Sometimes amongst the bum jokes you’ll learn something really Quite Interesting on QI.
Last week I learnt that when washing hands, how clean you get them is not about the heat of the water, which can’t possibly be warm enough to kill off bacteria and escape without serious burns. Rather, it’s about how vigorously you wash them — that is, you’re getting the bacteria off your hands, rather than killing them.
There’s probably more to it than that — the Wikipedia article on hand washing notes that: warm, soapy water is more effective than cold, soapy water at removing the natural oils on your hands which hold soils and bacteria. Contrary to popular belief however, scientific studies have shown that using warm water has no effect on reducing the microbial load on hands.
Perhaps I’ll just stick to my current habit: soap and warm water.
4 replies on “Hand washing”
Here’s a related article from The Conversation:
http://theconversation.edu.au/mondays-medical-myth-you-have-to-wash-with-hot-water-to-kill-bugs-3086
Another insight from Japan. Most public bathrooms do not have hot water nor soap nor paper or hand driers (though this is changing little by little). Men and women are supposed to carry a ‘handkerchief’ to wipe their hands with after washing. But its been observed many times that ‘handwashing’ after bathroom functions involves (a) trickling water over a few seconds or (b) doing nothing at all. A couple of years ago we had a massive scare campaign about avian flu and at my university antibacterial gel dispensers were spread throughout the university for public use. I’m not going to get into a rant here, but there are bodily practices here that don’t make sense, but people will go hell-for-leather when it comes to wearing masks to avoid (a) spreading or (b) catching and contracting airborne diseases. The effectiveness of these masks is still questionable.
Anyhow, wash hands thoroughly, and in between hand washing (when you touch other items) don’t touch your face.
And after washing hands, you have to dry them…
http://www.abc.net.au/science/articles/2011/02/15/3139197.htm
In college, we (Tim and I) were in a reproductive biology class in our Agri. engineering course. As an example of bacteria growth we each took a handprint in a plate of agar agar. Then washed our hands normally, then again handprint into another agar agar plate. Then we washed our hands really throughly with nailbrushes and soap, and again handprint into another agar agar. All three were left to incubate overnight. The two unwashed and normal washing were about the same in bacteria growth. The good handwashing one was marginally better. So, not a big difference between handwashing and not, sorry. But any bit likely helps in the stop of viruses, I’d guess.