Campaigners welcome car-free zone in central London

rayjay wrote:

Face mask do nothing ..https://accountingweekly.com/face-masks-pose-serious-risks-to-the-health...

does anyone really think that if everyone rode  to  work in London on a bike it would be some kind of cycling utopia in London. It would be absolutely carnage . This is not  Amsterdam or Copenhagen. You have to be realistic.  Cars will be used , look the covid cases in London are now tiny in a few weeks there probably won't be any cases in London . The vast majority of people who get covid  ( whatever it is ) are absolutely fine , it's a tiny minority of 65 000.000 that are affected by this . Scaremongering needs to stop .More people die from influenza ,100.000 die from respiratory illnesses every year in the Uk .  .

That face mask article makes some interesting points:

Quote:

They found that about a third of the workers developed headaches with use of the mask, most had preexisting headaches that were worsened by the mask wearing, and 60% required pain medications for relief. As to the cause of the headaches, while straps and pressure from the mask could be causative, the bulk of the evidence points toward hypoxia and/or hypercapnia as the cause. That is, a reduction in blood oxygenation (hypoxia) or an elevation in blood C02 (hypercapnia). It is known that the N95 mask, if worn for hours, can reduce blood oxygenation as much as 20%, which can lead to a loss of consciousness, as happened to the hapless fellow driving around alone in his car wearing an N95 mask, causing him to pass out, and to crash his car and sustain injuries. I am sure that we have several cases of elderly individuals or any person with poor lung function passing out, hitting their head. This, of course, can lead to death.

I don't like the sound of hypoxic drivers - that's bound to cause more crashes.

Quote:

There is another danger to wearing these masks on a daily basis, especially if worn for several hours. When a person is infected with a respiratory virus, they will expel some of the virus with each breath. If they are wearing a mask, especially an N95 mask or other tightly fitting mask, they will be constantly rebreathing the viruses, raising the concentration of the virus in the lungs and the nasal passages. We know that people who have the worst reactions to the coronavirus have the highest concentrations of the virus early on. And this leads to the deadly cytokine storm in a selected number.

That's similar to the re-infection that I mentioned in an earlier post. I wonder if it could be one of the reasons that healthcare workers seem to be so bady affected.

I don't agree with you that we shouldn't worry about covid because only a small number are make seriously ill - the numbers involved can still easily overwhelm healthcare services if we do nothing.

"if you are not sick, you should not wear a face mask... the vast majority of people infected by the virus, one experiences either no illness (asymptomatic)...". Sheer genius.

I think Vietnam's success is down to their aggressive testing and tracing - you know the kind of thing that has been known to be effective in containing epidemics. They also acted very early and restricted travel into the country (almost seems like the opposite of the "strategy" taken by the UK).

Of course, wearing face masks is very common in their culture anyway, so that may well have prevented some spread as well.

You can only do tracing if there are few cases in the first place. So you must keep transmission muted. So the two strategies go hand in hand.

Wearing facemasks for the protection of others has taken root because their culture is not founded on the primacy of the individual. Whereas over here the entire discussion around facemasks hinged on what they could, or more likely could not, do to protect the wearer.

Testing and tracing is easier with fewer cases, but it's still the most important tool in the toolbox. There's a reason that the W.H.O. has been saying "Test, test, test".

I'm not convinced that facemask wearing is strongly related to selfishness though it's an interesting idea. As a counter-point, I found this article that relates facemasks to historical incidents and a cultural belief in bad air/ki: https://qz.com/299003/a-quick-history-of-why-asians-wear-surgical-masks-in-public/

My concern with using face masks is down to whether they are measurably effective when used in a non-clinical setting or whether they are more of a cargo-cult type of thinking i.e. copying a behaviour without understanding why it is effective for that person. (Like lowering your handlebars because pros do it)

I've now started carrying around a neck scarf/gaiter thing to be used as a face mask, but haven't been seen any signs that they should be worn in the shop (which I don't mind doing). I visited a big chinese supermarket this afternoon (mainly to buy kimchi and frozen thai fish cakes) and the staff there seemed split half and half between wearing masks or not.

Edit: Here's the current W.H.O recommendatons on when and how to use face masks: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks

hawkinspeter wrote:

I'm not convinced that facemask wearing is strongly related to selfishness...

Inversely related. It is undeniable that the debate over here centred around how effective they are in terms of self protection. Their benefit in terms of protection of others has been wholely ignored until recently. And since viewed in terms of self protection for public use they came up short, such use was deprecated. That we might wear a facemask to protect others rather than ourselves never came up for consideration - it's a cultural thing.

Quote:

My concern with using face masks is down to whether they are measurably effective when used in a non-clinical setting ...

Why, when it is not required to perform a clinical function in the public setting?

In the clinical setting it needs to be able to protect the wearer against inhaling aerosolised virus in the air. That is an exacting technical performance standard, not required in the public setting, where the mask only needs to present a physical barrier to droplets of spit when the wearer speaks.

For how do you imagine the virus makes the jump from one to another, and why do you suppose distance is one safeguard - what is distance guarding against? It's the reason you don't take the front row seats at the theatre; unless you like a 'shower' you want to be about, oh, 2m back?

And the problem with distance, as TFL (and schools, etc) are discovering, is that distance takes space. Facemask don't.

You may be right about face masks, but ultimately I'm going to follow the W.H.O. recommendations as they do know about evaluating different public health measures and their benefits. Currently they don't have enough data to recommend public face masks, but that could change of course.

And the question the WHO asked themselves:
"Can wearing a mask protect you against coronavirus?" (my emphasis)
https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-f...

They have an agenda to protect scarce supplies of medical grade PPE. Quite right too. But the other question, can wearing a facemask protect others from you, does not implicate medical grade PPE

If they don't even ask the other question it's going to be a while before they find the evidence on wearing (non-medical grade) masks to protect others.

Even when the WHO ask the question about wearing masks in public, they still are concerned only with the benefit to the wearer, and remain driven by the imperative to protect supplies for health workers:

"However, there is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses, including COVID-19. Medical masks should be reserved for health care workers."
https://www.who.int/publications-detail/advice-on-the-use-of-masks-in-th...(2019-ncov)-outbreak

Is there good evidence that any sort of face covering reduces transmission rates?

Rich_cb wrote:

Is there good evidence that any sort of face covering reduces transmission rates?

I found this article: https://www.google.co.uk/url?q=https://www.theguardian.com/world/2020/ma...

Seems to be more opinions than evidence. At least there'll be more data points as the pandemiccontinues.

Rich_cb wrote:

Is there good evidence that any sort of face covering reduces transmission rates?

You could listen to this guy:
https://m.youtube.com/watch?v=gAk7aX5hksU

There is also this (from 2013 !)
https://pubmed.ncbi.nlm.nih.gov/24229526/
"The median-fit factor of the homemade masks was one-half that of the surgical masks. Both masks significantly reduced the number of microorganisms expelled by volunteers, although the surgical mask was 3 times more effective in blocking transmission than the homemade mask."

Given that the goal is to get R0 below 1, a "significant reduction in microorganisms expelled" is exactly what the doctor ordered.

Good one! However, I don't see much difference between protecting yourself vs protecting others. If a population has higher levels of infection then the risk of catching it also increases, so it doesn't make much sense to only care about your own risk. I doubt that the W.H.O. only considers that one single question in isolation as that sounds like more of a political stance and I don't consider them to be hugely political.

hawkinspeter wrote:

Good one! However, I don't see much difference between protecting yourself vs protecting others.

The critical difference is the sort of mask you need.

To protect yourself your facemask needs to be able to prevent you breathing in the virus in aerosol form. That's difficult to do, aerosol particles are very small. You need a high grade facemask and you need to wear it correctly. Such masks are in short supply, so it makes no sense to squander them on a public who might not even wear them correctly.

But we do not exhale virus aerosols. We spit out saliva droplets. Much easier to catch a droplet of spit than an aerosol. And saliva droplets is the main way we transmit to others within 2m range. Beyond 2m and gravity claims the droplets - hence social distancing advice.

So where do aerosols come from? One source is the same saliva droplets, if they become bouyed up on air currents long enough to evaporate down in size to the point that they remain airborne. At that point a simple facemask won't protect your neighbour. But that aerosol started out as a droplet that would have been cought at source had the originator been wearing a simple mask.

So if we rely on self-protection we need to steal medical grade masks from the NHS. If we rely on mutual protection then more commonly available masks will do.

More important than the direction of protection (which I don't think makes much difference when considering populations) is whether home-made face coverings can work as a safe harbour for virus-laden droplets. You may be asymptomatic and decide to wear a face covering to protect others just in case, but inadvertently keep infecting yourself and thus keep the infectious period going for longer. There's also the additional infection route from a mask to the fingers and then onto surfaces which could lessen the benefit of hand washing.

If face covering is effective then it's a cheap and easy precaution to take. If it's not very effective, then it could end up disastrous especially if people take more risks due to it. Personally, I'm hoping for the former.

hawkinspeter wrote:

inadvertently keep infecting yourself

I don't think that is a thing, like lifting yourself up by your own bootstraps.

Quote:

There's also the additional infection route from a mask to the fingers and then onto surfaces

Hmmm - but if it was not in the facemask where else would it be already?

Quote:

If face covering is effective then it's a cheap and easy precaution to take. If it's not very effective, then it could end up disastrous especially if people take more risks due to it.

No, they are taking those risks already, look at the buses. It's less a case of we'll all wear facemasks now so we can forget social distancing, more that social distancing is already breaking down (inevitable if we are going back to work/school) so we'd better take other precautions.

That's not really how it works though. You're not emitting a standard size of large particle that only breaks down into smaller ones once it's left you. You're emitting a mix of particles across the whole range of sizes.

And when 'larger droplets' are being referred to, these are droplets > 5 microns - that's much smaller than the width of the finest human hair. It's unclear how many of these would actually be caught by commonly available masks, particularly if they're loose fitting or looser weave.

So while wearing these masks would probably give some reduction in your chances of spreading the virus beyond 2m, it may not reduce it as much as you think, and certainly wouldn't prevent it altogether.

You will never take any measures if you are waiting on 100% prevention. How about a "significant reduction", would that be worthwhile for you if it were readily achievable?
https://pubmed.ncbi.nlm.nih.gov/24229526/

I'm not arguing against (or for) using them; just pointing out that it's not correct to suggest that they would completely stop you spreading the virus.

It looks like the masks they tested reduced infection rates to somewhere (roughly) around 1/5. The question then would be, would risk compensation and other unintended behaviour consequences (fiddling with the mask etc.) carry a greater increase in risk than that reduction?

[Interestingly, their results appear to suggest that the biggest effect is not on spread through the largest particles, but on the mid-sized ones - though the sample sizes are quite low, so that may be a little misleading.]

Quite so. Did I suggest 100% effectiveness? If so, my bad.