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> The best valves filtered particles very well without any mitigation That's not supported by the study: 17% max penetration for surgical masks vs 55% for valv
by ricardobeat 6y ago
> The best valves filtered particles very well without any mitigation
That's not supported by the study: 17% max penetration for surgical masks vs 55% for valved masks without any 'mitigation'. They only perform similarly for inwards flow, which is expected when both have an N95 rating.
- maxerickson 6y agoThe first paragraph of the conclusions: Based on a sample size of 13 models, this study found that unmitigated FFRs with an exhalation valve that were tested in an outward position(with particles traveling in the direction of exhalation) have a wide range of penetration, emitting between <1% and 55%. Further testing could measure greater particle penetration. See where it says "between <1%"? And Figure 5 shows the variation between the models.
- ricardobeat 6y agoThe range doesn't tell the true story. In Figure 5, the majority of models are worse than surgical masks, above 20%, vs "Particle penetration through the surgical mask ranged from 2% to 17%". Only 3/13 performed better, and 1% is just the lower quantile for a single one of them.
- maxerickson 6y agoRight, and the ones that perform the best? Presumably if the goal was to standardize on good valve performance, the performance would align with the best models rather than the majority.
- incrudible 6y agoYou are still conflating the mask cloth with the cloth mask. It is not plausible that a loosely worn cloth mask performs nearly as well as the cloth itself.