Why doesn’t the tube make handpoles out of self-sterilising metals? And what is grippage?

Why don't these kill germs? The interior of an ageing Circle line train in 2010. Image: Maurits90/Wikimedia Commons.

In February 2015, bacteriologists from Cornell University published their results after spending more than a year swabbing New York City’s Subway trains and stations for bacteria. The results sounded icky: not only are there hundreds of different microbial species living throughout NYC’s transit system, on the poles and seats and turnstiles that humans touch every day, but half of them were completely unfamiliar to science. Anthrax and the bubonic plague were among those bacteria which were recognised.

Of course, the fact that New Yorkers aren’t dying off like 14th century Europeans implies that the dirtiness (or, rather, perceived dirtiness) of the subway isn’t a pressing public health issue. The study authors were keen to point out that commuters shouldn’t overreact to the news.

The same will apply to London, both in terms of the microbes living throughout the Underground and in the near-non-existent risk they pose to travellers. Yet as I was sat on one of Transport for London’s new S Stock trains on the Hammersmith & City line last week, fully aware of the first signs of a cold in my nose and my throat, my thoughts drifted to that study.

TfL likes to colour-code its lines so that the interior decor of the trains matches the lines they run on (so orange on the Overground, blue on the Piccadilly, etc.). These new trains are running on the Metropolitan (purple), District (green), Hammersmith & City (pink) and Circle (yellow) lines – yet all are decked out in bright, garish yellow. God knows what’s living on those neon poles and handstraps that keep passengers from falling down.

We know that public transport is a vector for disease transmission, especially when it comes to seasonally-influenced illnesses like the flu. We also know that there are materials which self-sterilise – that is, they’re highly toxic for any single-cell organisms that are unfortunate enough to land on them. This “oligodynamic effect” was first discovered in 1893, and lots of different metals – from silver to aluminium, lead to copper – possess it.

So the question is: why aren’t the hand poles in Underground cars and on buses made of antimicrobial metal?


A Santiago metro station, complete with bacteria-killing handrails. Image: AntiMicrobialCopper.com.

In some parts of the world, the answer is actually “they are”. The subway system in the Chilean capital Santiago, for example, uses antimicrobial brass handrails, which were installed in 2011 as part of a wider healthcare campaign. But this is an exception, not a rule.

Jean-Yves Maillard is a pharmaceutical microbiologist from the Cardiff University who researches the use of antimicrobial materials in hospitals, and specifically the two most promising metals: silver and copper (or alloys of copper, rather). It turns out that these things kill germs best when “humidity is 100 per cent, so they are underwater – and that’s not how these surfaces exist on the metro, or Tube, or buses.”

Instead, to get a better idea of how well they work, he’s tested them when they’re dry (which means between 30 and 40 per cent humidity, which is typical for the UK), and when they have “droplets” (i.e. someone’s sneezed) on them.

The results are still impressive: within 30 minutes of contact with the most effective copper alloys, 99.99 per cent of Staphylococcus aureus bacteria – a bug responsible for everything from skin infections to respiratory diseases, and including the infamous antibiotic-resistant MRSA strain – were exterminated in the droplet test, while the dry test still saw around a 90 per cent reduction.

“When it's very dry – the worst case scenario, a very dry summer and so on, above 20 degrees – you'd get something like 99.99 per cent reductions within 30 minutes,” he said. “If someone sneezes, then after 30 minutes on that surface the bacteria is likely to be killed. I imagine for some viruses it would be the same as well. [But] if you haven't got droplets, then that activity really drops sharply. You'll get at most 90 per cent reductions, but probably less than 90 per cent, within 30 minutes. You'll kill some, but not all.” Silver was less effective in the droplet test, and not effective at all in the dry one.

This might make switching to copper-based antimicrobial subway and bus poles seem like an easy win that TfL missed when ordering its newest trains. But Maillard is keen to stress that there are some important downsides.

It rhymes with "fromage"

Firstly, if a surface is cleaned relatively frequently, then the extra cost from using more expensive materials might be more than those of simply paying for someone to wipe everything down a bit more frequently each day, for the same result. And these surfaces are no substitute for cleaning – Maillard emphasises that antimicrobial surfaces work “in addition” to cleaning, not as a replacement. And, when I contacted TfL, health & safety director Jill Collis made it clear that they clean the network “throughout the day and night” already.

The second reason is appearance. According to Collis, “the handrails in carriages are designed to be easy to see, meet safety standards and be suitable for daily use by millions of customers”. (I also discovered that the internal TfL term for the things that passengers hold onto isn’t “handrails”, but “grippage” – pronounced to rhyme with “fromage”.)

This is an important point – and TfL also said that, in accordance with the Vehicle Accessibility Regulations Act 2010, “any passenger handrail fitted in or to a rail vehicle must … contrast with the parts of the rail vehicle adjacent to that handrail”.

In other words, the bright colours on the Tube are primarily so that the visually-impaired are better able to see them. While the brass handrails of the Santiago subway may look somewhat classy, they also blend into the background in dark, underground spaces.

A third important issue is value for money. The handrails on the Tube are made of aluminium, which has a good ratio of weight to cost to strength; copper and silver, less so. “In hospitals, the debate is all about costs,” Maillard said. “[Surfaces] maybe get cleaned once a day, and with copper surfaces there are indications that at the end of the day the [the microbial burden] will be less than normal metal surfaces. That's the interest in it. But the big question is, is it cost effective?”

Then there’s even a fourth issue, most relevant to silver, which is that it perversely seems to make drug-resistant superbugs more likely. Making subway poles out of solid silver is, clearly, ridiculous, but it’s common for nano-particles of silver to be placed within other material to give it some antimicrobial properties – not as good as copper alloys, of course, but still something.

Maillard points to a January 2015 report from the EU Commission’s Scientific Committee on Emerging and Newly Identified Health Risks (Scenihr) into the possible dangers posed by the use of nano-silver in medical and consumer devices. It found that research is “urgently needed” into the possible toxic effects of long-term exposure to silver in consumer products, and also that the genetic adaptation of bacteria to silver could increase resistance.

“What you will find is that now you have a huge amount of surfaces that contain antimicrobials,” Maillard explained. “Lots of plastics, washing machines, photocopiers, in pens, televisions, television remote controls – most of them contain silver or nano-silver, because they don't affect the colour. The concentration that they use is very low, there are question marks over its efficacy, and questions about whether it's going to promote resistance of those organisms with those products.”

So, put it all together and it doesn’t look good for Tube poles that clean themselves. Copper alloys work best, but would have to be painted to comply with health & safety legislation, defeating the purpose. And, while it’s possible to stick silver particles into the paint as an alternative, it’s not very good, especially when the extra cost is factored in – and that’s without considering make it more likely that truly nasty bacteria can thrive and evolve on public transport.

Best stick to hand sanitising gel. Much easier.

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Here’s how Copenhagen puts cyclists at the top of the social hierarchy

A cyclist in Copenhagen, obviously. Image: Red Bull/Getty.

Have you ever wondered why Britain is not a nation of cyclists? Why we prefer to sit in traffic as our Dutch and Danish neighbours speed through the city on bikes?

Forget about hills, rain, and urban sprawl: the real reason we aren’t cycling is much closer to home. It is not just lack of infrastructure, or lack of fitness, the reason that 66 per cent of Brits cycle less than once a year, is because of status.

An obsession with social status is hard-wired into our brains. As we have built a society that relies on cars, the bicycle has slipped to the periphery, and gone from being regarded as a sensible mode of transport, to a deviant fringe-dwellers choice.

Even though cycling to work has been shown to be one of the most effective things an individual can do to improve health and longevity, researcher David Horton thinks that there are a set of collective anxieties that are stopping us getting in the saddle. These include not just an unwillingness to be made vulnerable, but fear of being thought of as poor.

A quick look over the North Sea shows that there is an alternative. Danish culture has elevated cycling to the point of reverence, and the social status of cyclists has followed. As we have busied ourselves building infrastructure that testifies to the dominance of the car, Denmark has been creating magnificent architectural features, aimed specifically at bike users. The Cycle Snake, or Cykelslangen, literally suspends the cyclist above the city, metaphorically elevating the cyclist and creating a sense of ceremony.

In doing so, they are subtly persuading people of all backgrounds to see past their prejudices or fears and take it up as the clearly better choice. This means there are more women cycling, more older people cycling, and more ethnic minorities cycling. The activity is less dominated by comfortably middle class white males: there are cyclists from every side of the community.  

The Cykelslangen, under construction in 2014. Image: Ursula Bach and Dissing+Weitling architecture.

Despite abstract motivations like getting ripped and conquering global warming, it is only when the bike path becomes the obviously better choice that people will start to cycle. It can take years of traffic jams before people try an alternative, but if you make motorists jealous of cyclists, then the tables can quickly turn.

Another way that Copenhagen has done this is by taking privileges normally afforded only to the motorcar, and given them to the bike. The city has ensured that cycle routes do not include blind corners or dark tunnels, and that they form a complete, coherent network, and a steadily flowing system – one that allows cyclists to maintain a reasonable pace, and minimises the amount of times you have to put your foot down.

The ‘Green Wave’, for example, is a co-ordinated traffic light system on some of the main thoroughfares of the capital that helps minimise the amount of cycle congestion during peak times. It maintains a steady flow of cycle traffic, so that there is no need to stop at any point.

Small measures of prioritisation like this one increase the sense of safety and consideration that cyclists experience, making it natural for the citizens of a city to act in their own self-interest and get on their bike.

As well as redefining the streets around the bicycle, the Copenhagen Cycle Chic blog positively fetishises cyclists. The tagline “dress for your destination, not your journey” depicts the social fashion life of the cycle lane as a “never ending flow of happy people heading from A to B”. Its writers are  literally making cycling sexy, dispelling the idea that going anywhere by bike is odd, and helping the world to see that the bicycle is actually the ultimate fashion accessory.

So unlike in London, where cycling is still a predominantly male pursuit, Copenhagen sees a more even split between men and women. Not just because they feel safer on the roads, but because culturally they are comfortable with their appearance as part of a highly visible group.

So while our low level of cycling is partly due to our physical infrastructure, it is also due to our cultural attitudes. The mental roadblocks people have towards cycling can be overcome by infrastructure that is not only safe, but also brings old-fashioned notions of dignity and grace into the daily commute.

Of course, office shower facilities might stop cyclists being ostracised, too.