Nope — You’re Not (Entirely) Safe from COVID-19 Outside Either !
We have known for quite some time, from numerous studies, that viruses like COVID-19 are transmitted by particles that travel through the air when people cough, sneeze, speak and even breathe. Until recently however, we had little information about how this airborne transmission is impacted by being outdoors in slight breezes. Now we do…
A recent study that appeared in the American Institute of Physics publication Physics of Fluids (May, 2020) provides just that valuable insight. Conducted by Professors Dimitris Drikakis and Talib Dbouk at the University of Nicosia, Cyprus, this study shows that a mild human cough (in air at ~ 70○ F and 50% relative humidity) unexpectedly propelled saliva-disease-carrying droplets considerable distances depending on environmental conditions such as wind speed, temperature, pressure and humidity. (Note that saliva droplets are like rain and aerosols are like fog…so the fact that relatively large viral droplets can travel this far should be very disconcerting. Indeed, a single droplet can have as many as 200,000 aerosol particles…and experts believe that you only need ~ 1,000 of them to become infected).
The graphic below, from that study, illustrates the activity of a person’s airborne droplets in slight wind, blowing from left to right. Here is how to interpret it.
With no wind, the saliva droplets did not travel the full six-foot recommended physical distancing length ─ a recommendation that is outdated and based on science that is more than 80 years old, from before we knew about aerosol transmission; but that’s another issue altogether.
Example A: With just a slight breeze of ~ 2½ mph, saliva droplets were able to travel a distance of ~20 feet in five seconds; and they were found suspended at heights from ~ 20 to 65 inches.
Example B: With a moderate breeze of ~ 4½ mph, saliva droplets were able to travel the same distance in just 1.6 seconds; and they were found suspended at heights from ~ 40 to 65 inches. Yikes !!!
According to the researchers “The droplet cloud will affect both adults and children of different heights” and “shorter adults and children could be at higher risk if they are located within the trajectory of the traveling saliva droplets.”
What does this mean? It means that just because you are outdoors ─ and physical distancing the recommended six feet ─ does not mean that the person who is 15-20 feet away isn’t unwittingly sending you some of his/her COVID-19 infected saliva (something that should be very disconcerting given that it only takes a very small number of those particles to infect someone).
The moral of the story: don’t develop a false sense of security believing that because you are outdoors you a safe from getting infected by COVID-19; you are not. Wear your face mask outside….!!!
This is a sample of what you will learn by reading my new piece on COVID-19, its transmission and face mask efficacy. At 75 pages, and having 176 cited references, it is aptly entitled The Definitive Employer Guide to Purchasing Face Masks for Your Valued Employees. Click here to download it.
Richard Nicholas, a forty-year veteran of the TPA industry, is the Founder of the TPA Network Research Consortium, an emerging industry-wide research initiative purpose-built to help health plan sponsors evaluate new medical technologies and health innovations.
Our research into COVID-19 led us to create a unique new type of protective face mask intended and designed to provide a meaningful degree of wearer protection and inhibit dangerous bio-burden build up. To learn more about it and the Research Consortium, see www.ResearchConsortium.org or email Richard@ResearchConsortium.org