Nov. 18, 2011 – Building a Better Toilet
Toilets, as most of us know them, haven’t changed much since the 1800s—they use a lot of water, and require an infrastructure that many communities can’t afford. Ira Flatow and guests look at the problem of access to sanitation, and how engineers are making toilets better.
IRA FLATOW, HOST:
This is SCIENCE FRIDAY. I’m Ira Flatow. Tomorrow is World Toilet Day, and if you have a toilet, that’s a cause for celebration, because more than a third of the world’s population does not. For 2.6 billion people, going to the bathroom is, well, there is no bathroom to go to. People don’t have access to the sanitation and sewer systems that we take for granted here. Without a place to go, people defecate into ditches, waste gets dumped into waterways and diseases spread.
The sponsors of World Toilet Day are trying to change that by bringing attention to the problem. And one sponsor, the Gates Foundation, is challenging engineers to build a better toilet, giving them money to do it. It’s called the Reinvent the Toilet Challenge. Frank Rijsberman is director of water sanitation and hygiene at the Bill and Melinda Gates Foundation in Seattle. Dr. Rijsberman is here with us. Welcome to SCIENCE FRIDAY.
FRANK RIJSBERMAN: Thank you. Good morning, Ira.
FLATOW: Good afternoon to you. Rose George is author of “The Big Necessity: The Unmentionable World Of Human Waste And Why It Matters.” She joins us from the BBC in Leeds. Welcome to SCIENCE FRIDAY.
ROSE GEORGE: Thank you.
FLATOW: Dr. Jim McHale is vice president of engineering at American Standard Brands in Piscataway, New Jersey. You know they make all those bathroom fixtures, including that famous toilet that seems to swallow everything up on YouTube. Thank you for being with us today, Jim.
JIM MCHALE: Thank you, Ira.
FLATOW: Let’s talk a bit, Dr. Rijsberman. Tell us about World Toilet Day and what the point of it is.
RIJSBERMAN: Well, World Toilet Day tries to bring across the same point you just made, that an astonishing third of the world population does not have access to flush toilets. Yes, flush toilets have saved more lives than any other invention, but at the same time, lack of them still causes an incredible number of death among young children from diarrhea.
FLATOW: With two and a half billion people, that’s a big number. How do you even get your arms around it? How do you tackle that problem?
RIJSBERMAN: With great difficulty. A lot of people are trying that, in fact, and we are doing things. It’s not as if we have to reinvent the toilet before we can start working on that problem, but yes, we do think that particularly for people who live in slums in developing countries, in very high density, low income areas, we don’t really have a toilet that works for poor people.
FLATOW: So you’re looking for, actually – you said we don’t have to reinvent the toilet, but you are actually asking people.
RIJSBERMAN: Yes, we are asking people to come up with a toilet that does not flush, you know, clean water down an expensive set of pipes to get into a waste water treatment plant where we’re spending even more energy and money to get that waste out again. We’d love for people to have what we sometimes call the cell phone of sanitation, an aspirational product that actually recovers resources from waste. There’s a lot of energy in human waste. There is nutrients there, and we’d love to find a way to reuse those directly without relying on flushing your waste down the drain with clean drinking water.
FLATOW: So you’re looking for some really creative engineering and giving money to engineers to design a better toilet.
RIJSBERMAN: Yes, indeed.
FLATOW: And how long is the contest going to go on for?
RIJSBERMAN: Well, within a year we’d love for people to show that their crazy ideas have some value and then next year August we hope to have a big fair where people demonstrate all those prototypes. And then we’ll have more money to take the best ideas forward into toilets that people can actually use.
FLATOW: Mm-hmm. And so how do you apply for – if you’re an engineer and you have a crazy idea, how do you get a grant from you folks?
RIJSBERMAN: Well, we had several open contests and Daniel Yeh that you are going to talk to later was one of the hundreds of people who sent us those ideas and then we have those reviewed by external experts and we funded a bunch of these, about 26 in April and another 31 that were published just last week.
FLATOW: Let me bring out Dr. Yeh. Dr. Daniel Yeh is an engineer who was working on one of those toilets. Welcome to SCIENCE FRIDAY.
DANIEL YEH: Hello, Ira. Great to be here.
FLATOW: Thank you very much. Can you give us an idea what your idea is?
YEH: Okay. Well, I guess, to start, I need to talk about how we currently treat waste. Typically, in municipal waste water systems, you know, we use what’s called activated flush(ph) , which is a rather energy intensive way to get rid of the organic material, namely in waste. As Frank said earlier, this is energy intensive and also does not recover energy. So we’d like to do it differently. We’d like to do it using (unintelligible) organisms, which are naturally present.
And through the (unintelligible) organisms, you can reroute the organic content or the electrons that are embedded in the organic material into methane. And then, along with that waste, there’s nitrogen phosphorus, like Frank mentioned, so the trick now is to have you get to the nitrogen phosphorus in the water safely, and we will be doing this in conjunction with a membrane, an ultra-filtration membrane.
FLATOW: So the idea is not to just dump the waste. It’s to, more or less, recycle it back into something else.
YEH: It absolutely is. Because if you look at waste, what’s waste to us is actually food for microorganisms. And when you really come down to it, it’s nothing more than carbon nitrogen phosphorus. But it’s just the fact that there’s pathogens in there. There’s also a social stigma attached to it, so we need to find ways to overcome those.
FLATOW: And how much time do you think it will take you to come up with a working idea here?
YEH: We have already built it in the lab and we call that a NEW generator, which means nutrients, energy and water, NEW generator. We have a working prototype in the lab and what we’re doing now through the Gates Foundation Grant is to move that into the field for a field demonstration and to ruggedize(ph) the unit.
FLATOW: Is it something that anybody could build, even, you know, in a place that doesn’t have a lot of resources?
YEH: I think you’re going to need some resources to build it, but then the challenge is how we’re going to make this fit into the existing sanitation cycle and then of course affordability will be an issue. But, you know, I like to always look at it like the USB drive example. You know, when the USB drive first came out many years ago, it was very expensive and, you know, frankly, I don’t know how that works. But now you can get one for, what, $5?
YEH: And so I think if there’s a demand, we can create a (unintelligible) market structure, anything can be affordable.
FLATOW: All right. Good luck to you, Dr. Yeh.
YEH: Great. Thank you.
FLATOW: Thank you for taking time with us, Dr. Yeh. Daniel Yeh is an associate professor of civil and environmental engineering at the University of South Florida in Tampa. We’re talking World Toilet Day coming up tomorrow around the world and we’re talking about toilet technology. Let me bring on Rose George. She is author of “The Big Necessity: The Unmentionable World Of Human Waste And Why It Matters.” Why is it so unmentionable, Rose?
GEORGE: Well, I think actually one of the good things that since I wrote that book, which was in 2008, I think it’s become much less unmentionable. And – but there is a conversational and societal taboo about this and it’s – the interesting thing about this taboo is that it’s not actually that old. It only goes back 200 or 300 years, which is just about the same time that the flush toilet became the norm and so you had this odor-free device that you could have inside your house, which was unthinkable beforehand.
If you’d ever encountered a 17th century privy, you wouldn’t want it anywhere near you. So you had this clean and nice, fresh-smelling device. And at this same time, I think, because we could do that, because we could put it behind a closed door, we could also not really think about it and not discuss it. And that’s had really quite damaging effects up to the point where, you know, as Frank said in 2011, we’re in this ridiculous situation of children dying of the runs, of diarrhea, and surely, you know, we can solve that.
FLATOW: Do you think that if some toilet designers of 100 years ago were alive today, they could walk up to the modern toilet and say, I can still fix that?
GEORGE: I think if you took a standard western toilet, yes. I think if you took – there are these quite amazing Japanese high tech toilets, and that’s a whole different kettle of fish.
But I think, yes, if you got hold of Joseph Brown or Alexander Cummings and asked them to fix a toilet, I suspect they’d be able to. I don’t think Alexander Graham Bell would be able to get to grips with an iPhone quite as easily.
FLATOW: Jim McHale, you work on some of the cutting-edge designs in toilet technology for American Standard. What are some of the challenges in toilet design today?
MCHALE: Well, first, let me say, we are also interested in the work to help developing countries get toilets. And I’ve been talking with Frank about what we can do to help. But here in the U.S. market, the challenges are more around water conservation, what can be done to change the designs to get toilets to function properly on less water. There’s the EPA’s water sense initiative that tries to promote the use of what we call ATTs, toilets that function on 20 percent or less water than a typical 1.6 gallon toilet.
So we spent a lot of time designing toilets that work on less water, but actually that really flush well and aren’t going to cause somebody to have to flush the toilet twice because that really is the nemesis of water conservation is when somebody has to flush twice or three times to really clean the bowl.
FLATOW: So that’s a real engineering challenge, then.
MCHALE: Absolutely. We use the best available tools and find the best available people to solve that problem just like any other industry would solve their problems.
FLATOW: 1-800-989-8255 is our number. Talking about engineering toilets on World Toilet Day tomorrow. You can also tweet us @scifri, at S-C-I-F-R-I. Let’s go take a call or two before the break. Let’s go to Russell(ph) in Cincinnati. Hi, Russell.
RUSSELL: Hey, how you doing?
FLATOW: Hey, there.
RUSSELL: Hey, I’m sitting here listening to this and I’m thinking to myself why – what’s the big deal? The (unintelligible) toilet has been around since the ’60s, I know that much, and that’s a composting toilet. It already exists. And when you drive through all the rest areas and more of the public restrooms that you go into now, they’ve got toilets and urinals that don’t use any water at all. So I’m just…
FLATOW: Yeah, Frank, good question.
RUSSELL: …it already exists, so why are we trying to find it?
FLATOW: Frank Rijsberman?
RIJSBERMAN: Yes. And indeed, that has been a common reaction. People have been proposing composting toilets to us. And indeed, if you have a mountain cabin here in the U.S. or so, that may very well be a good solution. They’ve been around a long time. They’ve been tested in developing countries and they work for some specific conditions, but for those that we’re looking at, slums, lots of people sharing toilets, they fill up too quickly, they don’t properly function.
So we recognize that for some conditions, composting toilets work well and actually we have some grants that make those even better, but for the majority of the conditions we’re looking at, it’s not a good solution. We want something – in fact, the composting toilet is sort of an improved outhouse, if you like. We’d love to get to a toilet, an aspirational product, the cell phone of sanitation, that you and I would also want to have in our house and that doesn’t reduce the flush to, say, 1.4, 1.2 gallons per liter, but to zero.
FLATOW: All right. There it is, the iPhone of toilets. We’re gonna come back and talk more with Frank Rijsberman, Rose George, author of “The Big Necessity: The Unmentionable World Of Human Waste And Why It Matters,” Jim McHale, vice president of engineering at American Standard Brands in Piscataway, New Jersey. Our number, 1-800-989-8255. Maybe you have an idea for the toilet of tomorrow, the iPhone of toilets. We’ll be right back after this break.
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FLATOW: This is SCIENCE FRIDAY. I’m Ira Flatow. We’re talking this hour about the toilet of tomorrow, what would be the ultimate toilet, how should it be designed, with Frank Rijsberman, director of water sanitation and hygiene at the Bill & Melinda Gates Foundation. Rose George, author of “The Big Necessity: The Unmentionable World Of Human Waste And Why It Matters,” Jim McHale, vice president of engineering at American Standard Brands in Piscataway. Our number, 1-800-989-8255.
Jim, you heard Frank say that the ultimate toilet would have no water in it. Is that something practical for an American consumer, though?
MCHALE: In the short term, probably in my lifetime, I would say no. It – there’s very cultural aspects with a toilet as well. People – Frank mentioned how people don’t like to use composting toilets and a lot of it has to do with the smell. Water has – the main function of water is that it reduces the smells during the process, so I really cannot see that happening in the near-term.
FLATOW: Rose George?
GEORGE: I think, I mean, it’s certainly true that there are cultural aspects to sanitation, which make it extremely tricky to solve or to find a perfect solution across the world, which is probably partly why we’re in the situation. But I am more optimistic, I think, possibly than Jim. I mean, one of the lovely anecdotes I was told was from a Norwegian professor who told me that a friend of his, their children, their family had a composting latrine at home, thought that was completely normal.
And the day that they went, started kindergarten, were absolutely appalled to find that they had to drop their waste into a load of water and they just didn’t like the plop and the splash. So it’s – I think things can change slowly. I certainly don’t think that the composting toilet is a solution in many situations. But the point about sanitation, the trick to solving sanitation which we’re now all understanding is that you have to be flexible. One solution is not going to fit someone else, as Frank said.
You can’t really be imposing sewers in a slum, for example, or composting toilets because nobody’s – no authority is going to want to install infrastructure in a slum because that would automatically imply that people have land rights. So there’s all sorts of political issues. So this issue is really complicated. That makes it fascinating, but it also makes it a huge challenge.
FLATOW: But composting toilets, they’re used in public places. I know around here in New York, the Queens Botanical Garden has a wonderful composting toilet. It looks great and it has no smell. Took a tour of it once myself. There are other places that use it. Perhaps public places are where we might see them blossoming, for lack of a better word. They don’t smell at all. You know, it’s surprising.
RIJSBERMAN: They can work and we are certainly not against composting toilets and we’d love to see them improved further. Normal composting can take up to six months before all the pathogens are really removed from the waste, particularly worm eggs persist very long. So we’d love to have something that is really safe, much quicker than that, which probably involves higher temperatures. But we are certainly not against composting toilets. But as you say, they’ve been around for a long time and they’ve had, clearly, if you like, issues to be adopted at a wide scale. We’d love to see something that gives billions of people a new toilet much before Jim passes away.
We have to be rather more impatient optimists than that. And we think we can see solutions that will be ready for millions of people more like in three to five years, rather than 20 to 30.
FLATOW: If I heard what you just said, that if, you know, it’s too long to wait for a few months for all these pathogens to settle out, are you saying that you might be able to create a toilet that sort of sterilizes itself?
RIJSBERMAN: Yes. We have a lot of other options that are currently being researched. I mean, like Daniel Yeh, we have about 60 of those grants this year and some people propose to use a method that is similar to creating charcoal. It’s called creating bio-char. In essence, you heat it up to about 250 degrees, which after 10 minutes is pretty sure to no longer have pathogens. And it creates this bio-char, which is like charcoal, which you can then either put in the soil as a soil improver or in some cases where people cook on charcoal, it could even be cooking fuel.
FLATOW: So you have to not only create a new kind of toilet, but you need a system for disposal of what’s left in the toilet.
RIJSBERMAN: That’s critical, yes. And actually, we are saying where the current methods all look at this as waste that is costly to remove, we are looking at it as resource recovery, as recycling and that can actually get some money back to people that makes this all affordable.
FLATOW: So, like we used to throw out newspapers and bottles, which we don’t do anymore, we recycle them, somebody might come by – somebody might – our toilet might be situated maybe with a door on the outside of our home or our building and somebody could come by and just replace it or the removable parts.
RIJSBERMAN: Yes. Actually, those kind of cartridge toilets are definitely being researched. We are working with a small NGO called Sanergy that, in Kibera, one of the worst slums in Nairobi in Africa, brings people these little cartridge toilets that actually do fit in their homes and collects them every couple days and then brings them to a neighborhood recycling place where you’d have a machine that creates bio-char, like charcoal, out of human waste. And that actually – for us, you’d be able to reduce the cost of treating waste to zero by basically generating revenue out of waste.
FLATOW: Jim McHale, you have this great video of an American Standard toilet, Standard Brand toilet on the internet that, no matter what you throw down there, from a dozen golf balls to 53 chicken nuggets or 56, is it, everything flushes. And with one flush. What is the engineering miracle there? What did you accomplish? How did you figure out how to do that?
MCHALE: That’s our H2 option siphonic(ph) dual flush toilet. The trick to getting toilets to flush that well is all optimization of the internal chambers that you can’t see. The water is flowing through different passageways that leads to the tank and eventually winds up in the bowl and down the trapway and down the drain. And as I think I mentioned earlier, we use computational fluid dynamics to understand the flow through those chambers and to reduce turbulence wherever it occurs so that we’re not wasting any of the energy in the tank.
Any of the energy of the height of water in the tank. Or that’s the only potential energy available to remove the waste. So the channels have to be designed perfectly to not waste any of that energy and make it do the work that we need it to do.
FLATOW: How about the composition of the toilet itself, the porcelain? Is there a special material, coating or something that’s on there?
MCHALE: Well, we – the other aspect is – there’s removing the waste, there’s also cleaning the walls of the bowl. And there we’ve engineered what we call ever-clean antimicrobial glaze. The glaze is the glass coating on a piece of ceramic, what makes it look white and shiny is actually a glass coating. We’ve engineered that glass coating to be ultra smooth on the nano scale so that material doesn’t stick to it. That also helps with the flush because we don’t need to use as much water to wash the bowl, so the bowl – and we can put more water into powering the flush and moving waste down the drain.
FLATOW: Yeah, ’cause as we said before, that double flush is what wastes a lot of that water.
MCHALE: Yes, it does. And that’s – sometimes toilet designers will miss that aspect of it. And you can have a bowl that removes solid waste very effectively, but if it doesn’t clean the walls, people are going to – they’re going to flush it twice.
FLATOW: You know, the toilet I hate to use the most is the one in airplanes that has that air sucking through the toilet bowl. I think that’s really probably – ’cause my own – it’s so loud, it really hurts your ears. I wonder if it breaks OSHA rules or something for sound level in some way. Has anybody thought of using that kind of technology, though, I wouldn’t want to use one myself?
RIJSBERMAN: Yes, actually. In places where – in China, where they don’t want to use six liters or 1.4 gallon or so to flush their toilets, the next thing, if you use only the one liter or so that people use to clean themselves, that’s not enough to transport the waste, so then you have to have vacuum tubes in apartment buildings. Not necessarily the cheapest option, but that helps like an airplane toilet to move waste with very little water.
FLATOW: Let’s go to Debbie(ph) in Layton, Utah. Hi, Debbie.
FLATOW: Hi there.
DEBBIE: I just have a quick comment. My family and I lived in Shanghai, China, actually, until just a couple years ago and we always thought it was so interesting. You know, the vast majority of toilets, especially in public places, are – we call them squatters for, you know, lack of a better term. And even when you could find a Western toilet, we would go in and we would very often see footprints where people had stood on top of the Western toilet because they thought that it was unhygienic to sit on a toilet where someone else had sat.
And they didn’t know how to use it. And I just wondered if you could comment on the cultural implications of trying to switch, even in a country like China that obviously has the money and the political will to do it, still has not happened. Thank you.
FLATOW: Thank you. Rose George? Any comment?
GEORGE: I’ve heard of that as well. It’s pretty common to hear of footprints on the seats. I mean, I’m not sure if Jim from American Standard is going to like this, but ergonomically and biologically, it’s actually much better for us to squat anyway. So they’re actually – I’m not actually against those mysterious footprint leavers on toilet seats. Obviously, hygienically, it may not be the best thing, but if they wipe it afterwards then I don’t see that much wrong with it. So I don’t see it as a huge cultural barrier. But it is interesting, if you look nearer to China, if you look at Japan, they went from, in about 60 years, from a nation of people who squatted and used pit latrines, essentially, to people sitting on Western seats and using Western-style toilets – oh, they’re much improved and innovated upon, certainly more advanced in terms of robotic technology and stuff.
So it can be done, but it was a massive cultural shift. And it was very difficult, and took about 20 years or so. We just – we have all these quirks about our attitude to how we dispose of our own human deposits. I don’t like to use the word waste. I avoid it if I can. But we’re not rational beings about this, which is what makes it such an interesting topic and endlessly rich.
FLATOW: Because we know we do use manure from other animals as fertilizer and don’t think twice about it. But people would be a little squeamish to use human waste.
GEORGE: I – when I was in a village in India, in (unintelligible), I remember vividly meeting a young woman who – I was talking to her about whether she wanted to use a biogas digester, which is an anaerobic digester, which – they’re very popular China, about 18 million households have them. And there’s – they’re very energy efficient. You just tap off the meter and then you can produce – you can use it for cooking gas and use electricity. But in India, there is an attitude towards human waste which is very different. And it’s very much seen as a taboo. So she looked absolutely horrified and then immediately stuck her hand in a big bowl of green cow manure and started spreading it all over her wool. So, you know, we are strange creatures.
FLATOW: Here’s a tweet, came in from SCIENCE FRIDAY in Second Life. It says: Why isn’t water from showers and washing machines normally reused for flushing toilets? It’s even illegal by city building codes. Why – we’re not drinking it. Why should we not use it. Any thoughts on that?
MCHALE: That actually is being done in some areas. It’s called gray water reuse. People are collecting the water from the sink where you wash your hands or collecting the water from the shower and reusing it to flush the toilets. Actually, I think the Gates Foundation headquarters has toilets and urinals that function like that. A lot of new buildings are putting in systems to handle gray water in that manner. It’s an infrastructure challenge, though, you need to put in the system to do it, but it’s certainly feasible.
GEORGE: I think it’s – so I think it’s a regulatory challenge as well. I think a lot of times – it’s not that it’s illegal or legal. It’s just that the regulations aren’t there. So people – you do have a kind of underground gray water recycling community, and that they’re not quite sure where they stand. But it makes – it just makes perfect sense. There should be more of it.
FLATOW: I’m Ira Flatow. This SCIENCE FRIDAY from NPR. Rose, you went to Japan to investigate the toilets there. We have seen pictures of these toilets that cost thousands and thousands of dollars. What’s your feeling about this?
GEORGE: Well, I have to confess I do actually have one, so I feel very happy about it. But it was given to me by Toto, who is the leading brand and I should say – without wanting to give them market advantage – the second brand is called INAX. Anyway, there are basically three big Japanese plumbing companies who have developed these astonishing toilets. And, of course, you don’t need a several thousand dollar toilet. I mean, they are amazing, but what they do do, which is I think the biggest selling point, is that they can clean you.
So if you actually think about toilet paper, toilet tissue, it’s not – we’re using something dry to clean the dirtiest parts of our body, whereas we wash everything else. It really doesn’t make much sense. Whereas these Japanese toilets, and you can just get a sort of add-on toilet seat, which has an in-built bidet nozzle. And I think hygienically, they are far superior to my toilet in the U.K., for example.
FLATOW: But then you’re using more water.
GEORGE: You are using a little more water. I haven’t looked into the exact statistics of it, but it’s not that much. It’s – because if the nozzle is efficiently designed at the correct angle – and trust me, these Japanese companies have spent years and millions of dollars doing the research to put it at an exact angle. I think it’s quite efficient. Oh, the other difficulty with these toilets is they do need electricity, so if you’re trying to reduce your carbon footprint, then maybe they’re not for you.
FLATOW: Certainly, that’s the last thing you’re going to worry about if you have one of these toilets, is whether you have enough electricity for it.
RIJSBERMAN: The challenge for our toilet inventors then is to come up with a toilet where even Rose would replace her Toto with one of our reinvented toilets. And frankly all our reinvented toilets do use water to clean people, but that takes maybe half a liter or a liter. What we are against is the larger amount of water to transport our waste. And while we really talk about the toilet only now, we are, of course, thinking of the whole system. It’s not so much a toilet that is unaffordable. It’s the sewers and the wastewater treatment plants that are unaffordable.
There are some 2 billion, if you like to call them, toilets out there, they’re really latrines and septic tanks, that are not connected to anything. And indeed part of our work is not only to reinvent the toilet, but to link services to those latrines and septic tanks so that they can be safely emptied because today, those toilets are often emptied by hand, by bucket, and then that waste is dumped around the corner in the alley where kids play. So beyond the actual toilet that we sit on, it’s really the whole system of sanitation services that interests us.
And a lot of the money that we give out – and we are, by the way – and I can tell you that as a news item, we are announcing a whole new set of grants tomorrow on our blogs, some $48 million worth of new grants. But a lot of that is not for reinventing the toilets as the user interface. It’s also for systems that are safe and affordable for people to empty their latrines and to generate energy and nutrients from that waste.
FLATOW: Allright. Thank you very much, and we’ll be watching for that announcement tomorrow. Frank Rijsberman is the director of water sanitation and hygiene at the Bill & Melinda Gates Foundation in Seattle. And they have the Reinvent the Toilet Challenge. They have about eight people in the running – eight organizations running to – is there a prize for that or just – you’ve already given out the money in challenges?
RIJSBERMAN: No. Part of the challenge is they’ll come and present their prototypes next year, and then the winners will get more money for the best toilet.
FLATOW: Great. Rose George is author of “The Big Necessity: The Unmentionable World of Human Waste and Why It Matters,” a very good reading book. You know where you might want to read that book. Jim McHale is vice president of engineering at American Standard Brands in Piscataway, New Jersey. Thank you, Jim, for taking time to be with us today.
MCHALE: It’s my pleasure.
FLATOW: Have all a great weekend. We’re going to take a break and we’ll be right back. Stay with us.
I’m Ira Flatow. This is SCIENCE FRIDAY from NPR.
To educate the people about the dangers of open defecation why not film a little experiment I have come up with. You go to the place where they are defecating and dust the flies with an obvious unnatural color of powder. Then film the flies as they return to the home with the dusted powder on their backs. Continue filming them as they land on surfaces in the home including food. Doesn’t need dialogue to communicate the message, The images are enough. The film makers of MicroCosmos could tell you how to even film the flight of the flies. Charles A. Bowsher