KN95 vs. N95 Masks – It Is Time to Use Common Sense

July 31, 2020

Harsha Moole, M.D., MBBS


Summary of KN95 vs. N95 Masks:

KN95 vs. N95 Masks. Due to the shortage of N95 masks, we have to consider using equally effective alternate options. N95 is a certification issued by US authorities. Masks that have equally effective properties as N95 masks go by different names in different countries based on their independent certification systems. (KN95 – China, P2 – AS/NZ, 1st Class – Korea, DS FFRs – Japan). Considering the life and death situation we face in the hospitals, we have to push our health care administrators to consider getting us these equally effective alternative options since N95s are not available. At the end of the day, we have to prioritize our patient’s health, our health and our families health.

Learn about COVID-19 transmission on a separate blog post: How is COVID-19 Transmitted? What is the Right Mask for COVID-19? A Physician-Scientist’s Perspective.

Learn about COVID-19 test sensitivity on a separate blog post: COVID-19 Test Sensitivity is Unclear. How Accurate is COVID-19 Test?

We are in dire circumstances, and dire situations call for ‘out of ordinary’ actions.

I am an internal medicine physician, and I am exposed to patients under investigation (PUI) for COVID 19. Lack of appropriate PPE is putting me at high risk for contracting the virus. This is in turn putting my family and other sick patients I see at risk.

Cutting to the chase, we know that the N95 masks are an appropriate PPE for healthcare providers. Currently, the N95 supply is unable to meet the demand. Appropriately priced N95 masks are not available for bulk order at least until late April or May 2020.

Now, if you do not have access to N95, can you use equally effective alternative options (KN95) in the US hospitals/private practices/providers? Isn’t using these alternative options better than using a “bandana” or a regular surgical mask or a handmade cloth mask?

There are more than a few N95 equivalent masks available worldwide. As per a comparison study performed by 3M – it is reasonable to consider China KN95, AS/NZ P2, Korea 1st Class, and Japan DS FFRs as “equivalent” to US NIOSH N95 and European FFP2 respirators, for filtering non-oil-based particles such as those resulting from wildfires, PM 2.5 air pollution, volcanic eruptions, or bioaerosols (e.g. viruses).

These masks have similar superior properties as N95, but they go by different names based on where they are certified.
The WHO (World Health Organizations) considers N95 equivalent to KN95 and other similar masks. (WHO Article 1. WHO Article 2.)

Although the US authorities recommend using N95 masks, we have to take into account the current situation, and act accordingly. We need to prioritize the safety of our patients, families, and ourselves.

Do we let the current-day US regulations become a factor that determine if you – your family – your patients live or die?
I know it sounds dramatic, but that is the current unfortunate situation.

We should all reach out to our respective hospital/private practice leadership, to promote and advocate the use of equally effective alternate options for N95 masks.

If you own an independent practice, or if you have authority to pick your own PPE, you should strongly consider these equally effective alternate options (KN95 vs. N95) as opposed to other less effective options (bandana/surgical mask/cloth mask). After all, the end result matters in these circumstances, not how you achieve it.


Fit testing for respirator masks:

  • Fit testing performed by institutions ensures that the wearers have minimal air leak. Currently in the US, we do not have fit tested N95 equivalent masks readily available. The N95 equivalent masks are made by different brands, in different shapes, with a non-reliable availability and supply chain.
  • It is impossible to fit test every healthcare worker with every mask type. In this current dire situation that we are experiencing, one should think about the next best alternative to the fit tested N95 equivalent, which is a non-fit tested FFP2 or KN95 or other N95 equivalent masks. Healthcare workers should be able to trial the available models and use the FFP2 or KN95 or other N95 equivalent mask that fits them the best.
  • A randomized clinical trial (RCT) of 1,441 health care workers in 15 Beijing hospitals was performed during the 2008/2009 winter. Non-fit-tested N95 respirators were significantly more protective than medical masks against clinical respiratory illness. Rates of infection in the medical mask group were double that in the N95 group.
  • Unlike N95 masks, the KN95 and FFP2 masks are manufactured by hundreds of companies. They vary in shape, size and fit. It is important to use the one that fits you the best. There is no easy way to try out these options. In my case, I ordered small quantities of several models of FFP2 masks from China, fit tested myself, and picked the one that fit me the best.


Mask procurement difficulties:

This topic was excellently summarized in this NEJM correspondence: The New England Journal of Medicine – In Pursuit of PPE

FFP2 or KN95 are a good alternative, however we have the following challenges:

  • Concern for fake products with poor quality
  • Transportation delays, with new stringent quality control regulations from Chinese govt. (probably for the good)
  • MOQs are too high for regular clinics to afford.
  • US regulatory bodies trying to divert the supplies
  • Concern for improper mask fitting on the face. We usually cannot test the sizes of these masks before we order.


Custom fit KN95 masks:

After jumping through multiple hoops, we finally get hold of FFP2 / KN95 masks. That’s great, now we have masks with a good quality material that can defend us against the virus. Problem is, they are one size fits all – regular size. This results in a poor seal, and a high risk for air leaks. We have to use some street-smart tricks to make sure that the mask creates a good seal.

We have been using two techniques to help customize the masks to the wearer, and secure a tight seal:

  • Adjusting the size of elastic straps by tying a knot at the end of the straps. This reduces the length of the straps to the desired fit, thereby creating a tight seal to prevent any leaks.
  • Nose bridge is another common site for an air leak. We bought aluminum nose clips that are bendable and have a self-adhesive on one side. We stick these strips on the nose bridge part of the mask, to make it a compact and tight fit on the nose. This prevents fogging of glasses, and also prevents air leaks.

The eventual goal is to prevent any air leaks. Unfortunately, the design/material of surgical masks and bandanas (home made masks) create too much air leak. There are many common misperceptions of what masks to use, and when to use. Please refer to this detailed post that summarizes the use of masks in COVID-19 –


If you need N95 masks, fill out the details here. I will forward that to a few bulk manufacturers.

I hope we have access to the appropriate PPE that we need to take care of our patients and our families.

Learn about the right mask to use for COVID-19 on a separate blog post: What is the Right Mask for COVID-19? How is COVID-19 Transmitted? A Physician-Scientist’s Perspective.

Learn about the accuracy of COVID-19 test on a separate blog post: How Accurate is COVID-19 Test? COVID-19 Test Sensitivity is Unclear.

Keywords: KN95 vs. N95


KN95 vs. N95

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Authored by Harsha Moole, M.D., MBBS

Hey there! I hope you enjoyed reading this blog. PhysicianEstate is my brain child and passion project. I run this platform to empower entrepreneurially motivated physicians to make financially educated investment decisions and discuss asset protection strategies. Lots of important but free content here and here! If you have any questions or if you are interested in partnering with me, let’s connect!



Comment as guest


N95 is a a compromise choice. The 95 means it filters 95%. And that is 95% of particles bigger than 0.3 microns in size. The virus is 0.125 microns. So airborne virus particles are not filtered by the mask.

Even if the viruses are attached to droplets, as in a sneeze, and assuming ZERO airborne virions, the N95 lets through FIVE PERCENT.

So, five percent of death leaking through is being passed off as acceptable?

there are N100 masks, which filter 99.97%. Why, at a minimum, aren’t pushing for those?

Half and full piece respirators are better, and positive air purifying respirators better still.

I’m a physician, and also a fireman and hazmat tech. I wouldn’t go into a burning building or a hazardous scene with PPE that leaks 5% of methyl ethyl death in. Nor should I go into the ER or ward with a compromise mask, meant mostly as a placebo to comfort the health care workers enough so they don’t walk out en masse..

Alice Wei, MD

This is in reply to Don’s comment.
0.3 microns is the MPPS, Most Penetrating Particle Size used to test N95 face masks.
It may be counterintuitive, but smaller particles are more easily filtered because of the way these particles move. You may recall from Chemistry or Physics (if you want to relive that pain) the concept of Brownian motion. It refers to the random movement of microscopic particles suspended in liquid or air, simply bumping into each other and the surrounding gas or liquid molecules. Particulate matter smaller than 0.3 microns are subject to these motions during their path towards your face (and hopefully a mask). Since they do not take a direct linear path, but rather zig zags as they get pushed around by other molecules, they are more easily deflected.

Particulate matter larger than 0.3 microns, would either bounce off or be entrapped by the fibers of the mask, as you would expect.

In contrast, 0.3 microns is the most difficult particle size to filter because it is small enough to pass through typical barriers, yet large enough not to be affected by Brownian motion. That is they take a direct and linear path towards your face (and mask) but small enough to pass between the woven fibers. Hence the “most penetrating” designation. Soot, smog and dust falls into this size category.

The “95” in N95 does indeed refer to at least 95% of MPPS being filtered in tests. But that means 95% of the 0.3 micron particles. It is therefore a safe assumption that a much higher percentage of smaller particles in the size range of viruses such as the ones that lead to COVID-19, are effectively filtered.

Important to note however, that unless these masks are worn properly after a fit test, all of the above won’t matter. So please look online for a tutorial on how to test that you are wearing it properly. And please folks, reserve these masks for the people that actually need them.

Randal Mandock, Ph.D.

Assuming the applicability to an N95 respirator of Figure 4 in, the “95” in N95 indicates 0.95 fractional collection efficiency at 0.3 microns. Note the trough is at 0.3 microns. Collection efficiency increases on either side of 0.3 microns. “Each SARS-CoV-2 virion is approximately 50–200 nanometres in diameter” (cited in Wikipedia (SARS-CoV-2) from Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. (15 February 2020). “Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study”. The Lancet. 395 (10223): 507–513). Since 50-200 nanometers is a range smaller than 0.3 microns (300 nanometers), the collection efficiency for the SARS-CoV-2 virus ought to be higher than 0.95. Thus the “95” in N95 might be considered a minimum filter efficiency for SARS-CoV-2 size particles. On the other hand, since these particles attach to or are incorporated into aerosols and droplets, aerosols near 0.3 microns in diameter will be filtered at 95% efficiency, but most coughed, sneezed, and exhaled particles will be filtered at greater than 95% efficiency (assuming again the applicability of Figure 4 to N95 respirator efficiency). This is the reason why N95 respirators are considered safe for use in the case of SARS-CoV-2. Certainly N100 would offer even more protection, but if the only available respirator is N95, one should consider it safe enough for medical use.


Don, you are absolutely incorrect on your assumptions that since the n95 is rated at .3 microns it fails against smaller particles. As a Hazmat technician, you should understand that the smaller particles are captured via an electrostatic method, while larger particles are simply ‘filter blocked.’ The hardest particles to capture are the .3 micron particles, as they are too small for the filter capture method and too large for the electrostatic capture. So, in effect, they are more effective against both smaller (virus/bacteria) size particles than .3 micron particles.

Gail MI Williams

WHat the difference in KN95 and N95?

Catherine Mills

Thanks for the informative article. We just received KN95 masks at our dental practice. I practiced wearing one of them. I was wondering if you would share where you were able to get one-sided adhesive, bendable noseclips to attach to the masks to prevent the fogging.
A dental hygienist

David G

Hello Dr. Moole, I would love to discuss your mask options. I am connected to folks looking for and providing solutions. I responded to your questionnaire.

Thank you,

David Gilbert


“On March 24, 2020, the FDA issued an Emergency Use Authorization (EUA) for importing non-NIOSH-approved N95 respirators… The FDA did not list KN95 respirators made per China’s standards in this EUA because of concerns about fraudulent products listed as KN95s.” from

Perhaps you should have invested in some N95 masks.


@ Robert If you read the entire section at the link that you have posted, it mentions conditions under which KN95 masks are indeed acceptable to use along side other masks of various designations. While it states that there is a concern regarding fraudulent KN95 product, it goes on to say that some non-EUA certified products are acceptable. Perhaps you should post the entire findings as reported in the article that you are referencing.

Diane M Hicks

Thank you for this article. I am an RN in East TN with family members who are hospitalists in Philadelphia and NYC. We are all having extreme difficulty getting PPE, especially masks. I was given a few masks that are stamped KN95, are small, white, rounded and fold in half, with elastics. They are not rigid. How can we know if they are real or fake? I don’t want to take risks but as you said, we need to use common sense and protect ourselves, patients and family. Thank you

Jimmy Fortenberry

I am a importer and work with the FDA and CE certificates on the KN95 and N95 in bulk to hospital or government .Premiere Mask and Medicals Supplies.
Jimmy Fortenberry
256 393 0340

Star Adams

Thank you for explaining the differences.

Craig Ley

We are an industrial manufacturer in Oregon. We had a supplier in China who could ship us the KN95 masks. Until, we found that they would not be allowed into the US, because they are not US Certified and OSHA would not accept non US certified.


Thank you, for the information .

Sam S.B.

Thanks for the info from Dr. Moole, Dr. Don xxxx., and Dr. Alice Wei. Dr. Don, if you know of any place right now where many of us can get an N100, I’m sure you can share that information to your fellow physicians and firemen, and our front-liners in the battle with COVID-19. Because the reality in the world right now… everyone is looking for even a surgical mask, or even a dust mask normally sold in hardware stores, are no where to be found. That governors and local officials are urging people to make cloth mask or bandanas, and donate our N95 masks to our healthcare front-liners. I think a KN95 is the most that may still exist, even if it’s a China rating code.


Dr. Wei, Can you provide references on the hypothesis that because it filters 0.3 microns, it will better filter smaller particles. The physics you use sounds reasonable but Brownian force is easily overcome by the force of respiration. One could argue that particles less than 0.3 are more likely to pass through.
Sadly the fact is that this size particle has never been tested. Seems like N95 was developed for industrial not healthcare use.
Don’s comments seem pretty reasonable too.
And while KN95 is better than nothing, there exist many untested variables.
Would prefer a real respirator if I had a choice.

fred mallone

where is the article that shows theWHO considers n95 and kn95 the same?

Dr. Ping TAN

How can you test a KN95 respirator mask from China is up to its specified standard and not a fake one ? I have a couple of types of KN 95 from different companies and I also has U.S made N95. I am a family doctor and I sometimes see patients with flu-like illness . Therefore, ? Covid-19 ! Thanks

Matthew Gavlick

Thankyou for the article Sir.May God bless you and keep you.Jesus is King


Love your website creation


so when you look at the 3M chart for N95 vs most of the others (KN95) the others have a much higher leak rate (</= 8%) vs the N95. So isn't the concern more the ability of the N95 to stop the higher leak rate from the other masks? Assuming all of the other things are the same.

Danielle Cass

Thank you for this piece about KN95 VS N95 masks. I’m a nurse in LTC. We are being rationed masks and recently management switched out supply to KN95, but they don’t fit my face. I needed info to relieve my concerns. But regardless if they are an equivalent, after trying them-they just don’t fit my face shape. I told management I had air leaks, and they said that is all they can get. So, I guess I will be scrambling to find my own better fitted N95s now so that I can continue to provide care, because in LTC staffing is at an all time critical low, and I will not abandon my patients in this time of need.

Danielle Cass, BSN, RN

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