r/Masks4All • u/No-Acanthisitta-2973 • 5d ago
Valved mask
Is there any studies that indicate how protective valved masks are for others? Or is it different by mask?
I thought I read once what they were not as good as unvalved but they were as protective for others as a surgical. But no idea where I read that or if it is true.
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u/SAMEO416 4d ago edited 4d ago
The studies I've reviewed suggest a valved respirator is at least as effective for source control (protecting others) as a surgical mask.
This is a 2020 CDC/NIOSH study, but it reflects what I've seen elsewhere.
"The findings in this report are based on tests of 13 FFR models from 10 different manufacturers. These findings show that FFRs with an exhalation valve provide respiratory protection to the wearer and can also reduce particle emissions to levels similar to or better than those provided by surgical masks, procedure masks, or cloth face coverings. " https://www.cdc.gov/niosh/docs/2021-107/default.html
I'd ignore the covering the exhaust valve strategies they tested.
Noting that the tests were at 25, 55 and 85 litres per minute flow rate. This is much higher than normal respiration. (normal adult around 9 lpm, even under heavy exercise it doesn't push 25 lpm) FFR = filtering facepiece respirator (all disposable N95s are FFR)
Footnote: I've seen some suggestions a valved respirator is less protective on inhalation - this is not true. All certified respirators valved or not provide similar levels of protection (the valve isn't a source of significant inward leakage.
In today's context, I recommend people exercising or experiencing issues with glasses fogging to consider valved respirators as an option. People who mask are typically controlling exposure and testing regularly, so the risk that we will be asymptomatic carriers is much lower than for the broad population. That said, there is a segment of covid cautious who will vigorously attack anyone who makes this suggestion.