The Science Behind the Use of Face Masks

Medically reviewed by Dr. Jen Taylor
Medically reviewed by Dr. Jen Taylor on September 16, 2020
Naturopathic Doctor
Updated on April 22nd, 2021

Face masks have become part of our daily lives in 2020. As the country returns to in-person social interactions within schools, colleges, office spaces, and travel, you may be wondering how well your face mask protects you from SARS-CoV-2 while diminishing the spread of COVID-19.

You will learn a little bit more about the science behind wearing a face mask and how SARS-CoV-2 is spread in this article.

COVID-19 Stands for CoronaVirus Disease(1), first identified in 2019 caused by the virus: SARS-CoV-2. Infection may trigger severe acute respiratory illness, fever, cough, myalgia (muscle aches), fatigue, and many other variable symptoms.

Human-to-human transmission of SARS-CoV-2 is possible anytime people talk, breathe, cough, or sneeze because these actions cause droplets and aerosols that can spread the virus from person to person.

While droplets are larger particles that fall faster and thus do not spread as far, aerosols are smaller particles that may linger in the air and spread further from the point of origin.

While there is an argument that aerosols may cause a greater risk of transmission, viral spread tends to lessen with aerosols because of dilution and inactivation of viruses while suspended in the air. However, aerosols tend to be inhaled easier and travel deeper in the lungs, which increases the risk of contracting the SARS-CoV-2 virus.  

[Also Read: How to Wear a Face Mask: Dos and Don’ts]

How effective are face masks against COVID-19

Because of the droplet and aerosol transmission, scientists have not understood the efficacy of personal protective equipment in lessening the transmission of SARS-CoV-2. Inanimate objects such as door handles, pens, chairs, etc. are also known as fomites and can also harbor droplets that can transmit viral particles.

Fomites do this in two distinct ways: spreading the virus to a new host through direct contact with the contaminated object (such as sharing a pen) and generating aerosols that linger in the air. Common aerosolization methods include fast running tap water, toilet flushes, and certain medical/dental procedures.

Studies have shown that particles may remain viable in aerosols for 3 hours and 72 hours on some surfaces such as plastic and glass. At present, the scientist has not determined the minimum viral load (amount of virus particles) necessary for SARS-CoV-2 infection.

However, it has been suggested that anything that reduces viral load might be useful in reducing the chance of infection and the spread of COVID-19.  

Protective Face Masks are the most common personal protective equipment used to decrease droplets’ spread in the air. There are three major types that are being used in the United States of America: Homemade masks, surgical masks, and N95 masks. The use of masks addresses two concerns.

A mask will reduce the number of droplets and aerosols going into the respiratory tract of a susceptible host and will also control the droplets and aerosols coming out of an infected patient to lessen the spread of particles containing viruses.

The efficacy using masks depends on the type of mask and assuming that the mask is worn properly. Studies have shown that surgical masks are 2-3 times better at controlling viral transmission than a typical homemade mask.

The N95 / FFP2 (Europe’s equivalent of the US N95 mask) provided about 50 times more protection than a homemade mask and 25 times more than surgical masks.

However, no mask is guaranteed to fully prevent SARS-CoV-2 transmission, so social distancing is recommended for protection and limiting spread.

Masks can make a difference in keeping you healthy during this time. When an infected person with COVID-19 sneezes or coughs within a meter of you and they are not wearing a mask, you are likely to inhale the highly contagious virus and become infected due to the amount of particles inhaled.

If you are wearing a surgical mask, you inhale approximately 20-30% of the viral load compared to not wearing a mask. Infection is still possible, but less likely.

Likewise, if you are wearing a N95 mask, you may inhale less than 5% of viral load compared to not wearing a mask, and the possibility of infection is significantly reduced. 

[Also Read: Best Types of COVID-19 Face Masks]

Popular myths about Masks

1. Masks reduce oxygen intake and prevent carbon dioxide from escaping.

  • Nope – oxygen is 0.120nm, and carbon dioxide is 0.232nm. N95 mask pores are about 100-300nm, meaning a single pore allows over 1500 molecules of oxygen to enter and over 850 moles of carbon dioxide to exit.  
  • Coronavirus particles are about 120nm. Compared to oxygen, they are 1000 times larger.
  • Masks are remarkably effective at blocking droplets, which have average sizes between 1000 and 10000nm.
  • Galen Rupp ran 28:38.17 to win the 10,000m race at the 2011 USA Track & Field Championships wearing a mask due to allergies. This is a pace of 4:34 per mile for over 6 miles.  

2. You do not need a mask if you are social/physical distance.

  • Sneezes may project larger virus-laden droplets upwards of 6 meters in horizontal distance from their point of origin.
  • Other studies have shown that when an infected person coughs/sneezes, a cloud of viral-laden droplets appears to come out and may travel 7-8 meters from the point of origin.

3. Masks only help if someone has symptoms.

  • Nearly half of all infections are caused by people who are pre-symptomatic (positive for COVID-19, but have not developed symptoms yet), or asymptomatic (positive for COVID-19, but not showing any symptoms).

4. Wearing a mask will weaken the immune system

  • Your immune system has been exposed to hundreds of thousands of foreign particles called antigens throughout your life. It recognizes these antigens and applies the appropriate response, or it develops a new response if it is a brand-new antigen to your body.
  • Even if your mask filtered out 100% of all antigens, which is not possible with the typical mask, your immune system would still be kept strong because viruses and bacteria can still enter our food and drinks.

About The Author:

Jen TaylorDr. Jen Taylor is a licensed Naturopathic Doctor from Rochester, New York. Her interest in health and wellness stemmed from her experiences as a youth and college athlete.

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