Is the current aim to reduce or eliminate exposure to the virus?

[MarkyT]

Requiring them on public transport might have another side benefit - wearing one is not enjoyable, so it might cause people to choose other modes where they don't have to wear one for now. I doubt I will go off randomly riding trains (even where allowed) until mask use is no longer necessary. I'm not massively scared of catching COVID, however I am not going to do something for pleasure that would require an unpleasant thing to be done to do it - that would be like going and riding 153s for fun.

What I am slightly concerned about is a general requirement for wearing one outside, as this may pose issues with regard to exercise, certainly there's no way I can run with one, I can barely get enough air in without one (the joys of exercise induced asthma).

I also can't drive with one because the diversion of the air makes my glasses steam up! (Yes I've tried, I wore one the other day for some volunteering and didn't take it off when I got in the car, and had to remove it very quickly as it removed my ability to see! ) Don't know how glasses wearing medical staff avoid that being an issue.

Randomly riding is probably not to be encouraged anyway, but there are an awful lot of people for which rail travel will once again become essential when they start going back to work regularly. The fact that the roads will become seriously congested if significantly large numbers attempt to shift to cars will drive people back to alternatives eventually, mask or no mask. As to spectacle-wearing, I found that I can perch my glasses a little further out on my nose to avoid misting. More chance of them falling off if I turn my head quickly though!

 

[Bletchleyite]

If you don't like him, don't listen to Peston. Listen to Jeremy Howard, the Scientist from the Masks 4 All movement instead.
Here's a comprehensive FAQ he prepared for skeptics about public mask-wearing:

Redirect

www.fast.ai

That's like the cycle helmet pro/anti lobby websites.

Got any properly-researched papers that don't start off with a bias?

 

[MarkyT]

Correlation is not the same as causation

No, but there's absolutely no doubt that any kind of mask covering the mouth will stop ejection of nearly all infected droplets of spit and mucus from the mouths of those who may not be displaying any symptoms in the most contagious stage of the illness.
Is the following list of countries wrong in their approach?:

 

[Bletchleyite]

No, but there's absolutely no doubt that any kind of mask covering the mouth will stop ejection of nearly all infected droplets of spit and mucus from the mouths of those who may not be displaying any symptoms in the most contagious stage of the illness.
Is the following list of countries wrong in their approach?:

They might be, or they might not be. That's why we have studies, to find out properly.

 

[MarkyT]

They might be, or they might not be. That's why we have studies, to find out properly.

I know, but we haven't got time in this case for endless formal reviewed studies and papers, although they are going on clearly. How many individuals are we prepared to kill for the trials? The point is that masks put a barrier in front of all mouths in public to stop the infected droplets at source. That's obvious, isn't it? The virus exists in droplets. it doesn't just float around in the air on its own. That much is well known. The droplets get smaller the further they project from the mouth, and with time as they evaporate, so clouds of them can float around for a time, but not if they were arrested beforehand. Droplets can fall and settle on surfaces that can be touched later and transferred to others' faces inadvertently. Stop the droplets at source; that's engineering, not research, or rocket science. As to extent of wearing, clearly on most quiet UK residential streets, in the country, in private cars not shared with anyone else, they're rarely necessary, but as soon as distancing becomes difficult and especially in confined spaces, surely wearing masks is common sense (however much I usually dislike that phrase).

 

[Qwerty133]

I think they will be essential as the lockdown is gradually eased. For essential workers who have to travel and work on public transport, they are desperately needed NOW. The number of London's transport workers who have already been taken ill and died is a testament to the particular risks of that environment, to which all riders are clearly also exposed, some of them health workers travelling to hospitals and other care environments. Sadiq Khan has already asked the health secretary to make masks compulsory on London's transport network, but no word yet... I don't know whether TfL have the powers to do it themselves.

I think Sadiq Khan has jumped on the mask idea as it is something that wouldn't be his fault when the real issue is likely to be to do with a lack of hygienic hand washing facilities at many locations.

 

[MarkyT]

I think Sadiq Khan has jumped on the mask idea as it is something that wouldn't be his fault when the real issue is likely to be to do with a lack of hygienic hand washing facilities at many locations.

Definitely an issue for staff I'd agree, and needs sorting, but even with adequate washing facilities, they'd still be at risk from the airborne droplets. If I was in London you wouldn't catch me in a tube station or train as a passenger at the moment if I could possibly avoid it. I think masks are a very sensible measure on all transport, not only to control transmission but to help rebuild confidence, which will be very necessary for the future. They are now required on MTA and other public transport in New York, after scores of staff deaths and reports that the subways could have been one of the primary vectors for transmission between members of the public in their terrifying outbreak. Also in the USA, here's a Seattle conductor refusing access to a streetcar passenger without a face mask in 1918 during the Spanish flu pandemic:

 

[bramling]

I think Sadiq Khan has jumped on the mask idea as it is something that wouldn't be his fault when the real issue is likely to be to do with a lack of hygienic hand washing facilities at many locations.

Khan is in a spot of bother at the moment, as he’s (largely unfairly) being blamed by just about everyone for reducing Underground services. Unfortunately this has partly come about by some poorly thought through statements earlier on in all this where it was implied that reducing Underground services was a response to falling passenger numbers. This wasn’t the case at all, the reduction in services was due mainly to staff non-availability, but the narrative has stuck and people have it in their minds that it was some kind of money-saving decision from Khan and thus an error of judgement.

*Anything* which helps dig Khan out of this hole is likely to be propagated as a damage-limitation exercise, especially with the complementary bad story about the bus driver fatalities (for which I think there’s more accountability within TFL as protection for this group of staff should reasonably have been foreseen).

Add in to this the increasing financial pressures on TFL which will inevitably require government support, and this all adds up to a brown-stuff storm.

Having said all that, anything’s probably worth a go at the moment. As long as there aren’t any disbenefits associated with wearing them then it’s worth pursuing.

 

[Bletchleyite]

Having said all that, anything’s probably worth a go at the moment. As long as there aren’t any disbenefits associated with wearing them then it’s worth pursuing.

There aren't really disbenefits of wearing homemade cloth ones (other than in vigorous exercise which some won't be able to do any more). The disbenefit of people pursuing medical grade ones, and you know they will, is that they get them instead of the NHS.

 

[Qwerty133]

Khan is in a spot of bother at the moment, as he’s (largely unfairly) being blamed by just about everyone for reducing Underground services. Unfortunately this has partly come about by some poorly thought through statements earlier on in all this where it was implied that reducing Underground services was a response to falling passenger numbers. This wasn’t the case at all, the reduction in services was due mainly to staff non-availability, but the narrative has stuck and people have it in their minds that it was some kind of money-saving decision from Khan and thus an error of judgement.

*Anything* which helps dig Khan out of this hole is likely to be propagated as a damage-limitation exercise, especially with the complementary bad story about the bus driver fatalities (for which I think there’s more accountability within TFL as protection for this group of staff should reasonably have been foreseen).

Add in to this the increasing financial pressures on TFL which will inevitably require government support, and this all adds up to a brown-stuff storm.

Having said all that, anything’s probably worth a go at the moment. As long as there aren’t any disbenefits associated with wearing them then it’s worth pursuing.

What Khan is seemingly failing to realise is that there must be an explanation as to why tube drivers have been catching the virus at an increased frequency compared to the general public, despite them spending relatively little time in public areas and therefore having little difference in terms of exposure to airborne virus particles than regular commuters. This would suggest that the cause must be something that drivers are coming into contact with that commuters are not.

 

[MarkyT]

What Khan is seemingly failing to realise is that there must be an explanation as to why tube drivers have been catching the virus at an increased frequency compared to the general public, despite them spending relatively little time in public areas and therefore having little difference in terms of exposure to airborne virus particles than regular commuters. This would suggest that the cause must be something that drivers are coming into contact with that commuters are not.

Possibly driving quickly through the breath and ejected droplets of thousands of passengers facing the platform edge with the cab window open when entering stations? Thinking about it, it's probably worse than standing in one place as a platform attendant.

 

[bramling]

What Khan is seemingly failing to realise is that there must be an explanation as to why tube drivers have been catching the virus at an increased frequency compared to the general public, despite them spending relatively little time in public areas and therefore having little difference in terms of exposure to airborne virus particles than regular commuters. This would suggest that the cause must be something that drivers are coming into contact with that commuters are not.

For all I know there could be some mileage in the idea that Underground drivers are more prone to coughs as a result of working in a dusty environment.

However, firstly many Underground drivers are shielding so that’s a proportion of drivers off the table for a start. Transport staff in general aren’t known for being the most healthy, and in an industry where many people stay in the same role for many years there’s a fair share of staff at the older end of the age range, with older tending to mean greater likelihood of underlying conditions.

As for the rest it’s hard to comment. Messrooms and canteens tend to resemble mini social clubs, and until very recently were in no way laid out in a way that would aid social distancing. I suspect that any outbreaks in the early days would have got round pretty readily. Add in a proportion of staff who travel to/from work on public transport which at the time might have been crowded (just because shift workers tend to travel at odd times doesn’t always mean their trains are empty).

 

[bramling]

Possibly driving quickly through the breath and ejected droplets of thousands of passengers facing the platform edge with the cab window open? Thinking about it, it's probably worse than standing in one place as a platform attendant.

Nice idea, but most Underground cabs don’t have opening windows. The only exception is the Bakerloo Line. A few drivers drive round with cab doors open, but would have been unlikely to be doing that in winter!

 

[MarkyT]

Nice idea, but most Underground cabs don’t have opening windows. The only exception is the Bakerloo Line. A few drivers drive round with cab doors open, but would have been unlikely to be doing that in winter!

So on modern units where's the air inlet for cab ventilation?

 

[bramling]

So on modern units where's the air inlet for cab ventilation?

Good question and I’ve had to go delving deep into an Alstom technical data book to get an answer. That answer is that for the 95 and 96 stocks fresh air is taken into the air conditioning system via a small grille on the cab front.

There’s no other cab ventilation as far as I know apart from two automobile-style grilles either side of the driver, which are essentially useless. Unlike the “wasp dispensers” on mainline trains, on Underground trains these essentially dispense dust and not much else!

I can only comment for those trains as I don’t have any technical handbooks for any other stocks which go into that level of detail.

 

[MarkyT]

Good question and I’ve had to go delving deep into an Alstom technical data book to get an answer. That answer is that for the 95 and 96 stocks fresh air is taken into the air conditioning system via a small grille on the cab front.

There’s no other cab ventilation as far as I know apart from two automobile-style grilles either side of the driver, which are essentially useless. Unlike the “wasp dispensers” on mainline trains, on Underground trains these essentially dispense dust and not much else!

I can only comment for those trains as I don’t have any technical handbooks for any other stocks which go into that level of detail.

Lets hope there's efficient filtration in the air-con. I'm sure it's good for dust, which is clearly a well known issue in tunnels, but does it filter out droplets as well? Whatever the answer, pre-filtration installed on the mouths of passengers waiting on platforms must represent a significant improvement to the general environment of stations.

 

[bramling]

Lets hope there's efficient filtration in the air-con. I'm sure it's good for dust, which is clearly a well known issue in tunnels, but does it filter out droplets as well? Whatever the answer, pre-filtration installed on the mouths of passengers waiting on platforms must represent a significant improvement to the general environment of stations.

Can’t answer that one. As you say there must be filtration in there, but my info doesn’t go into specifics.

I can see there does seem to be a case for masks as a way of protecting others, and I suspect it will happen. Let’s see how long it takes to materialise...

 

[MarkyT]

I assume we're talking about a dedicated small aircon unit for the drivers cab here as I know there's non for the passenger accommodation famously on the deep tube, and subsurface only got it fairly recently with the S stock.

 

[HH]

As for the rest it’s hard to comment. Messrooms and canteens tend to resemble mini social clubs, and until very recently were in no way laid out in a way that would aid social distancing. I suspect that any outbreaks in the early days would have got round pretty readily. Add in a proportion of staff who travel to/from work on public transport which at the time might have been crowded (just because shift workers tend to travel at odd times doesn’t always mean their trains are empty).

I suspect that mess rooms and canteens are a major issue in such environments. My observations are that staff (mainly male) are often not properly physically distancing. The fact that some of the early TfL bus deaths were controllers and not just drivers, adds weight to this theory. I have to see it as a failure of management to understand the issue and come up with solutions.

 

[Bletchleyite]

What Khan is seemingly failing to realise is that there must be an explanation as to why tube drivers have been catching the virus at an increased frequency compared to the general public, despite them spending relatively little time in public areas and therefore having little difference in terms of exposure to airborne virus particles than regular commuters. This would suggest that the cause must be something that drivers are coming into contact with that commuters are not.

Messrooms?
People sneezing on the driving controls?

 

[Bletchleyite]

Possibly driving quickly through the breath and ejected droplets of thousands of passengers facing the platform edge with the cab window open when entering stations? Thinking about it, it's probably worse than standing in one place as a platform attendant.

I very, very much doubt that, as it's said it's quite a heavy virus and falls to the floor very quickly, plus the strong wind as the train approaches will disperse it all. It'll be other aspects of the job.

I know you're seeking to justify masks but this is tenuous even by the standard of tenuous things.

 

[bramling]

I assume we're talking about a dedicated small aircon unit for the drivers cab here as I know there's non for the passenger accommodation famously on the deep tube, and subsurface only got it fairly recently with the S stock.

Yes correct only for the driver’s cab. I couldn’t comment on how the S stock system works.

 

[MarkyT]

I very, very much doubt that, as it's said it's quite a heavy virus and falls to the floor very quickly, plus the strong wind as the train approaches will disperse it all. It'll be other aspects of the job.

I know you're seeking to justify masks but this is tenuous even by the standard of tenuous things.

The virus itself is microscopic and its weight is negligable so if it could exist in the environment on its own then it could be suspended and blown around in air currents like very small particulate matter. It is most commonly found suspended in spit (basically water) droplets expelled from the mouths of those who are infected, often unknowingly at the time, through coughs, sneezes, talking and possibly heavy breathing during and after exertion. Those droplets project forward in the exhalation, the largest falling nearest , the smallest going further and also growing smaller with time through evaporation, which is clearly affected by temperature. The smallest droplets can stay in the air for a while in a cloud that can be left behind by a moving subject for example. While in a surface station I agree the moving air of a train approaching will probably disperse any such moisture clouds. In the confines of a tube platform it will tend to compress and agitate the air containing that aerosol like a loose fitting piston in a cylinder. I would suggest that is bad for everyone breathing in that environment. The particular effect on drivers was merely a brainstorm suggestion in the spirit of all ideas being valid as initial entries on the risk register. Other suggestions, of poor messroom hygiene, contaminated cab controls etc are all highly plausible. Each might have some part to play and many could plausibly be mitigated by mask wearing and/or other measures.

 

[bramling]

The virus itself is microscopic and its weight is negligable so if it could exist in the environment on its own then it could be suspended and blown around in air currents like very small particulate matter. It is most commonly found suspended in spit (basically water) droplets expelled from the mouths of those who are infected, often unknowingly at the time, through coughs, sneezes, talking and possibly heavy breathing during and after exertion. Those droplets project forward in the exhalation, the largest falling nearest , the smallest going further and also growing smaller with time through evaporation, which is clearly affected by temperature. The smallest droplets can stay in the air for a while in a cloud that can be left behind by a moving subject for example. While in a surface station I agree the moving air of a train approaching will probably disperse any such moisture clouds. In the confines of a tube platform it will tend to compress and agitate the air containing that aerosol like a loose fitting piston in a cylinder. I would suggest that is bad for everyone breathing in that environment. The particular effect on drivers was merely a brainstorm suggestion in the spirit of all ideas being valid as initial entries on the risk register. Other suggestions, of poor messroom hygiene, contaminated cab controls etc are all highly plausible. Each might have some part to play and many could plausibly be mitigated by mask wearing and/or other measures.

Presumably there’s also the simple issue that Underground drivers, like bus drivers, will have been working in some of the parts of the country where infection rates are highest, for example Brent.

One would expect rates amongst Underground drivers to be lower as they’re less exposed whilst carrying out the physical task of driving, but otherwise their level of contact with others probably isn’t that different. Of possible note is that in a few cases bus drivers share Underground staff canteens I believe, this may well not have helped.

Going forward we’re bound to see a difference in rates relative to elements of the rest of the population, as Underground drivers will have been at work for the duration so have had less opportunity to fully lock down, both in the earlier “work from home if you can” stage, to the fuller lockdown currently in place.

 

[Bletchleyite]

The virus itself is microscopic and its weight is negligable so if it could exist in the environment on its own then it could be suspended and blown around in air currents like very small particulate matter.

I've not got a reference, but I definitely recall reading that for a virus coronaviruses are quite heavy and they do not remain suspended for any appreciable length of time. As I said, if they did it'd spread like measles does (which is much smaller and does remain suspended) and the R0 would be up in the 10s or more like measles.

It is most commonly found suspended in spit (basically water) droplets expelled from the mouths of those who are infected, often unknowingly at the time, through coughs, sneezes, talking and possibly heavy breathing during and after exertion. Those droplets project forward in the exhalation, the largest falling nearest , the smallest going further and also growing smaller with time through evaporation, which is clearly affected by temperature. The smallest droplets can stay in the air for a while in a cloud that can be left behind by a moving subject for example. While in a surface station I agree the moving air of a train approaching will probably disperse any such moisture clouds. In the confines of a tube platform it will tend to compress and agitate the air containing that aerosol like a loose fitting piston in a cylinder. I would suggest that is bad for everyone breathing in that environment. The particular effect on drivers was merely a brainstorm suggestion in the spirit of all ideas being valid as initial entries on the risk register. Other suggestions, of poor messroom hygiene, contaminated cab controls etc are all highly plausible. Each might have some part to play and many could plausibly be mitigated by mask wearing and/or other measures.

Have a read of this with regard to the issues with that very basic level of consideration:

The Viral ‘Study’ About Runners Spreading Coronavirus Is Not Actually a Study

Belgian researchers chose to bypass all standard science publishing protocols to publish research that has been overhyped and isn't well understood.

www.vice.com

 

[Domh245]

It's far more likely for the virus to have spread through the driver population by contact with infected surfaces (in the cab or messrooms) than by aerosol transmission agitated by the passage of trains.

The amount of virus expelled by any infected person is going to be small, and when diluted by the air you're looking at absolutely trace levels of virus in the air. Unless the platforms are a pea-souper of droplets you'd have to be unbelievably unlucky for a droplet containing the virus to work it's way into the cab and for that to then be inhaled by a driver. In contrast, a driver will work many trains a day (particularly on lines where stepping back is used) and each train will see many drivers over the course of the day before being stabled (and maybe disinfected) - when in that cab they're repeatedly touching surface which haven't been cleaned and inevitably touching their face - a surefire way to spread the virus quickly. Even despite being well shielded from the population at large, it only takes one driver to catch it and infect a couple of cabs for it to begin spreading rapidly.

Occams razor and all that..

 

[Bletchleyite]

Agreed.

There may be a case for masks for passengers due to the inability to maintain 2m distancing (this is the reason for medical staff not treating known COVID patients wearing PPE - you can't treat someone from 2m away!), but I think @MarkyT is reading a little too much into this situation.

 

[bramling]

It's far more likely for the virus to have spread through the driver population by contact with infected surfaces (in the cab or messrooms) than by aerosol transmission agitated by the passage of trains.

The amount of virus expelled by any infected person is going to be small, and when diluted by the air you're looking at absolutely trace levels of virus in the air. Unless the platforms are a pea-souper of droplets you'd have to be unbelievably unlucky for a droplet containing the virus to work it's way into the cab and for that to then be inhaled by a driver. In contrast, a driver will work many trains a day (particularly on lines where stepping back is used) and each train will see many drivers over the course of the day before being stabled (and maybe disinfected) - when in that cab they're repeatedly touching surface which haven't been cleaned and inevitably touching their face - a surefire way to spread the virus quickly. Even despite being well shielded from the population at large, it only takes one driver to catch it and infect a couple of cabs for it to begin spreading rapidly.

Occams razor and all that..

Part of the difficulty with all this is no one really knows how many asymptomatic cases are out there.

When we take into account that many of the staff will be off as a result of shielding rather than isolating, and that some of the isolations will be due to other family members (for example children who until comparatively recently would have been at school), I’m not sure the absence levels of Underground drivers through suspected infection are *that* high. Certainly there haven’t been the numbers of high-profile deaths like we’ve sadly seen with the bus drivers.

 

[Domh245]

Part of the difficulty with all this is no one really knows how many asymptomatic cases are out there.

When we take into account that many of the staff will be off as a result of shielding rather than isolating, and that some of the isolations will be due to other family members (for example children who until comparatively recently would have been at school), I’m not sure the absence levels of Underground drivers through suspected infection are *that* high. Certainly there haven’t been the numbers of high-profile deaths like we’ve sadly seen with the bus drivers.

Sure, and with you being 'on the ground', I'll take your word that most staff absence is down to shielding rather than infection/self isolation (indeed, if it was infections you'd have expected the numbers available to increase again recently) - but I think it's still far more likely that any infection spread amongst drivers would have been through contact with contaminated surfaces than aerosol.

 

[MarkyT]

Have a read of this with regard to the issues with that very basic level of consideration:

The Viral ‘Study’ About Runners Spreading Coronavirus Is Not Actually a Study

Belgian researchers chose to bypass all standard science publishing protocols to publish research that has been overhyped and isn't well understood.

www.vice.com

Thanks for that. I had doubts over the importance of the heavy breathing hypothesis, and the conclusions about how wide a berth is needed around athletes were absurd, but there's no doubt coughing, sneezing and talking are sources of variable sized droplets which can be projected considerable distance. They are the source of all transmission, whether directly to others nearby or through settling on surfaces touched later. Non of this detracts from the desirability of blocking the droplets at source with some kind of covering I'd suggest. In the absence of any other close public gatherings, public transport, especially in the vehicles, has to be one of the most important places to introduce mask wearing, due to difficulty of distancing maintenance, exposed surfaces frequently touched and the wide geographic spread of people brought together randomly in close proximity. This is assuming of course that the intention IS to prevent spread as much as possible. By all other policy indicators it appears that remains the intention, but the UK stance on mask wearing is beginning to look curiously out of step with developing policy in the rest of Europe now. Even France, that 'well known centre of civil obedience and order' has recommended general non medical mask wearing and mandated it in some places.

Another image from early 20th century USA: