Are ASTM Level 3 Masks the New N95?

1. The Filtration Altercation:  Are ASTM Level 3 Masks the  New N95?  By Puraka Masks  January, 2021     

2. How do ASTM Level 3 masks stack up against  the competition?    If you consider yourself a mask nerd, there’s a good chance Level 3 Surgical Masks are on  your radar. This type of face covering, officially known as an ASTM F2100 Level 3 Surgical  Mask, is gaining a reputation as something of a contender in the world of protective face  masks.    Level 3 masks are being described as an FDA-approved heavyweight in the field of  questionable fabric masks, or even as a lightweight alternative to medical-grade respirators  like the N95.    Is the hype around Level 3 masks deserved, or are these just scrubs trying to punch above  their weight? Before putting your money on the line, here are some important differences  between Level 3 surgical masks, N95-type respirator masks, and fitted cloth masks using  PM2.5 filters.   

3. Filtration    When talking about face mask effectiveness, we like to break things down into the ​three  Fs:​ filtering materials, facial coverage, and fit. Despite being the least important of the three,  filtration is usually the first thing people ask about, so let’s start there. Just be sure to read  the other sections too, because even though contemporary Level 3 masks can compete  with the big boys on filtration material and coverage, they are often outclassed when it  comes to fit.    Level 3 Surgical Masks    By now you’ve probably heard the refrain that surgical masks are designed as barriers  against fluids, not as barriers against airborne particles. Traditionally this is true. From a  regulatory perspective, FDA-approved surgical masks, even the mighty ASTM F2100 Level  3s, are not engineered to filter the same degree of fine aerosols as N95-type masks and  other industrial-grade filtering facepiece respirators. For you upper-level mask nerds, a  certified Level 3 mask needs to filter a critical mass of particles between 100 to 5,000  nanometers (0.1 to 5 microns), but the test particles are typically at least 600 nm (0.6  microns) wide.     There’s now ​plenty of evidence​ that COVID can spread via much smaller particles than the  kind surgical masks are designed to protect against. As a result, surgical mask  manufacturers are racing to get their scrubs tested to the more rigorous levels required by  the N95 standards. In fact, some level 3 masks score impressively well on these tests,  achieving filtration efficiency comparable to N95 (or KN95) respirators in the ultra-fine  aerosols range (75nm / .075 microns).* The caveat? These are the pre-fit scores. Keep  reading, or scroll to the fit section below. 

4. Surgical Mask  Category  Sub-micron  Filtration  Leakage  Assessment  Particle Size Tested  Level 1  >95  Not required  .6 Microns (Lower) / 2  Microns (Upper)  Level 2  >98  Not required  .6 Microns (Lower) / 2  Microns (Upper)  Level 3  >98  Not required  .6 Microns (Lower) / 2  Microns (Upper)  N95 Respirators    N95 masks are the workhorse of respirators, and that’s because they work. A certified N95  respirator must filter at least 95% of particulates in that same ultra-fine aerosol range. The  tradeoff with this consistently high degree of protection is reduced airflow, so people with  certain pre-existing conditions are not advised to use medical-grade respirators on an  ongoing basis.    PM2.5 Filter Masks    Unlike medical respirators and Level 3 surgical masks, a multi-layered "pm 2.5 mask" is  designed to work in conjunction with a specially-designed pm2.5 filter insert, and vice versa.  This unique approach can be confusing, and because pm2.5 filter masks are engineered to  a Chinese standard rarely used outside of Asia, there isn't as much laboratory data for  western consumers to evaluate to when considering their mask options.**    Our advice? Think of a pm2.5 filter mask as a multi-layered fabric mask equipped with many  of the ​facemask elements recommended by the CDC​, but enhanced with a powerful  electrostatic barrier that covers most of the mask’s face. The lab test for the pm2.5 filter itself 

5. is essentially the same as the N95 test, and ​a certified pm2.5 filter​, like the ones produced by  Puraka, can score as high as 99% on standalone efficiency testing.    Of course, because a PM2.5 filter isn't airtight, 99% isn’t the real score. Just like the Level 3  surgical masks that score high on materials filtration, you have to test for fit and leakage to  know if the mask actually works. That's one of the main differences between a pm2.5 filter  mask and a level 3 surgical mask: the pm2.5 mask standards require leakage to be part of  the test, which we’ll discuss in the fit section. We’re getting there, we promise!  Face Coverage:   

6.   To achieve good coverage, a mask should cover your nose, extend under your  chin, and be sufficiently wide. The under-chin extension is especially  important for masks that are not sealed, like the Level 3 surgical mask and a  fabric mask using a pm2.5 filter. They are also important if you have a beard!    In this case, Level 3 surgical masks, NIOSH-certified respirators, and pm2.5  filter masks are all designed to offer comprehensive coverage over these  areas, so we can consider this box checked.    Now, on to the fun stuff!  Fit:    Level 3 Surgical Masks    When considering Level 3 Surgical Masks, the most important factor to know  and understand is how well these masks work when you factor in fit.  Remember, unlike N95 and PM2.5 masks, Level 3 certification for surgical  masks measures only the material itself, and doesn't account for how well the  mask filters when worn on your face.    The ASTM F2100 specification offers up this caveat clearly, saying it “only  evaluates the materials used in the construction of the medical face mask,  and not the seal." The testing language under ASTM F2299 is even more 

7. explicit, stating: "the integrity of the seal to the wearer's face is not evaluated  in this test".     To illustrate how much fit impacts a Level 3 Surgical Mask’s ​true ​filtration  efficiency, let’s go back to the Level 3 masks mentioned above. These were  the ones that scored similarly to a KN95 or N95 mask on a materials-only  basis. In one case, a popular FDA-approved Level 3 mask dropped from 92%  sub-micron filtration to 77% during fit testing. In another case, a well-known  Level 3 mask that surpassed 90% on a materials-only basis filtered only 11% of  particulate matter when worn by a real human being. This shows the  dramatic difference between a surgical mask with good fit, and one with too  many gaps. Check out ​Aaron Collins’ youtube channel​ to see the tests.  Level Three Surgical  Mask  Pre-fit Score (Materials  Only)  Post-fit  Score  Sample One  91%  11%  Sample Two  92%  77%  N95 Respirators    N95 masks are in a league of their own when it comes to fit, and this is by  design. Under the NIOSH standards, N95 respirators must be fitted to the  individual wearer in order to minimize gaps and create a seal between the  wearer’s face and the outside world. When correctly fitted, an N95 mask  achieves a filtration efficiency practically impossible to achieve with a Level 3  Surgical Masks or cloth mask and PM2.5 filter.   

8. On the other hand, ​studies​ strongly suggest that because N95-type masks  are rigid, even the very smallest gaps can cause them to lose a  disproportionate amount of filtration compared to more flexible fabric masks.  If you needed another reason to stay away from N95s - besides the fact that  medical respirators are still in short supply and needed by health care  professionals - this fact should be reason enough!       

9. PM2.5 Filter Masks    Accounting for fit, a certified PM2.5 mask can filter between 65-90% of  particles in the fine aerosol range, depending on the mask grade, or level.  Most masks that use the square pm2.5 filters are considered level “B”, which  corresponds to 85% overall filtration.    Compared to a Level 3 Surgical Mask, a fitted mask with a PM2.5 filter is not  only comparable in terms of efficiency, but more importantly, they are 

10. measured to achieve this high level of filtration when worn by an actual  human being, as opposed to simply testing the fabric.  Are There Other Options to Consider?  Two other types of masks worth knowing - especially if you're a mask nerd -  are “FFP2” and “KN94”. There's two upsides to these professional respirators  we would point: first, they are comparable to an N95 in terms of filtration, and  second, we understand that unlike N95 testing, which assumes the wearer’s  head is fixed in place, the fit testing for FFP2 and KN94 masks must account  for movement. In our view, this kind of testing is more appropriate for  real-world conditions, including kids who fidget.    The downside tends to to be increased breathing resistance, consistent with  the fact that these are medical-grade respirators that were not originally  designed for regular use by the general public.  Takeaway on FDA Level Three Surgical Masks  There seem to be some really good Level 3 surgical masks out there, but it's  important to keep in mind the FDA and ASTM F2100 certification on their  own will not tell you much about whether the mask actually filters... the  official standard only tells you about the material itself. This kind of makes  sense if you think about a surgical mask's original purpose. They are designed  to stop liquid droplets, and if the droplets breaks apart when they hit the  material, the surgical mask should be reasonably expected to prevent most of  the smaller particulates from finding their way through the fabric.    Ultimately, when comparing surgical Level 3 masks, PM2.5 filter masks, and  N95 respirators, there are benefits and downsides to all three. However, we 

11. do recommend against using a Level 3 surgical mask unless you've seen test  results that show a high degree of filtration even after accounting for fit.    Along those lines, there’s a growing interest in “harnessed” Level 3 masks,  which might do a better job at minimizing gaps than surgical masks with ear  loops. If any of our readers have come across test data for ASTM Level Three  surgical masks that use harnessed head straps rather than ear straps, we'd  love to see it, so please let us know!  How Do Puraka Masks Compare?  At Puraka, we design our masks to use square filters often used for the 85%  level "B" masks, since the square-type are more widely available compared to  the folding-type pm2.5 filters sometimes used for the 90% level “A” masks. We  do incorporate certain elements of the level “A” masks, including the  medical-grade polypropylene lining embedded in our ​Essential Line​. Our  filters are laboratory tested to approximately 99%, and test results for our  Universal Line of masks, which doesn’t incorporate the polypropylene, come  in around 88% accounting for fit.    In anticipation of the new ASTM / CDC standards for barrier face coverings,  we have contracted with TUV SUD, one of the top global laboratories, to  conduct additional testing on our Essential Masks. This will include both  sub-micron filtration testing ​and​ a fit analysis, as required. We expect to have  those results by mid-February and will publish them as soon as they are  available.  * Because level 3 surgical masks tend to fall short in filtration efficiency when  accounting for fit, we decided against naming the brands. Check out ​Aaron  Collin’s youtube channel​ to see the actual masks tested. 

12. ** PM2.5 masks are regulated by the Chinese ​GB/T 32610​ standard.