We can all help curb the spread of the coronavirus by wearing masks. The key is that we all need to participate in order for this to work. This is because the main reason for wearing a mask is to protect others from you. People without symptoms are known to cause spread of the virus so collectively if we all wear masks to protect other people and everyone is wearing masks, then we are all can be protected. Of course there is not 100% protection; the type of mask, and the other components of social distancing of 6 feet and avoiding crowds, frequent hand washing, and avoid touching the face (mouth and nose) need to be in practice as well.
In choosing a mask 3 important things to consider are fabric, fit, and functionality or breathability. The fit and seal on your face is essential for adequate protection against the release of respiratory droplets and also from particles that you breathe in in the case of using an N95 mask for individual protection. Of course functionality or breathability is key; the seal on your face is secondary if you actually can’t breathe through the mask well enough without struggling. The main non-medical grade masks that are available today include cloth masks made from fabric with or without other multiple layers of other material or a cloth neck gaiter. Medical grade masks include N95 respirators, KN95 respirators, and surgical masks.
The World Health Organization is now recommending masks and you can find the detailed guidance here. The tightness of the weave is very important. If you hold up the mask to the light and can easily see the outline of the individual fibers, then you know that mask is not going to filter out much. A tight weave 100% cotton would be a good fiber. Cotton fibers that a three dimensional structure which adds some texture to aide in blocking particles; versus the synthetic fibers which are smoother and more two dimensional. A study in ACS Nano found most synthetic fabrics rank poorly, there were 2 including a an 100% polyester that did well.
Multiple layers may also help like placing a filtering material like polypropylene in between two layers of a tight weave fabric. At Walmart they sell Oly-fun which the brand name of the fabric. It’s also called spunbond. Polypropylene is not just a physical filter but it also holds an electric charge which means it can have static electricity. We all remember static cling when we rub 2 pieces of fabric together and then they stay together. The principal of the electric charge holding on to things , in this case droplets that are either coming or going is an important added benefit to this fabric. It is rather unique in that the electrostatic charge is maintained even with the humidity of your breath as you exhale. After washing the fabric you can recharge it by rubbing it with a plastic glove for about 20 seconds. A 2 layer tight weave cotton mask can filter out 35% of small particles. Adding a filter made of 2 layers of charged polypropopylene could boost filtration by another 35%. Of course, having another cotton layer touching your face brings the most comfort. In a pinch, you could use 2 sheets of facial tissue instead but there won’t be any electrostatic charge benefit. Having 3 or more layers of cotton can also make a good mask.
Masks with pleats or folds are better because there is more air flowing through the fabric itself than leaking out through baps at the sides of the mask Adding a layer of pantyhose can also help force particles to through the mask rather than going around it. You can cut a an 8-10 inch length of hose from top to bottom from one leg of a pair of house and pull this on top of your mask.
People have tried neck-gaiter masks or buffs as well. They are made of synthetic material that wraps around the face, covering the nose and mouth and in theory may limit air escape around the sides which can happen from wearing masks. Masks that have exhalation valves allow easier exhalation but also releases unfiltered air so you’re not protecting others if you happen to be contagious.
Cloth masks need to be washed daily with soap or detergent and hot water. They need to be completely dry before wearing it again so that you can efficiently breathe through it. Also fungi and other microorganisms are less likely to grow in a dry mask.
Medical grade masks include N95 respirators which are designed to create a tight seal around the nose and mouth. With a good seal, 95% of small airborne particles are blocked. Both the wearer and the people around a protected. The mask is made of fine polyoproylene fibers which are electrostatically charged as previously discussed and trap incoming and outgoing particles and droplets.
KN95 respirators are made in China and regulated by the Chinese government. They are supposed to filter out 95% of small airborne particles as well but quality standards vary widely and there are many counterfeits so they are not used by healthcare workers in general.
The N95 masks are still in short supply and needed most by healthcare workers so the cloth masks are the first line recommendation for the general public. But even if you have access to one you still need to practice safe social distancing, frequent hand washing, and avoid crowds. Also, you need to remember even at peak efficiency these masks are not meant for protection over a prolonged exposure time, for example, it is most effective in short exposures blocking particles out but over a long period (hours) of continued exposure in tight indoor spaces there may be limitations.
Surgical masks are disposable masks designed to protect the wearer from large particle droplets or fluid splashes in the air and not very small particles. Most are made of paper with a few brands made of polypropylene. They can block the majority of respiratory droplets emitted from an infected person if properly worn but in general it will not protect the wearer from inhaling small droplets or particles like an N95 respirator. Depending on the material, manufacturer, and shape of the mask they can block around 30% of small particles up to 80% of particles.
The most important thing to remember is that the mask is only part of the whole ritual to slow down the spread of the coronavirus. The main purpose is to reduce the spread to others in the event you have the virus but do not have any symptoms. The other aspects of this new ritual include social distancing both keeping 6 feet away from others and avoiding crowds (especially indoors), frequent hand washing, and to avoid touching the face. Hopefully, with the participation of everyone we can slow the spread of the virus and keep the most vulnerable safe.