Masks & distancing from the 4th of July

The COVID warning level has decreased to 3, the 2-metre rule is becoming 1, and the pubs are re-opening! Can we all now safely face-palm the government’s initial response (god I miss touching my face), storm the beaches, and finally start licking door-knobs again?

Unfortunately not… and I imagine changes in rules on July 4th could leave people wondering what the hell we’re supposed to be doing to protect ourselves now. This post will discuss our options to avoid COVID, as I see it, along with a bit about masks and an experiment you can try yourself along the way.

Take-home message: Keep social distancing to protect yourself and others, wear a mask to protect others, and you don’t suck the way you probably think you do (literally – this isn’t a confidence builder this time).

Here’s how that fits together…

As always, it’s important to remember that nothing about COVID-19 has actually changed… The virus is still here and will spread in the same way… So, following the relaxation of guidelines in parts of the UK on July 4th, what are we actually meant to be doing to protect ourselves? Stick on a mask and gloves (commonly called ‘personal protective equipment’ or ‘PPE’) and get back out there right?… Not quite.

As a scientist I have spent years using PPE in the lab, and the truth is that PPE is actually the LAST resort to protect yourself. This is because PPE only works when you have already allowed the hazard to get within centimetres of you – it’s far safer to not let the hazard get that close in the first place… Imagine having a friend who likes to randomly swing a baseball bat around – yes, you could rely on your friend being able to stop the bat mid-swing 1 cm from your face, but you know you stand far less chance of being hit if you just stay 2 metres away from them! Or even safer, just stay home and avoid your psycho-bat-swinging friend altogether…

I’ve previously written about how we can use the timeline after COVID infection to identify signs of a second wave. We could also apply a similar logic before the point of infection and use this to guide our decision making. The order of events before infection would be:

  1. Staying home and avoiding infected people entirely
  2. Being 2 metres away from an infected person
  3. Being 1 metre away from an infected person
  4. Stopping infection with your PPE
  5. Infection

This order of events actually provides a pretty good ranking of each option’s effectiveness in protecting from COVID: most effective is staying home aka lockdown (Point 1), next best is social distancing (Points 2-3), the worst option is relying on PPE (Point 4).

The further away you are from the infection, the more chance you have of avoiding it.

Unfortunately, this ordering also mirrors the economic impact of each option: most damaging is lockdown (Point 1), next most damaging is social distancing (Points 2-3), least damaging is wearing PPE (Point 4).

We know lockdown works really well at halting the spread of COVID, but the need to get the economy going means we can’t stay home as much, so we will be doing less of Point 1 from July 4th. In all honesty, even remaining in lockdown for years would not rid us of COVID-19 (e.g. what happened in New Zealand). This makes it all the more important we learn to live with social distancing, ideally over 2 metres where possible, but at least over 1 metre if not (Points 2-3). Relying solely on PPE for protection isn’t a good idea, as not only does it let COVID get closer to you, PPE is challenging to use correctly and also this misses out the safer options in Points 1-3 (hand washing would also come at point 4, but should absolutely be kept up as a final fail-safe). If you’re not convinced by this line of thinking, I should point out that this ranking of options actually exactly matches the ordering of government guidelines to avoid COVID (here)… I hope clarifies some of why we are getting this guidance and how to choose the best options.


It’s also important to understand there’s a difference between a mask that can protect you from COVID (PPE like an N95 mask) and a `face covering’ that can stop you from spreading COVID (surgical mask, bandana, etc). We’re actively asked not to buy protective masks to save these for the NHS, and the whole point of surgical masks is to protect the patient undergoing surgery, NOT to protect the surgeon who is wearing it, so you may wonder why bother wearing a mask at all?…

I was trying to come up with good analogy to explain this, but I think this picture is a pretty good start point (apologies for the American use of the word ‘pants‘):

Credit to Reddit for this one.

There’s 3 more lessons we could take from this picture that aren’t stated: 1) it’s not just 1 person getting peed on, it could be 20 or 30… 2) if you might have pee on your pants (from yourself or someone else), you’d be sure you wash your hands after touching them and wouldn’t let your pants come into contact with anything else… 3) having someone else’s pee on your pants is really no better than having someone else’s pee on your leg, pants only work well if someone else is wearing them…

That brings us nicely to the question of why a surgical mask/face covering can stop you from spreading COVID but can’t protect you from it? Well, my best stab at the answer may come across as slightly rude, so please bear with me…

It’s because you don’t suck as hard as you blow…

Hang in there, this does make sense…

So it’s quite easy to understand how we blow air out of our lungs– you compress your lungs, and it pushes the air out. Simple. So you may think the reverse happens when you breathe in – you expand your lungs and suck air in… But this isn’t strictly true, you expand your lungs but actually the air just flows back in to fill the space – there is very little ‘sucking’ force involved. It’s actually just atmospheric air pressure pushing air in.

If you don’t believe me, we could try an easy experiment to prove this:

Take a (clean) sheet of paper and hold it just in front of the tip of your nose with the bottom hanging in front of your mouth. Try to blow the paper away from you – it’s easy right? Now try to suck it towards your mouth…

God, I can see why scientists normally stick to the lab… plus I really hope no one else can suck the paper onto their mouth, and it’s not just that I have a massive nose…

The point here is that when you breathe out you push air in a directed flow into something covering your face, which would catch some of the droplets containing COVID-19. When you breathe in, the air flow just takes the path of least resistance, same as water, electricity, or people who don’t return the damn shopping trollies. This means that air will just flow through the gaps around the mask, rather than through the mask… This is why there’s little/no protection for the wearer, but there is some protection for people around them. As the problem we’re facing now is on a global scale, ‘some protection’ may have a massive impact.

There’s evidence showing masks decrease exhaled COVID-19, reports suggesting the point a country adopted masks may have determined how badly affected it was by the initial wave, and others suggesting masks may be a key factor in stopping a second wave. Many countries now enforce wearing masks in public, including on public transport in the UK (quick video from the NHS).

If you think back to our timeline to protect from COVID infection, you could add in someone else wearing a mask too, probably somewhere around Point 2:

  1. Staying home and avoiding infected people all together
  2. Being 2 metres away from infected person OR infected person wearing a mask
  3. Being 1 metre away from infected person
  4. Stopping infection with your PPE
  5. Infection

That means that while staying home and social distancing is your best option to avoid infection, someone else wearing a mask is also actually one of the best options we have. However, to be very clear: thinking a surgical mask protects the wearer (it absolutely doesn’t) and giving up social distancing would be a pretty good way to get straight to point 5 on the list…

Currently it’s a personal choice to wear a mask in public/shops in parts of the UK, but there’s nothing in law saying you can’t wear one if you understand why it’s important (and people won’t know who you are anyway as you’re wearing a mask…). I think one of the best sayings I have come across about masks is:

“my mask protects you, your mask protects me”.

And how do you get someone else to wear a mask to protect you? I don’t know, I’m just a scientist… But I guess a pretty good start would be to put on a mask and protect them.

Sometimes the hero is just an ordinary person wearing a mask… Can’t believe I managed to crowbar a Batman reference into the blog! Also, the mask should cover both the mouth and nose – otherwise it’s like wearing a condom with the tip cut off.


Next time, I’ll probably write a bit about the second wave we’re all worried about. I really hope I’m wrong here, but I think we’ll see this in the US death toll from ~July 6th.

3 thoughts on “Masks & distancing from the 4th of July

  1. Thank you so much for all this information. Straight forward to read, understand and remember.
    I am 75yrs old so learning as much as I practically can, is very valuable for me.


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