With COVID-19 sweeping the nation and the world at large, people are more worried than ever about their health and personal well-being. Public spaces are no longer safe without some form of Personal Protective Equipment (PPE). While there are various forms of PPE, one of the most common types of PPE for protecting against COVID-19 are surgical masks.
Unfortunately, there’s a lot of confusion over who is supposed to use surgical masks, how much protection they offer, and how they differ from other forms of PPE. More specifically, many people want to know how effective surgical masks are at filtering out airborne particles (especially COVID-19 particles).
In this guide, we will provide a complete breakdown of surgical masks, including the different types, how they should be worn, and their efficacy at filtering out airborne particles. We hope to answer all of your questions so that you can get through the COVID-19 pandemic safely. But first, since it is a common point of confusion, let’s take a look at the difference between surgical masks and non-surgical masks.
Surgical Masks vs. Non-Surgical Masks
There are many different forms of non-medical and medical face masks. One of the most common and popular forms of face mask is the simple cloth mask. Cloth masks can be single, double, or triple layers. As you can imagine, the more layers a mask has, the more effective it will be. That said, cloth masks are generally not used by nurses, physicians, or other medical personnel, as they are not the most effective form of protective face mask.
Non-Surgical Cloth Masks
Non-surgical cloth masks are popular because they are reusable, comfortable, and often feature unique designs. Additionally, cloth masks are widely available at retailers around the country. Moreover, cloth masks are a great option for those who want to stay safe on a budget. There are various online tutorials to teach you how to make a cloth face mask at home with materials you probably already have around the house. However, we recommend using the Center for Disease Control and Prevention (CDC) guidelines if you plan to make your own cloth mask.
Non-Surgical Face Coverings
Though they may not qualify as “masks,” there are various non-surgical face coverings used to protect against COVID-19. For example, many people choose to cover the lower half of their faces with scarves, bandanas, neck gaiters, balaclavas, and other makeshift cloth coverings. However, a Duke University study shows that these solutions are highly ineffective and, in some cases, may do even more harm than good by spreading particles further.
Non-Surgical Face Shield
Another example of a non-surgical face covering is the face shield. Though face shields are used by medical professionals, they only offer some protection against fluid splatter. They offer virtually no protection from airborne particles, as they do not prevent the nose or mouth from inhaling foreign particles. Thus, face shields should only be used as an added layer of protection in tandem with a more effective form of face covering. In fact, the CDC has stated that, as long as you wear some kind of face mask, a face shield is largely unnecessary.
Now that we’ve covered all of the non-surgical masks and face coverings, it’s time to look at surgical masks and what sets them apart from the rest. As the name implies, surgical masks were originally designed so that surgeons would be protected from large particle bacteria and fluid splatter during surgery. They are typically more effective than cloth masks, as they are made from a non-woven, double-layered material that both simultaneously repels fluids and absorbs large airborne particles. However, surgical masks cannot provide 100% protection from airborne particles.
Different Types of Surgical Masks
Despite the name, surgical masks are not just limited to surgeries or even medical procedures. In fact, there are many different kinds of surgical masks, some of which are not suitable for a surgical environment at all. So, let’s take a closer look at the different types of surgical masks and how they are used:
2-Ply Surgical Masks
If you’ve ever watched a TV medical drama or seen medical workers on the news, you’ve probably seen some form of the standard, 2-ply surgical mask. However, they are not just limited to medical personnel. Surgical masks can be worn in any medical environment or, in the case of COVID-19, in any public area.
As the name implies, 2-ply surgical masks have two layers. They are typically blue or green on the outside and white on the inside. The exterior layer is made of a non-woven polymer material that repels liquids (typically polypropylene), while the interior layer serves as a filter for large airborne particles.
2-ply surgical masks require fewer materials and are therefore cheaper and faster to produce than more protective masks. However, this also means that they are not the most effective type of surgical mask. As a result, these masks are often reserved for non-surgical environments. For example, a dentist might use a 2-ply surgical mask while cleaning a patient’s teeth.
Alternatively, a nurse might use a 2-ply surgical mask while checking patients into a medical facility.
2-ply surgical masks do not fit tightly over the face, though they do completely cover the mouth and nose. They are intended to provide ease of use, comfort, and moderate efficacy. However, 2-ply surgical masks are single-use only. They cannot be washed and can only be used one time. While there’s no set time period after which you must replace a 2-ply surgical mask, it is generally a good idea to replace it if you feel that it is wet or has somehow been contaminated.
3-Ply Surgical Masks
3-ply surgical masks use the same concept as 2-ply surgical masks, but they have an additional layer of protection. These surgical masks are sometimes known as “procedure” masks. With a 3-ply mask, there is a middle layer that electrostatically absorbs particles to provide a much higher level of filtration and protection. Though 3-ply surgical masks cannot provide 100% protection, they are far more effective than 2-ply masks. As a result, surgeons and physicians who might be exposed to fluid splatter or airborne particles typically use 3-ply surgical masks.
Just like 2-ply surgical masks, 3-ply masks do not fit tightly over the face. They are easy to put on and remove, while also providing a high level of protection and moderate comfort. Additionally, 3-ply surgical masks are single-use only, so you cannot wash them or use them more than once.
N95 Masks (And Above)
Though N95 masks are distinct from standard surgical masks, they can (and are) used in surgical settings. N95 masks provide some of the greatest protection from fluid and airborne particles. Unfortunately, there is a worldwide shortage of N95 masks due to the COVID-19 pandemic. As a result, they are generally reserved for medical workers. Since surgical and non-surgical masks provide good protection in public settings, it is not necessary to wear an N95 mask outside of a medical setting.
N95 masks are named for their filtration efficacy. As the name implies, N95 filters out 95% of airborne particles. This is significantly higher than cloth masks and even most standard surgical masks. That said, N95 masks are made using many of the same materials as traditional surgical masks. The primary differences are that N95 masks fit tighter against the face, have additive protection, and are designed to filter out both large and small air particles.
In addition to the N95, medical workers can also use the N99 and N100 masks. Though less common, these masks offer nearly 100% protection against airborne particles. The average consumer does not have access to these kinds of masks, as they are exclusively reserved for medical personnel.
How to Measure Surgical Mask Efficacy
Since there are different types of surgical masks, there has to be a system to measure the efficacy of different masks. Generally, this process involves several important metrics:
- Fluid Penetration Resistance
- Vapor Permeability
- Water Repellency
All of these factors contribute to the overall performance of a surgical mask. However, the efficacy of filtering out airborne particles mostly depends on just two of these factors: filtration and exposure. Both of these factors can be measured using a system known as Particle Filtration Efficiency (PFE). According to Nelson Labs, PFE “involves the generation of a particle aerosol using NIST traceable polystyrene microspheres with a Particle Measurement Systems (PMS) Model PG-100 particle generator. The particles are counted with a PMS Model LASAIR II-110 or 310 laser particle counter.”
In laymen’s terms, airborne particles are generated and sent through a surgical mask. The number of particles recorded after penetration of the mask is divided by the total number of particles generated. This leaves researchers with a percentage that estimates the approximate percentage of total particles that a surgical mask is capable of filtering out or repelling entirely.
How Effective Are Surgical Masks at Filtering Out Airborne Particles?
While the testing system outlined above determines how effective a surgical mask can be, it doesn’t determine why some masks are more effective than others. There are three primary factors that contribute to efficacy: materials, additives, and the filtration process. First, let’s evaluate how materials can affect the performance of a surgical mask.
Surgical Mask Materials
According to a recent study on mask filtration efficiency, the most common materials used to produce surgical masks are polymers like polypropylene. Polypropylene treated with dimethyl-dioctadecyl-ammonium bromide can even help attract bacteria and catch them in the filtration process. For the purposes of this study, researchers tested four different materials: polypropylene fiber, polyester rayon fiber, glass fiber, and cellulose fiber. The experiment showed virtually no difference between polypropylene fiber and polyester rayon, though both materials outperformed glass fiber and cellulose fiber.
Surgical Mask Additives
N95 masks are more effective than standard surgical masks for several reasons. In part, they perform better because of several additives. A traditional 2-ply or 3-ply surgical mask is simply a rectangular material that covers the mouth and nose. Alternatively, N95 masks have additives like nose foam, a metal nose seal, a plastic face seal, a PVC exhalation valve, and up to six protective layers. Without these additives, filtration and exposure performance declines.
Surgical Mask Filtration Process
There are five primary processes for mask filtration: gravity sedimentation, inertial impaction, interception, diffusion, and electrostatic attraction. Gravity sedimentation and inertial impaction filter particles based on size, making these processes most effective in protecting against larger particles. Interception involves the interaction between a particle and the filtration material, catching small to medium-sized particles. Diffusion is the most effective method for capturing smaller particles. Finally, electrostatic attraction works to catch both large and small particles by attracting them to the filter.
Surgical Mask Efficacy
Assuming that you are wearing a mask correctly and practicing other safety procedures (social distancing and proper hygiene), traditional surgical masks can filter out about 50%-70% of airborne particles. According to a 2011 study of healthcare workers, those wearing standard 2 or 3-ply surgical masks were twice as likely to experience a respiratory infection than those wearing N95 masks, which filter out 95% of airborne particles.
In addition to the materials, additives, layers, and filtration processes, the efficacy of a surgical mask can also depend on your behavior. If you wear a surgical mask incorrectly, it could filter out no particles at all. For example, some people wear their mask over their mouth, but not their nose. Unfortunately, this could expose them to COVID-19 and other airborne diseases. Additionally, if you frequently touch or adjust your mask, this could increase the risk of airborne particles reaching your mouth or nose.
Medical face masks prevent disease by protecting the wearer from fluid splatter, large airborne particles, and some smaller particles. As a result, medical-grade surgical masks are one of the best methods for protecting yourself against COVID-19. However, surgical masks are not 100% effective. Even N95 masks, which are some of the most effective masks available, filter out about 95% of airborne particles. The best cloth masks only filter out somewhere between 30%-70%. Surgical masks generally fall somewhere in the middle, offering between 50%-70% protection. However, depending on the material and filtration process used, it could provide even greater results.