Comparison of Mask Ratings, Standards, and Filtration Effectiveness (N95, KN95, FFP1, FFP2)

Mask ratings can be confusing: N95, KN95, FFP1, FFP2, P2, or surgical mask? This quick run-down of mask specifications covers mask types, mask ratings, and their effectiveness at filtering particles.

Let’s begin by discussing mask types or certification types. There are generally three commonly used, disposable masks: single-use face masks, surgical masks, and respirators.

Table of surgical and N95 respirator mask standards in Europe, USA and China

Mask Standards and Effectiveness Bottom Line

  1. Single use masks (normally one layer, very thin) are typically only effective at capturing larger dust particles, but can do so fairly well.
  2. Surgical mask standards have higher requirements for capturing virus-sized (0.1 micron) particles, however they vary by region.
  3. Pollution masks (respirators) typically capture >90% of virus-sized particles. You can use the rating system in the table above to see the exact proportion each certification requires. This includes ratings such as N95, KN95, FFP1, FFP2 and FFP3.

Mask Standards Vary by Country

Each country has their own certification standard for each mask type. For example, Europe uses the EN 14683 standard for surgical masks, whereas China uses the YY 0469 standard. Each standard varies a little by country, however they are broadly similar. For respirator masks, China uses the KN standard (e.g. KN95) and the US uses the N standard (e.g. N95).

Read more: what’s the difference between KN95 and N95 masks »

Requirements Are Lowest for Single Use Face Masks

The standard with the lowest requirements on filtration effectiveness are the single use face masks (not to be confused with surgical masks). Surgical masks have higher requirements, and respirators have the highest requirements. Respirators also usually fit tighter around the face (data shows they score higher on fit effectiveness) than surgical masks and single-use face masks.

N95 Mask Fit Test Filtration Effectiveness

Coronavirus & Mask Livestream

Wondering whether masks work to protect you against the coronavirus? Check out our livestream recap covering all the info here!

3M vs. FFP1 vs. FFP2 vs. N95 vs. KN95? What Do Mask Numbers and Letters Mean?

A visitor to the website asked this in the comment section on coronavirus and Pitta masks a few days back:

Could you please explain: if a mask is FFP2 or 3, but NOT 3M – what does it mean exactly concerning COVID-19? Thank you!

Here’s an explanation on the difference between N95, 3M and PM2.5, to help you out.

N95, N99, FFP1, FFP2 and FFP3 Mask Ratings

The ratings cover (most importantly for us) the filtration level, among other things. You can think of them like G, PG, PG-13, R ratings for movies. The movie ratings cover who can watch them.

Movie rating system like ffp1 ffp2 n90 n95 n100 respirator rating system

EN 149:2001+A1:2009 / ASTM F2100 / NIOSH

These are standards for masks. They specify the rules and testing methods companies should follow to rate their masks. These standards define the N95, FFP1, and FFP2 ratings above. Using the movie rating analogy, you can think of it like this: the people reviewing movies and choosing the appropriate movie rating must have a set of rules to decide if the movie is considered PG-13 or R. They’ll follow these rules to rate the movie. These standards are the set of rules for masks.

Why are there so many? Standards labelled “EN” are for the EU. ASTM F2100 (NIOSH) is for the US. Many other countries will have their own rating systems too.

3M Masks?

3M is a company that manufactures masks. They generally produce masks that meet KN95 or N95 standards. Buying masks from a trusted company may reduce the odds of the masks failing quality standards.

What Are KF94 Masks?

KF94 is a respirator mask standard of South Korea. KF94 masks are similar to N95 and KN95 masks, but instead of filtering out 95% of particles, they filter out 94%. In Korea, KF94 respirator performance standards are not considered to be equivalent to N95 or FFP2 respirators, while Korea’s 1st class respirators are.

PM2.5 vs. N95

As we now know, N95 is a mask rating. PM2.5 refers to “particulate matter” or a fancy way of saying “pollution particles” that are in the air. The 2.5 refers to the size of these particles as being 2.5 microns or smaller. This picture can give you a visual example of how big PM2.5 particles are.

Size of coronavirus particle pm2.5 and bacteria

FFP2 vs. N95

FFP2 and N95 masks are quite similar in regards to filtration effectiveness. The key difference is FFP2 follows the European EN 149 standard, while N95 follows the American NIOSH standard. FFP2 must filter at least 94% of airborne particles, while N95 must filter at least 95%.

Medical Grade Air Purifiers?

This article has covered medical grade masks, but they’re just one tool in protecting against airborne pollutants and viruses. When indoors, HEPA air purifiers are extremely effective at removing viruses and other pollutants from the air. So what is the deal with medical grade air purifiers? Do you really need a “medical grade” purifier?

Learn more: what are medical grade air purifiers »

Bottom Line: To Understand Mask Ratings

1. Three randomized studies have found surgical masks are just as effective as N95 masks at preventing virus transmission. They hypothesize the main reason for this is that any mask can reduce the hand-to-face contact, although we don’t know this for sure.
2. If you’re wearing a mask with a valve, you are protected. The valve does not bring in any outside air into the mask. Fit-test data has found that masks with valves are often among the highest scoring.
Mask Fit Effectiveness Valve vs No Valve
However, valves will not protect other people as well. If you are sick, and you breathe out, some of the moisture from your breath can expel through the valve, potentially putting others in danger.
3. Tests have found that DIY masks can filter a percentage of virus-sized particles. While they’re not as effective as surgical or N95 masks at filtering viruses, they can still provide some benefit. They can also reduce hand-to-face contact.

Smart Air


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Read More: Four Steps to Choosing the Best Air Purifier

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90 thoughts on “Comparison of Mask Ratings, Standards, and Filtration Effectiveness (N95, KN95, FFP1, FFP2)”

  1. Filtration Efficiency: This refers to a mask’s ability to filter out particles, typically measured as a percentage. The higher the filtration efficiency, the better the mask is at trapping particles. Commonly used metrics include Particle Filtration Efficiency (PFE), Bacterial Filtration Efficiency (BFE), and Viral Filtration Efficiency (VFE). Higher-rated masks generally have higher filtration efficiency.

  2. The effectiveness of different masks at preventing the spread of respiratory droplets and reducing the risk of exposure to the SARS-CoV-2 virus, which causes COVID-19, can vary based on the mask’s material, design, and fit.

  3. One commonly used rating system is the N95 rating, which is used by the National Institute for Occupational Safety and Health (NIOSH) in the United States. N95 masks are designed to filter out at least 95% of airborne particles, including those that are too small to be seen by the naked eye. They are considered to be highly effective in preventing the spread of respiratory viruses such as COVID-19.

  4. A mask can be rated in three different ways:

    1. Mask working pressure (MPAP)

    2. Mask-fitting test pressure (MFTSP)

    3. Filtration effectiveness (FE)

  5. So you don’t mention whether or not an ASTM Level 3 is practically much better at filtering aerosols than a cheap 3 layer surgical mask. Are there tangible benefits to upgrading to ASTM masks? If chinese masks have low PFE rating and european masks don’t even test for PFE, are they far inferior? It sounds like according to you, these cheap non-certified masks are still great at filtering aerosols.

    • Hi Jonathan. Double check the standard on the box of the 3-layer surgical mask you have. Is it a YY0469 mask, or something else? Once you have that information, you can compare the standards in the table above.

      Are ASTM Level 3 masks better? It’s difficult to give a definitive answer, but data shows that surgical masks are surprisingly effective at capturing viruses:

  6. Please can you compare surgical mask and pure cotton DIY mask with pocket for insertion of PM 2.5 filter.

    I want you to compare the filtration and protection ability.

    My understanding is that pure cotton DIY mask will do better with PM 2.5 filter inserted. This is because of the 5-layer filtration technology whereas surgical mask has 3 layers of filtration.

    Please elaborate on this more and clarify these points for me.

    • Hi Mishael! Song here.
      We have never tested the mask you mentioned. We can’t just guess without any real data. If you have DIYed some samples and is willing to send several to us, we can offer testing service.

  7. COVID is a respiratory virus, not a hand virus. Please show me the science that proves that our hands become infected and are main source of infection and contamination, instead of our mouths. Much disinformation about hand contamination has distracted America from using face masks. The self protecting people of Wuhan doned face masks automatically before the lockdown, proving that they crushed COVID with face masks, not social engineering like lockdown, distancing, testing, tracking, etc..which are not effective preventative measures in an AIRBORNE PANDEMIC.

    • Hi Steve! Song here from Smart Air China.
      I do agree with your attitude towards masks. But the correct usage, including keeping hands off the masks in the outside, matters much as well.

  8. Hello, was wondering if you had a link or copy of the paper published from the study that obtained this graph?

    • Hi Rhiannon! Song here!
      I am not sure which graph you are referring to. The main graphs in this post are based on Smart Air tests instead of any other paper, which can be sourced and obtained from our previous posts.

  9. Thanks for the info.
    I noticed the 3M 900V is listed twice in the Fit Test chart above. It is listed as both 99.4 & 92.3 filtration. Are there 2 different models of this mask?

  10. The above statement that the 2.5 refers to 2.5 microns or less is misleading. Masks with the designation of 2.5 means that particles that are 2.5 or larger are captured at 95% and may capture smaller particles as well but less than at 95%. The other misleading statement is that cloths masks are not effective at preventing hand touching the nose or face. I have worn the cloth masks and have realized that I begin to touch my nose and face as soon as it becomes damp with moisture. The moisture becomes noticed after only 1/2 hour of use. In fact, I’ve noticed that many people who wear mask touch their face and adjust the mask constantly.

      • I’ve learned quite a lot about masks since this all started, and you should too.

        Yes, a 2.5 mask might stop a 0.1 micron particle — more than you’d think.

        Not mentioned anywhere in your site, that I can find, is that masks like 3M N95s are using electrically active charges on their filtration fibers to attract and trap the really tiny particles that the density of the filtration media couldn’t possibly stop. Brownian Movement and van der Waals attraction and all of that stuff that most people slept through in school.

        It makes the entire mask debate thing a whole new ballgame if anybody cares to try to discuss and present it to the public.

        Where do you stand on this?

        Any of your products that you will certify as taking advantage of these principles?

        • Why do you believe a 2.5 mask would be effective at catching particles 25 times smaller ? These masks are designed to prevent larger bacterium and dust particles. Completely useless against viruses . The N95 masks are only slightly effective at 300 nanometer

  11. Valve masks don’t let in outside air, are they rebreathers? Really even an n95 mask lets in some virus laden air. 5%, so if this is such a contagious virus they are useless. Virus infections occur through contact with ekes and none of these masks protect the eyes from airborne viruses. A little physics would tell you if you sneezed or coughed none of these masks would prevent a burst of air from escaping the mask.

  12. Can’t somebody weigh in with hard data to counter the claims that: wearing a mask drops the O2 to a dangerous level; raises the CO2 to a dangerous level; gives you CO poisoning; makes you sick(er) because you’re rebreathing your own germs; whatever stupid stuff they can dream up. PLEASE! We’re out here on our own fighting the conspiracy theories on the Internet.

  13. I’ve been re-using my surgical mask enclosed in a sleeve. The sleeve is to prevent the surgical mask from getting dirty.

    After each use, I wash the sleeve and disinfect both sides of surgical mask with hydroxyl ions generated by my Winix air puriifier, which is the PlasmaWave function. I do wonder whether I should get rid of the inner most and outer most layer of surgical mask, so that the hydroxyl ions can get to the melt-blown material easier.

    Would be nice if somebody can verify such practice.

  14. I see disposable face masks that say they are “FDA registered” or “FDA Approved” or “FDA certified”. Is any of that true? And where can I find a what official standard a disposable face mask has met?

    • Hi Adele, Liz here. FDA approved is applied on medical devices. So if you see a mask is FDA approved, it means that the mask is exempt from premarket notification requirements.But FDA approve doesn’t say the grade of the masks. The standards listed in this article tells how well your mask would do for filtering particular sized particles.

  15. Hi

    In South Africa we have very expensive NanoWave masks. It’s a sponge type mask with a filter and it says EN 149:2001 + A1:2009 on the mask. From your article this does not seem to mean anything. Do you know anything about them?


    • Hi Dianne, EN is the standard for European standard, and EN149:2001 are designed to protect against solids, water-based aerosols, and oil-based aerosols. In contrast, there is also a standard EN149:1991 which is allows for the testing of respirators against solid aerosols only. A1:2009 is the amendment version (likely the 2009 is the amendment year). You can find the standard full info online.

  16. What about electrical masks? I d just buy the Xiaomi Q5 pro and I dont have enough evidence on how this mask can protect from coronavirus. It suppose it filter 2.5 ppm enforced for additional filters.
    Do you have more information please?

    • Hi, Eduardo, Liz here. I looked it up and seems like Xiaomi doesn’t sell this model in major Chinese online shopping sites. Anyway, I still did some dig in and found the mask has four layers and basically like a N95 mask with a carbon filter layer. The fan (the part you can charge) is helping to breath easier, not to help on increasing filtration rate. So, I’d say if it works well, it should have about the same filtration rate as a N95 mask or a surgical mask. However, we never tested the model so I don’t have the data for comparison. Still, hope this helps!

  17. Paddy hope you are doing well and safe. What are the materials used for different kind of masks, what’s sets a mask from another. How do I know the mask I’m buying is made of what’s it’s supposed to be made off?
    I’m a dentist in the us and I’m planing to go into production of masks. What are your recommendations thank you

    • Good question, Vincent! The PDF you linked to seems to be a university thesis by students at the University of South Florida. Having said that, it’s worth giving the data a look! One thing the students don’t mention is the exact model of mask they used. In our tests, we’ve found that some surgical masks have performed better than others, so it’s important to know the model of the mask you’re using. If the mask is marked as meeting the ASTM F2100 grade I II or II, then it is a requirement to meet this filtration! If it does not, then it cannot be called a surgical mask.

      It’s very common to mistake single use face masks as surgical masks (they look almost identical). That’s why it’s important to check the standards and certifications of the mask.

  18. Can someone please confirm is a 3D disposable mask from China with a D rating and GB/T32610-2016 adequate protection against Covid to be used in an Office location

  19. Thank you very much for your time to write this article. Really helpful to understand how masks works and its ratings.

  20. Whoops, after I asked about for more info about the protective properties of surgical masks I read your “Is Washing Masks Effective After Virus Exposure?” which answered my question. Wish my google search would have pointed me to your great website.

  21. What are the “protective properties” that are lost if surgical masks get wet (or are gently washed in soap and sanitized )?

  22. Great resource but wish I was smarter with this stuff. I am finding these specs on filters I purchased but see their specs are showing up as single use and N95 filtration ratings. I could use some help understanding what that means. Are these single use face mask or N95 equivalent? Thanks so much.

    YY/T 0969-2013: BFE 99.7% filter efficiency
    GB/T 32610-2016: PFE 92.6% filter efficiency for 1 layer (we are using 2 electrostatic layers)
    GB2626: >95% at 0.3 microns

    • GB2626 is equivalent to N95 respirator. GB32610 is China’s antidust face mask standard (not for medical use). YY/T 0969 is China’s disposable medical mask standard, but not for surgical mask which needs to meet YY/T 0469 standard

    • ” YY/T 0969-2013: BFE 99.7% filter efficiency” is single use surgical mask ( or face mask)

      None of your got is the medical N95 respirator in China, which is GB 19083. “GB/T 32610 and GB 2626 require same particle filtration efficiency test as GB 19083. As the standard for medical use masks, GB 19083 standard requires splash resistance test” .

      “GB/T 32610 is the daily protective mask standard, not medical mask standard. It lists three protective class: A, B, C. Class A type mask provide 95% particle filtration, it can provide almost enough protection [for viruses ] in general conditions.”

      Here is a blog with more details:

  23. It is too good information on right time.I do try to help the factories and to standardize manufacturing mask and PPE ,

    • Hi Claudette, N95 and KN95 ARE filtration rate standard. No matter how many layers do the manufacturer use in the mask, they should be racing the claimed filtration rate. An additional layer may help to increase the filtration rate, but we haven’t done any test on this 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 want to test. To vote on what test you expect to see and support our campaign, visit our page here:

  24. Suggestion for the excellent Mask Comparison Chart above:
    I believe it would be illuminating to many confused students of mask standards (and save them even more time trying to google the answer for themselves) to list/distinguish in the “Respirator Mask” row above, the different standards for Medical vs Industrial masks with the same filtration criteria. For example, :
    – China: GB19083-2010 (medical)
    – China: GB2626-2006 (dust or industry)
    BOTH use the ratings => KN 95, KN99, KN100.
    It took me a while to figure out that one could buy KN95s under one or the other standard, with the same *filtration* criteria, which mattered in my non-medical use cases, but with different other criteria, like fluid resistance. i believe the same goes for the USA N95 ratings, but your experts can determine appropriate medical vs industry standards to list.

    Thanks so much for considering. I think your Mask Standard Comparison chart is getting a lot of Play (I’ve even been sharing it even with some chinese sellers, who are trying to do their best, but are not entirely clear on the BFE and PFE ratings.). Hence I hope your experts consider it worth their time to update it along the way. I’m sure you have other priorities and are not “responsible” for clarifying everything to the public, but you’ve sure been an important resource to many of us trying to help high-risk individuals (eg grocery store clerks and vulnerable folks with outside caregivers) find a reasonable mask for their risk.

  25. I realize GB/T 32610-2016 is a broad testing standard (and saw the related prior comment) which alone indicates little about a given mask’s particle filtration effectiveness. Nonetheless, seemingly reputable Chinese mask manufacturers, diligent with detailed product info, are labeling boxes with no more than GB/T 32610-2016. (Yes, I do follow up with makers to ask about specific PFE’s.) Nonetheless, might GB/T 32610-2016 find a place in your mask comparison chart, showing the required PFE to meet each defined “Class” of the standard? While I haven’t read the text of the standard itself, there seems to be an awful lot of ambiguous or incomplete information provided online by earnest evaluators/explainers/brands. Eg, (i) PFE ratings may be supplied without associated particle size indicated; (ii) Manufacturers often list GB/T 32610-2016 “Level I – III” in charts rather than “Class A – D”, which apparently refers to protected-against environmental pollution levels of 2.5 micron particles; and (iii) “Reputable” Manufacturers list GB/T 32610-2016 on their boxes and Product Info, routinely lacking any further classification by “Level” or “Class,” while also not confirming PFE particle size or % effectiveness. Confusing! Inclusion in your mask comparison table, if possible given different approaches to classification, would be an enormous benefit to consumers who may find this one of the few available possibly virus-size-filtering non-medical mask standards. At least we might better know which questions to ask well-meaning manufacturers with ambiguous information. Thank you for the definitively helpful site! (I’m submitting a webpage of “reputable” manufacturer’s GB/T 32610-2016 product info. Mid-page, click Product Line for a typical comparison chart with GB/T 32610-2016 “Levels” mentioned, but no definitive Level indicated for the product. I submitted questions to them and await a reply.

    • IS 9473:2002 is the Indian standard applicable for filter half masks (to protect against particles They use rating similar to EU standard…

  26. Hello.

    I see the wrong information in the table in the column “Filtration Effectiveness”, where it is stated that the FFP3 standard corresponds to 95% efficiency for 0.3 Microns. According to other sources, it is 99% for the FFP3 standard. Resp. I didn’t find any information as you have on the table here. Therefore, the N95 / KN95 standard corresponds to the FFP2 standard and the N99 / KN99 standard corresponds to the FFP3 standard. Please verify and correct it.

    • Mask standards with Levels I and II having identical BFE and PFE likely differ in other tested criteria, *possibly* things like fluid resistance (at certain fluid pressures) and breathability (resistance to air pressures), that affect comfort and safety in medical environments, but that don’t directly relate to the filtration of virus-sized particles. Beyond this general statement, I’m not currently informed enough to tell you which tested criteria they differ on.

  27. The problem with buying masks from factories is if you mention EN14683 certification they all say yes we make to that standard but EN14683 is not the actual standard its the certificate the standard is the type of mask within the certification. It’s a trap if you just ask for the general certification & not the specific mask type i.e. IIR.

    • So true. But where do I find a source for the specific mask type i need? What are the keywords for these mask types like IIR?

  28. First thank you for what you are doing. Your site is so full of great information. I cant tell you, how good it is to go to one site and to find so many answers, that seem so hard to find otherwise.
    Regarding Covid19:
    Can I add a hepa filter inside a Cycling mask (either Vogmask or other), to increase the effectiveness?
    How can I clean this type of mask? On the Vogmask site, it says to only use soap and water, not to submerge. Washing with soap and water will not kill the covid19 virus and their site also says, to not microwave them because they have not been tested with microwave. I have been seeing so much conflicting information about how long the virus lives, so I am trying to find other ways to disinfect whichever mask, I choose. Have you ever tested Vogmask or similar mask, in the microwave?
    I also found this mask, Rockbros; Is this basically the same as Vogmask? It has listed under features KN95. Does this mean it filters like a medical N95 mask?
    Rockbros cycling mask features:
    o KN95
    o Neoprene Fabric and Activated Carbon to keep dust out
    o Ergonomics Design make you feel comfortable
    o Velcro fastening design
    o Replaceable filters and exhalation valves to keep the inside of the mask well ventilated
    Thank you

  29. The filtration %, is that when worn or not?

    Why the hell don’t surgical masks capture virus sized particles? Seems most relevant in the hospital setting.

    • True “medical surgical” masks (well, some of them) DO filter virus-sized particles. See ASTM F2100 and YY0469-2011 in chart above. So maybe you’re asking why the other “surgical mask” standards don’t filter (or aren’t tested for) 0.1 micron-sized particles? I suggest because they were designed to protect patients from the sneezes and coughs of doctors and nurses performing invasive procedures. They weren’t designed specifically for infectious disease wards, like the N95s.

    • This seems like a crucial question, considering the other article here now showing that surgical masks are basically as effective as the N95 type.

      So how can we tell the difference when we buy them, especially when we buy them without the box or any model numbering on them?

    • You have to see ON THE LABEL OR BOX the specific standards met/tested — otherwise don’t assume anything about the mask, even if offered by a well-meaning supplier (like my local US pop-up grocer). For instance, the following example “surgical mask” standards are printed on legitimate mask boxes/packaging: USA standard “ASTM F2100 Level I”; or Chinese standard “YY0469-2011” usually accompanied by these exact words: “Medical Surgical Mask” or “Disposable Surgical Mask.” It is not legal for Chinese Mask Makers to use the word “Surgical” (in Chinese or English) unless the mask conforms to YY0469-2011; hence, boxes labeled “Disposable Medical Mask” may be legitimate and may meet another standard, but would not filter any virus-sized particles. Unfortunately, in the US at least, “surgical mask” is commonly used to refer to ANY of those often-blue pleated rectangular masks. NOTE: It’s a different matter entirely to verify the authenticity of labeling, but all of the labeled YY0469-2011 masks I’ve seen thus far (on Chinese AliEpress site) have been legitimately approved by the government (when I checked the product registration number, which ALSO appears in fine print on the label, against the gov’ts web site). For the extremely resolute, willing to tackle YY0469-2011 mask verification on a site entirely in Chinese, this site describes how to do so: . Again, I’m not an expert and can’t evaluate whether this site is perfectly trustworthy, but it was helpful to me and the product registration verification steps have been echoed by various Chinese mask sellers I’ve interacted with.

  30. Hi, great investigations, thanks for sharing it!
    About claiming that surgical masks are “just as effective as” N95 masks at preventing virus transmission, though… no! Data from those clinical studies are just too weak statistically to compare the two types of masks. And lab testing says that surgical masks are a bit less efficient, so it seems reasonable to infer it’s so when worn in real life too.

  31. This is a wonderful website. Kudos for doing important work!

    I saw that your blog entry on sterilization comes down on the side of letting time do its thing. I was wondering if you’d consider testing steam, or UV-C. Steam might have similar effects to other solvents in reducing static charge, but maybe not… UV-C lamps have to be used very cautiously, but LED versions are available now.

    Finally maybe I missed it, but have you addressed the difference or similarity of NK 95 vs N 95 standards? Availability of N 95 is very limited in the US but NK 95 through Asia seem to be plentiful…

  32. Any info polypropylene it’s the non woven material surgical mask are made from. I found a USA manufacturer in the form of upholstery fabric but it’s available in varying degrees including 100% polypropylene. Easier to sew right up for DIY Mask hopefully as close as a DIY’er can get to the real thing. Thanks enjoying all the fantastic information on the site

    • I have the same issue with that article, and wanted comment there on a study which showed the effects of UV light on virions.

      My understanding of their table 2, was that UV light is somewhat effective at deactivating coronavirus. Am I correct in my interpretation? Could high intensity UV be used to decontaminate masks with out deteriorating their effectiveness?

    • Wow that’s scary, I really hope there is a flaw in their experiment… Since the mask is made of porous material it’s surprising that the virus is surviving longer than if it was on glass.

    • I wanted to comment on that blog post too, that masks would be more akin to plastic thant cardboard…
      This preprint says “a significant level of infectious virus could still be detected on the outer layer of a surgical mask on Day 7 (~0.1% of the original inoculum)”.
      And that 5 min at 70°C inactivates it — maybe that’s better than microwaves for treating masks?

    • So, heat is efficient:
      > With the incubation temperature being increased to 70 C, the time for virus inactivation was reduced to 5 minutes.

      And it persists for a *long* time on surgical masks:
      > Strikingly, a significant level of infectious virus could still be ∼ 0.1% detected on the outer layer of a surgical mask on Day 7 (of the original inoculum).
      Which is consistent with the idea that those masks are more akin to “plastic” than to “cloth”. (As presumed in another post, where for some reason I did not manage to publish a comment.)

  33. Hi,

    I bought some COLDEX surgical masks whicht should filter 99,7% of 0,1 micron size particles, which is even better than FFP2 masks. Sound good to be true. Can you guys say something about this?

    Do I really have to pay to see the S Norm ASTM F2001 norm or is the a link for free PDF version?

    BTW: Awesome website!

    • Hi, Kelly, which data info particularly you are looking at? We should have our engineer to double check it if there’s something off!

  34. Hi there,

    Can you please explain if mask that have GB/T32610-2016 on it is good for coronavirus? I cant find what particle size it can filter. I found this at Xiaomi airpop mask. What eu/us standartd are comparable?
    Thank you.

    • The GB/T32610-2016 is a testing standard used in mask manufacture. It is not the grade of your mask. You can ask the manufacturer or try to find the grading information on the package of the mask.

  35. Hi Paddy,
    Amazing blog with relevant and useful information. I am noticing many people wearing single use face masks these days, is there any study or comparison on their effectiveness to a DIY 100% cotton face mask? A new issue has started to emerge and it is the environmental impact single use face masks are creating – pollution from making them and also littering and landfill. Would love to hear your thoughts on this 🙂


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