This paper is the third in a series on the pandemic disease, COVID-19. The first paper focused on safely reopening your business.  The second paper concerned the issue of face masks which have become the primary PPE or personal protective equipment to prevent the disease. Additional protective measures which everybody is familiar with are frequent and thorough (at least 20 seconds) hand washing and social distancing where every person is no closer than six feet to the next person. And we cannot forget protective clothing, gloves, and face shields, depending on the situation. So, with that introduction, let’s dive into exposure!

Exposure Routes

The SARS-CoV-2 novel corona virus which causes COVID-19 is no different than any other biological airborne contaminant when it comes to exposure routes into the body. It may enter the body through inhalation, injection, or ingestion. Inhalation is obvious because you breathe it into your body. Injection covers all other routes except ingestion. So if the virus gets on your hands and you touch your eyes, it can enter your body. If you touch your nose inside, you have injected it, but then you inhale it. I am not aware of it entering the body through cuts, but as we all know, we learn more and more about this virus every day! The same can be said for ingestion, that is you swallow it. Supposedly, the acidic nature of the stomach renders it harmless, but once again, stay tuned!

Inhalation of the Virus

So, by the process of apparent elimination, we are left with inhalation as the primary exposure route for SARS-CoV-2. And what you typically breathe in are respiratory droplets which contain the virus. If it were the virus alone, we would all be in trouble because of the virus’s size. The virus is approximately 0.1 micron (micrometer or 1/1,000,000th of a meter) in diameter, which is like 1/1,000th the size of an average hair (70 microns in diameter). Or, it is 0.00000393701 inches! It is very small! And, from our last paper, it would pass through the material of an N-95 respirator (certified by NIOSH, the National Institute of Occupational Safety & Health, which is a part of the CDC, the Center for Disease Control, because it only stops particles which are 0.3 microns or larger in diameter.  But an N-95 does stop respiratory droplets because they are 5 microns and larger.

So, you ask, why bother? Because, typically the route of infection is via those droplets according to the World Health Organization (WHO,, not via airborne transmission of the virus alone.  And, if the N-95 is sealed to your face properly, it stops those droplets coming to you from others and it stops your droplets from reaching them. The reason is that the respiratory droplets are 5 microns and larger, which are much larger than the 0.3 micron threshold for N-95 respirators.

COVID-19 - Surgical MaskThat cannot be said about surgical masks, cloth masks, masks made of other materials, handkerchiefs, or neck gaiters. Those all pretty much stop your droplets from getting out, but because they do not seal properly to your face, your droplets can get out and reach others.

N-95 Use and Care for COVID-19

So, now that you are convinced an N-95 is best, how do you use it? Reuse it? Clean it? Disinfect it? Stay tuned and those questions will be answered in our next paper!

Environmental Safety ConsultantsSo there is a discussion of how you get COVID-19. If you need any assistance, ESC ( is here. We have a board Certified Industrial Hygienist (CIH) on staff and have been providing respiratory protection services to our clients for thirty years. We have the credentials and experience to help you with your respiratory protection needs. We are just a telephone call (800-226-1735) or an e- mail away ( Contact us today!

Face Masks and COVID-19


This paper is the second in a series on the pandemic disease, COVID-19. The first paper focused on safely reopening your business. The current paper will concern the issue of face masks. These face masks are part of PPE or personal protective equipment which has become an everyday term since the pandemic began in this country last year. It is refreshing to be able to discuss PPE without the listener’s eyes glazing over! Of course, PPE can include gloves, suits, hearing protection, face shields, hard hats, steel toed boots, and more, but this paper concerns face masks for respiratory protection. 

Face Masks and COVID-19 Primer 

The face masks used to protect people from breathing in SARS-CoV-2 (the novel corona virus which causes the disease COVID-19) have included surgical masks, N-95 masks, handkerchiefs, face shields, neck gaiters, and more. None of these actually filter out the virus (which is approximately 0.1 micron in diameter), but rather, they filter out respiratory droplets that are expelled when people exhale, talk, sing, laugh, cough, sneeze, etcetera.

Of the masks above, N-95s offer the best protection. To explain, the N stands for non-oil proof, so they do not work in an oily environment – anywhere there is oil in the air, typically as a mist. Next, the 95 means that they filter out 95% of particles 0.3 micron in diameter. Dioctyl phthalate is the chemical used to test the respirators. If they pass the test, the manufacturers can deem them N-95 respirators after meeting other certification requirements of NIOSH (the National Institute of Occupational Safety & Health, which is a part of the CDC, the Center for Disease Control, ( Once they meet the certification requirements, they can display N-95 labels. 

How to Wear the N-95  Face Mask

The N-95 face mask has two straps, a lower, and an upper strap. Firstly, put it on the lower strap by putting it over the head and then lowering it so it rides along the back of the neck. Secondly, put the upper strap over the head and rest it on the crown in the back.  Thirdly, seal the face piece snugly over the nose, down the face, around the mouth, and beneath the chin. Finally, bend the part that goes over the nose so it fits closely over the bridge and down the sides. By following these steps, the N-95 will be sealed to the face so no air comes through cracks, which means the mask filters the air inhaled and exhaled. Which brings up a point that exhalation valves do not filter exhaled air. People can inhale the germs, so exhalation valves are not recommended.

What if you Can’t Get an N-95 Face Mask for COVID-19 Protection? 

If you cannot get an N-95 face mask for COVID-19 protection, use a surgical mask. If one is not available, use a cloth filtering mask. The other types of masks are on down the list. 

How often Can I Wear the Face Mask? 

The face mask is not designed to be worn over and over. Throw it away after each use or disinfect it if possible. As with everything else, consult the manufacturer. 

Tell Me More about Inhalation Exposure from the COVID-19 Virus

Inhalation exposure from the COVID-19 virus is the topic of our next paper. We will discuss airborne exposure of the virus itself and exposure to respiratory droplets. Stay tuned! Environmental Safety Consultants

So there is a discussion of face masks and protection from the SARS-CoV-2 which causes the disease COVID-19. If you need any assistance, ESC ( is here. We have a board Certified Industrial Hygienist (CIH) on staff and have been providing respiratory protection services to our clients for thirty years. ESC has the credentials and experience to help you with your respiratory protection needs. We are just a telephone call (800-226-1735) or an e mail away ( Contact us today!