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!