I understand that discussions about wearing masks for protection from COVID can evoke some strong emotions and differing opinions.  However, I believe that using basic math we can come to the realization of what truly works and what does not work.

Let’s first look at what is a virus and the sizes of viruses:

A virus is a microscopic infectious agent that can only replicate inside the living cells of an organism. Viruses can infect all types of life forms, including animals, plants, and even bacteria. They consist of genetic material (either DNA or RNA) surrounded by a protein coat called a capsid. Some viruses also have an outer envelope composed of lipids.

Viruses are not considered living organisms because they lack the cellular machinery necessary for metabolism and replication. Instead, they rely on hijacking the machinery of host cells to reproduce and spread. When a virus infects a cell, it injects its genetic material into the host cell. The host cell then uses its own machinery to produce viral proteins and replicate the viral genome, leading to the assembly of new virus particles. These particles can then infect other cells and spread throughout the organism or to other hosts.

Viruses can cause a wide range of diseases in humans, animals, and plants, including the common cold, influenza, HIV/AIDS, COVID-19, and various forms of cancer. They can be transmitted through various routes, such as respiratory droplets, bodily fluids, contaminated food or water, or through vectors like mosquitoes.

Viruses are not dry particulates in the sense of being non-living dust or debris. When viruses are outside of a host organism, they can exist in various states. For example, some viruses can be suspended in droplets of moisture expelled when an infected person coughs or sneezes, or they can remain on surfaces for a period of time.

Viruses typically range in size from about .0125 microns to .4 microns depending on the type of virus. For example, an HIV virus is about 0.16 microns, Influenza 0.05 microns, Covid 0.04 microns per average.

It’s also important to understand that a virus is not a chemical.  Chemicals are substances composed of atoms or molecules with specific chemical properties. They can be inorganic (such as salts and metals) or organic (such as carbon-based compounds). Chemicals can exist in various forms, including solids, liquids, and gases.  Chemicals do not reproduce on their own. They can undergo chemical reactions and transformations but do not have the ability to replicate themselves.  Chemicals can have various effects on organisms, depending on their properties and concentration. They can be beneficial (e.g., nutrients, medications) or harmful (e.g., toxins, pollutants) to living organisms.  Some chemicals are extremely dangerous to people even at very low levels.  These chemicals are time weight averaged and given Permissible Exposure Limits (PEL), Parts Per million (PPM) or Lethal Dose that will kill 50% of tested subjects (LD50) and/or Immediately Dangerous to Life and Health (IDLH).  These measures help regulatory agencies and organizations establish safe exposure limits and guidelines for handling hazardous chemicals in various settings, including workplaces, communities, and the environment. By monitoring and controlling exposure to hazardous chemicals, these measures help protect human health and prevent adverse health effects.

Another thing to keep in mind when dealing with chemicals versus viruses; chemicals will always react the same way to anyone regardless of age, gender or race.  Viruses affect everyone differently depending on their age and other underlying health issues.  Chemicals generally exhibit predictable behavior and effects, viruses are more dynamic and can interact with human populations in complex and variable ways.  Viruses do not have a PEL.  This is very important to keep in mind when deciding what type of protection device you must wear to protect yourself.

The structure and the size of a particulate is very important to know when choosing the proper respiratory protection.  A perfect example of this is the OSHA requirements for protection against spray paint.  Spray painting can produce a variety of airborne particles, including fine droplets of paint and vapors. While an N95 respirator can filter out solid particles such as dust, it may not provide adequate protection against vapors or very fine particles that can penetrate the mask’s filter.  For protection against spray paint, especially in situations where vapors are present, it’s generally recommended to use a respirator that is specifically designed for chemical exposure, such as a respirator with organic vapor cartridges or a supplied-air respirator.  This is very similar to the OSHA requirements for virologists.  It is recommended that they use a Powered Air-Purifying Respirator or Full-Face Respirator or Powered Air-Supplied Respirator or even Biohazard hoods or Enclosures.  These regulations can be found in the Respiratory Protection Standard (29 CFR 1910.134).

Let’s now move onto what we are being recommended to wear for protection against Covid; Cloth masks, surgical masks, and N95 masks and their protection factors.

NIOSH (National Institute for Occupational Safety and Health) is a federal agency in the United States that is part of the Centers for Disease Control and Prevention (CDC). NIOSH’s primary mission is to conduct research, develop guidance and recommendations, and provide training and education to improve occupational safety and health in the United States.  NIOSH is responsible for a wide range of activities aimed at preventing work-related injuries, illnesses, and deaths.  It is NIOSH that helps develop guidance and recommendations on how to keep people safe if/when a worker may encounter different viruses.  As to this date, NIOSH does not approve or certify homemade cloth masks for protection against anything, including viruses.  So, let’s all agree to take that option off the table.

Surgical masks are primarily designed to protect patients and others from the respiratory emissions from the WEARER, such as droplets expelled during talking, coughing, or sneezing. They are also used to protect the wearer from large-particle droplets, splashes, and sprays that may contain infectious agents.  They do not protect the wearer from aerosol transmission due to the lack of a filtration medium and side protection for such airborne particulates.

N95 masks are primarily designed to filter out airborne particles, including dust, smoke, and certain types of aerosols, but they are not designed to protect against liquid splash or immersion. While N95 respirators can provide a high level of filtration efficiency for solid particles, they are not effective barriers against liquids.

The filtration material used in N95 respirators consists of tightly woven fibers that can effectively capture airborne particles, but they do not provide a waterproof barrier. If exposed to a liquid medium such as water or bodily fluids, the liquid can penetrate through the mask’s filtration material and potentially reach the wearer’s respiratory system.

The term “N95” refers to a type of respirator or filtering facepiece respirator (FFR) that meets the filtration efficiency standards set by NIOSH. The letter “N” indicates that the respirator is not resistant to oil. N95 respirators are intended for use in environments where no oil-based particles are present, such as construction sites and manufacturing facilities.  The number “95” indicates that the respirator is designed to achieve a minimum filtration efficiency of 95% for airborne particles with a size of 0.3 microns or larger. This means the respirator is capable of filtering out at least 95% of particles of this size when properly fitted to the wearer’s face.

The construction of an N95 mask typically includes several key components:

  1. Filtering Material: The most critical component of an N95 respirator is its filtering material, which is typically made of multiple layers of nonwoven synthetic fibers. These fibers are electrostatically charged to enhance their filtration efficiency. The electrostatic charge helps attract and capture airborne particles, even those as small as 0.3 microns in diameter, through a mechanism known as electrostatic attraction.  However, viruses typically do not have a net electrical charge because they are composed of biological molecules such as proteins and nucleic acids. These molecules are made up of atoms with positive and negative charges, but overall, the virus, as a whole, tends to be electrically neutral.
  2. Meltblown Layer: The middle layer of the filtering material in an N95 respirator is usually a meltblown polypropylene layer. This layer is responsible for capturing and trapping small particles through mechanical and electrostatic mechanisms. The fine fibers in the meltblown layer creates a dense network with a high surface area, increasing the likelihood of particle capture by utilizing the Brownian Motion Principles of Filtration.  The meltblown layer is much thinner in a KN95 and does not utilize the Brownian Principle to its fullest potential.  A KN95 use is not approved by NIOSH nor OSHA in any work environment in the United States.  The KN95 is the Chinese equivalent to the US N95.
  3. Outer and Inner Layers: The outer and inner layers of the N95 respirator may consist of spunbond polypropylene or similar materials. These layers provide structural support and help maintain the shape of the respirator. The inner layer, which comes into contact with the wearer’s face, is typically softer and more comfortable.
  4. Exhalation Valve (Optional): Some N95 respirators are equipped with an exhalation valve, which allows for easier exhalation and reduces heat buildup inside the mask. The valve opens when the wearer exhales, releasing exhaled air and moisture, which can help reduce discomfort during prolonged wear. However, N95 respirators with exhalation valves are not suitable for use in sterile environments or situations where source control is important, as they allow exhaled air to bypass the filtration system.

The construction of an N95 respirator is designed to provide a tight seal against the wearer’s face, ensuring that air is filtered through the respirator material rather than leaking in through gaps around the edges. Proper fit testing and seal checking are essential, and the wearer must be clean shaven to ensure that an N95 respirator provides effective seal protection against airborne particles.

Now let’s put this equation together.

An N95 respirator is designed to filter non-oil based dry particulates 0.3 microns or larger.

Coronavirus is carried through wet respiratory droplets generated when an infected person exhales, talks, coughs, or sneezes.  The size of this virus is 0.04 microns.

To build a visual picture, let’s move the decimal point over two spots to the left and instead of microns, let’s call it inches.  We now have a 30-inch ball and a 4-inch ball.  Picture this in your mind, an NBA basketball is 27 inches and a woman’s college softball is 4 inches.  If I were to build a net that is designed to stop 95% of the basketballs launched at it, would you feel comfortable to stand behind the net?  I’m sure you would.  If I were to switch and start launching the softballs at that same net, do you still feel comfortable standing there?

Please keep in mind.  It is your responsibility to follow all of the safety standards your employer requires of you, whether you agree with them or not.

The information provided is based on general knowledge accumulated over 30 years of working in the safety industry and as a certified OSHA safety consultant and basic principles in virology, physics, and mathematics. No specific external sources were referenced or cited but can be verified on OSHA and CDC websites.