Why Are Masks and Physical Distancing Effective?
Overview
As the WHO declared COVID-19 a global pandemic, face masks became a new normal almost overnight. Additionally, we started to maintain 6ft. distance between each other in a practice known as physical distancing. These were due, in part to a global strategy to minimize the transmission of COVID-19. Stores began requiring the use of a face mask. And soon after, state governments were doing the same thing. Alongside these requirements, steps were implemented to ensure proper mask usage. However, there was a lack of explanation as to why masks are effective. This article will outline several reasons why masks and physical distancing are essential steps in stopping the transmission of COVID-19.
Viral Transmission
In order to understand the effectiveness of preventative measures, it is important to understand how viruses are transmitted from person to person. SARS-CoV-2 spreads by respiratory droplets, or small wads of moisture, released from talking, coughing, sneezing, etc. These droplets travel through the air until they find a new surface to land on. A new infection can begin when the virus lands in someone’s mouth or nose nearby or inhaled by the lungs.
Physical Distancing
The specific value of 6 feet (or 2 meters) is no arbitrary number. In fact, when respiratory droplets are released into the air, most droplets fall to the ground within 6 feet of the infected individual due to their weight. Any person within that distance is coated with viral particles, inevitably infecting them. By maintaining 6 feet (or 2 meters) for physical distancing, this allows room for most of the virus to settle to ground and to, ultimately, minimize transmission risks.
The droplets that do not fall to the ground evaporate creating aerosolized microdroplets. These tiny balls of infection can suspend in the air and travel with currents much farther than 6 feet. Masks help prevent the aerosolization of respiratory droplets.
Masks Prevent Aerosolization
A common counter-argument to masks is the fact the SARS-CoV-2 virus is smaller than the filtration size of the mask weaving. Intuitively, this would make a mask ineffectual. However, with a mask, within the warm, humid space between the fabric and the mouth/nose, respiratory droplets do not have enough time to evaporate. The size of respiratory droplets is, in fact, larger than the filtration size of masks, preventing the aerosolization.
Masks Reduce Particle Momentum
Whether it be breathing, talking, coughing, or sneezing, air particles leave the mouth and nose at large speeds that propel the viral particles for long distances. Face masks act as a barrier that don’t stop the movement of air flow, but reduce the speed at which they travel. Although this does not stop the aerosolization of viral particles that escape, it does prevent them from travelling long distances.
N95 Masks Trap Small Particles
This might sound counterintuitive but if the mask acts like a strainer, how can they filter out the smallest particles? Well, a mask isn’t like a strain. It should be considered more like a spiderweb. At such small scales, molecules become attracted to surfaces due to Van Der Waals forces. Essentially, it is electrical forces of neutrally charged molecules.
In order for the mask to trap particles, the particle must come into contact with the fibers of the mask. Large airborne particles have enough inertia to travel in a straight line. At one point or another, most large particles will come into contact with a fiber. As size decreases, the inertia also decreases. Small airborne particles have minimal inertia, where they are bounced around by larger air molecules. This random motion, again, almost guarantees contact with a fiber.
A problem arises with medium-sized particles. The amount of inertia is too much for them to be bounced around, but too little for them to travel in a straight line. Instead, they travel with the air as it flows around fibers, causing them to dodge multiple layers of fibers.
N95 Masks Are Electricized
No, an N95 mask cannot shock you, unless it has static electricity. Electricized means that the material in question has been given electrostatic properties, similarly to magnetization of a metal. These electrical forces attract particles to the surface of the electricized material. With the same properties of trapping particles, electricized fibers can attract all particles. This is a solution to the limited filtration of medium-sized particles based on inertia.
The electrostatic properties of an N95 mask can easily be damaged by improper cleaning. This is why they are meant to be disposable. Although, in other CScreener articles, it is stated that the CDC had no recommendation for the use of Ultraviolet Sanitization, this method shows promising results as a moderate decontamination process due to the high demand among healthcare professionals.
N95 Masks Protect the Wearer
Each of the previous reasons for mask effectiveness are made from an assumption that the wearers are infected. However, N95 masks also offer some benefits for the healthy wearer. There are several attractive layers of fabric that viral particles need to pass in order to escape the mask. If two people are wearing masks, the viral particles have to bypass several more layers before reaching the healthy person.
For surgical and clothe masks, their level of protection for the wearer is minimal. In order to combat the N95 mask shortage for healthcare professionals, we encourage users to use surgical and clothes masks.
Conclusion
Based on the transmission rate of SARS-CoV-2, masks and physical distancing are preventative measures that block the flow of viral particles. Moreover, with modifications, masks are enhanced with properties to improve effectiveness. By design, these mechanisms are not arbitrary for slowing the spread of COVID-19. It is essential that masks and physical distancing are combined as preventative measures and practiced as regular habits for most individuals in a population in order to capitalize on the highest effectiveness and stop the spread of COVID-19.
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