Public Transport and Infectious Diseases
This is a rough set of guidelines for how to make public transport networks more resilient to infectious diseases. While this post is inspired by the Covid-19 pandemic, some of what I’m going to discuss here is relevant to infections in general, both seasonal flu and future generational epidemics.
I’m aiming mainly at people who work for public transport authorities and can act to epidemic-proof their systems in the future, but some of the guidelines may be helpful for riders. The key takeaway is that public officials probably should not want to shut down the system or discourage people from riding it; thus, as a rider you probably shouldn’t avoid the trains except insofar that you should avoid most places you’d take them to, like crowded offices and events.
Finally, let me be clear: my expertise on public health approaches zero. I have a fair amount of general knowledge of how different urban rail systems operate, but more about network design and costs than public health. To the extent I’m ahead of anyone else on this issue, it’s that I’ve seen so much wanton incuriosity in the West (especially the US) toward Asian practices, and therefore asked around for East Asian practices rather than trying to learn worst industry practices from Europe and North America.
The scope of this post
The scope of what best industry practices are on epidemic prevention is, roughly, the high-income major cities of East Asia, plus Singapore. China is excluded on purpose: a country that arrests doctors for telling the public about the coronavirus isn’t really where you want to get disease prevention tips from. Instead, the low infection rates so far in Taiwan, Hong Kong, and Singapore, and South Korea’s ability to control the infection through mass testing after the explosion in cases at the Shincheonji church, suggest that those countries should be the models. Japan may be a good example as well, but the state is undertesting, so the full extent, while apparently lower than in Western countries, may be understated.
I have talked to people in Singapore, Hong Kong, and Seoul to understand the situation on the ground there. In Taipei and the cities of Japan I have not, and am relying on media report; I know I have commenters who live in Japan, so if you have anything to say about the efforts there then please do speak up and contribute, regarding both the measures taken and current infection rates.
This is necessarily a volatile situation. It’s possible that in a month, Germany and France will have controlled the infection while the rich countries of Asia will look as dire as Lombardy looks right now. I don’t think such an inversion is at all likely, but ultimately, I am describing the best information available as of 2020-3-11.
Do people need to stop taking mass transit?
Probably not. I emphasize probably because the different in-scope cities are reacting differently, and we don’t yet know for certain whether avoiding the trains is correlated with greater safety from infection.
In Singapore, life goes on. I have family there; I’m told that the MRT is not less crowded than the usual at rush hour, but the buses are definitely less crowded. The estimate I heard is that 1/3 to 1/2 of the population on the street is wearing surgical masks. Instead of shutting down schools and offices, the state imposed a mandatory quarantine on people arriving from early-infected countries including China, and went as far as revoking the green card of a permanent resident who violated the quarantine.
Update 2020-3-12: my sibling reports that, first, the mask-wearers are largely Chinese, not ethnic minorities like Malays and Indians, and second, ridership on the MRT is noticeably down at rush hour, with some empty seats where normally trains are standing-room only.
In Hong Kong, it is exactly the opposite. The state is not terribly relevant – the population does not trust it. There was early caution due to social memory of SARS, leading to rapid social distancing, closing down schools, offices, and public events. I’ve asked Lyman Stone and Trey Menefee for their impressions. They both said the MTR is empty nowadays, and Lyman reminded me that ridership was down even before the epidemic on account of a popular boycott in response to the company’s collaboration with regime security. The total social distancing means people travel little, but when they do, it’s often by TNC, leading to a lot of Uber traffic; drivers even put hand sanitizer in the back of their cars and make an effort to clean the interior well, to attract passengers afraid of catching the disease.
In Seoul, the situation is different, in that there was a big flare of the epidemic thanks to the so-called patient 31, a member of Shincheonji, who transmitted the virus around the group. Until a few days ago, Korea was the #2 country in the world in confirmed cases, after China, but Italy and Iran have since overtaken it and the US is poised to overtake it soon too. But new infections are down thanks to an aggressive regime of testing. Public transportation is still in operation – Min-Jae Park, an NYU student from Korea who has been working with me and Eric Goldwyn on our construction costs project, said that there is noticeably less ridership according to family but also,
Yesterday, there has been a group of confirmed cases in a same workplace including commuters via transit to and from Seoul. The government did declare that it is almost impossible track back individual patients to show if transit is a hazardous environment. However, since the early stages, the national and local transit authorities has been aggressively sanitized the public realm especially in transit. Additionally, the ridership of the transit decreased overall, as the remote working culture started to become naturalized.
So far, there has not been a substantial case that proves that transit needs to be reduced or shut down, but we shall see how the yesterday’s case turns out. I will update to you if any policy change comes up relating to the virus, but I think that is probably the last thing the government want to do in scale of national lockdown Italy did.
My other source on Korea’s response is Nick Plott, a.k.a. Tasteless, a popular esports caster. In a short video about the virus and its effect on esports, he mentions the effect on Korea, and says that public transport in Seoul is deserted. My hunch is that Min-Jae’s take, although second-hand, is more accurate than Tasteless’s, and public transport in Seoul still has a fair amount of ridership, if not nearly so much as before the pandemic.
Update 2020-3-12: Min-Jae clarifies that as of the morning of the 13th Korea time, there is a shift to private transport even though the government says public transport is safe; he guesses ridership is down 20-30%.
In the big cities of Japan, ridership is down, though not by much relative to the magnitude of the crisis. The media quotes 10-20% declines in ridership on the Yamanote Line and on lines around Osaka, and 20-30% declines in ridership on the Nagoya subway. Maciej Ceglowski is visiting Japan and reports that the trains in Kyoto “are not crowded at all,” adding that about 3/4 of the people wear masks. Japanese office culture is resistant to working from home, as is I think office culture elsewhere in Asia-Pacific, and this has hampered social distancing efforts.
Finally, in Taipei, I do not have any information regarding public transport usage during the pandemic. That said, some circumstantial evidence that it is still going on is that the region has just opened a new circumferential line, the Yellow Line, and even let passengers ride for free for the first month, getting more than a million riders in 25 days, which is low but not outrageously so for a new circumferential line.
How can mass transit be made less infectious in the future?
There are two ways passengers can infect other passengers in public. The first is directly, through coughing, sneezing, or casual touching combined with touching one’s own face. The second is through intermediate surfaces, called fomites in epidemiology, such as poles, seats, door handles. Neither disease vector can be eliminated, but there are design elements that can greatly reduce both.
Infrared sensors for temperature checks
It’s possible to take people’s temperatures passively using infrared sensors. Taipei installed such sensors at one MRT station and is about to do so at six additional central stations. People with fever above 38 degrees will not be allowed into the station, and people with temperature between 37.5 and 38 degrees will have to undergo an ear temperature check to confirm that they do not have a fever. I saw this system at the airport when I visited Taipei three months ago, where it was used to screen passengers with fever.
This system requires all station entrances to be staffed. This may be expensive in smaller cities, but as a temporary measure during an epidemic, it’s fully justified. If you’re the government, you can afford to bust the budget in an emergency to make sure people can travel around the city without contracting a fatal disease.
Temperature checks will miss asymptomatic cases, but this is fine. The epidemiologist-turned-data-scientist Maria Ma summarizes the best available research on Covid-19: while asymptomatic transmission is possible, it requires much closer contact than being together on a train.
Every station entrance should have hand sanitizer in sufficient quantities for the expected passenger traffic. Some office and university buildings already have this solution, even in the West; this is especially common in Singapore. My recollection of Taipei is that it had hand sanitizer at stations even in December, but I am not completely certain this was from Taipei and not Singapore or Bangkok.
Seoul offers disposable chopsticks for pressing elevator buttons. In the short run, transit agencies that use button-operated doors, such as those of Berlin and Paris, should do the same at stations and inside train cars, space permitting. In the long run, European agencies should be more like Asian (or North American) ones and have automatic doors opening at every stop.
In the long run, it’s also beneficial to design train interiors to inhibit the spread of viruses and bacteria. Some materials catch bacterial and viral infections more than others – for example, a 2015 study by Biranjia-Hurdoyal, Deerpaul and Permal finds that synthetic purses have far more bacteria than leather or cloth ones; this should be equally true of train seats. Moreover, the poles should be coated with copper, as it has biocidal and antiviral properties – a 2013 study by Salgado et al finds that coating ER surfaces with copper reduces the risk hospital-acquired infections, from 12.3% to 7.1% when all infections are included or from 8.1% to 3.4% excluding MRSA and VRE.
Fare barriers and station entrances should be designed to minimize fomites. The best option here is not used in Asia: no fare barriers at all, with proof-of-payment fare enforcement. But the smartcard systems and automatic fare barriers so common around Asia are a good second best, as they do not involve physical contact with foreign objects. The worst options are metal turnstiles that passengers turn with their hands, cage-style turnstiles, or heavy doors that passengers must push on their way out; these are found in New York and Paris, and should be replaced to reduce the spread of disease in the future.
Transport companies should clean their vehicles and stations regularly. This may not be realistic at bus stops, but is realistic on buses and trains and at all train stations. That ten-year-old piece of gum stuck to the floor of your New York subway station is not by itself a vector for a virus that only spread to humans three months ago, but if it’s still there, then so is the tissue thrown yesterday by someone who just got sick.
Seoul is using drones to spray disinfectant on hard-to-reach surfaces, such as playgrounds. This can also be used at railyards and elevated rail stations to speed up the process.
The guidelines above are designed for passenger safety. What about employee safety? This, I believe, is a smaller problem, at least in countries that are advanced enough to have good sick leave. It is notable that even in Hong Kong, trains are running, albeit the buses run at lower frequency as people are staying home.
A train driver works sitting alone in a cab separated from where passengers are is not at great risk, and neither is a bus driver separated by a glass screen. There is risk of worker-to-worker infection, especially if drop-in crews are common to control turnaround times, but it’s easier to test workers for fever and send sick ones home with pay than to deploy infrared sensors at every station entrance. As an additional layer of safety on top of temperature checks and generous sick leave, agencies should clean train and bus driver cabs between every crew change.
It’s workers who are together all the time who should not be going to work – that is, the head office. Planners, schedulers, managers, and clerical workers can work remotely, albeit at reduced productivity. Making regular plans to reduce infections during flu season, and planning how to respond to bigger epidemic threats in advance, is therefore useful since it doesn’t stress planning capacity at a time when productivity is the lowest.
Sounds like some good advice Alon.
Amtrak sent me an email today to try and reassure me about their COVID-19 mitigation. I was a little disconcerted when one of the two items they identified was making antibacterial products available to customers. Since COVID-19 is a virus this isn’t likely to do much good.
Hopefully someone at Amtrak empowered to do something will read this post.
Some antibacterial products are also good against viruses, like normal soap. But usually biocidal substances are ineffective, yeah, hence the constant advice to just use soap.
..More than you ever wanted to know
That’s for disinfection, I didn’t go bother to look up the definition for sanitizer or antibacterial. Sanitizer may not have a definition. If the container says “Kills cold and flu viruses” been tested to do that. In the U.S.
DId it say “antibacteriaL” or something else? The FDA has definitions and antibacterial doesn’t mean the same as sanitizer or disinfectant. Mix the bleach with water, you should always mix the bleach with water, it’s a disinfectant and at lower concentrations it’s a sanitizer. Which public relations people aren’t aware of. Or they decided many people don’t know what virucidal means and used antibacterial. Antibiotics don’t do you any good if you have something viral. Viruses are delicate little things and if it’s ripping the bacteria to shreds, outside your body, it’s doing the same to the viruses. I’m sure there are exceptions but viruses are delicate little things.
There is all sorts of stuff floating around the interwebs these days. 60 percent alcohol kills almost everything and if if’s that stuff that smells like alcohol they likely put a bit more than 60 percent in. Because if it’s not at least 60 percent they can’t call it sanitizer. Not in the U.S. anyway. Assuming sanitizer has a definition. And you have to rub your hands together until it’s dry.
And soap is ambiguous. They are telling you to use the sudsy stuff you clean with. It rips stuff like bacteria and viruses to shreds. That didn’t get floated away and flush down the drain.
Actually the main effect of sanitisers which can be ethanol or mild surfactants (detergents) is not so much that they kill the bugs or viruses, but rather that they break up clumps. All bacteria and viruses have high MOI, multiplicity of infection, and this really reflects not the absolute number of the bug/virus but the occurrence of agglomerations as it is these, not single bacteria or virus particles, that induce the vast majority of infections. That is, bugs don’t at all like to be lonely. Singly, they may not be technically dead but effectively they can’t do much. So ethanol or detergents break up agglomerations and reduce infectivity. Of course the washing of hands with a dob of detergent (best applied to dry hands before water) sluices them off skin.
All our ocular and bucal secretions, tears & saliva etc, are loaded with the enzyme lysozyme as one of our primary infection barriers. which does exactly this: breaks up clumps of bacteria and some viruses, so it is not exactly killing them but reducing their infectivity. (To be clear, lysozyme can kill bacteria by digesting their cell wall but it doesn’t have to do this to be antibacterial.)
There have been studies of flushing your hands with water, flushing your hands with water while going through the motions of washing and washing with a… cleanser… It dislodges what is left and anything that hasn’t been dislodged has a rough time with the cleanser. Which is why you have to do it for 20 seconds. If the plain water didn’t give it a rough time. Lots of this stuff doesn’t like plain water. The UV light isn’t breaking clumps apart, it’s ripping their delicate little selves to shreds.. Like it did you your coworker’s eyes.
More or less correct.
UV inflicts damage on DNA, or RNA in the case of coronaviruses, which is manifested* when it attempts replication in the host (infected) cell: can’t be replicated past so the product is short stretches of “broken” DNA or RNA and replication products. Non viable (though, for completion, sometimes upon very high rates of infection some viruses may even overcome this by assembling a single good copy from a high density of incomplete fragments!).
*i.e. the UV doesn’t “blast the virus apart”, neither the virus particle nor its genome, and the damage only becomes manifest when it infects the host cell.
Useful, thank you.
Re the infrared thermometers: Do you know how much one costs? Also, do you know if it requires constant monitoring i.e. does it beep/sound an alarm when someone above a certain temperature is detected?
From the photo in the article linked from Alon’s essay, Taiwan’s MRT is using a high-resolution thermal IR camera with a human operator. Total hardware cost is probably in the range of $5000 to $10000 USD. Training and staff costs extra.
The setup in the photo is much more of a feel-good measure rather than a serious attempt at screening, however. The camera is not positioned to give the operator adequate sightlines over all passengers, especially in crowded conditions. Feverish people could easily slip through, especially if they were intentionally attempting to evade the checkpoint.
Doing this right would be seriously expensive. I think the easiest way to implement fever checks would be as part of a faregate, with a low-resolution thermal IR camera feeding specialized face recognition software designed to measure head temperature. The faregate would lock if the would-be passenger’s temperature was too high or was unreadable due to facial coverings. It might be possible for passengers to defeat this system by washing their face with ice water prior to entry, however, so its use against deliberate quarantine breakers would be limited. False positives caused by people who’ve been running, or have recently drunk alcohol, could also be a problem.
I don’t know the cost. I imagine it’s fairly high judging by the fact that Taipei is only buying 16. It also requires stations to be staffed, but East (and Southeast) Asian stations are always staffed anyway, this isn’t Berlin.
Remember to thank your bus driver during this stressful time!
Many operators will soon not be able to report to work, either because they are taking care of themselves or their loved ones.
Now is the time for transport providers to have a game plan of shifts in ranked order that can be pulled as labor becomes increasingly unavailable, even if operators aren’t “officially” sick themselves. A pre-made plan saved my previous employer from stress and kept customer complaints down my minimizing the pain.
(The thermometer recommendation would probably be illegal in the US as a health care privacy violation, but pandemics have a way of throwing these rules out the inward-opening standee window.)
Thanks for this article.
I think an easier, or at least more universally applicable, solution is to use one’s knuckles rather than fingers. I can’t remember when I adopted the habit, possibly when I used the Paris Metro a lot, but I continue to use this small trick reflexively today including for elevators buttons etc. I know I am awfully prone to poking my fingers in my eyes no matter how much I know it is a bad habit; early in my research career I got an eye infection which was probably Adenovirus picked up from my lab (it was embarrassing as it provoked an official OHS investigation) and that possibly was when I started disciplining myself to use knuckles not fingers for public buttons. Eye infections are particularly scary things and though not many of these URTI viruses cause actual infection of the eyes, they all can enter via that route which is why googles are a crucial preventative measure in the close proximity of heavily infected people.
This is almost certainly why it is more important for infected people to wear masks than uninfected people, and why the efficacy of masks (worn by uninfected) in prevention is so poorly supported by data (without eye protection, masks are not sufficient–though that is my surmise rather than proven fact, but to be clear it is known that masks alone don’t have much effect on protection but masking the infected does reduce spreading–hope that is clear?).
As to surfaces, fomites, cleaning etc. I think a lot of this is over-rated and much of it is public theatre. This type of virus really doesn’t like to survive in the environment. Though there is a frustrating lack of clean data on SARS-CoV-2 I seriously doubt it persists in infectious form for very long or we would be seeing a much more prevalent problem. The media “survives on surfaces from 2 hours to 9 days” is polemic and more misleading than useful advice, IMO. However I do agree that a bit of hand cleansing after exitting crowded public spaces (transit etc) is a good idea. But note that this is not because these viruses enter via skin, but because we touch our faces so much and this is almost involuntary and essentially uncontrollable. The important thing is to fiercely resist touching your face, let alone your eyes, until you exit the danger zone and sanitise your hands.
There are some very peculiar behaviours of this virus/disease such as the Italian versus Korean experience. And why so far Australia has only 100 cases (all but one or two originating overseas); politicians like to boast it is their early blocking of 50,000+ students returning from their NY break in China, yet Canada allowed their Chinese students to return and also doesn’t have a big issue (so far). I think it must be much simpler and probably is that here it is peak summer and (until last week) this means hot and dry, and that is very unfavourable for these viruses and why they are so seasonal. That is, R0 is very low in Australia (this is not an explanation for Canada …. so far). But in any case it does seem to me that R0 is low for this particular virus. In fact, notwithstanding the lack of data, it really looks like both R0 and morbidity are low for this virus, or at least a fair bit lower than many early estimates floating around.
Note that Korea is a special case in that the religious sect was not in Seoul and being so insular and peculiar, probably mostly infected themselves rather than outsiders and was thus more limited and easier to limit spread. For Italy I am not sure we will ever know (because the truth won’t get out) but I am not even convinced it is necessarily real, or at least as high as stated–which seems a bit unreal; have they really diagnosed all these people or are they (or some hospitals, centres) just marking normal flu and flu-deaths down to this virus? (Pick your reasons from underfunded health system to wanting to access special funds or just the usual dysfunction between higher management versus field workers etc). Yeah, like Iran’s claim to have tested all 50,000 released prisoners … sure. As it spreads more to France, UK and northern Europe I think we will get a more informative story (though summer is coming and might save them quite a bit, yet oddly might add to misunderstandings, ie. the season change might mask some of the story).
It is a bloody scandal that the US has failed on the testing front (and though many innocent will suffer, at least a bit of deserved justice might rain down on Trump for his cuts to CDC etc and his ridiculous meaningless brogadacio). Because normally I would turn to the CDC for reliable information and interpretation–at least they are being honest and admit they don’t have enough data to comment on these issues. Incidentally, while they may have quasi-valid reasons, I don’t think WHO pronouncements are to be taken literally. I expect this to change in the next two weeks or so.
There is a paper on SSRN which suggests that ncov-19 has the highest R0 at temperatures of 5-11 degrees C and 47-79% relative humidity. I have nowhere near the background to evaluate these claims critically. If true, however, this would explain both of your Canada and Australia observations: most of Canada is far colder than that at the moment and most of Australia is far warmer. If true, also expect all hell to break loose as temperatures rise in most of North America and Northern Europe in the next few weeks.
it’s not 11 degrees indoors. . . . . and during the heating season it’s very unlikely the relative humidity is approaching 50 percent, indoors.
When I read this (below) yesterday I thought of you Adirondacker. (Another of your replies may be more germane but I’m too lazy to search for it.)
But honestly most of the long-winded arguments, in this paper and what it reports of the WHO etc, is rather beside the point, at least at this time during the uncontrolled phase of this pandemic. While I seriously doubt that the virus is in fact technically airborne* it doesn’t matter a damn to the argument for wearing masks–because masks will protect against both droplet and airborne* forms. I think this is another example of a huge organisation that is top-heavy tying itself up in managerialist knots. Thye began by deliberately denying the truth about masks–which they told themselves was for “good” reasons–and still find it difficult to unwind from that position even though they knew then as they know now, it was and is unsupportable and is so obviously doing massive damage. The merest hint of confusion on this subject is making it much harder to recommend, or even mandate, mask wearing in public especially in crowded situations. Here’s another relevant recent observation:
*”Airborne” means tiny aerosol droplets, not the big droplets from sneezing or coughing because their big size cause them to drop out due to simple gravity. These tiny droplets are typically produced during normal speech, a certain (low) amount from normal breathing (if people are super-spreaders, ie. have high virus loads in their upper respiratory tracts). Also, while I certainly accept the claim (bolded in the citation above) of a very short half-life of virus in such droplets outdoors, I am unconvinced UV at the low levels in sunlight has anything much to do with it, at least in 6 minutes (it will have an effect over longer times). It is much more likely to be simple warming and drying of those tiny droplets. Not mentioned in all the media coverage of this topic is that these tiny “droplets” in some senses may persist in air for hours but they don’t persist as droplets, but only as remnant dehydrated material, ie. virus particles and whatever else was in the saliva. Some viruses have evolved to survive this but most have not and that includes (almost certainly) this virus. The confusion here comes from the lack of distinction between mere detection of the viral nucleic acid by very sensitive methods (PCR-based) versus infectious virus. Plus the extreme rapidity of dehydration of those micro-droplets under normal conditions, and not the high-humidity (60%) conditions in most laboratory experiments for reasons I explained in a separate post ages ago.
Is there a point somewhere in there?
I though it was the warm dry air. How’s that working out in Victoria? Or Arizona?
Exactly as this theory would predict. Did you not read the bit that said that the hot weather has its effect, on increasing infection rates, by forcing people indoors for the aircon. At least in places like Arizona, Texas and Florida. Proximity combined with less air circulation or sunlight.
As to Victoria, to their shame it’s the same effect as Singapore’s second wave, ie. the authorities neglected to get the message across to ethnic communities in those social housing blocks combined with many of the residents not having good English or not being attentive to English-language media. They’re still doing it, as during the total lockdown of the tower blocks many residents still didn’t know what was happening and for how long, and apparently many of the meals delivered to them contained pork (high fraction of muslims among the residents). In Melbourne which likes to boast about being one of the most multiculturally sensitive places in the world! Probably wasn’t helped by outsourcing security to private contractors who are notoriously slack on training their casualised workforce.
As well, did you see the numbers? Yesterday saw ≈60,000 new cases in the US while the panic in Melbourne is over 190 new cases (almost none in the other states), a 300x difference and still ≈24x after normalising on population. Of course the panic is because they had thought they were close to elimination of community transfer (which the other states have achieved, all new cases being imports, often those in quarantine and a few quarantine evaders). Note that it is winter in the southern hemisphere, and Melbourne has the worst in Oz (worse than more southerly Hobart).
In Israel the second wave is specifically not about ethnic minorities, unlike the first wave. Turns out having a venal, corrupt prime minister who breaks quarantine and refuses to admit wrongdoing does wonders to sap the public will to maintain social distancing. Somehow the most responsible government in the area right now is the Palestinian Authority, which is terrifying.
Which theory? You have hinted at more than a few and contradicted yourself at least once.
FYI, more discussion of UV sterilisation.
The article has a lead photo of a metro carriage with gigantic (apparently) UV lamps in action. Maybe, but I don’t understand the photo because UV-C lamps are invisible except for a low purple glow, and because almost all “clear” glass or plastic totally blocks it, ordinary cameras and lenses can’t capture it. Only quartz glass transmits UV-C but it is extremely expensive and I don’t know of any lenses and filters made of it. And digital camera sensors won’t be sensitive to it either. Film, maybe. In scientific imaging applications, eg. to visualise DNA, secondary light emission (fluorescence), often involving special dyes that bind the nucleic acid and re-emit in the visible wavelengths, is used.
Plus, if they were genuine UV-C lamps I hope the photographer was protected because they would be delivering a dose that would be instantly damaging. By which I mean the damage would be instant, though like sunburn it wouldn’t be manifested biologically, eg. as blindness or skin burns, for at least an hour–this is part of why UV is so dangerous as you are unaware of the damage until it is too late. This level of UV would be highly destructive of parts of the train such as the seat coverings and any paint would peel or turn into chalk. You might get away with a few exposures but this is not a sustainable method in normal environments. For example in biological containment hoods, in which the UV lights turn on when the glass door is closed, are all stainless steel or glass, as most plastics and other materials simply won’t stand up to the bombardment.
Something from the article that I am having trouble getting to grips with:
I can only think that Edward Nardell (Harvard Medical School; I cited him in an earlier post on this subject) has been mis-cited or out of context because this is seriously wrong. Even aside from the blinding effect on our eyes, UV-C is hugely carcinogenic. Sure, UV-A and UV-B cause more cancer but that is because UV-C in sunlight striking the earth is absorbed by almost everything so is almost totally removed by the atmosphere (the reaction is what creates upper-atmosphere ozone which in turn even more strongly absorbs short-wavelength UV, ie. UV-C) while weak some UV-A and less of UV-B get through and are what cause sun-burn and cancer (and cataracts). Note that, until recently UV-A (with inevitably a bit of UV-B) lamps were used as tanning lamps (and disco balls) because the low risk was deemed acceptable but scientific opinion has changed on that and they have been outlawed in most jurisdictions. It’s complicated because some low exposure to sunlight is protective because it induces low-level but very significant DNA repair and DNA surveillance biological responses in our skins. (This is in addition to protective production of melanin, ie. tanning, plus triggering increase immune surveillance.)
Anyhow, most of the article concerns driving the air to the UV, via fans and UV lamp enclosures in ceilings or air-conditioning ducts etc. This is what happens in specialist situations like clean rooms, maybe surgeries (not sure how much) and, as I wrote elsewhere, I believe most passenger airlines have UV as part of their air recirculation systems (which is a very good thing and might explain why no SARS-CoV-2 transmission has been traced to air travel. I know it seems incredible to many but this remains true). Certainly I believe such installations–which are not particularly expensive in capital or running costs relative to the air installation–are a good idea for restaurants and other crowded indoor public spaces. Though you can be sure Health & Safety will be rigorous, and homemade devices or cowboy manufacturing will be/are outlawed as they should be.
1) The NYC/MTA is experimentally using xenon excimer lights to sterilize its subway cars.
Excimer lights are too powerful to run continuously, and are operated in pulsed modes. They blast photons across a wide spectrum (from vacuum-UV to visible). It takes about 30 minutes to do its job. Because of shadows, many of these systems move a bit while operating to get better coverage. There are ongoing legal battles between the UV-C lamp proponents vs. the excimer proponents about which systems are better, and what they can say about each other in their marketing literature.
2) Airplane air is very high quality. The bleed air from the engines is used. The cabin gets new, fresh, outside air every 5-10 minutes, and the air circulation is good and uniform. The major issue is when loading/unloading/parked, the cabin air can get stale.
3) Because of Covid, there have been proposals to update the building code to require UV-C sterilization in the air ducts for nursing homes. Some proposals for hospitals and other public spaces are to have UV-C horizontally in the air space above peoples heads, to provide disinfection while the air circulates, but to avoid direct human exposure (most materials heavily absorb UV-C, so there isn’t much risk of reflection).
4) UV light in the sub-200nm range will create ozone (breaks down the oxygen in the air). This can be a good thing (ozone is a gas, so it can “get in the cracks” where light doesn’t get to) but it is dangerous as well. Mercury vapor lamps will do this if they use highly transparent quartz glass. Some UV-C mercury vapor lamps use specific formulations of quartz glass to allow the UV-C to get out, but block the the vacuum-UV to be “ozone-free”. UV-C LEDs exist, but are less efficient than mercury vapor lamps, so UV-C LEDs are typically only used where there are lots of on/off cycles, or where the risk/threat of releasing a small amount of mercury should the tube break is considered too great.
Thanks for that information. A pity the journalist didn’t provide some of it.
(1) The Xenon lamps make some sense, though as I have written the whole thing is fairly pointless re this virus. I wonder how they will decide if this strategy is worth pursuing? (Answer: they won’t do real virus survival studies because …. they already show little point, especially if done once a day overnight.)
(2) Good to have that confirmed about airplane air quality.
(3) Absolutely they should make UV sterilisation of recirculated air a normal part of air systems in all care situations but arguably in most crowded indoor situations (malls, big shops etc). Re reflections, the main problem is metal which is highly reflective of UV, however there are relatively easy ways to counter that (but there was a rather too casual dismissal of it in ceilings in that article; UV is too dangerous to be treated in a cavalier fashion–but in fact it is already highly regulated, which again journalists should have found out about.)
(4) I assumed the amount of ozone produced is too low to really matter in these situations? (Compared to radiation from the sun passing thru tens of kilometres of upper atmosphere.) The main output from those lamps is 254nm and is the sterilising wavelength because it is absorbed by DNA (and RNA) causing chemical damage. UV-A (eg. the 365nm line wavelength produced by these lamps) produces the same kind of damage but much less efficiently, nevertheless it is cumulative and a long-term exposure risk because unlike the shortwave UV, it is not blocked by standard glass or plastic.
Bottom line is that this treatment of transit carriages is pure theatre, and worse, IMO it produces false notions of what is protective and what the true risks are w.r.t. this virus. It cannot have any impact whatsoever in terms of making transit safer to use.
Sorry, forgot to ask: Do Xenon Excimer lamps look anything like that lead photo in the article?
Its caption reads: “A quartz UV germicidal lamp is used to disinfect a train at the Svblovo station of the Moscow Metro transit system.” but I am quite sure it is not a UV germicidal lamp unless the photography is v. special which seems unlikely. I hesitate to reveal my ignorance re photography but I believe most so-called “UV photography” isn’t really, but is capturing objects and people illuminated with UV (and mostly UV-A) and thus the light is secondary fluorescence. Though Kodak do make a uv-sensitive sensor, clearly it is for extremely specialist scientific & industrial applications (and must have an entirely quartz light path).
Anyway, my question to you is: does that light in the photo look like Xenon Excimer to you?
From what I understand those lamps look like germicidal uv lamps, ie. only visible part is a violet glow (and one only “looks” at them thru very protective goggles). Like here:
1) The MTA system is from Puro Lighting. It is excimer. Excimer light goes into the visible spectrum.
2) The county hospital a few blocks from my house uses a robotic UV-C (mercury lamp) system from Tru-D.
Click to access Tru-D-2019-Brochure_Pages.pdf
Exactly. That is a very good explanation for both Canada and Australia. And those are fairly tight conditions which I wouldn’t expect to exist for long enough (example not thru a 24h cycle) in most of Europe as spring comes on. And I understand that the European winter was exceptionally mild this year (climate change, bien sur) so it’s probably already there, in a safety zone.
Hah! On tonight’s tv news,and probably around the world, they showed a compilation of clips of politicians and health experts recommending against touching your face, followed a matter of seconds later, the same speaker … touching their face.
While Trump has tried to cut the CDC, he never got them through congress. He was able to fire some people on a pandemic response team, but there were not at the CDC. He claims there were needless bureaucrats, it is entirely possible by not having to go through them things are faster – we will never know of course. The issue has become political and nobody wants to admit their side did anything wrong,and everyone wants to blame the other side for anything they can.
I hadn’t noticed your post before but are your seriously attempting to be an apologist for Trump and his White House?
Rightwingers everywhere seem intent on driving budgets deep into deficit by constantly raising defense spending while simultaneously reducing spending on things that actually are a much bigger existential threat, like climate-change and infectious disease.
In that old post I wrote: “As to surfaces, fomites, cleaning etc. I think a lot of this is over-rated and much of it is public theatre. This type of virus really doesn’t like to survive in the environment. Though there is a frustrating lack of clean data on SARS-CoV-2 I seriously doubt it persists in infectious form for very long or we would be seeing a much more prevalent problem. The media “survives on surfaces from 2 hours to 9 days” is polemic and more misleading than useful advice, IMO. However I do agree that a bit of hand cleansing after exitting crowded public spaces (transit etc) is a good idea.”
Here we are 4 months on, and the obsession with “deep cleaning” etc has reached almost absurd proportions, and it continues to distract from more important strategies. Today:
Speaking of corona… what the hell is happening over there? Did Australia somehow go from a month of no domestic transmission to a day with the same new case count as Germany? What the hell is going on in Victoria?
Alon: “What the hell is going on in Victoria?”
It is related to my last post: distraction from the actually important things. Having said that, Melbourne has imposed mandatory mask wearing, though only in the postcode zones representing these latest outbreaks! Will they wait for each new hotspot breakout before slamming that barn door? Seems the answer is yes!
In Victoria some 40% of all deaths are from aged-care homes, and the really significant thing:
A report on the public broadcaster last night showed that staff had not received proper instruction (and this, 6 months after pandemic struck the world!) and there were innumerable first-hand reports of visitors seeing staff talking to each other face-to-face, and congregating in their staff rooms, all without any masks or any PPE. Some are blaming poor communication to the large number of immigrants with poor English who do these jobs, but I am sceptical to how much that contributes to the problem. Instead it shows the unsurprising result when you lightly regulate, often allow self-regulation, of a for-profit industry.
The big factor is that many of these staff work in many different aged-care homes with one superspreader documented to have spread it across 4 facilities. The real driver is that these workers are casualised and if they don’t work, they don’t get paid; more outrageous for Australia is that they were specifically excluded from the (conservative) federal government’s first job rescue scheme, ie. payments of $1500/fortnight if they are laid off (this has affected about 3 million of the casualised workforce, obviously deliberately by this govt). Naturally this means when these workers get ill, especially if not very seriously (ie. asymptomatically) they are reluctant to follow instructions and stay away from work! Finally, after the Victorian breakout:
It is exactly the same thing that caused the breakouts from the quarantine hotels: private contractors were hired to run this and they simply didn’t bother with any of the recommendations. They hired the cheapest (youngest) untrained people on short-term contracts and gave them no meaningful instruction, indeed some were told to turn up with their own PPE. The public broadcaster actually showed the government contract and the clauses that specified that it was the contractor’s responsibility to instruct their staff in these things. But of course no one expects these profiteers to suffer anything at all. They are the usual suspects, Serco, C4 (mostly British) though the pandemic has uncovered a previously unknown one:
We’ve had at least a decade of exposés of these outsourced security companies and their awful operating habits, and nothing happens. It never will with conservatives in power but even Labor is reluctant to challenge them because the habit and the business has become so integral in how so many things operate in the country. There have been hopes raised that the pandemic may finally bring some real change–in aged-care regulation, in childcare (which has become outrageously expensive, entirely driven by for-profit industry though totally dependent on federal payment) and many other things. But I remain sceptical, and certainly with conservatives who believe, rightly, that they’ve got away with it and with almost all the media on their side ….
I should update my post earlier today: Victoria has today extended the mandatory mask rule to the whole state:
(I can’t locate my more relevant PO comment–on Norman Swan–so will put this here.)
Like father, like son.
You know the latest Trump interview to go viral? The “it is what it is” (150,000 death) in the interview by Jonathan Swan of Axios news agency?
Jonathan is the son of Australian physician-broadcaster, Dr Norman Swan, who had 15 seconds of fame months ago via his Coronapod podcast reports on Australian ABC public radio.
Another approach that might work for bulk disinfection would be to install UV-C (germicidal) lamps in transit vehicles. After the vehicles end service for the day, clean them by hand to remove opaque debris (tissues etc) then run the UV-C lamps for a few hours until the start of service. Appropriate lamp placement and interior design (e.g. hard seating and no horizontal rails) should allow for complete disinfection of most passenger contact points with limited manual labor.
The UV sterilisation is used for specialist science labs (and of course in all laminar flow bio-containment hoods) but not so effective for transit. As well as dangerous–in one of my labs another colleague-scientist managed to blind himself, luckily temporarily, though I imagine it rebounded in his old age, by working in a hood without turning the UV light off–it’s generally not possible; he was a chemist working in a bio-lab and was somehow ignorant as to the severity of UV; it reflects off stainless steel like light off a mirror.
The simpler method is to just heat up the carriage for a brief period (maybe 50°C) and that will be very effective for most viruses and most bacteria.
I’m surprised there was no interlock on your colleague’s UV-C hood lighting. UV-C devices used for water purification tend to be interlocked to protect maintenance technicians from accidental exposure. UVDI’s commercially available UV-C room sterilizer for medical applications is even interlocked with motion detectors to shut off if someone enters the room while it’s operating.
Heat’s an interesting idea but I wonder about heat-up and cool-down times. I believe 56 degrees for 30 minutes is the requirement for inactivating ncov-19. Given the thermal mass of a transit vehicle I’d expect it to take several hours to heat up to temperature and several more hours to cool down enough to be comfortable for passengers. This would limit maintenance windows. Energy use (and, in areas that don’t have carbon-neutral electrical power, CO2 emissions) would also be considerable.
Yes, hoods have safety interlocks so it shouldn’t happen but I think he didn’t turn the light on. Today there are usually interlocks on the glass plate that must be in the down (blocked) position before the UV will turn on; this was a long time ago. He was also using it as a chemical hood rather than bio-hood and so wasn’t familiar with the UV. He was also using it over a weekend when few others were around.
Anyway, as this ancient accident shows, using UV would invoke a whole raft of complicated and expensive safety measures. And ones that I couldn’t disagree with. It’s not practical for a whole fleet of transit cars.
Re heating. That suggestion (56°C, 30min) is overkill, probably designed for 99.9% removal or similar. For effective decontam, probably need nothing like that, especially since transmission by this means is almost certainly a tiny fraction of direct transmission (droplet from proximity to infected people), ie. it is much exaggerated. As I say, this type of virus (and most viruses) really doesn’t like such environments–dry, hard surfaces. Give them a blast of dry heat (above body temp.) and their infectivity drops like a stone (even without any treatment infectivity is dropping fast over time).
However I agree that it is often difficult to convince management or OHS officers about measures that may be effective but are not 99.99% removal of the target. Blame-shifitng, liability etc etc.
I’ve just read that Tom Hanks and wife Rita Wilson have been admitted to Gold Coast hospital and tested positive for COVID-19! I’m pretty sure they picked it up outside Australia. This will really be a disaster for the tourist industry if we commit megastaricide!
WIkipedia says there are 6418 subway cars in NYC. Where do you find 6418 of these devices, whatever they are, and install the electrical infrastructure to power them by the end of next week? Or even 3209 of them? Then halfway through it’s first run of the day someone sneezes.
UV? Absolutely. It is quite impractical.
For the heating, I assume, perhaps incorrectly, that such a system is already in situ?
But you know what? I agree. It’s all overkill and would have very little measurable impact. We should focus on the more important stuff.
The installed heating system has overheat protection and can’t get the car up to those kind of temperatures. And depending on how that is implemented heating the car hot enough to kill things may disable the heat until someone replaces a part. And it’s likely the virus is fragile, just sitting out service for a few hours is good enough. All the other lovely things that can fester on stuff that people have touched, probably not but we aren’t worried about those. … Until halfway through the first run of the day someone sneezes. And the aerosols go right through their cargo cult surgical mask. ….Don’t touch your face, wash your hands. If you can’t wash your hands rub them in 60 percent or more alcohol for at least ten seconds. And hope this isn’t easy to spread through the air.
I don’t disagree.
Masks (they’re not surgical grade) only work to intercept actual droplets not what is left when droplets dry (if the virus survives in the dry form). But I reckon there are several reasons why the data don’t reveal that masks provide little protection (for the wearer): 1. they have to fit perfectly or air simply flows around them; none of these things fit very well; 2. exposed eyes (apparently ears are entry points too!).
To see what an effective mask looks like, you need to look at those that are legally mandated in particular occupations like sanding timber or especially stoneware (where asbestosis is the risk).
Masks should be reserved for those already infected where it is proven they do actually reduce transmission.
Just a couple observations from Taipei. I’ve been taking the MRT to and from work (Red, Blue, and Brown lines) for the past couple of months. From what I can tell ridership is pretty much the same. Close to all people wore face masks when the outbreak started to get out of hand in China. The number of people with masks has been decreasing since and is probably closer to 70% now. This is mainly due to difficulty in acquiring masks. The government has limited the purchase of masks, and one could almost always find long lines in front of pharmacies. People are still generally cautious and limit personal activities, but overall the situation is quite calm compared to other areas.
Oh, interesting. I read about the mask rationing – what do you make of the media reports of increasing mask production capacity?
Mask production capacity has gone up, from around 4.5 million/day now to 9.2 million and eventually to a goal of 13 million. But with 23 million people that’s not enough for one per person per day, and a significant amount will be reserved for healthcare workers and other industries (including frontline transportation workers) so rationing will continue for the foreseeable future.
Metro Taipei has not yet made February ridership numbers public yet, but my impression is that peak travel is roughly unchanged but off-peak travel has fallen way off. The January numbers seem to support this: 1/30 and 1/31 were first two weekdays after the Chinese New Year holiday, and they had 1.9m and 2.0m passengers respectively, compared to 2.3-2.4m weekday ridership the system was getting before the holiday. (Awareness of the situation was building through January and really hit the mainstream with the Wuhan lockdown on 1/23, so the new year’s holiday is a good approximation of the before-coronavirus and after-coronavirus line.)
I meant to link to the January ridership chart in my comment. Here it is: https://web.metro.taipei/RidershipCounts/c/10901.htm
Weekday ridership was around 2 million, down from 2.3-ish million in late 2019. But then suddenly Friday the 28th was down to 1.4 million, where previous Fridays were at 2.1 million.
Oh, they must have gotten it up right when I was writing my comment.
Feb 28 is a public holiday in Taiwan, so that’s where the ridership drop came from.
The situation is quite similar here in Sapporo. About 70% of people are wearing masks. Shelves are typically empty of any masks, and any restock sells out within an hour of being placed. Many people are asking why 70% even have masks when the supply is so sparse- apparently some have large stocks at home because they have chronic pollen allergies and are drawing from that previously acquired stockpile, and about 30% are reusing their masks after washing them. The government is prioritizing distribution of masks to hospitals and other institutions, as well as rural areas- Hokkaido’s regional towns and cities have been hard hit by carriers who have spread the virus after returning from the Sapporo Snow Festival last month- Sapporo residents less so as they generally avoid the Snow Festival even in normal times.
Here in Sapporo the rush hour subway trains are noticeably (especially the mornings) less crowded, mainly because schools are closed for at least the remainder of the month, and some companies are letting employees come in later in the morning. Off peak the drop in ridership is more dramatic, probably trains are at most 25% capacity, at least on the line I use to get to work. JR Hokkaido starting on the 23rd is going to cut back the number of intercity services (ltd. expresses) 15~20 percent on the trunk lines for one month, the first such curtailment of services in the nation. Commuter, local services and the shinkansen will not be affected.
I would guess that Singapore looks like it’s doing nothing because the behind-the-scenes measures are still working, but the folks just said that the blunt tools like office closures may have to come out once things start to escalate.
Yes, the trains are just a little less crowded, I’ll miss that when it’s over especially since I use the Circle Line and that has a chronic undercapacity issue. Hand sanitizer dispensers have been popping up, though.
Meanwhile, since Americans are weird, Jarrett Walker is starting to ponder about what happens once Americans start abandoning transit, and transit can’t pay its expenses.
Yeah, my sibling updated me saying that at rush hour today the trains had some empty seats (I didn’t ask which line, my sibling takes the bus and is relaying what housemates are saying). Also per my sibling, the ~1/3 of the population wearing masks on the street are mostly (all?) Chinese, because Malays, Indians, and white people are genetically immune or something.
I’ve heard some people online say that front-door boarding has been banned in some cities in Europe to give the bus driver some distance since buses generally don’t have separated cabs. Passengers can still get on using the other doors to board. I wonder how effective this will be for employees?
And given that this is happening in places where all-door boarding is common, I would imagine this would be a lot more difficult for systems in North America to implement quickly.
I think in North America, separated cabs are more common, because of historic concerns about crime?
Yeah, the Nuremberg area has this measure, disallowing ticket sale by the driver and reduced frequencies as the main measures
Tape a sign on the front door that says “Enter in rear, no fare being collected” You need a photocopier and a roll of tape for smaller systems and larger systems have print office and a office supply depot that can handle it.
I’ve seen a load of pictures on Instagram of this, in all kinds of cities, like Prague, Graz, The Hague and Berlin. There’s also been something on the PID website in Prague saying that the front door is (for the time being) only for the driver.
Perhaps I should add as well that they’re only separated by safety tape. I wouldn’t be surprised if there are more substantial solutions in the works
In Vancouver, all buses with rear doors already have farecard readers. Rear door boarding could be implemented overnight without much of an impact beyond the loss of fares from people who pay in cash. Vancouver is not the kind of place that would let little things like preserving the operation of an essential service during a pandemic get in the way of institutional inertia or trigger the dual moral panics over fare evasion and poor people riding transit, however, so this is unlikely to happen.
Yes, can confirm this is happening. I wonder how long it will be before there are kits with pre-cut perspex, etc. to separate the driver from the passengers. Perhaps we might see fully separated cabs like on British half-cab buses
They remind you not to touch your face but they are useless otherwise. The aerosols go right through them and they aren’t sealed.
Madrid Metro is running “rush hour” mode on all trains that support it: all doors open automatically at stations, without riders needing to press the button. They are also leaving the heavy station doors open so there’s no need to push them. Regional leaders have recommended people avoid public transport, but given the massive incompetence at managing the system they’ve shown over the last decade, I wouldn’t trust that to be an empirically-justified suggestion.
Concerning the protection of workers, I’ve seen activists pushing for the city buses going cashless, now that contactless card payment is widely available there. Bus ridership is down by 43% compared to last week, while road traffic is down between 10-20%.
Also, intercity trains are still running for some reason, radiating infected university students to every corner of the country. Even though Madrid concentrates half of all cases in Spain, the government hasn’t had the guts to order a Lombardy-style total lockdown of the region.
Re: cutting frequencies in response to lower ridership: unless agencies face severe operator shortages, I don’t think it’s a good idea, beacuse it doesn’t help with reducing crowding. It’s not like that is going to close the hole in the budget anyway…
Wait there are metros where you have to push a button to open the door?
quite a few across Europe yes. It’s a relief in Amsterdam where it often gets windy and rainy and the metro is mostly elevated.
Every train in Berlin (and I think also elsewhere in Germany but I’m not sure), every RER train and the older Métro trains in Paris, maybe also London and Stockholm but I don’t remember anymore.
Nuremberg metro has “push to open” doors. The older ones even with quite substantial handles that require a bit of force to push
London’s all have push buttons but the doors open automatically. The mainline train doors don’t open automatically
San Diego Trolley for sure, though I think that can be overridden by the train operator. SF Muni Metro may also be in the same position, though BART and DC Metro are automatic doors. Vienna U1 is all manual with door handles (a surprise when I first encountered it!). I can’t remember if the Prague and/or Budapest Metro systems are automatic doors or not.
Some random rail and transit news, from today, due to the covid-19 outbreak:
I’ve heard from a contact that ridership in Seattle is down 33 percent.
VIA Rail (Canada’s version of Amtrak) has suspended multi-day, transcontinental, trains for the foreseeable future. These trains are primarily land cruises, however, so the transport impacts will be minimal.
Metrolinx (Toronto) is reducing service frequencies for regional rail and bus service around Toronto due to low ridership.
Translink (Vancouver) is proud to announce that they are disinfecting their buses once a week to protect the public. No comment.
I fear that getting riders back. and undoing these service cuts. after the first wave of the epidemic passes could be very, very difficult. Very few people will be willing to ride transit voluntarily if it means even a 1% chance of death.
Are the service reductions you’re hearing off mostly peak or off-peak? Because WMATA heard the cut-the-peak message and is running Saturday service all day, which means a train every 12 minutes on each line because its preexisting off-peak service is absolute garbage.
Metrolinx hasn’t announced specific service cuts yet. According to their announcement, updated schedules will be made available at noon (eastern time) on Sunday.
One cause of transit closure will of course be tube / bus drivers becoming sick themselves. London Underground confirmed its first case of a tube driver ill with Covid-19 last week and the RMT Union were quick to demand more protection for staff. Of course a less crowded system must enhance the possibility of avoiding the virus so reducing service through lower ridership is a backward step. Reducing through lack of staff or to protect them may be inevitable however. My partner thinks there has been a drop off in tube ridership in the last week. We are trying to use the surface Thameslink service rather than the deep level tubes at the moment.
Instead of constant cleaning, we could plate things in copper, which kills viruses and bacteria. Might be more expensive upfront, but will easily be recouped by cutting labour required to clean the surfaces.
Do both, copper reduces infection rates, IIRC by a factor of 2, but doesn’t eliminate them, nor is it a viable material for train seats.
You never have maintained copper have you?
Copper and bronze require a lot of work, at least from my experience in trying to clean and shine them. The stainless steel bell carts (the stainless steel in the elevator is a real pain to clean) are far easier to keep shiny than the bronze ones, and honestly my hotel (well, my former employer) doesn’t see me spending a hour on bell carts as being very predictive. Plus, the bronze bell carts come with plastic handholds.
Here is an interesting detailed summary of travel patterns worldwide during coronavirus restrictions: