Some quick notes on hand hygiene

This seems like an easy thing to do a rough cut on.

Benefit:

" Adults average about 2 to 4 colds a year" - https://www.webmd.com/cold-and-flu/common_cold_overview

" People usually recover in seven to ten days" - https://en.wikipedia.org/wiki/Common_cold

Assume your productivity is halved (Mine is far worse, since ~90% of the value of my time is when I'm operating at peak, which I can't do at all when sick.)

"Handwashing can prevent 21% of respiratory sicknesses" - https://globalhandwashing.org/about-handwashing/why-handwashing/health/

So handwashing would save an average of 0.2*8.5*3*0.5=2.55‬ days of productivity.

Cost:

30 seconds per handwashing * 15 times per day * 365 days / 18 waking hours per day = 2.5 days of time.

So as long as you're completely neutral to the externality costs like making other people sick, don't mind the physical unpleasantness of getting sick, and there's no scary superbug going around, this seems like, well, a wash.

If you have kids, you'll get sick more, and washing has correspondingly higher benefits. And if you come into contact with the elderly, very young, or the otherwise sick, the externality costs are far higher, and you're a jerk for not doing this.

Bottom line: yes, it's only marginally beneficial. But if 2019-NCoV is at all worrying, it likely tips the balance. Now instead of arguing about the exact numbers here, i.e. justifying your inaction by explaining to the world why the costs are higher and the benefits are lower, go wash your hands.

I agree. It is very common for field experts and authorities to issue directives without considering the associated time costs, especially when these costs are small when measured relative to the relevant behavioral unit (e.g. 30 seconds per hand washing). If you consider each directive individually, it often seems that the benefits justify the costs. But when both costs and benefits are aggregated over time, a different, more pessimistic picture often emerges. I wash my hands ~10 times per day, and so invest ~30 hours per year on this habit. Is this sacrifice worth it? It isn't obvious to me that it is.

I am reminded of that satirical post where Rob Wiblin describes his "daily routine for maximum productivity", comprised of dozens of activities many of which seem individually worth doing. Clearly, however, the routine as a whole is a net waste of time, since it would require a large fraction of the day to complete, thereby decreasing productivity overall. This suggests that our "micro intuitions" aren't very reliable, and that we should check them by considering the big picture.

I don't have a long reply to this yet since I didn't get the chance to look up actual data (as opposed to recommendations) but I'd be interested to

Insofar as a health intervention is ineffective it could be for one of three reasons:

• The base rate of the thing it prevents is low
• The intervention is not good at preventing the thing
• The thing is not that bad even when it does happen

Which is your main sticking point here?

Yep, as always context matters. Have you been doing something that puts stuff on you hands that is no already spread everywhere you are and will touch or for some reason has caused a significantly higher concentration on your hands versus the environment?

As the OP points out, after washing actions matter too. But it more than merely the act of drying your hands.

Last, to some extent your hands are well prepared to deal with a lot of stuff -- that is exactly what our skin evolved to too: protect our internals from the external. So a good part of the hygiene is also about just where you put your hands on your own body. Rub your eyes a lot? Perhaps better than washing would be using a clean tissue, then throw it away. Byte your fingernails, or stick you fingers, hands on/in you mouth a lot? Stop or be aware of what you've been touching since the last cleaning (were you just cutting up the raw chicken that you will cook for dinner?)

Studying this with Anki is a waste of time in my opinion. Just execute the instructions three times and you're good to go. Physical skills are best learned physically.

So this particular physical thing has one big advantage, in that you can go through the motions of it anywhere without much inconvenience or embarrassment. I think that makes at least a basic "practice this" card useful as a reminder. I'd predict that someone who had a periodic ping to check on/practice the habit would be more likely to keep it; do you disagree?

This argument has always seemed suspicious to me from a rationality perspective. Do you take other steps to deliberately expose yourself to pathogens (e.g. playing in the mud, or deliberately dropping your food on the floor before eating it, or licking unsanitary surfaces, or seeking out coughing/sneezing people to be close to)? If not, why not? Do you have some reason to believe the current level of exposure you get from not washing your hands is optimal (or at least close-to-optimal) from the perspective of improving your immune system through exposure?

The above paragraph probably sounds uncharitable. I can think of ways the "improve your immune system" argument might be true. There is an argument that early-life exposure to germs might strengthen the immune system and decrease allergies (the "hygiene hypothesis"). But it does seem to prove too much, especially given the vast and obvious gains in public health through hygiene and sanitation over the past 150 years. And it should seem especially suspicious when you're (a) going against a very strong expert consensus, in favour of (b) being lazy about something everyone kinda wishes they could just be lazy about.

Hey, at least (2) is good rationality practice. :P

I don't know if you have it, or if I could find it, but there was a great time laps YouTube on that very thing. Lead me to try remembering to do the same (but is not as big of a deal as I live alone and rarely entertain at the house).

masks […] help prevent touching one's mouth and nose

I agree in the case of someone who knows what they're doing. For many, however, a mask does the opposite. Yesterday I went out for two hours and saw someone re-pinching the wire above the nose, someone pushing the mask around their face, and someone taking the mask off and putting it in her pocket.

The latter seems innocuous, but think about it: Taking the mask off, she touched the outside, which had caught all the nasty viruses. Thereafter she ate lunch. Then, coming back from the cafeteria and after touching many shared surfaces, she probably put the mask back on, touching the inside in the process. Then the inside touches her face.

It seems like the recommendation is about preventing dirt on your hands to enter your body. If the hands of a woman are contaminated with a virus washing hands after going to the toilet instead of before poses the risk that the virus enters the body.

On the other hand unless you are currently ill, the pee will unlikely be a vector for viruses.

> Consider that we're starting from a status quo where most people's hands are washed 3-5 times a day, even if lazily.

Disagree, many people probably fall below this.

"it's not 100% effective, but I don't think it has to be in most circumstances."

Ineffective handwashing is basically useless other than removing visible dirt. The difference between doing a good job and doing a typical job is the difference between actually getting rid of the germs and preventing and infection or not.

"Is there good epidemiological data that estimates how many disease transmissions have insufficient hand hygiene as an important/necessary vector?"

Yes, and that's why epidemiologists and health economists keep recommending people washing their hands, putting up posters to that effect, etc.

"Because I would bet that outside of unusual cases like food service and medical workers, the number is low."

Yes, for food workers (who also do a bad job washing, and can't/don 't take time off when sick,) the impact is far worse.

Source: Forthcoming paper I wrote with Dave Denkenberger.

There's enough variance that relative recommendations ("more often", "more completely", "more time spent") are difficult to take seriously.

I wash my hands maybe 2-3 times per day and apply Purell (the brand provided at work) another 1-2. I don't spend over 10 seconds, though I do try to get all surfaces. Will the marginal improvement of adding one instance or 5 seconds of additional scrubbing noticeably reduce my risk? I can't find any study that has this level of granularity.

Is there good epidemiological data that estimates how many disease transmissions have insufficient hand hygiene as an important/necessary vector?

As opposed to what? Direct airborne transmission via breathing in droplets?

My model of the spread of colds and flu and so forth is that it is primarily down to bad hand hygiene. I'd predict (with pretty low confidence) that more people get infected through getting virus on their hands and then onto their face / into their mouth than by breathing in virus directly. I'll look into this more when I get the chance, though, since lots of people are asking about this.

Yeah, this is something I worry about as well. It's probably a good idea to clean your phone with hand sanitiser regularly, but unless you're doing it multiple times per day (which nobody is) it's still going to be a big problem. AFAICT most people never clean their phones at all.

If you are the only person touching your smart phone and not give it to other people that should reduce a lot of the potential of them as a vector. If you in addition don't press it against your face, it's not clear to me why it would make sense to worry about it.

Instead of sanitising light switches, stop having light switches. Movement sensors/Google Assistent can switch lights without any need for touching switches.

But if, like the crushingly vast majority of households and most workplaces, you do in fact have light switches, you should sanitise them.

Doorknobs are awful technology to the point that Australia recently outlawed them for new bulidings. Handles are still problematic but have a larger surface area so different people touch at different places and less pressure is also helpful.

I was using "doorknobs" as shorthand for any kind of door handle. If you have door handles, you should sanitise them. I think this is unhelpful pedantry.