A mask may not protect the wearer, but it will help prevent the wearer from spreading the virus to other people.
Masks prevent respiratory droplets (produced by talking, coughing, and sneezing, for example) from spreading germs to other people. Some people find typical masks uncomfortable because they can trap moisture against the face and may opt for ones with one-way valves or vents. Unfortunately, this creates an effective channel for exhaled droplets to reach others, defeating the purpose of the masks. This is why the CDC recommends using masks without an exhalation valve or vent.
Masks alone are not enough.
You can reduce the spread of SARS-CoV-2 by wearing masks in addition to practicing other preventive measures, such as social distancing, frequent and effective handwashing, and cleaning and disinfecting frequently touched surfaces.
Surgical masks are ONE-WAY.
Let me repeat that one more time for emphasis. Surgical masks are ONE-WAY. The concept of flipping the mask based on situation is a MYTH. If you wear the mask inside out, it’s not going to help anyone.
Why are they one-way? Surgical masks can’t be reversed because they have three specialized layers. In the name of science, I dissected one so I could show you.
Zoomed in view of the stitching that keeps the 3 layers of a surgical mask together.
Dissected surgical mask, side view.
These handy little forms of PPE (personal protective equipment) are specifically designed to protect a patient on the operating table from the respiratory droplets of a surgeon, who is breathing, talking, and potentially sneezing above a patient’s open abdomen/brain/etc. They do this by intercepting and diffusing those droplets and by minimizing lateral dispersion (sideways spread). First, droplets are captured by a water-loving absorbent layer, typically white. Anything that makes it beyond this layer is then filtered out (remember, these filters won’t trap viruses because they are really tiny). If a droplet isn’t caught by the filter, it hits the final, water-repellant exterior layer, often blue or green, which further helps to minimize the chance it will spread to those around the wearer. These masks are not intended to protect the wearer.
Outside – water repellent
Middle – Filter
Inside – water absorbent
What happens if my mask is inside out?
If your mask is inside out, the moisture repellant side is up against your face. When you exhale, water vapor won’t be absorbed by the mask and it will become wet. The mask then loses its ability to efficiently filter and trap droplets and you will likely find the damp mask pretty uncomfortable. With the mask inside out, the absorbent layer now faces the environment and has become a droplet landing zone. If you touch the contaminated exterior of the mask and then touch your face, or re-use the mask instead of replacing it, you increase your chances of getting sick. This virus is already super effective at spreading; let’s not make it even easier!
Masks don’t work when:
- dirty or wet
- upside down/inside out
- not covering your nose or your mouth completely
Under any of the above conditions, the filtration efficiency and protective capability of the mask is compromised.
Didn’t the CDC say NOT to wear masks?
Yes, but here’s why. Previously, the CDC and the WHO recommended that only those with symptoms should wear masks. They’ve since modified this recommendation because:
- SARS-CoV-2 can be spread by asymptomatic individuals or before symptoms appear
- Surgical masks are prioritized for healthcare workers coming into contact with many patients
You should still prioritize surgical masks for healthcare workers. Cloth masks, however, are more effective than not wearing anything — although not a substitute for social distancing, not touching your face (cloth masks also provide a tactile reminder not to touch your face), and frequent hand washing.
- Wear a mask that properly fits, and in the right orientation.
- Don’t wear masks with exhalation valves/vents.
- Always practice social distancing and hand hygiene. Wearing a mask is not a substitute for these behaviors.
- Don’t touch your face!
A final note
I don’t need to tell you that this pandemic has been difficult for so many people. Everything about our daily lives and how we provide for ourselves and our families has been affected. The disproportionate effect of COVID-19 on certain racial and ethnic minority groups has led to increased awareness of systemic racism and inequity, from housing to education and everything in between. If you don’t consider this virus a serious problem, I urge you to thoughtfully reflect on what privileges you may knowingly or unknowingly hold, and how no individual experience is reflective of our country as a whole. If you’re in a position to doubt whether or not this is a big deal, you may not recognize how fortunate you are to have some degree of financial stability or greater access to health care that others do not. I urge you to trust evidence-based science and to trust your public health officials. Please protect yourselves and others by observing the rules of masks, distance and hygiene.
Do you have questions, comments, or suggestions for my next experiment/dissection?
Email firstname.lastname@example.org or comment below!