We are living in strange times these days, having radically shifted our behaviors and lifestyles in response to the COVID-19 pandemic. These times can also be very confusing, as recommendations for best practices are evolving as the virus spreads and we learn more about it. One of the recommendations that has changed is regarding the wearing of masks for the general public. Before, we were saying “don’t bother wearing a mask” and now we are saying “yes, please wear a mask in public.” So why this change, and what does it mean for you?

First, let’s consider the two possible primary functions of a mask in the context of infectious respiratory virus:

  1. The mask wearer is infected, and the mask serves to block their respiratory particles from being expelled into the air, where they could infect an uninfected individual
  2. The mask wearer is uninfected, and the mask serves to block incoming virus that has been expelled from infected individuals 

There are different types of masks, which have varying degrees of filtration capabilities and therefore provide different levels of protection (Fig 1).

Figure 1: Different types of masks offer different levels of protection


Why were we initially advised against mask wearing? 

When COVID-19 was first reported in the US, our population was mostly uninfected and we hadn’t yet observed significant community spread. At this time, the wearing of masks was not encouraged for a few key reasons:

  1.  While N95 respirators are highly effective at protecting uninfected individuals, they are not practical for public use because they require a proper fit, are uncomfortable, and are in incredibly short supply.
  2.  Regular surgical masks are fairly effective in preventing infected individuals from spreading virus, but early on most individuals were not infected. These masks are also limited in supply.
  3.  Given the supply limitations, these masks should be prioritized for use by healthcare workers who are at the highest risk and are in much greater need of protection.

Why are we now being asked to wear a mask?

It has become increasingly apparent that the majority of the population is going to be infected with this virus at some point, which is a big shift in perspective from thinking about a largely uninfected population. Perhaps even more importantly, it has become clear how easily this virus can be spread by individuals who are infected but are not showing noticeable symptoms. Thus, it has become imperative for each and every one of us to take precautions as if we were infected and shedding virus particles in our breaths, coughs, and sneezes. These shed virus particles can lead to transmission if they are directly inhaled by an uninfected individual, or if they land on a surface which an uninfected person touches and then transmits to themselves by touching their eyes, nose, or mouth. Wearing a mask can reduce the shedding of virus particles from infected individuals, which is is one way we can help decrease the chances of an uninfected person getting sick (Fig 2).


Figure 2:
Wearing a mask can reduce the spread of potentially infectious respiratory particles into the atmosphere (image created using BioRender).


Now that we have been asked to wear masks, what kind of mask is best? 

While in an ideal world, an N95 respirator or surgical mask would offer the best protection, as described above these masks are in short supply and need to be prioritized for use by healthcare workers who need them the most. Thus, the recommendation for the general public is to make and use masks from supplies found at home. While fabric or other homemade masks are not as effective as surgical masks, especially when it comes to blocking small virus particles, they can still minimize the extent to which larger droplets from a potentially infected person are expelled out into the atmosphere when that person talks, exhales, coughs, or sneezes. If you have stockpiles of N95 respirators or surgical masks at home, please donate them to your local hospital or healthcare facility and use a homemade mask for yourself instead.

What do I need to know about wearing a homemade mask?

Wearing a mask can feel a bit uncomfortable, so you may want to practice wearing your mask for short periods of time at home before going out for extended periods of time. You will need to adjust to the sensation of pushing your breath through a physical cloth barrier. 

When wearing your mask, make sure the mask covers your face well from above your nostrils (around the bridge of your nose) to below your chin. Any mask that does not completely cover the mouth and nose is not effective. When wearing your mask, do not ever pull it down under your nose or mouth. In fact, when wearing your mask, do not touch it with your hands at all! Handling your mask while in use may increase your risk of transmitting virus either to you or to your environment. All adjustments to your mask should be made before you leave your house to ensure it is securely in place. Ideally, the mask should form a tight seal around the bridge of your nose, your cheeks, and under your chin.

How do I properly take my mask on and off?

It is important to be mindful when putting on and taking off a mask. When putting on a mask, first make sure your hands are thoroughly washed. Lift the mask by the ties or elastics on the side and secure it onto your ears or head so that the front of the mask is over your nose, mouth, and chin. If additional adjustments are needed, tug the top or bottom edge of the mask to ensure your nose and chin are well covered. If your mask has an adjustable nose piece, press it into the shape of your nose with your fingers. Avoid touching the front of the mask while putting it on as well as when taking it off. Once your mask is on and properly adjusted, do not touch it until you are ready to take it off.

To remove the mask, use a similar strategy as before. After thoroughly washing your hands, undo the mask straps and hold onto those as you lift the mask away from your face. Again, do not touch the front of the mask. If your mask is not reusable, dispose after use. If you have a reusable fabric mask, machine or hand wash it in hot, soapy water. Either way, wash your hands thoroughly once more after handling your used mask.

How do I make a mask?

There are many ways to make a homemade mask depending on the resources you have available. The two main features that will determine the efficacy of your mask are the material the mask is made out of and how well it fits around your face.

If you are going to make your mask from fabric, choose a tightly woven, high thread count fabric without a lot of stretch. Dish towels, pillowcases, and cotton T-shirts are some of the best materials you can find at home to fashion a mask out of. For a disposable mask, blue shop towels are a great choice if you have them handy, and have even been shown to be more effective than cotton masks. Other home and office supplies like hair ties and paper clips can be used to help improve mask fit and secure it to your face.

There are many tutorials online available for sewn fabric masks, no-sew fabric masks, and disposable masks. It’s just up to you to decide how you want to make your mask and get started!

What now?

Remember that wearing a mask helps reduce spread, but it does not offer full protection either for you or for the world around you. Mask-wearing is just one way we can reduce risk; it is important to continue to adhere to all other risk-reducing safety recommendations. Follow shelter-in-place orders, maintain at least six feet of distance between yourselves and others, do not touch your face, and regularly wash your hands thoroughly. If we each perform our due diligence in following all of these precautions to the best of our abilities, we will be able greatly slow and reduce the spread of COVID-19.


Dr. Noll and Dr. Blake are recent graduates from UNC Chapel Hill. Dr. Noll studied the role of host genetic variation on influenza susceptibility while obtaining her degree in microbiology and immunology. Dr. Blake studied adverse human health effects associated with exposure to common environmental contaminants while earning her degree in toxicology. Both are avid science communicators!


2 Replies to “On mask-wearing in the age of COVID-19”

  1. Thank you so much for the detailed information particularly about the wearing and removing of the mask. I have been making them and will share the info with mask buyers.

Leave a Reply

Your email address will not be published.