Monday’s Friday Reads – 20 April 2020

1. In the $234bn railway link, his use of messed up “$500mm p/km”. Or “per/kilometer” makes my brain itch.

   Also the recommendations to use shallow stations.. while likely true, misses the point that all the low-hanging fruit in London is gone, stations have to be deep to avoid all the other things in the way.. it would be interesting if he was able to add in the overground into these numbers which carries as many passengers as some cities metro systems and was built way more efficiently.

2. @ALISTAIR TWINAME

   I find it most intriguing that in that article there are costs listed for virtual lines that have shared infrastructure. There is no “Circle Line” of 27.2km, it’s about 400 meters of track in the east of the City. The Met line shares with the Hammersmith & City in Zone 1 and the Piccadilly in Zones 5/6, so the Met showing up as 66.7km is another overlap. See also Overground/Bakerloo between Queens Park and Harrow & W.

   I’m sure that shared bits of the Jubilee/Met in North East London, District/Pic in West London and Jubilee/DLR in East London suggest and oversimplification.

3. The Times article on poor air in the underground is paywalled, but I have read several other articles saying the same thing recently, and indeed the detailed government investigation into the subject, which was based on detailed testing. What I can say is that The Times headline has sloppy usage of the word “worse”.

   There has been a detailed investigation into the subject by the Committee on the Medical Effects of Air Pollution.
   https://www.gov.uk/government/publications/particulate-air-pollution-on-london-underground-health-effects
   And this is based in part on academic studies such as
   https://www.sciencedirect.com/science/article/pii/S0160412019313649?via%3Dihub

   The uniform conclusion of these is that we do not know whether on balance the air pollution inside the tube is worse for your health than the air pollution out on the street. This is because the nature of the pollution is quite different in the two places. The Times can only say it is “worse” only in the sloppy sense that certain pollution numbers in the tube are higher than the equivalent number on the street, though other numbers are lower. But even for the numbers that are higher, we cannot say that is “worse”, because the pollution is different. For example PM2.5 level may be higher in many parts of the underground than on the street, but the nature of particles is quite different in each location. They may be more benign, or indeed less benign on the Tube. We just don’t know. My guess is that the health consequences are different. And then you get to that old conundrum, which is worse, 10 people with this disease or 5 people with that other disease, which might arguably be a more horrible disease. Often these are unanswerable questions.

   Although we don’t really know how bad the air quality in the underground really is, in terms of its health consequences, certainly it raises the point that the air quality in the underground could be really bad. And it is not as bad in other underground systems.

   And also, now when I see people riding bikes with air pollution masks, I can think to myself, “Would you wear one of those when travelling on the Underground? No? So why wear one riding a bicycle?”

4. The difference between pollution exposure for cyclists and tube travellers is not just about the level of pollution in the air. When cycling, you’d typically breath more deeply and at a higher rate, so the impact of any pollution on your lungs would be deeper and more severe.

5. @Alice
   It is not quite as obvious as that. In reality it is a rather difficult trade-off which depends in part on how and where you ride your bicycle, even in central London. But one major point in that trade-off is the exact opposite of what most people might think.
   (1) You are much *less* exposed to pollution on a bicycle or on foot than you are in an enclosed mode of transport. Seems very surprising. But that was the result of this experiment carried out by Kings College London. It seems enclosed vehicles tend to concentrate the pollution in their interiors, up to five times the level outside the vehicle. The experimenters suggested this might in part be due to the effect of being stuck in standing traffic, but that is only a supposition.
   https://www.healthyair.org.uk/healthiest-transport-option-video/
   (2) As you correctly say, you breathe a larger quantity of air while exercising. How much depends on how hard you exercise. Can be up to about 6 times more for the highest intensity of exercise. But my guess is that is only achievable in short bursts and may depend on your fitness level.
   (3) Pollution is much worse on heavily trafficked streets and major junctions. There are pollution maps of central London that show that effect rather starkly, at least for certain specific pollutants. So you can often adjust your exposure by choice of route.
   (4) The limited effectiveness of masks , which (in a practical mask) can only protect you against certain types of pollution, mainly particulates in a certain size range. If they had chemical activity to protect you against chemical pollution like NOx, carbon monoxide, ozone, and so forth, I doubt they could process the large quantity of air you’d want for exercise and be a small practical mask.

6. @ALICE / @IVAN

   Also you can Google “THE GREAT BRITISH URINE TEST” which is a TV pop-science show from Channel 5. One of the participants is a London taxi driver. The fact that they seriously consider that he might be at death’s door because of his exposure to pollution is quite fascinating (and fixable, it turned out).

   Given what we now know about the correlation between pollution and CV-19 deaths and disease, it might just turn out that London bus drivers have been making themselves insulated against everything BUT the cause of their terrible risk profile.

   I mean, a fatal respiratory illness might be worsened by traffic fumes, it seems almost plausible.

7. @BrianButterworth

   It’s crucial to note that correlation is not causation. There are new studies coming out about the correlation between CV-19 and air pollution, like this one we in Industry Posts, but they’ve not yet been peer-reviewed (which takes months).

   And as new information on COVID shows its effects on the cardiovascular system, specifically the appearance of blood clots in even healthy infected individuals, it is clear that there are many facets to this virus. Hence we do not yet understand the full spectrum of how COVID affects the body.

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