🧵 1/12 Testing of the Zimi ZM95W (earloop only) which is under a newer Chinese kids mask standard. Surprisingly this is not a KN95 like the other kids Zimi I tested. It is actually listed as GB/T 38880-2020, Class W. Follow to see what that means. 
2/12 You may have noticed your KN95 says "GB 2626-2019" or 2006. It is required for this to be on the mask to meet the standard. This means the mask maker tested it things such as the particle filtration efficiency (PFE) (%) is ≥95%, the breathing resistance is ≤210 Pa.
3/12 So the kids masks with GB/T 38880-2020 standard means that: breathing resistance is ≤ 45 Pa for Class F(protective) masks, and no strict requirement I found for Class W(hygenic) masks like the ZM95W- but it happens to be 45Pa. This means the kids masks are more breathable.
4/12 Class W masks must have a PFE of 90%, and Class F masks require PFE of 95% to pass. This is just the minimum performance of the filter media and per my results below the ZM95W actually exceeds both the Class W and Class F requirements!
5/12 Another noteworthy requirement- GB/T 38880-2020 requires adjustable straps(earloop/ headband). Tests on earloops have shown that adjustable earloops are quite important and should be required. Testing earloops at default tension could be like testing an unpinched nose wire.
6/12 How did it do? Extremely well for a breathable kids earloop mask! An overall fit factor of 35 means that 97.1% of the particles were blocked. Thus it exceeds the standard even for Class F protective kids masks when taking my son's individual fit into account.
7/12 But this is just a 5 minute test and surely can't reflect real world protection for my son because it's an earloop right? It will surely just fall off his face because he is talking or moving? Nope. It even held up when I continued the test for 30+ mins. Overall FF 40.
8/12 And also our experience of true real world use you can see here. Unfortunately a wearable portacount will not be available or affordable anytime soon but it survived the running, jumping, playing, jumping jacks test today.
9/12 Do I recommend this? Not quite yet unless you have a portacount. Like the other kids Zimi I had to modify it before it could seal over my son's nose. The face seal has to be cut down otherwise it won't seal over the nose bridge. Fit is also quite individual for all kids.
10/12 Zimi should offer a high nose bridge version or alternatively they could place lines to cut the face seal as I did. This mask design is excellent IMO and should be informative to mask makers outside of East Asia. I hope to see similar masks in North America & elsewhere.
11/12 What are my takeaways? It is important to have a children's mask standard that ensures that masks are breathable and thus more comfortable. Earloop masks should include earloop adjusters and we should adjust them just like we pinch nose wires(though zimi lacks a nose wire!)
12/12 Questions? Comments? Concerns? DM's always open.
Also see my other recent thread on Zimi for more information on the design
https://x.com/CriticalAerosol/status/1753638261636157655?s=20
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