Thursday, April 26, 2012

Bathroom Floor Herd Immunity

I was in the gym with SMH and we'd adjourned to the locker rooms to shower.

SMH is American, and a fairly organised kind of fellow. As a result, he had his shower thongs (or flip flops, in the parlance of these lands).

I, on the other hand, manage to be chronically disorganised. It should thus come as no surprise to find out that despite meaning to do so for about 3 years, I still haven't bought a spare pair of thongs and put them in my gym bag.

Now, I lean towards the laissez faire attitude to hygiene. The human immune system is incredibly well suited towards things like touching bathroom door handles and toilet seats without collapsing in a quivering heap of bacterial infection. Most purported hygiene issues (outside a hospital or food handling setting) are largely just a feeling of ickiness masquerading as health concerns.

Boy howdy do Americans go crazy for bathroom hygiene. There is a shocking number of otherwise sensible people who literally will not touch a bathroom door handle, and will grab a paper towel to open the door because they're so paranoid. This even makes its way on to official instructions sometimes, like here. There doesn't seem to be much of a sense of historical perspective - back in the 60s, I'm pretty sure people weren't using paper towels to open doors (not least because paper towel wasn't that common). I'm also pretty sure they weren't dropping dead from bathroom-door-related infections either. Perhaps, just perhaps, all this craze for hand sanitisers and never touching any public surfaces is just modern man turning into a complete weenie.

Nonetheless, showers in gyms do run the risk of getting fungal infections. The floors tend to be always wet and slightly warm, and lots of feet are walking over them. So it probably is prudent to get a pair of thongs.

But despite 3 years of not wearing them and showering at this gym, I'd pretty much been fine.

And I finally figured out why.

Herd Immunity.

When enough people are vaccinated against a disease, it becomes hard for the disease to spread. As a result, people who don't get vaccinated get to free ride off the added group protection from those who do vaccinate.

And something similar happens with bathroom floors. In the US, the vast majority of people wear thongs to public showers. I'm quite sure this is due to the hygiene/gross-out combo, and not out of any sense of public-spiritedness. But the effect is the same - if there are very few people who aren't wearing thongs, there's very few people likely to be spreading around foot infections. And that means that it's actually pretty safe for free-riders like me to go without.

I'm like the Jenny McCarthy of the gym shower world, free to be recklessly stupid and indulgent thanks to everyone else's good decisions, meanwhile imposing a small negative externality on everyone else by my own actions.

It's just like Tom Petty sang:

And I'm Freeee
I'm Freeee Riiiiiddding.

Good times.


  1. Fact: people's hygiene habits are very heterogeneous. So why does my unwillingness to touch other people's shit on bathroom handles make me paranoid?

  2. I guess it depends on the motivation. If you just find it gross, it's hard to argue with that - being grossed out is almost purely a matter of taste, where heterogeneity is king.

    But if the worry is health-related risks in touching the bathroom door, that's a more falsifiable claim. My unscientific prior is that these worries seem overblown. Then again maybe I'll change my mind if I end up catching the norovirus.