Airflow Videos Show Masks with Exhalation Valves Don't Slow Spread of Covid-19
nist.gov
nist.gov
As an aside, if you have a valved N95, just put some duct tape over the valve and voila, unvalved N95.
It's been proved that masks help the wearer too.
It's also being theorised that masks, due to not being perfect, is giving immunity by exposing one to lower viral loads and leading to very mild or asymptomatic disease.
It's an interesting idea "everyone else is responsible for avoiding the invisible thing you're spreading around", interesting in a stupid way, but interesting.
It doesn't contradict the claim in this article, but it's an interesting thing to ponder about the risk of the general public having seemingly all standardized on cotton masks.
A one-way filter does not stop the spread from both sides as well as a two-way filter.
Then again - as long as you're wearing any kind of mask, you're making a difference.
Wear a good one that protects you and others if you want this BS to be over sooner.
Wear none if you want to be that guy in every zombie movie that doesn't take the first infected seriously and dooms the planet.
I get angry that it should even be something to point out, can't people think?
N95 masks are fine, surgical masks are fine, masks with valves (or any other creative form of face covering) are explicitly not.
In the very early days of mandatory masking you could get away with a doctor note. Now you need a negative test not older than 72 hours in addition to a doctors note if you try such shenanigans.
I, for one, agree.
E: Clarification
It seems like this is the year all science is done through videos and diagrams.
It doesn't. The video starts with a good 3 second disclaimer about just this. Either way, I'll bite.
It's been shown that SARS-Cov2 is transmitted through the air[1], amongst other ways.
Visualizing the flow of one person's breath you can identify the route that the breath takes. Generally, if the breath goes past or through a lot of fabric, the larger water droplets tend to stick to the fabric. The virus is usually carried in the air on tiny airborne water droplets. This means that if water droplets stick to the inside of the mask's fabric, a lot of the viruses will as well, thus decreasing the spread. You know a mask works because it feels a bit damp inside. That's a sign of it doing the job.
A mask will not fully "stop" the spread. It helps to reduce the velocity of the air exiting your body, and captures a lot of the water vapor that carries the virus.
> It seems like this is the year all science is done through videos and diagrams.
There is no better way to relay the information gathered through schlieren imaging than to just show the recording. That's why its called "imaging".
The mask is not just about stopping you getting infected by something, it’s also about reducing your ability to transmit it to others. In fact a mask is more effective at limit transmission from you than to you. That’s why we have multiple layers - everyone wears a mask, limits travel, limits exposure to others, ensures as much distance as possible, maximizes the surrounding air volume when in the presence of others, etc.
Masks are better at preventing outgoing transmission than incoming so you’ve deliberately ruined the thing that a mask should be most effective as.
I don't think anyone is saying vented masks are ideal. Though they are probably better than most simple cotton masks, they aren't as good as an unvented N95.
A face shield without a mask is worse than just a mask.
More like: masks with exhalation valves don't slow spread of covid -as well as masks without-.
You are still personally protected just the same. And if you are personally protected, you are less likely to catch the virus and spread it along.
let's say your mask protects you from N% of the droplets you inhale.
and let's say MY mask protects you from N% of the droplets I exhale.
Now, are you more protected if: a. Only I wear a mask. b. Only you wear a mask. c. We both wear a mask.
Obviously, one of us wearing a mask is better than neither of us wearing a mask.
I think maybe the implication is that if the person wearing the mask already has covid, it isn't going to slow the spread to others. Which makes sense. But if you at least wear a valved mask, you will be less likely to catch covid in the first place.