Friday Reads – 24 April 2020

1. I’m not convinced the NYC subway coronavirus spreading theory is cr@p at all. That no obvious line of high infections (presumably showing homes of the infected) follows any subway corridor on a map seems to me an extraordinarily flawed counterargument, especially as city metros are not always last or first mile systems and serve wide hinterlands as they pass through many different types of land-use enroute..

   I think East Asian experience has shown that in this kind of event, early implementation of mandatory face covering is essential on public transport (among other crowded areas) for ‘source control’ reasons to arrest inevitable transmission. The term ‘Source control’ means a barrier of some sort, a ‘pre-fitted handkerchief’, an ‘exhaust filter’ if you like, to stop potentially infected droplets and microdroplets leaving a wearers’ mouth into the confined, comparatively still air of a passenger compartment or other enclosed or crowded public space.

   A major risk is that many infected people develop no symptoms at all or only suffer very mild effects in the early stages so don’t self isolate despite being unknowingly contagious. Their microdroplet clouds, from coughs or sneezes, even talking, can float for a considerable time in still air and stand a good chance of infecting others if inhaled. Transport is particularly risky because it brings strangers together from wide areas randomly into small enclosed spaces for non-trivial periods of time, sharing the same air, Adequate distancing is often impossible to maintain, no matter how hard each individual tries. The strangers will then part company and could carry the virus far and wide to new destinations, to homes, work-places, businesses and educational establishments where the whole cycle begins again.

   Some East Asian cities with their dense populations and high public transport usage have managed to fight the coronavirus successfully without severe lockdowns, but with mandatory public mask use implemented quickly. If infection numbers can be controlled with such simple low tech methods, the subsequent task of testing and contact tracing of the remaining smaller numbers becomes much easier, cheaper and less invasive to the privacy of the majority. Medical PPE masks are not necessary or desirable for this. Clearly, those need to be saved for healthcare professionals in such a time of great demand, unless the state can also organise sufficient large scale procurement and distribution for the public, as occurred in Taiwan. Otherwise, scarves, bandanas, home-made and purchased reusable cloth masks are all perfectly adequate for source control, as long as they properly cover the mouth when worn, and the majority actually use them.

   Mask wearing is one simple thing we can all do to help save lives and suffering, and, as part of a balanced set of measures, can potentially help to get the emergency over with more quickly, allowing a gradual restart of the economy to take place with all forms of transport once again playing their valuable parts.

   Like the Streetsblog author, I’m concerned about anti-urbanist interests cynically expoiting the emergency to declare the demise of cities and mass public transport and possibly influence political agendas and funding decisions accordingly, but the terrible toll of death and suffering in NYC cannot simply be willfully disconnected from crowded environments like the subway either. Lessons in timely reactions to these events need to be learned to allow cities to continue to function. Cities are where a very large proportion of the human population will continue to live and work the world over and that’s not going to change any time soon. Cities need efficient mass transportation to exist. How to deal with dangerous communicable disease outbreaks is a management problem, not an existential one.

2. Mark, your last paragraph makes sense, but whether wearing a mask is a good idea is not as simple or clear-cut an issue as you seem to think: there is evidence that, if not done properly (and in everything we do there are lots of people who don’t do things fully properly), it can even make things worse.

   See https://www.sciencealert.com/this-is-why-advice-on-whether-you-should-wear-a-mask-is-just-so-confusing for example, and some quotes from there:
   “When we combined the results of these trials that studied the effect of masks versus no masks in health-care workers and the general population, they did not show that wearing masks leads to any substantial reduction of influenza-like illness.”
   “There are several possible reasons why masks don’t offer significant protection.”
   “The apparent minimal impact of wearing masks might also be because people didn’t use them properly.”
   “Masks may also provide a false sense of security, meaning wearers might do riskier things such as going into crowded spaces and places.”

   I suggest we all need to look at the evidence and follow expert advice before we advocate for actions that may not be appropriate.

3. @BETTERBEE, 8 May 2020 at 09:47

   The document you reference, over a month old now, acknowledges that masks COULD have a useful role, especially as we transition out of lockdown and public places become busier :
   “Another possibility is a “2 x 2″ rule: if you are outdoors and within 2 metres of other people for more than 2 minutes you need to wear a mask. Mask wearing for the possibly infected, to prevent spreading the infection, warrants rigorous and rapid investigation. It could be an alternative or a supplement to social distancing, hand hygiene, testing, and lockdowns.”

   In the USA, many statewide and local mask requirements to varying extents have been implemented following their CDC recommendation, including on transport in NYC. The US perspective may have been heavily influenced by this detailed peer-reviewed and formally published mathematical modelling study:
   https://www.sciencedirect.com/science/article/pii/S2468042720300117
   This concludes: “…our findings suggest that face mask use should be as nearly universal (i.e., nation-wide) as possible and implemented without delay, even if most masks are homemade and of relatively low quality. This measure could contribute greatly to controlling the COVID-19 pandemic, with the benefit greatest in conjunction with other non-pharmaceutical interventions that reduce community transmission. Despite uncertainty, the potential for benefit, the lack of obvious harm, and the precautionary principle lead us to strongly recommend as close to universal (homemade, unless medical masks can be used without diverting healthcare supply) mask use by the general public as possible.”

   This video, from NHK in Japan, uses laser illumination and high sensitivity cameras to show very graphically how large droplets are ejected from the mouth when coughing and sneezing and also how clouds of microdroplets are also emitted, even when talking, and remain airborne for long periods of time in confined areas with little airflow. Simulations show how these clouds, potentially infected, could remain airborne and spread in enclosed areas for over 20 minutes making contact with multiple individuals unless flushed out by air currents.
   https://youtu.be/H2azcn7MqOU

   My opinion has also been influenced by a recent paper on public mask-wearing written by Trish Greenhalgh, Professor at The Nuffield Department of Primary Care Health Sciences, University of Oxford
   “Masks for the public: laying straw men to rest”
   https://www.authorea.com/users/316109/articles/446320-masks-for-the-public-laying-straw-men-to-rest
   This link is a preprint, but with some revisions, the paper has been formally peer-reviewed and published in a professional journal:

   Abstract
   “This paper responds to one by Graham Martin and colleagues, who offered a critique of my previous publications on masks for the lay public in the Covid-19 pandemic. I address their charges that my co-authors and I had misapplied the precautionary principle; drawn conclusions that were not supported by empirical research; and failed to take account of potential harms. But before that, I remind Martin et al that the evidence on mask wearing goes beyond the contested trials and observational studies they place centre stage. I set out some key findings from basic science, epidemiology, mathematical modelling, case studies and natural experiments, and use this rich and diverse body of evidence as the backdrop for my rebuttal of their narrowly-framed objections. I challenge my critics’ apparent assumption that a particular kind of systematic review should be valorised over narrative and real-world evidence, since stories are crucial to both our scientific understanding and our moral imagination. I conclude by thanking my academic adversaries for the intellectual sparring match, but exhort them to remember our professional accountability to a society in crisis. It is time to lay straw men to rest and engage, scientifically and morally, with the dreadful tragedy that is unfolding across the world.”

   In mainland Europe, a number of countries have introduced nationwide mask requirements (in conjunction with other measures), starting with Czechia, Slovakia and Austria. These have all since experienced dramatic reductions in numbers of new infections. As they start to relax their lockdowns, Italy, Spain, France and Belgium have recently introduced face-covering requirements for indoor public spaces such as shops, and these rules all include public transport.

   In East Asia, mask-wearing was introduced very quickly and in many cases a full lockdown was avoided entirely, with public transport usage remaining at levels much closer to normal than in Europe. While some new small infection clusters have continued to occur there, often originating from failures in inbound traveller testing from other parts of the world with less efficient control, these have been suppressed very quickly through efficient contact tracing and testing. An interesting comparison of two such incidents in South Korea can be found in this Medium article, including how authorities approached the practicalities of contact tracing and the difficulties faced in a very quiet rural area compared to a dense city:
   https://medium.com/@slowblogger/how-mask-made-the-difference-two-coronavirus-stories-from-korea-97e6fc4200ea
   Spoiler alert: The rural outbreak, where mask-wearing was not widespread, was very much worse than the urban incident, where masks were common.

   I think the UK outside Scotland is fast falling behind the best practices of other European countries and the USA in this matter, which is particularly worrying for our densest cities including London. I accept that outside, in typical quiet suburban streets, parks, etc where distancing is usually practical, masks probably provide very little benefit for the wearer, or for protecting others, but once inside confined spaces with limited air-flow and other busy areas where distancing can be difficult to manage effectively, then requirements to wear face-covering for ‘source control’ reasons rather than primarily to protect the wearer seem (to me at least) a potentially very effective measure. WHO guidance on this remains very non-committal though. They don’t recommend general public mask-wearing clearly, but they also don’t discount that there could be potential benefits. They ask nations considering such measures to be clear about their objectives and to make detailed recommendations about what kind of coverings are acceptable etc while acknowledging there is little research on the subject. I suggest that is now changing.

   [Mask effectiveness is quite a tangent from transport, so whilst we will allow this comment, we shall not entertain any further discussion of this topic. LBM]

4. Bringing this discussion back to transport, there’s a very interesting article by Todd Litman at https://www.planetizen.com/blogs/109146-lessons-pandemics-transportation-risks-and-safety-strategies, throwing further light on the NYC Subway issue and offering views on the relative safety and affordability of different modes of transport in times of pandemic.

   Well worth a read.

5. The Tod Litman article is fair and balanced, but I’d still say the map analysis has been rather problematic all along, as it doesn’t really look at what ‘transit’ and particularly longer distance rail transport actually does in large urban areas, which is to move people from areas they live in, which in many cases is rather car dependant suburbs on the periphery, to or through more transit dependant areas closer in, and ultimately to central business zones where there are often very few residents at all. The denser so-called ‘transit dependant’ areas are usually more walkable too, so people who live in them may paradoxically not need to use transit very frequently, as they have all the services they need within easy walking or cycling distance. The further-flung suburbanites, who may catch the train into town for work everyday, or leisure occasionally, routinely have to use their cars by contrast for most other journeys, simply because their services are all much more thinly spread, and of course they may also have to drive to, or be dropped off by car at, the station.

   Thus how crowded a subway train is at any point along its journey has very little to do with how car or transit-dependent that particular area is, yet could have a lot to do with how likely on-board transmission of virus is via airborne aerosol. While measures can increase the convenient walkable and cyclable distance in all areas, the longest intra and inter-urban journeys are still going to be unattractive by these active modes to most travellers, say anything over three or four miles, or involving a steep or long hill, or in wet weather, so I expect public transport demand will increase again, possibly dramatically as lockdown is eased. UK appears to be planning to allow buses and trains to run at around 10% normal capacity in this period to allow full social distancing without introducing any ‘additional personal hygiene measures’. Contrast this with mainland Europe, where 40% or 50% capacity is being planned typically in conjunction with ‘additional personal hygiene measures’ I wonder which of these will be most effective in both meeting demand and suppressing transmission.

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