒效果

 

自制的桌布口罩捕获了60%0.02-1微米颗粒。当然,外科口罩和N95口罩能捕捉到更多的颗粒,但数据显示自制口罩在捕捉病毒大小的颗粒方面并不是毫无用处。

 

自制口罩、外科口罩和N95口罩过滤颗粒效果对比

 

 

 

自制口罩可以戴多久?

 

然后他们测试了戴了3个小时后的口罩的效果,口罩上有了湿气后,效果会不会减弱呢?

 

自制口罩、外科口罩、N95口罩使用三小时后过滤颗粒效果对比

 

结果发现,口罩上的湿气和佩戴口罩的时间,对任一种口罩的有效性几乎都没什么影响。事实上,自制的口罩在3小时后过滤病毒大小的微粒的效率提高了5.8%

所以,自制口罩在戴了几个小时后,并不会降低它们的有效性。

 

 

自制口罩对儿童的防护效果如何?

 

接下来,他们找了115-11岁的孩子,来测试了自制口罩的效果。当孩子们戴上自制的口罩时,0.02-1微米的颗粒物只被清除了52%,看得出来儿童的效果几乎比成人低15%

 

儿童和成人佩戴自制口罩、N95口罩、医用外科口罩的效果

 

有趣的是,外科口罩和FFP2 (N95)口罩对儿童的效果也较差。这和Smart Air为印度儿童测试口罩效果的测试结果相似,该测试发现儿童佩戴口罩的效果低于成年人。数据表明,给孩子们佩戴非常合适的口罩是比较困难的。

 

印度儿童测试口罩密封效果

 

 

总结:自制口罩到底能不能对抗冠状病毒?

 

数据显示,用一层棉布或一块桌布自制的口罩可以过滤大约50-60%的病毒大小的颗粒。这代表它们的效果比外科口罩和FFP2 (N95)口罩差。

戴自制口罩3小时对口罩的过滤效率并没有显著的影响。

DIY口罩也适用于儿童,但对儿童的防护效果不如成年人。

 

聪明空气科普雾霾之时

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Dr Pravesh Mehra

How about disinfecting the mask, using 1% hypochlorite solution.
Then drying in a clean area either under UV light or sun for 3 hrs.
Then reusing.
So, for every 8 hrs of use, disinfect n dry, use for the next 6 days.
Hope the fit n filtration stays to the prescribed limits.
This will clearly help us, as healthcare providers, n be economical, cost effective and at the same time provide quality care, during this time of pandemic.

Liz - Smart Air

Hi Dr. Pravesh, Liz here. Have you read our article on how to disinfect the mask? Here is the link: https://smartairfilters.com/en/blog/disinfect-clean-n95-mask-virus-coronavirus/ we also have an article on how UV light can help to disinfect the mask, https://smartairfilters.com/en/blog/uv-light-disinfects-masks/ So leaving the mask under UV light and let it dry for a enough amount of time would do the work.

Cara

I recommend testing Norwex microfiber masks. They are just being produced and tests show they capture 81% of .1 micron sized particles. I think that warrants further investigation. They are washable and reusable. Making them not only economical and safer than DIY masks, but also more eco-friendly than disposable masks.

Dawnie Dávila

How often do you need to replace filter?

Liz - Smart Air

Hi Dawnie, we haven’t tested any mask with an inserted layer yet. But if you want to use one, I’d say replace it as often as you would replace your mask. However, I don’t see the point of replacing just the middle layer when the outer layer is the most like to get in contact with the virus (if there’s any).

Cara

Are you asking about the Norwex microfiber mask? If so, there are no filters. Thd masks are made of the same microfiber material we use in our window cloths. Tbe fibers are extremely small, only 1/200th of a human hair.

Dominique Cuccia

What are the materials of your mask? They are printed- so what makes yours different than home made?

Liz - Smart Air

Hi Dominique, Liz here from Smart Air. Check out this new article for more testing materials we’ve done in the past weeks with more details on the materials we used: https://smartairfilters.com/en/blog/best-diy-coronavirus-homemade-mask-material-covid/

Cara

Hi Dominique! Norwex’s microfiber is unlike anything you can buy off a shelf. Norwex’s personal use masks are made from the same microficer as their Window Cloths. All of Norwex’s microfiber is 1/200th the width of a human hair!! With homemade, you do not have access to microfiber that small. Most store bought microfiber is only split 6 ways, while Norwex’s fibers are split at least 200 ways. Hope that helps.

Jose Casiano

Ok what about microfiber towels. I detail cars and notice this on the package of one of my bags of microfiber towels. Useful Tip: Did you know that microfiber picks up approximately 99% of bacteria and viruses without the need of chemicals. https://www.walmart.com/ip/Auto-Drive-Multi-Purpose-Microfiber-Towels-4-Pack/44457274
I have the larger packs i figure that a tighter not pattern would be best.

Liz - Smart Air

Hi Jose, We haven’t tested the microfiber towels yet. We know there’s a huge demand for reliable, science-backed data right now, so we’ve created a campaign to gather information on what our readers wants to test. To vote on what test you expect to see and support our campaign, visit our Fundly.com page here: https://fundly.com/best-diy-mask-materials