Depending on where you reside in the world, you are likely already familiar with the terms N95, KF94 and KN95. These certifications, among others, are what divide masks from respirators. Any device holding one of these certifications is a performant respirator capable of filtering a high percentage of fine and ultrafine particles.
However, although most people are familiar with these standards due to the ongoing pandemic, there is little information about the exact differences and similarities between each certification. With the similarity of the names, it's easy to think that these standards are identical. However, there are some key differences worth noting!
In today's article, we want to look at each standard's specifications and see what device is best for you. Although N95 devices are widely touted as the gold standard, this isn't always the case! There are many cases where an N95-certified respirator might not be for you.
The key difference between the three standards that we will discuss today is that they are certified by organisations within different countries. NIOSH certifies N95 devices in the U.S, the Standardization Administration of China certifies KN95 devices in China, and the Ministry for Food and Drug Safety approves KF94 devices in South Korea.
Each of these organisations approves respirators under their respective guideline. Each guideline is shown below:
NIOSH-42CFR 84: N95, N99, N100
GB2626-2006: KN90, KN95, KN100
MFDS Notice No 2015-69: KF80, KF94, KF99
It is worth noting that all three standards have different tiers. For example, NIOSH also certifies N99 and N100 devices, the Korean MFDS also certifies KF80 and KF99, and the Standardization Administration of China certifies KN90 and KN100 devices. However, these devices are far less common than their counterparts. As such, this article will be comparing the equivalent devices in the 94-95% filtration range.
With that being said, let's begin by looking at the similarities between each device.
Similarities Between N95, KN95 and KF94
Comparison of respirator standards. Image from 3M.
The most apparent similarity between these devices is that each is rated to filter ≥ 94% of particles. In the case of KN95 and N95 respirators, this number increases to ≥ 95%. However, while this difference may make N95 and KN95 devices appear superior, the difference is extremely minimal. In fact, studies found KF94 devices to provide equivalent or similar filtration to N95 devices in many cases (1).
Another study found that out of ten tested KF94 devices, all were capable of > 98% filtration (2). While this isn't true for all respirators, it shows that all of these devices are comparable when it comes to filtration. Further, The test methodologies used to certify ≥ 94% filtration are also similar across all, with comparable flow rates, test agents, and particle sizes used.
This shows that devices from all of these standards perform similarly, at least when it comes to filtration capabilities. However, besides filtration, there are relatively few similarities between these devices. Let's dive into more details and see the differences between each respirator type.
- http://aaqr.org/files/article/668/36_AAQR-13-06-OA-0201_991-1002.pdf
- https://www.koreascience.or.kr/article/JAKO202008662608015.page
N95 Respirators
Certified under NIOSH-42 CFR 84, N95's are likely the most well-known respirator on the market. Each device has to undergo stringent tests that approve only the highest-quality devices. One of the significant advantages of the N95 standard is that you can also check the authenticity of a device on the CDC website.
However, for public use, N95 devices have a lot of downsides. First, these respirators are created for occupational professionals in fields that require PPE. This means that while they provide high filtration and good protection, they are often not the best choice for general users. Let's discuss why.
Due to their occupational nature, N95 respirators have been designed with fit-testing in mind. Fit-testing involves using a test agent (qualitative fit testing) or a machine (quantitative fit testing) to check for leakage in a respirator. Medical and other professionals regularly undergo such testing to confirm that their N95 respirator fits correctly with no leaks.
While fit testing will provide the best protection for respirators under all standards, N95 respirators are designed specifically for those with access to such tests. This is a stark difference to respirators such as KF94-certified devices that are intended for public use.
Due to needing fit testing, NIOSH does not test TIL (total inward leakage) on respirators. Both KF94 and KN95 devices must undergo leakage testing and have ≤ 11% TIL (KF94) or ≤ 8 TIL (KN95)(1,2). These leakage tests are carried out on a range of individuals who must don the respirator and perform activities.
This is important because most of us don't have access to professional fit testing services. On the other hand, KF94 and KN95 devices are designed for general use and are required to have minimal leakage on everyday wearers.
Further, compared to the KF94 standard, this certification is far less strict regarding inhalation resistance. Inhalation resistance signifies the difficulty that the user must go through to breathe in. NIOSH requires that respirators show ≤ 343 Pa (pressure drop at 95 L/min), whereas KF94 requires ≤ 70 Pa (at 30 L/min).
While most N95 devices will show far lower than 343 Pa, finding a device with exceptional inhalation resistance is possible. However, since the KF94 standard is consumer-focused, this standard is more stringent at typical breathing rates and shows why N95 devices are not inherently the best for general use.
There is no denying that N95 respirators provide high filtration efficacy and meet stringent quality standards. However, N95 devices are often not the best choice for everyday use simply because they are not designed for it.
- https://www.mfds.go.kr/eng/brd/m_65/down.do?brd_id=engcovid1902&seq=6&data_tp=A&file_seq=1
- https://multimedia.3m.com/mws/media/1791500O/comparison-ffp2-kn95-n95-filtering-facepiece-respirator-classes-tb.pdf
KN95 Respirators
KN95 respirators were largely unknown in western markets until the pandemic began. These days, KN95 respirators are almost as well known as N95 devices - unfortunately, they often aren’t known for good reasons.
Before discussing the intricacies of the KN95 certification, we must address the elephant in the room. That is counterfeit respirators. We recently wrote a whole article about the issues posed by counterfeit respirators and how you can avoid purchasing counterfeit respirators.
While counterfeit devices can, be any respirator - not just KN95s - there is no denying that subpar and fake products are most commonly ‘KN95’. New York Times recently investigated and found that out of the top 50 KN95 devices on Amazon, very few were legitimately certified devices (1).
Therefore, while the KN95 standard itself is a stringent standard that certifies effective devices, caution needs to be exercised when purchasing these products. If you’re unsure how to tell counterfeit devices, make sure to read our recent article on the matter.
So, with that out of the way, let’s discuss what KN95 means. KN95 devices are certified under the GB2626-2019 standard in China. Overall, the standard has very similar requirements to NIOSH’s N95 certification. However, there are a few key differences.
When it comes to filtration, KN95 devices must demonstrate ≥ 95% filtration. In this respect, they are equal to N95 and slightly better (in theory) than KF94 devices. However, when it comes to flow rates and inhalation and exhalation resistance testing, KN95’s are virtually identical to N95 devices (2).
The most significant difference between these two testing standards is that KN95 devices must undergo TIL (total inward leakage) testing on various human subjects performing different exercises. This means that where N95 devices rely solely on fit testing, KN95 devices must be tested by real people and display an average TIL under 8%.
This is because the KN95 standard is designed as a more general-use standard. Where N95 devices are created for occupational use, KN95s are used by both occupational professionals and consumers for protection from air pollution.
While KN95 devices are tested on human subjects, it is worth noting that these respirators are designed to fit people with facial features common in that region. Therefore, the TIL testing may not apply to individuals in different areas or with other facial features.
Interestingly, despite being equivalent to N95 devices in almost every way, KN95 devices are very different design-wise. 3M set the standard for N95s, and these devices are all based on a bra cup (3). Yes, you heard that right! This is why nearly all N95 devices have an elliptical shape.
On the other hand, KN95 devices tend to have a triangular edge on the front with curved sides. This means that the fit between typical N95 and KN95 devices could vary greatly. If you’re unsure which device to choose, we recommend that you pick one of each and see which style fits better.
Overall, KN95 respirators perform similarly to N95 respirators but they also have to undergo TIL testing. If you can find a legitimate KN95 manufacturer, these devices are a good choice. However, finding devices that perform as advertised can be a challenge in itself.
- https://www.nytimes.com/2021/11/30/health/covid-masks-counterfeit-fake.html
- https://multimedia.3m.com/mws/media/1791500O/comparison-ffp2-kn95-n95-filtering-facepiece-respirator-classes-tb.pdf
- https://www.npr.org/2020/05/21/859991324/how-one-woman-inspired-the-design-for-the-n95-mask
KF94 Respirators
KF94 devices are the third and final respirator standard that we want to discuss today. These devices are interesting because they are not intended to be used in occupational settings. Instead, the Korean Ministry for Food and Drug Safety (MFDS) has a dual rating system designated for such devices.
KF ratings come in three levels, KF80, KF94, and KF99. Their occupational-use counterparts are named Second Class, First Class, and Special Class, respectively. Despite the different classifications, these devices perform very similarly for the average consumer.
MFDS themselves have stated that KF94 and KF99 devices are equivalent to First Class and Second Class respirators along with FFP2 and FFP3 devices (1). Therefore, while the direct comparison to N95 and KN95 devices would be a First Class device, KF94 is similar in most key areas such as filtration, breathing resistance and TIL (1).
This makes KF94 respirators unique on this list as they are the only public use devices. Due to this different focus, more emphasis is put on making sure that the devices are breathable and usable in daily life. An excellent example is how KF94 respirators generally replace head straps with earloops.
While head straps are undoubtedly a more secure fitting method, they are also impractical for public use. For typical users, a mask will likely be donned and doffed multiple times in day-to-day use. In this situation, head straps can become a hindrance. KF94 respirators are designed with these factors in mind.
N95 vs KF94 filtration. Source.
The most apparent difference between KF94 respirators and their KN95 and N95 counterparts is the minor filtration difference. KF94 devices must display ≥ 94% filtration. However, studies have shown that KF94 devices can perform significantly better than the standard requires (2). In the end, the best performing device will be the one that fits best.
Similarly to NIOSH-certified devices, MFDS keeps an updated database of every officially certified KF94 device. While the website is only available in Korean, it's relatively to verify the authenticity of a brand or device by using Google Translate (or Papago, which tends to be more accurate).
KF94 devices are only tested for inhalation resistance at 35 L/min. This is significantly lower than the 85 L/min used by the KN95 and N95 standards. Average human breathing rates vary from 6 L/min to 90 L/min, depending on how active the individual is (3). Therefore, while KF94 devices must show ≤ 70 Pa at 30 L/min, breathing resistance can surpass these other respirators at higher flow rates.
Exhalation resistance, on the other hand, is the same as an N95 respirator and slightly higher (250 Pa vs 300 Pa) than a KN95 device. However, it's worth remembering that these are the maximum levels for certification - most devices will have significantly lower resistance.
Finally, similar to the KN95 standard, KF94 devices must show ≤ 11% TIL. This is tested across a range of human subjects performing different exercises. This TIL percentage is higher than the ≤ 8% required by the KN95 standard.
Overall, KF94 devices - if fitted correctly - are perhaps the best respirators for public use. They are designed to provide high filtration while maintaining high breathability at lower breathing rates. N95DECON has even commented that KF94 respirator's exhibit consistently excellent performance' (4).
Of course, that isn't to say that KF94 respirators are perfect. Their boat shape will provide an excellent fit for some individuals, but others cannot seal the respirators securely. KF94 respirators also tend to exhibit weak nose strips.
- https://overseas.mofa.go.kr/hk-en/brd/m_1495/down.do?brd_id=8158&seq=761355&data_tp=A&file_seq=2
- https://www.mfds.go.kr/eng/brd/m_65/down.do?brd_id=engcovid1902&seq=6&data_tp=A&file_seq=1
- https://www.bbc.co.uk/bitesize/guides/z3xq6fr/revision/2
- N95Decon
Conclusion
Although there are some fundamental differences between N95, KN95 and KF94 devices, they are also similar in performance. The most significant difference between these devices is the intended use case.
KF94 respirators are created for widespread public use, KN95 are designed for both occupational and general use, and N95 devices are intended for occupational use only. However, NIOSH does not currently certify public use devices, and until recently, there was no local community-focused mask standard.
The American Society for Testing and Materials (ASTM) has recently released the ASTM F3502-21 standard for community masking. However, while this standard is an improvement over commonly used cloth and surgical masks, it's far from a respirator standard as it only certifies devices for ≥ 50% filtration.
This leads to a significant discrepancy when comparing N95 respirators to KF94 and KN95 respirators. The latter both have to undergo further testing to show that they are capable on general users without access to fit testing. With that being said, these devices are designed for and tested on subjects with facial features common in their respective regions.
The difference between these standards can be attributed to the experiences of East-Asian countries. There has been a greater need for public use devices in both Korea and China due to previous outbreaks such as MERS and SARS. On top of this, air pollution tends to be a far more significant issue. As such, there has been a need for easily-accessible and usable respiratory protection.
Many countries didn't experience severe air pollution or viral outbreaks before COVID-19 and therefore haven't seen a need to create consumer-focused respirators. However, COVID-19 may prompt local public respirator standards to be created in the U.S and EU in the future.
While all three standards offer similar filtration levels, it's worth sticking to KF94 and N95 devices wherever possible. This is because counterfeit and subpar KN95 respirators are a widespread problem, and it's difficult to verify the authenticity of such a device. On the other hand, both NIOSH and MFDS provide databases for certified N95 and KF94 products.
On top of that, both N95 and KF94 are recognised as devices that perform well and often exceed the standard's filtration and breathing resistance requirements. In the end, the best choice is whichever respirator fits you best. At this level of filtration, fit becomes the key factor that will influence protection.