This is Part 4 of a series explaining the COVID-19 pandemic. Please consider starting at Part 1: What is a virus or check out the whole series by clicking the button below.
A Brief History of Mask Usage
Today it’s common knowledge that microorganisms such as bacteria and viruses may cause disease in plants and animals (including humans). But a few centuries ago, the causes of infectious diseases and their methods of transmission were not known. Here is a brief summary of how our understanding of disease transmission has evolved and how science proved that something as simple as wearing a mask helps to prevent the spread of disease.
17th Century
Many of the top scientists of the era believed that disease was carried by bad smells or “miasmas”. As a result, their strategy to avoid spreading disease revolved around the avoidance of bad smells.
The first masks appeared during the later waves of the bubonic plague. A French doctor, Charles de Lorme, designed a special suit for physicians treating plague patients. It consisted of a large leather tunic, gloves, boots, a hat, and a mask in the shape of a bird’s beak that contained aromatic herbs.
.png)
Plague Doctor, Rome, Circa 1656 via Wikipedia
Even if the doctors of that time did not know the actual cause of disease transmission, this attire played a part in protecting them from the plague. The leather protected them from disease-carrying fleas, the gloves prevented direct contact with patients, and the herbs in the nose had antiseptic properties, thus neutralizing bacteria passing directly from one individual to another.
19th Century
In the mid-19th century, French chemist and microbiologist Louis Pasteur showed that fermentation and putrefaction are caused by organisms in the air. Later in the 19th century, scientists including Pasteur, Lister, and Koch proposed theories that living organisms called germs were responsible for causing and spreading disease.
“Germ theory, in medicine, the theory that certain diseases are caused by the invasion of the body by microorganisms, organisms too small to be seen except through a microscope.”
-Britannica.com
This theory revolutionized the human understanding of infectious diseases and toppled the miasma theory. In 1870 John Tyndall, an Irish physicist, presented a paper to the Royal Institution in London in which he demonstrated that dust in the air could contain germs and disease and that a cotton-wool respirator could filter them out. Applying his research, he developed a much-improved gas mask for firefighters.
“If a physician wishes to hold back from the lungs of his patient, or from his own, the germs by which contagious disease is said to be propagated, he will employ a cotton wool respirator … Such respirators must, I think, come into general use as defense against contagion.”
-John Tyndall, On Haze And Dust
20th Century
During the early 20th century, various types of cloth masks (made of cotton, gauze, and other fabrics) were used in US hospitals to protect healthcare workers from diphtheria and scarlet fever. Wu Lien-teh, a public-health specialist from Malaya, was investigating a pneumonic plague that had broken out in northern China. He developed a mask from layers of gauze enveloped in cotton, with ties so that it could be hung on the ears. This was the prototype from which the masks currently used in medicine today evolved.
During the 1918 Spanish influenza pandemic, masks made of various layers of cotton were widely used by healthcare workers and the general public. Gauze masks were used during the second Manchurian plague epidemic in 1920–1921 and a pneumonic plague epidemic in Los Angeles in 1924; resulting in a decrease of infection rates among healthcare workers.
During the 1930s and 1940s, gauze and cloth masks were used by healthcare workers to protect themselves from tuberculosis. In the middle of the 20th century, after disposable medical masks had been developed, the use of cloth masks decreased; however, cloth mask use is still widespread in many countries in Asia.
Modern Masks And How they Work
How Can Cloth Masks Prevent the Spread of Disease?
When we breathe, talk, cough, sneeze, or sing, we emit droplets across a range of sizes, and these particles may contain viruses. Putting on a cloth mask can trap these droplets and prevent the virus from spreading to other people.
Cloth is a woven material, with threads intersecting each other in a pattern. It’s true that there are gaps between the threads and that these gaps are larger than the width of a single virus. Sometimes people are lead to believe that the virus is able to simply sail through a mask, but this isn’t true.
.Although the size of a single virus is smaller than the size of the gaps between the individual fabric threads of the mask, the size of the droplets that contain viruses could be bigger than these gaps. In addition, even though there are gaps between the threads in cloth, the individual threads are wider than the gaps. In addition, each thread has microfilaments or imperfections that project into the gap, further providing an obstruction. Finally, a good mask has multiple layers (Health Canada recommends masks with 3 layers) for extra protection.
It’s also worth noting that the droplets containing the virus don’t move in a straight line - they move and swirl in the air which makes them aligning with and passing through a tiny hole very unlikely. And, as droplets are not living things they can’t change direction to go around the fibers or move to avoid obstacles in their path.
Don’t be concerned about an individual gap in the weave of a fabric - instead, think of the entire mask with multiple layers and how everything works together to act as a filter.
Source: Center For Disease Control
Source: The Conversation
What Is An ‘N95’ Mask?
An N95 mask is technically a respirator. In order to use the term N95, the mask (respirator) must be certified by NIOSH - the National Institute for Occupational Safety and Health. During the COVID-19 pandemic we have begun to think of them in association with the medical field, but N95 respirators are used as protection in a number of non-medical fields ranging from autobody repair to construction, welding, and more.
The name N95 is actually a description of the capabilities of the respirator. The ‘N’ means that the respirator is not resistant to oil, and the 95 means that they filter 95% of 0.3 micron and larger materials. There are even multiple types of N95 respirators - including those intended specifically for surgical use and those with or without breathing vent holes.
N95 Respirators utilize capture or filtration to remove airborne particles as described below:
The particles that come in direct contact with the fiber cannot pass through the filter
Larger particles have too much inertia and thus can’t follow the airstream as it is diverted around the filter.
Small particles are easily moved and deviated by air molecules, making it likely that they come into contact with a filter fiber.
For the particles that are neither small enough nor large enough to be captured by any of the methods described above, N95 respirators utilize a type of electrical charge. The charge on the fiber filter attracts the oppositely charged particle, stopping all oppositely charged particles from passing through the filter regardless of their size.
In all cases, once a particle comes in contact with a filter fiber, it is removed from the airstream and strongly held by molecular attractive forces. It is very difficult for such particles to be removed once they are collected.
What’s The Point If Masks Are Not 100% Efficient Or If Other People Don’t Wear Masks?
When it comes to viral science, numbers count. It is true that if everyone in a community wears a mask, the probability of infections drops drastically. The studies clearly show that the more people there are wearing masks, the less the disease will spread.
That is because wearing a mask helps not only the wearer from coming in contact with the virus, but also helps prevent an infected person from spreading the virus. In other words, they offer two-way protection: when breathing in and when breathing out.
Avoiding Misinformation And Memes
There is a lot of incorrect and misleading information available on the internet, and sometimes that information is shared by friends or family members; sometimes even people that we trust.
Just because someone shares incorrect information, that doesn’t mean that they are a bad person - it just means that they’ve made a mistake. Unfortunately, it’s not always easy to tell when a piece of information is wrong. The most convincing, and dangerous, forms of misinformation are those that appeal to our “common sense” or that seem logical when first viewed.
For example, look at this meme often seen on Facebook:
Don’t Be Fooled By Misinformation!
At first look, it appears to make sense: why do I need to wear such a complicated mask when using spray paint, but cloth masks with images of Baby Yoda are enough to protect me from COVID-19?
The answer, also explained above, is simply that while the gaps in a cloth mask may be larger than the size of a single SARS-CoV-2 virus, the virus spreads in liquid droplets. A single layer of cloth might not be great against a single virus, but a multi-layer cloth mask, as recommended by Health Canada, has been proven to be effective against droplets containing the SARS-CoV-2 virus.
Other common pieces of misinformation about masks are that face masks can cause other health problems (not true) or that if you wear a mask you don’t need to practice social distancing (you still do).
Sometimes misinformation comes from a misunderstanding of a scientific article, from old information, or a single report or study that might have errors in it. It’s always a good idea to search for multiple reputable sources of information when trying to confirm a piece of information or advice that you hear.
Wearing a mask is a simple thing that you can do to help protect yourself and others from COVID-19. The more things you can do (masking up, social distancing, staying home when possible) the more protection you afford to yourself and those around you, including the people that you love.
How To Choose The Right Mask
Here are a few things to consider when selecting a mask:
Wear a mask that fits snugly on your face
Put on the mask such that it covers both mouth and nose at all times
Choose a mask with two or more layers of breathable fabric
Use only masks without exhalation valves or vents because they may not prevent you from spreading COVID-19
For more details and the latest updates on mask recommendations, please visit:
World Health Organization: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks
Center For Disease Control: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover-guidance.html
Did you find this helpful? Consider making a donation to the Saskatchewan Science Centre!