Despite all our best intentions, accidents happen. Analysis of accidents in large complex systems such as power stations or plane crashes led to an understanding that "no one failure, human or technical, is sufficient to cause an accident. Rather, it involves the unlikely and often unforeseeable conjunction of several contributing factors arising from different levels of the system."

James Reason's Swiss Cheese Model is a memorable visual metaphor that illustrates how each safeguard may contain a latent flaw, or hole, and that an unfortunate circumstance, may result in these holes lining up to disastrous effect. It's also a nice reminder that multiple layers of defence will be more effective, but even with our best efforts, there's still potential for something to go wrong.

Excerpt from Revisiting the "Swiss Cheese" Model of Accidents (pdf), Reason, Hollnagel and Paries, 2006.

Coronavirus example from the Cleveland Clinic.

The Swiss Cheese Model

Life on a nuclear submarine is life under some pretty intense constraints. For one, there’s not naturally any fresh water and any time you use it the waste water builds up in the tanks and then has to be expelled, and when you expel it that makes noise, and because nuclear subs don’t want to give away their location they do their best to minimise the number of times they have to do that. That means taking care of all fresh water.

The other reason to take care of fresh water usage is that they have to make it the whole time — any fresh water for cooking, cleaning or drinking has to be made from sea water. If you drink a glass of water on a nuclear submarine you’re probably drinking the most expensive glass of water you’ll ever drink because it’s been desalinated by a nuclear submarine.

Hence the submarine shower with a total of 20 seconds of water: 10s with the water on, turn it off while you soap and scrub and finish with 10s of rinsing. That’s it. For me it’s a nice reframe in how much you actually need when you take a shower, and it still works. So if you fancy saving water and energy you could give it a try.

Submarine shower

In these times, and to be honest most times, washing your hands well is one of the very best things you can do to keep yourself healthy and free from infections.

You should use soap if you have it, it should take about 20s, and if you follow these steps you’ll cover pretty much all of the different parts of your hands. In standard, cursory handwashing it’s very easy to miss what ought to be obvious places to clean like your fingertips. Then try to avoid touching taps and door handles on your way out of public places.

I find doing these steps takes about 20s, but to make sure you could also try singing a song segment you like. NPR has some suggestions: Keep flu at bay with a song.

Some other hygiene sketches to bear in mind:

Sneezes and coughs are powerful things — a sneeze can travel up to 8m. So always make sure you do your…

Dry your hands with only one towel. And as a basic rule…

The handwashing guidance is from the wonderful NHS.

How to wash your hands

I was taught this originally for backpacking but it really always makes sense once you think about it. Pouring onto a hand keeps dirty hands out of the rest of the snacks in much the same way as a drinking fountain manages to be hygienic by shooting out the water.

Some alternative sides to sharing: compliments are gifts and give gifts others can give. And two more about germs: sneezes and coughs, and the Dracula sneeze.

Pour, don’t dip when sharing snacks.

Sneezing into your sleeve helps prevent the spread of cold and flu germs.

Dracula sneeze

Learned from Joe Smith’s short entertaining TED talk: How to use a paper towel.

Sketchplanations tagged with hygiene