The public health messaging on masks has been very confusing and has changed a few times. This will be a short clarification of the current thinking on masks.
First key point that we have learned during this pandemic is that masks seem to work to prevent transmission. How well they work, and who they work for, depend on the type of mask. Protecting the wearer is called “inward protection” and protecting others, “outward protection.” Much of what we think currently has been informed by simply comparing the slower spread of COVID19 in mask-wearing countries (Japan, China, South Korea, other eastern counties with a culture of mass masking) vs non-mask-wearing countries (generally western countries). There are ideas about why this works biologically, as well as epidemiologically (in the public health realm).
Masks are rated in studies by how many viral particles out of 100 would leak through if exposed.
Inward protection (protecting yourself): 1. FFP2/N95: The highest level of protection is this healthcare-grade mask. It blocks 99% (allows through 1% particles) when it is professionally tailored/fitted. Healthcare workers go through a mandatory custom fitting every year in order to work in the hospital, and having done it myself I can tell you it is complicated to seal the mask correctly. Fitting usually take 30 minutes per person and involves standing under a hood, and testing various smell/taste aerosols to be sure there is no leak. If worn correctly for 12 hours, the wearers face would be at a minimum indented/irritated. Pictured of Italian and Chinese doctors show facial bruising at contact points with the mask.
The public is being asked NOT to purchase these because there are shortages for front-line doctors, nurses, pharmacists Keeping them healthy is the key to keeping us all healthy.
2. Surgical/”Tie-on”: These block 75% of viral particles from entering. That is actually quite impressive for such a small intervention. They are what the public is being asked to wear.
3. Homemade/Cloth masks: While variable in fit and quality, those homemade cloth masks tested blocked 67% of viral particles from entering in studies.
Outward protection (protecting your community from yourself):
Before we discuss outward protection, something needs to be very clear. We have learned from countries that test everyone regardless of symptoms that THE CORONAVIRUS PANDEMIC IS BEING DRIVEN BY PEOPLE WHO FEEL HEALTHY BUT ACTUALLY UNKNOWINGLY SPREAD THE VIRUS. This was initially a theory, but now it is a fact. Thus, wearing masks decreases the spread in the community. And while inward protection is our gut concern, outward protection is the thing that will get us out of quarantine and allow the world to restart.
1. FFP2/N95: Prevent 70% viral particle spread. But again, these must be reserved for healthcare workers right now.
2. Surgical/”Tie-on”: Prevents 50% viral particle spread. This is what the public is being asked to wear. Preventing half of spread would slow the pandemic greatly.
3. Homemade/Cloth masks: Prevents 10% viral particle spread.
In short, we as a society need to shed our attitudes that masks are frightening, or ineffective, or indicate the wearer is ill. Instead, we need to accept that we are learning that masking can be effective, should be used by those feeling well, and are another way we can contribute to curbing the pandemic. We should not be buying specialty (FFP2/N95) masks out from under the healthcare workers who need them, but if you can get a cloth or surgical mask and wear it whenever you leave your home, it will protect you and those around you.
