Sure, sure, the Centers for Disease Control and Prevention says you should wash your hands for 20 seconds, using lots of soap and friction. But when that recommendation meets poorly stocked public restrooms, or distracted humans in a hurry, what happens to hand-washing effectiveness? Are some seconds better than none; is a soapless wash better than giving up; does hand lotion make germs sticky? And what if there’s no way to dry off?
Amid the current coronavirus outbreak, we here at Slate find ourselves flooded with questions about a humble practice we’ve always taken for granted. I spoke with Dr. Robert Amler, dean of the School of Health Sciences and Practice at New York Medical College and former CDC chief medical officer, to get some advice. With the stipulation that some of our weird queries don’t have strictly science-based answers, but could be answered from his own store of practical common sense, Amler agreed to play along.
Our conversation has been edited and condensed for clarity.
Rebecca Onion: OK, so we know you’re supposed to wash your hands for 20 seconds. If you only wash your hands for 10 seconds, do you get half of the benefit, or is it all or nothing?
Robert Amler: Well, 20 seconds is the recommendation, as you know. I don’t know if that’s been studied or if there’s any real data on what happens with a shorter time. The fact is, your hands have a certain amount of surface area, and you need to spend a second or more in each area. You want to cover the front and the palms of your hands. You want to cover the backs. You want to cover the spaces between the fingers and your thumb—those webs—and if you really scrub all that, it’s just probably going to add up to about 20 seconds.
We’ve noticed that in a lot of public bathrooms, there’s no soap or hot water. Is it still worthwhile to wash your hands under those conditions—or, maybe, should you wash longer to make up for it, if you don’t have soap or hot water?
Oh, well, the heat of the water is more a comfort factor than anything anti-bacterial. The heat does not protect against bacteria any better than cold water does. But of course it’s far more comfortable to use warm water than cold!
The soap does have anti-microbial properties; the chemical material of it is very destructive to these microscopic organisms.
So let’s put it this way: 20 seconds is better than 10 seconds, but 10 seconds is still better than zero. Soap is better than no soap, but washing with water is still better than nothing; you can try to make up for it by scrubbing your hands a lot more vigorously than you would otherwise.
If you really don’t have access to soap and water, the recommendation is hand sanitizer. And, if you can’t do a good job of cleaning your hands, be even more careful not to touch your face, until you can get those hands clean!
Have you ever carried soap in your bag, in case you come to a place where there’s no soap?
I’ve done that a few times, because when I travel sometimes you end up in a place where soap is not easy to find. When I travel, like most people, I carry hand sanitizer. Just today, going to several meetings where I shook hands and touched several other people, I had hand sanitizer with me the whole time and I was using it the better part of the morning.
OK, here’s another supply issue. Sometimes there are no paper towels, or just an air dryer, or neither! Is it better to wash your hands and not dry them, or not wash your hands at all?
You really need to wash your hands! Don’t take the absence of towels as a reason not to do it. The whole issue really is not bringing infective material onto your face, with your hands transferring the material to your face. So the name of the game is to keep your hands clean and not to touch your face. If there’s really nothing to dry them with, you could kind of flap them in the air for a little while.
One of my colleagues heard that you should wash your hands before you use the bathroom, and also after. That’s too much, right?
Well, it all depends. Where have your hands been? If you just came out of a crowd of people, and you were touching and shaking hands and grabbing and touching things, you might feel like you want to do the toileting functions with freshly clean hands, and then when you’re finished, because of contact with private parts and parts of the toilet, you will almost certainly need to wash your hands again. So washing before and after is not wrong!
In a related question, is it possible to overwash? Some people worry if they wash their hands too much, their hands will be cracked or dry, and that will make it easier for them to get infected by something.
Yes, some doctors and nurses and other health care people—they wash their hands constantly all day long, and use hand sanitizer all day long, and it is true that over time your skin takes a beating, and for some people they may have skin irritation. Your best defense against that is to use a soap that has a little lotion built into it, and maybe use a hand lotion on your hands at the end of the day, so that overnight the skin gets a chance to heal.
Does the application of hand lotion, just randomly during the day, have any effect on the transmission of bacteria?
I’m not aware—I wouldn’t expect any protection from it, but I’m not aware that it interferes with cleanliness.
We often hear, “Just sing Happy Birthday, or sing Happy Birthday twice,” and one of my colleagues said “Ugh! I just want to count to 20!” Is that OK?
What I recommend to my own patients is to time yourself. Some people sing it so quickly, and some so slowly. Time yourself! If there’s a song you like better, or counting, time that too. There’s nothing magical about the particular song you sing [laughs].
Here’s an etiquette question. We know most people don’t wash their hands well. If you are in a public restroom, is there anything you can do to try to encourage the people around you to wash their hands, or do you just leave them alone?
Well, unfortunately, that’s really a sociology question. I’m not well equipped to tell you, but I think a little politeness goes a long way.
I think the main thing is, you want to protect yourself—at the risk of sounding repetitive, wash those hands, keep those hands clean, and keep them off your face, as much as you can.
Yes, I know! But that’s it.