Ayesha Rascoe speaks with Mark Patrick Taylor of the Environmental Protection Authority of Victoria, Australia, about why he thinks everyone should remove their shoes before coming inside.

Transcript

AYESHA RASCOE, HOST:

There's one choice most of us face almost every single day when we get home - to keep or take off our shoes. The choice can be a divisive one. Personally, I'm team shoes off, but not immediately (laughter). But to scientists, the right choice is pretty clear-cut. Mark Patrick Taylor is the chief environmental scientist at the Environmental Protection Authority of Victoria, Australia. In a column for The Conversation, a nonprofit outlet, he argues people should take off their shoes inside their homes. And Mark joins us now from Sydney. Welcome.

MARK PATRICK TAYLOR: G'day. How are you doing?

RASCOE: So tell us, what does the science say? Should I start asking my guests to take their shoes off at the door?

TAYLOR: Well, I would, because the indoor is the indoor and the outdoor is the outdoor. Otherwise, why bother with it?

RASCOE: (Laughter).

TAYLOR: Now, perhaps the thing which grosses most people out is the unseen things that we can tramp in on the soles of our shoes, and that includes dog poo. Now, even if you're, you know, dodging dog poo on your footpath - it's like an obstacle course - the likelihood you'll stand in that or some bird poo or some other feces - you will bring it into your house if you don't leave them outside. And then that sloughs off, forms part of the dust in your house, which then can get remobilized. We have a 10-second rule in Australia.

RASCOE: Yeah. Drop - yeah.

TAYLOR: Do you have that?

RASCOE: We have five second - five seconds, yes (laughter).

TAYLOR: All right. The five second, 10 second. So let me put it to you this way. If you drop your sandwich outside in the gutter...

RASCOE: Yes, yes.

TAYLOR: ...Do you apply the five-second rule?

RASCOE: No, you don't eat it if it falls outside (laughter).

TAYLOR: Yeah, exactly. So if somebody is walking their shoes into your house and bringing all that filth into your house, do you apply the five-second rule?

RASCOE: No, no.

TAYLOR: So if you leave your shoes off and the inside of your house is clean, would you feel more willing to apply the five-second rule?

RASCOE: That makes more sense. It does make sense. The way you argue it, especially when you bring up fecal matter, then it's like, you probably right (laughter).

TAYLOR: It's pretty gross, and it's all there percolating on your food and in your nice glass of wine. I mean, you know.

RASCOE: On your food (laughter). How do we survive? That's the question (laughter).

TAYLOR: It's a good question. And actually, some people have raised this with me. And we don't want to live in sterile environments. And exposure to contaminants is actually - you know, does help - the evidence shows it does help build up our immunity. But my comment to that is, well, you don't go into bed with your shoes on, do you? You take them off because you don't want to make the bed dirty.

RASCOE: (Laughter).

TAYLOR: It's the same principle in your - in - you know, inside your living room - right? - where you make food and you eat and you relax.

RASCOE: So you're saying leave the shoes outside. Don't even bring them, like, by the door. Just leave them outside. But in America, people might steal the shoes.

(LAUGHTER)

TAYLOR: Yeah, well, in Australia, we have funnel-webs that might crawl in your shoes. So you have to check them before you put them on.

RASCOE: OK (laughter).

TAYLOR: You can - so what I suggest is you have an outdoor mat and an indoor mat. Take your shoes off outside and, of course, you can just pick them up and then put them inside on a shoe rack. The main thing is, people have to remember to clean their mats. Can't leave the mat out there for three years. It will become ineffectual. You need to wash it and knock all the dirt out. It's about minimizing.

RASCOE: OK. So what about, like, (laughter) if it's really important to a person - like, I have to keep these shoes on? Is there anything they can do?

TAYLOR: Why don't they have indoor shoes?

RASCOE: (Laughter) Have indoor shoes and outdoor shoes.

TAYLOR: I know there are some people that have indoor shoes. We have UGG boots in Australia or people might have slippers, et cetera. I know some people are a bit funky - oh, I'm not taking my shoes off. I mean, really, it's your house. Should be your rules.

RASCOE: That was environmental scientist Mark Patrick Taylor. Thank you so much for being with us.

TAYLOR: That's my absolute pleasure. And I hope you can keep your shoes off in your house...

RASCOE: (Laughter).

TAYLOR: ...And assist in reducing the transfer of the stuff outside to inside. Transcript provided by NPR, Copyright NPR.