COVID-19: Fake News or Safe News?
I might get “toasted” for this article, but let’s see what stirs….
This is not about Politics, but more my simple “Engineering” and Risk Management perspective.
I was watching the news this morning (12th March 2020) and Nicola Sturgeon (Scottish Politician) was talking about “self-isolation” by Nadine Dorries (UK Cabinet Minister). Speedy recovery Nadine…
The comment made by Nicola that caught my attention was “people are being contacted if they have been within 6 feet (1.83m) of Nadine for around 15 mins”.
I said to my wife “where are they getting these figures from?”
“From the experts, of course” my wife responded.
Hmmm….interesting. I am not sure if I agree with these figures….me thinks!
So, I did some number crunching, which is typical of a risk management geek 🙂
- Individual in a meeting room (or office environment) who sadly has the COVID-19 bug. They don’t know and you don’t know.
- It’s a smallish room, being just 2m x 2m x 2m (8m3 in volume).
Had to look these up to make sure I have some good data.
I suspect there are lots of ways making it complex, but let’s keep it simple for now (KISS).
- The Tidal Volume (TV) is the lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied. In a healthy, young human adult, tidal volume is approximately 500 mL per inspiration or 7 mL/kg of body mass.
- The Respiratory Rate (RR) is the number of breaths someone takes every minute. Normal relaxed breathing (Eupnoea) is between 12 and 20 breaths per minute. Let’s just say 20 for simplicity. They are working hard on that desktop or using their mobile phone intensely!!!!
- If my math is right, with a TV of 500 ml and a respiration rate of 20, this would equate to 0.01m3/min.
“Quickie” Risk Assessment
Firstly, these are just guesstimates and as mentioned earlier, we can make this model much more complicated.
Let’s assume that there is no air replenishment (oops), in that room setting of 8m3 volume.
That individual will have to be in that room for around 800 minutes (i.e., 13 hrs and 20 mins) for 1 complete air change.
Of course, if you have air ingress, egress, forced circulation or you are outside, all these make a big difference.
The risk equation is based on Consequences and Likelihood.
Sadly, we know what the Consequences are….so, how can we influence Likelihood?
If we think about Hierarchy of Controls:
- Elimination – Become a hermit, live on an island (perhaps not that practical), find a permanent cure…
- Engineering….barriers (i.e., avoid physical contact)
- Administrative – perhaps self-isolation?
- PPE – we know about these (masks, gloves etc).
I guess, we have some extremes and one of them (the most favourable – Elimination) is not really that viable, for now.
Now, I am not a HVAC or medical expert, however, it made me think about figures that are being thrown around and these are just my thoughts.
- There are some control measures that I can apply to reduce Likelihood. I certainly do this when I am travelling (e.g., surgical mask at airport).
- If I am in a room, I can check to make sure that the room is well ventilated (e.g., doesn’t have a stale or damp, smelly feel).
- Try and limit my exposure. The longer I am in a room with people, the greater the chance of me getting that dreaded COVID-19. However, this is still no guarantee, because I might be walking into the room when the meeting has been going on for ages and the air is already heavily contaminated! There is also medical advice that the virus can linger on solid objects for quite some time, hence transference is something not to overlook.
Do you remember the “old style” UK phone boxes?
Most of us know the “visual” size and the K6 version has an approximate volume of 2m3.
If someone with that dreaded COVID-19 virus was in that phone box, it will take 3 hrs and 20 mins for one complete air exchange (let’s say 3 hours as it’s easier to remember). That’s a long phone call…!
How many old style UK Phone Boxes can you fit into your office or working environment?