For folks going out to get groceries, will covering the face with any old piece of fabric make a difference? What makes N95 masks CDC approved?
In: Engineering
N95 means that it stop 95% percent of very small (0.3 micron) test particles.
Common fabric used to make fabric masks has fibers much further apart so it isn’t nearly as effective at stopping stuff from moving through the material.
But even a cloth mask can be upwards of 50-60% effective, so it’s hardly useless. In absence of a medical grade mask a cloth one is much better than nothing.
Keep in mind masks are most effective at preventing infected people from infecting others, not preventing healthy people from getting sick. Surgeons primarily wear surgical masks to prevent their germs from infecting patients, not the other way round. But under these circumstances it makes sense for *everyone* to wear a mask to slow infections and protect medical workers that are constantly being exposed.
Making both healthy and unhealthy people wear them is more effective combined that either.
Medical grade equipment that has been tested and used for many years vs getting ready to rob a train on horse back in the Wild West.
N95 masks when used correctly is certified to filter out 95% of all airborne particles. Some factories have designed masks that they can make in the current crisis but it is hard to make masks that filter more then 70% even with a design team having the right tools to measure it and testing out different designs. A makeshift cloth mask is much harder to use correctly without air leaking around it and will also typically have large gaps between the threads for particles to go through. So while it is better then nothing you should not expect it to stop a virus. What is better is if you use something like a paper towel which is pressed and not woven as a filter and the cloth just to keep it in place.
As for the specifics of the coronavirus we do not have any studies showing how effective just a cloth mask can be. We know the virus in itself is not airborne but rather spreads through liquid. However when you breathe and especially if you cough you will release spit into the air which may contain the virus. And it is likely that cloth will be better at stopping these droplets then it is at stopping dry particles. But it is pretty clear that a makeshift cloth mask will help reduce how far you spit when coughing and talking and will also make it easier to not touch your mouth and nose. So there is little doubt that it will help, but not how much.
Any covering is better than nothing. N95 filters 95% percent, surgical masks will cover most but not as much (as long as you’re wearing it correctly), and a cloth mask or scarf secured will precent droplets from leaving/coming into your various face holes. If you’re going out to the store or whatever and keep with the physical distancing of ~6feet, then a cloth mask or scarf should be sufficient. You only really NEED the N95 masks if you’re in direct contact with a contagion routinely or if you test positive.
As other people have stated, it’s about particle size. According to studies, a scarf or bandana does not have the ability to filter out covid-19 for the person wearing it because the virus is very small and those materials are too loosely woven.
The cloth masks people are making, if made of 2 layers of high thread-count cotton (tightly woven cotton), can filter about 70% of covid-19 particles which is pretty good. It’s even better if you use an inner layer of flannel.
An N95 mask filters about 95% of covid-19 particles.
However, they also found that almost any material (as long as it seals around the nose and mouth properly) works well for keeping spit or mucus droplets/covid-19 particles IN if an infected person wears it. This is why they want everyone to wear a mask. Many people are asymptomatic carriers and can be spreading the virus without knowing it.
Further new information has shown that if a covid carrier without a mask interacts with someone who is wearing a mask, there’s still a 70% chance of the mask wearer being infected. Even if you’re wearing an N95, the droplets from the infected person will still settle on your face and clothes where you may unknowingly transfer them.
If the infected person is wearing a mask, and you are not, the risk of you being infected drops to 5%.
If both of you are wearing masks, the risk of infection drops to 1.5%.
Again this is only if the masks are properly fitted to the face with little or no gapping and you still follow all the hand washing guidelines.
The grading of a mask basically tells you how thorough it is at removing particles from the air.
As an analogy, consider a mask like a form of sieve – it stops big particles like fluids passing through, but let’s through smaller particles like air.
A high grade mask like an N95 or better is like a fine sieve – only the finest flour or water will make it through, and any lumps will be filtered out.
A cheaper mask might be like a pasta strainer or colander – it has much bigger holes in it, which means it will stop larger items like pasta, but you will find that smaller stuff like rice may still get through.
With masks were are trying to stop small particles of fluid containing the virus, which can vary in size from what is essentially a gas, to the cloud of snot sent out by someone sneezing.
A cloth mask will help filter out the big droplets but will let through the smaller ones, while a higher grade N95 or similar mask will stop a lot of the smaller ones too.
A cloth mask helps, but N95 will help more.
It is also worth noting that you get lots of other grades of mask out there – everything from masks that will only stop things like sawdust and won’t really help at all against a virus, to a completely sealed suit to protect your against scary chemical attacks. So pay attention to what you are buying and make sure it is suitable.
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