0:00:04 > 0:00:05In the modern world, we've become
0:00:05 > 0:00:08accustomed to living in clean cities.
0:00:09 > 0:00:13But imagine every time you took a drink of water from the tap,
0:00:13 > 0:00:15you were playing Russian roulette with your life.
0:00:15 > 0:00:20Or the streets outside your door were almost knee-deep in filth.
0:00:20 > 0:00:23Well, that's what life was like in the western world
0:00:23 > 0:00:25just a century and a half ago.
0:00:26 > 0:00:27But over the next 100 years,
0:00:27 > 0:00:31we managed to rid many cities of this waste and disease.
0:00:36 > 0:00:38So, how did we get to be so clean?
0:00:40 > 0:00:43Well, it took guys like the maverick railway engineer
0:00:43 > 0:00:47who lifted a city to build America's first sewers.
0:00:47 > 0:00:51It's a crazy idea, but it's also kind of a beautiful one.
0:00:51 > 0:00:55And the doctor who added potentially-lethal chemicals
0:00:55 > 0:00:57to the water supply of an entire city.
0:00:58 > 0:01:01These are classic examples of the kind of people
0:01:01 > 0:01:03who actually made the modern world.
0:01:03 > 0:01:05People you've probably never heard of.
0:01:08 > 0:01:10These were the hobbyists,
0:01:10 > 0:01:13garage inventors and obsessive tinkerers.
0:01:13 > 0:01:16Ordinary people doing extraordinary things.
0:01:18 > 0:01:20The thing about these pioneers is
0:01:20 > 0:01:23they didn't just make our world a cleaner place,
0:01:23 > 0:01:26they also set off an amazing chain reaction of ideas.
0:01:28 > 0:01:29The results were innovations
0:01:29 > 0:01:32that would affect every aspect of our lives.
0:01:32 > 0:01:34From the world of hi-tech to fashion.
0:01:37 > 0:01:40Law and order...all the way to health.
0:01:40 > 0:01:45I want to show how these seemingly-unconnected worlds
0:01:45 > 0:01:47are linked by the unsung heroes of clean.
0:01:53 > 0:01:58All my career, I've been fascinated by ideas and innovation.
0:01:58 > 0:01:59From writing books about the great
0:01:59 > 0:02:01British innovators of the Enlightenment,
0:02:01 > 0:02:03or the Industrial Revolution,
0:02:03 > 0:02:06to my work with Silicone Valley start-ups.
0:02:06 > 0:02:08And what I've learned about innovation
0:02:08 > 0:02:10is that the experiences of the past
0:02:10 > 0:02:14are still the best road map for our future.
0:02:14 > 0:02:18And that's why I want to tell you the story of How We Got To Now.
0:02:40 > 0:02:44You know, you look around, today's city streets are so clean,
0:02:44 > 0:02:46you could eat your dinner off of them.
0:02:46 > 0:02:50A city like San Francisco spends 50 million a year
0:02:50 > 0:02:54spraying and sweeping and generally keeping the streets free of filth.
0:02:54 > 0:02:56But just a few feet below me,
0:02:56 > 0:03:00there is a tide of highly-toxic waste.
0:03:03 > 0:03:06'This deeply-unpleasant river of filth
0:03:06 > 0:03:09'is one of the biggest health issues cities around the world face.
0:03:11 > 0:03:15'To see it requires some serious safety gear,
0:03:15 > 0:03:17'a huge team of people...'
0:03:17 > 0:03:20There we go. OK. Oh, yeah.
0:03:20 > 0:03:22'..and nerves of steel.
0:03:24 > 0:03:26'Ironically, the story of clean
0:03:26 > 0:03:30'starts in the dirtiest place imaginable.'
0:03:30 > 0:03:33Another day, another sewer.
0:03:35 > 0:03:38All right, here we go. OK.
0:03:38 > 0:03:41I'm going in. I can already smell it from here.
0:03:41 > 0:03:43It's delightful. Yeah.
0:03:43 > 0:03:45All right, going down.
0:03:52 > 0:03:55These are San Francisco's sewers.
0:03:55 > 0:03:57There's over 1,600 kilometres of these tunnels
0:03:57 > 0:04:01that run beneath the city hidden from view.
0:04:02 > 0:04:05Oh, this space is incredible.
0:04:05 > 0:04:09It's really hot down here and the smell is just kind of overwhelming.
0:04:09 > 0:04:12There are lots of little critters walking along on the sides.
0:04:16 > 0:04:19This is, er...this is the underbelly of the city.
0:04:19 > 0:04:24I mean, in an incredible way, this is what makes cities possible,
0:04:24 > 0:04:27is this kind of space. But we never see it, we never experience it.
0:04:27 > 0:04:28It's an extraordinary thing.
0:04:30 > 0:04:32'But what's even more remarkable
0:04:32 > 0:04:34'is that many of San Francisco's sewers
0:04:34 > 0:04:37'were constructed well over 100 years ago.
0:04:40 > 0:04:42'This old infrastructure has now been expanded
0:04:42 > 0:04:44'as the city above has grown.
0:04:47 > 0:04:49'Which means it requires regular maintenance
0:04:49 > 0:04:51'by people like Gene Chruszcz.'
0:04:54 > 0:04:55So, where is all this waste...
0:04:55 > 0:04:59This is pouring out of someone's apartment building right here?
0:04:59 > 0:05:03This is a lateral going to the apartment building.
0:05:03 > 0:05:06So people taking showers, washing their dishes,
0:05:06 > 0:05:10going to the bathroom, it all comes into this sewer.
0:05:10 > 0:05:12And this is... Where is this flowing to?
0:05:12 > 0:05:14This is all going to flow to another big sewer
0:05:14 > 0:05:19and it goes to our sanitary plant, where it's treated.
0:05:19 > 0:05:21Amazing!
0:05:22 > 0:05:25'The journey from homes to waste water treatment facilities
0:05:25 > 0:05:29'is only made possible thanks to these amazing
0:05:29 > 0:05:30'century-old sewer lines.'
0:05:32 > 0:05:35This line was put in in, I think, 1868.
0:05:35 > 0:05:37- 1868?!- Yeah.
0:05:37 > 0:05:39The structure looks fantastic.
0:05:39 > 0:05:41- It's incredible.- Yeah.
0:05:43 > 0:05:45'Today, we take it for granted
0:05:45 > 0:05:48'there's somewhere for our waste to go when we flush the toilet.
0:05:50 > 0:05:51'But just five generations ago,
0:05:51 > 0:05:55'there were no comprehensive sewer networks anywhere in America.
0:05:56 > 0:05:59'It meant much of the filth you see down here
0:05:59 > 0:06:01'was on the streets and pavements.'
0:06:06 > 0:06:08You made a hard job easy.
0:06:08 > 0:06:11You guys done? Ready for stripping?
0:06:11 > 0:06:13Strip me.
0:06:16 > 0:06:19The history of clean streets is surprisingly short.
0:06:22 > 0:06:25As we rewind the clock, you can rapidly see our cities
0:06:25 > 0:06:27becoming ever-dirtier places to live.
0:06:29 > 0:06:33And nowhere is filthier or more unpleasant
0:06:33 > 0:06:35than mid 19th-century Chicago.
0:06:35 > 0:06:40The place where the story of clean in American cities first begins.
0:06:49 > 0:06:51It's hard to imagine it now,
0:06:51 > 0:06:57but Chicago in the 1850s was a truly disgusting place.
0:06:57 > 0:06:59I have a newspaper from the period, it was called,
0:06:59 > 0:07:02The Gem of the Prairie, which sounds lovely,
0:07:02 > 0:07:05until you actually read a description of what it was like.
0:07:05 > 0:07:08"The gutters at the street crossing were clogged,
0:07:08 > 0:07:12"leaving pools of an indescribable liquid
0:07:12 > 0:07:15"there to salute the noses of the passersby."
0:07:19 > 0:07:22Chicago has a very particular problem
0:07:22 > 0:07:24when it comes to keeping clean.
0:07:24 > 0:07:28Not only is it one of the fastest-growing cities in America,
0:07:28 > 0:07:31but in an age before the motorcar, all these people
0:07:31 > 0:07:34means there's an explosion in something else, too.
0:07:39 > 0:07:43We think of horses as these symbols of natural beauty.
0:07:43 > 0:07:47But imagine what it was like when all these cars were horses.
0:07:47 > 0:07:50When you take thousands of these and put them on the streets
0:07:50 > 0:07:53of an already-crowded city like Chicago,
0:07:53 > 0:07:54things can get pretty grim.
0:07:56 > 0:08:01Just imagine what this street would have been like 150 years ago.
0:08:01 > 0:08:04You're walking out in your fine 19th-century outfit
0:08:04 > 0:08:08and the sidewalk is literally lined with this.
0:08:08 > 0:08:12I mean, it's an appalling mix of human and animal excrement
0:08:12 > 0:08:15that you have to wade through on your way out to dinner.
0:08:17 > 0:08:20The city is convinced the smell of this toxic waste
0:08:20 > 0:08:24is causing the huge levels of disease they are experiencing.
0:08:24 > 0:08:26Something has to be done.
0:08:30 > 0:08:32So Chicago hires this man.
0:08:33 > 0:08:35Engineering maverick Ellis Chesbrough.
0:08:37 > 0:08:41Having spent a lifetime working as an engineer on the railroads,
0:08:41 > 0:08:45he may seem like an odd choice to clean up the city.
0:08:45 > 0:08:47But Ellis Chesbrough has a big plan.
0:08:51 > 0:08:55Chesbrough makes a pilgrimage to Europe.
0:08:55 > 0:08:57Now, when most Americans travel to Europe,
0:08:57 > 0:09:00they're there to see Buckingham Palace or the Louvre,
0:09:00 > 0:09:03but Chesbrough wants a grand tour of something else.
0:09:03 > 0:09:06He wants to see the continent's new sewers.
0:09:10 > 0:09:13While crowds enjoy the sights above ground...
0:09:15 > 0:09:18..Chesbrough is hard at work taking notes on the underground
0:09:18 > 0:09:20infrastructure of Europe's major cities.
0:09:22 > 0:09:24On his trip, Chesbrough sees just how important
0:09:24 > 0:09:27proper sewers are to the cities above them.
0:09:28 > 0:09:32And he comes away convinced that this new technology
0:09:32 > 0:09:34will keep Chicago clean.
0:09:34 > 0:09:39Only the city has a problem. It's too flat.
0:09:41 > 0:09:44And that means sewers can't drain properly.
0:09:44 > 0:09:46You could build them deep underground,
0:09:46 > 0:09:48but then the cost becomes astronomical.
0:09:53 > 0:09:56Chesbrough's got an incredible idea.
0:09:56 > 0:10:00If you can't dig down, why not lift the city up?
0:10:00 > 0:10:04And he's got the perfect technology to do it. The jackscrew.
0:10:07 > 0:10:11The jackscrew is a simple device used largely on the railways
0:10:11 > 0:10:13to lift trains on and off the track.
0:10:16 > 0:10:18But Chesbrough sees that it could be put to use
0:10:18 > 0:10:21in his sewer-building project.
0:10:26 > 0:10:29If you can use a couple of these to lift a locomotive,
0:10:29 > 0:10:31why not use them to lift a building,
0:10:31 > 0:10:34or a block, or an entire neighbourhood?
0:10:34 > 0:10:38It's a crazy idea, but it's also kind of a beautiful one.
0:10:38 > 0:10:42Using railroad technology to keep the city streets clean.
0:10:45 > 0:10:48Starting in the 1850s, building by building,
0:10:48 > 0:10:50Chicago is lifted by jackscrews.
0:10:52 > 0:10:55The spectacle draws crowds of startled onlookers,
0:10:55 > 0:10:59who watch on as a city is lifted right before their eyes.
0:11:04 > 0:11:06CHEERING AND APPLAUSE
0:11:06 > 0:11:12In 1868, one British visitor watches a 22,000-ton hotel be lifted.
0:11:12 > 0:11:15This is what he had to say about it.
0:11:15 > 0:11:17"The people were in it all the time
0:11:17 > 0:11:19"coming and going, eating and sleeping.
0:11:19 > 0:11:22"The whole business of the hotel proceeding without interruption."
0:11:24 > 0:11:28In 1860, engineers raised an entire city block.
0:11:28 > 0:11:33With super-human effort, almost an acre of five-storey buildings
0:11:33 > 0:11:35weighing an estimated 35,000 tonnes
0:11:35 > 0:11:39were lifted by over 6,000 jackscrews.
0:11:45 > 0:11:47As the jackscrews did their work,
0:11:47 > 0:11:49sewers were laid at the perfect angle to drain.
0:11:53 > 0:11:55With the buildings lifted,
0:11:55 > 0:11:58new foundations were built beneath
0:11:58 > 0:12:01and raised streets and sidewalks were installed.
0:12:02 > 0:12:05But buildings weren't just lifted in Chicago.
0:12:08 > 0:12:12To make room for the sewers, some got moved altogether.
0:12:19 > 0:12:21I've got a great quote.
0:12:21 > 0:12:24"Never a day passed during my stay in the city
0:12:24 > 0:12:27"that I did not meet one or more houses shifting their quarters.
0:12:27 > 0:12:30"Going out Great Madison Street in the horse carts,
0:12:30 > 0:12:33"we had to stop twice to let houses get across."
0:12:33 > 0:12:36There's a lot of traffic in today's Chicago,
0:12:36 > 0:12:38but at least you don't have to worry about houses
0:12:38 > 0:12:40going down the street in front of you.
0:12:47 > 0:12:50'By lifting these buildings, Ellis Chesbrough was able
0:12:50 > 0:12:54'to build the first comprehensive sewer network in America
0:12:54 > 0:12:57'and clean Chicago's streets of the muck and stench.'
0:13:01 > 0:13:04But the project was destined to have some remarkable
0:13:04 > 0:13:06and surprising consequences.
0:13:08 > 0:13:12When you do something as ambitious as lifting an entire city,
0:13:12 > 0:13:14it fires people up.
0:13:14 > 0:13:15Chesbrough had proved that
0:13:15 > 0:13:17even under the most difficult circumstances,
0:13:17 > 0:13:19sewers could be built.
0:13:19 > 0:13:23Inspired by Chicago's example, within three decades,
0:13:23 > 0:13:2620 American cities have built their own networks
0:13:26 > 0:13:28of underground sewer tunnels.
0:13:32 > 0:13:34But building sewers is just the beginning
0:13:34 > 0:13:37of a change that will transform our planet.
0:13:44 > 0:13:48With the muck off the streets, attention soon turns to trash.
0:13:51 > 0:13:54By 1914, over 70 cities in America
0:13:54 > 0:13:56are providing municipal refuse collection.
0:13:59 > 0:14:02By the 1930s, modern sanitation companies
0:14:02 > 0:14:04are collecting garbage for the first time.
0:14:06 > 0:14:09And American cities are becoming free of filth.
0:14:12 > 0:14:15But Chesbrough and his sewers do more than just keep cities clean.
0:14:16 > 0:14:18They prove that big infrastructure
0:14:18 > 0:14:21is essential for making cities function.
0:14:23 > 0:14:24All around the world,
0:14:24 > 0:14:27new underground building projects are begun.
0:14:30 > 0:14:35In 1863, in London, the first steam train travels under the city.
0:14:39 > 0:14:41In Paris, the Metro opens in 1900,
0:14:41 > 0:14:43followed soon by the New York subway.
0:14:47 > 0:14:49Pedestrian walkways and auto freeways followed
0:14:49 > 0:14:52by electrical highways and fibre-optic networks
0:14:52 > 0:14:54are created around the world.
0:14:54 > 0:14:56PHONE RINGS
0:14:59 > 0:15:02Today, whole parallel worlds exist underground,
0:15:02 > 0:15:04powering the cities above.
0:15:06 > 0:15:07It's a revolution.
0:15:22 > 0:15:26Chesbrough's sewers proved to be an inspirational feat of engineering.
0:15:27 > 0:15:31But unfortunately, they had a bit of a teething problem.
0:15:34 > 0:15:37The sewers were draining into Lake Michigan,
0:15:37 > 0:15:41which was the water supply for the city.
0:15:41 > 0:15:43Chesbrough may have made the streets clean,
0:15:43 > 0:15:46but the water was still filthy.
0:15:50 > 0:15:54And it wasn't long before the problems became apparent.
0:15:56 > 0:16:01In the 1870s, this was a regular sight in the bathrooms of Chicago.
0:16:01 > 0:16:04The water was so filthy with sewage
0:16:04 > 0:16:07that it was regularly filled with dead fish.
0:16:11 > 0:16:15One observer reported that the fish would actually come out cooked
0:16:15 > 0:16:18and locals would refer to their bathroom water
0:16:18 > 0:16:20affectionately as, chowder.
0:16:23 > 0:16:27As you might have guessed, mixing raw sewage with drinking water
0:16:27 > 0:16:28was not such a good idea.
0:16:28 > 0:16:32And not just because of the dead fish, or the smell.
0:16:32 > 0:16:35The problem was, the water could kill you.
0:16:43 > 0:16:47But most of the Chicagoans of the time were blissfully unaware
0:16:47 > 0:16:50that putting waste in drinking water was so deadly.
0:16:52 > 0:16:56No-one could see the hidden killers that lurked in dirty water.
0:17:05 > 0:17:06While Chesbrough's first sewers
0:17:06 > 0:17:09let Chicago's waste mix with its drinking water,
0:17:09 > 0:17:13today, Chicago does everything it can to keep the two separate.
0:17:16 > 0:17:20I'm standing above the latest addition to Chicago's sewer network.
0:17:20 > 0:17:22It's an epic project.
0:17:22 > 0:17:25They've been working on it for almost 40 years
0:17:25 > 0:17:28and it's cost nearly 4 billion.
0:17:28 > 0:17:32But to understand the true scale of this project,
0:17:32 > 0:17:35I need to go stand in this little yellow cage.
0:17:51 > 0:17:53'Around five times a year, heavy storms roll in
0:17:53 > 0:17:56'that can dump more than 30-billion litres of water
0:17:56 > 0:17:59'on Chicago in just a few hours.
0:18:01 > 0:18:04'This causes the sewer network first begun by Ellis Chesbrough
0:18:04 > 0:18:07'to overflow.
0:18:07 > 0:18:10'With nowhere to go, this mixture of rainwater and sewage
0:18:10 > 0:18:12'can spill out into people's homes
0:18:12 > 0:18:14'and pollute the waterways, causing huge problems.
0:18:21 > 0:18:24'This network of tunnels are designed to store and transport
0:18:24 > 0:18:28'this huge influx of dirty water and keep the city clean.
0:18:37 > 0:18:40'Hidden from view, this space will keep millions of people safe.'
0:18:50 > 0:18:51This is like a cathedral.
0:18:53 > 0:18:56This is like the Church of Engineering right here.
0:18:56 > 0:18:58Look how immense this is.
0:19:00 > 0:19:03'This huge project has over 500 people working on it.
0:19:03 > 0:19:07'And Kevin Fitzpatrick is one of the project managers.'
0:19:08 > 0:19:12This looks like the set of a science-fiction film, right?
0:19:12 > 0:19:14I mean, this is an amazing space to work in.
0:19:14 > 0:19:18The air makes it feel like you're on a science-fiction set here.
0:19:18 > 0:19:20We're about 300 feet underground
0:19:20 > 0:19:22and it's always cool and damp here,
0:19:22 > 0:19:25so you get a little bit of steam coming.
0:19:25 > 0:19:28In a big storm, how much water would be in this space?
0:19:28 > 0:19:30- This thing would be completely full. - Be completely full?- Yep.
0:19:30 > 0:19:33Polluted storm water would be coming through that tunnel,
0:19:33 > 0:19:36dropping right down here and shooting out into the reservoir.
0:19:39 > 0:19:42'But during a major storm, so much water falls
0:19:42 > 0:19:46'that even these vast tunnels are not big enough to hold it.
0:19:46 > 0:19:49'So an even bigger space is required to deal with all the water.'
0:19:51 > 0:19:53- So here we go into the quarry.- Wow!
0:19:53 > 0:19:56It's very hard to just tell the size of it.
0:20:05 > 0:20:06You walk out of those tunnels
0:20:06 > 0:20:10and then you're in this unbelievable, massive space.
0:20:10 > 0:20:14And how much water can this thing hold?
0:20:14 > 0:20:177.9 billion gallons worth of water when it's done.
0:20:17 > 0:20:21In a big storm, how high would the water eventually get?
0:20:21 > 0:20:23The water would get 300 feet above our heads.
0:20:23 > 0:20:25It'll go all the way up to the top?
0:20:25 > 0:20:27Almost all the way up to ground level.
0:20:27 > 0:20:29This is like the world's largest bathtub here.
0:20:29 > 0:20:31It is the world's largest bathtub.
0:20:31 > 0:20:33So it's basically a kind of giant buffer.
0:20:33 > 0:20:35You've got a storm, you can't deal with all that water,
0:20:35 > 0:20:36you've got to put it somewhere.
0:20:36 > 0:20:39We need somewhere to put it that's not polluting the waterways
0:20:39 > 0:20:42and that's not backing up in people's basements.
0:20:42 > 0:20:45- This is the location. - It's an amazing solution.
0:20:45 > 0:20:47Ellis Chesbrough would have loved this, right?
0:20:47 > 0:20:49He was all about big projects like this
0:20:49 > 0:20:52and he would have loved a project like this, I'm sure.
0:21:02 > 0:21:04Looking at the scale and expense of this project,
0:21:04 > 0:21:06you can understand just how hard it is
0:21:06 > 0:21:08to get clean water in fast-growing cities.
0:21:14 > 0:21:17But today's planners have a simple, but crucial
0:21:17 > 0:21:19piece of information that Chesbrough didn't.
0:21:23 > 0:21:26Human waste in drinking water spreads disease.
0:21:28 > 0:21:31To keep people safe, you need to do everything possible
0:21:31 > 0:21:32to stop the two from mixing.
0:21:34 > 0:21:37Discovering this one fact was the single
0:21:37 > 0:21:40most important breakthrough in our understanding of clean.
0:21:40 > 0:21:42TOILET FLUSHES
0:21:43 > 0:21:47The story of how we made that breakthrough?
0:21:47 > 0:21:51Well, it begins with a somewhat rock and roll choice of breakfast.
0:21:56 > 0:21:59To tell you the truth, I don't normally have beer for breakfast,
0:21:59 > 0:22:02but, actually, for thousands of years,
0:22:02 > 0:22:05this was the healthiest way to start the day.
0:22:07 > 0:22:10Our ancestors liked to have a drink or two.
0:22:10 > 0:22:13Benjamin Franklin, in his diaries, recalled how his colleagues
0:22:13 > 0:22:17would have a pint of beer before breakfast
0:22:17 > 0:22:19and then they'd have a pint with breakfast
0:22:19 > 0:22:22and a pint between breakfast and lunch.
0:22:22 > 0:22:25And of course, you have to have some beer with lunch.
0:22:25 > 0:22:27This is the point at which I'd need a nap.
0:22:27 > 0:22:30But they would charge on and have a pint around 6:00pm
0:22:30 > 0:22:32and then, of course, a pint
0:22:32 > 0:22:35to celebrate the end of a hard day's work.
0:22:35 > 0:22:38Now, this may seem a little excessive,
0:22:38 > 0:22:41but it's not quite as crazy as you might think.
0:22:45 > 0:22:48The beer-brewing process kills disease.
0:22:50 > 0:22:54Although no-one realises this in the middle of the 19th century,
0:22:54 > 0:22:56it means if you live in an unclean environment,
0:22:56 > 0:22:58beer is a very sensible drink.
0:23:04 > 0:23:07This quirky fact, that drinking beer can be safer than water,
0:23:07 > 0:23:11will help transform our understanding of clean.
0:23:12 > 0:23:15Ah!
0:23:18 > 0:23:22Beer will prove vital in solving the mystery
0:23:22 > 0:23:25of one of the deadliest killers in Victorian London.
0:23:29 > 0:23:31When we think about killers
0:23:31 > 0:23:35in the dark corridors of 19th-century London,
0:23:35 > 0:23:38we might think of Jack the Ripper.
0:23:38 > 0:23:42But the real killer that haunted the streets was cholera.
0:23:42 > 0:23:45Between 1831 and 1860,
0:23:45 > 0:23:49Cholera killed more than 140,000 people in Britain.
0:23:49 > 0:23:52And it did so in a truly horrific way.
0:23:54 > 0:23:56There's a particularly harrowing account from the time
0:23:56 > 0:23:58of a cholera victim near to death.
0:24:00 > 0:24:05It reads, "the mind within remains untouched and clear,
0:24:05 > 0:24:08"shining strangely through the glazed eyes.
0:24:08 > 0:24:11"A spirit looking out in terror from a corpse."
0:24:15 > 0:24:18Cholera is a horrific disease that still kills
0:24:18 > 0:24:21almost 100,000 people worldwide every year.
0:24:22 > 0:24:27But in the 19th century, doctors profoundly misunderstand its cause.
0:24:29 > 0:24:31The medical leaders of the time are convinced
0:24:31 > 0:24:34cholera is spread through the stink in the air.
0:24:40 > 0:24:45Proving them wrong will be a lifelong battle for this man.
0:24:45 > 0:24:46John Snow.
0:24:48 > 0:24:52A medic from the north of England whose experiences as a young man
0:24:52 > 0:24:55will lead to a radical new theory about the spread of disease.
0:25:02 > 0:25:04As an 18-year-old trainee doctor,
0:25:04 > 0:25:07Snow spends nearly a year
0:25:07 > 0:25:10in the mines of Killingworth in the north-east of England,
0:25:10 > 0:25:13treating miners who have been stricken with cholera.
0:25:13 > 0:25:17It's not the most pleasant way to start a medical practice,
0:25:17 > 0:25:20but what he experiences in the mine
0:25:20 > 0:25:25will spark an idea that will follow him for the rest of his career.
0:25:31 > 0:25:36Snow is breathing in the same putrid air as the infected miners,
0:25:36 > 0:25:40and yet, despite the time he spends with them,
0:25:40 > 0:25:41he doesn't seem to get ill.
0:25:47 > 0:25:50Looking around at the appalling sanitary conditions
0:25:50 > 0:25:52that the miners worked in,
0:25:52 > 0:25:54with the filth and the dirty water,
0:25:54 > 0:25:57something clicks in Snow's mind.
0:25:58 > 0:26:02It's just a glimmer of an idea, really.
0:26:02 > 0:26:04And it might have stayed that way,
0:26:04 > 0:26:07had he spent the rest of his life in a small town.
0:26:07 > 0:26:11But Snow's idea is going to blossom into something truly powerful
0:26:11 > 0:26:12when he moves to the city.
0:26:17 > 0:26:22In 1836, John Snow arrives in Soho in the heart of London.
0:26:27 > 0:26:31It's a place where beer is produced and consumed on a very large scale.
0:26:35 > 0:26:39It's also a place that is ripe for big ideas.
0:26:39 > 0:26:42A place that will help Snow make his breakthrough.
0:26:45 > 0:26:49In the mines of Killingworth, Snow had noticed that not everyone
0:26:49 > 0:26:53who breathed the air had come down with cholera.
0:26:53 > 0:26:56Now in London, he attends public lectures
0:26:56 > 0:26:58and learns more about the way that gases
0:26:58 > 0:27:01are distributed in the atmosphere.
0:27:01 > 0:27:04And he starts working on a radical new theory.
0:27:04 > 0:27:08Cholera is not in the air, it's in the water.
0:27:13 > 0:27:16Snow's radical idea flies in the face
0:27:16 > 0:27:18of the medical establishment's view
0:27:18 > 0:27:20that cholera spreads through the air.
0:27:22 > 0:27:26But to convince them he's right, Snow needs irrefutable evidence.
0:27:33 > 0:27:36In 1854, when a deadly cholera outbreak
0:27:36 > 0:27:38begins in the heart of Soho...
0:27:40 > 0:27:44..Snow realises it's an opportunity to gain the evidence that he needs.
0:27:48 > 0:27:51'But to prove his theory, he's going to have to take
0:27:51 > 0:27:54'a truly monumental gamble with his own life.'
0:27:57 > 0:28:00While the rest of the neighbourhood is fleeing in terror...
0:28:02 > 0:28:06..Snow bravely goes from door to door in Soho,
0:28:06 > 0:28:10recording the deaths at each address.
0:28:10 > 0:28:14And with this detective work, he assembles all the data
0:28:14 > 0:28:17and he makes a map.
0:28:17 > 0:28:19Now, it may not look like much,
0:28:19 > 0:28:24but this is actually one of the most influential maps ever produced.
0:28:29 > 0:28:33Overlaid on the map is the data John Snow has collected in Soho.
0:28:35 > 0:28:38Each of the black marks represents a death from cholera.
0:28:40 > 0:28:42As Snow builds up a picture of what's going on,
0:28:42 > 0:28:46the map reveals that the deaths are concentrated
0:28:46 > 0:28:49around a water pump on Broad Street.
0:28:50 > 0:28:53But there's one group of locals who escape the outbreak.
0:28:55 > 0:28:57The beer-drinking workers at the local brewery.
0:29:00 > 0:29:02Unbeknownst to them, their favourite beverage
0:29:02 > 0:29:05has kept them safe from the dirty water of Soho.
0:29:07 > 0:29:10It's all the evidence John Snow needs.
0:29:11 > 0:29:14By risking his life, Snow has proved
0:29:14 > 0:29:16that cholera is spreading through the water.
0:29:19 > 0:29:23It's an insight that will begin a new chapter
0:29:23 > 0:29:24in our understanding of clean.
0:29:32 > 0:29:35Thanks to Snow and his map,
0:29:35 > 0:29:37the authorities finally come around
0:29:37 > 0:29:41to one of the most important principles of public health.
0:29:41 > 0:29:45Access to clean drinking water is crucial for preventing disease.
0:29:48 > 0:29:51It's the principle that every relief worker in the world
0:29:51 > 0:29:54now follows after a major disaster.
0:29:55 > 0:29:58But Snow's map will have consequences
0:29:58 > 0:30:01that extend far beyond just public health.
0:30:04 > 0:30:08Snow's work helps inaugurate the new science of epidemiology.
0:30:08 > 0:30:12Using maps and surveys instead of lab-based experiments
0:30:12 > 0:30:15to uncover the patterns and causes of disease.
0:30:21 > 0:30:24In the 1950s, these techniques will be used by
0:30:24 > 0:30:25British doctor Richard Doll
0:30:25 > 0:30:27to reveal that lung cancer is linked
0:30:27 > 0:30:30to cigarette smoking, rather than car fumes.
0:30:33 > 0:30:37In the 1980s, police forces will combine data and maps together
0:30:37 > 0:30:39to reveal the previously-hidden patterns
0:30:39 > 0:30:41and causes of crime in cities.
0:30:44 > 0:30:48It's a technique that will revolutionise law and order.
0:30:52 > 0:30:55Today, the combination of local data and maps
0:30:55 > 0:30:58has become a vital tool for city dwellers all over the world.
0:31:06 > 0:31:10And all these developments have their roots in a map
0:31:10 > 0:31:13made by John Snow more than 150 years ago.
0:31:19 > 0:31:21John Snow makes clean water
0:31:21 > 0:31:24the goal for civil engineers in the rest of the century.
0:31:28 > 0:31:30The irony is, Snow made his breakthrough
0:31:30 > 0:31:34without actually knowing what it is in dirty water that kills us.
0:31:41 > 0:31:45This little creature is what John Snow was actually up against.
0:31:47 > 0:31:51It's a tiny organism that spreads through water and causes cholera.
0:31:56 > 0:31:59If you are unlucky enough to ingest cholera-infected water,
0:31:59 > 0:32:02there will soon be upwards of a trillion of these creatures
0:32:02 > 0:32:04living in your gut.
0:32:08 > 0:32:11And that spells death.
0:32:13 > 0:32:16Learning how to control bacteria in water
0:32:16 > 0:32:19would be one of our greatest challenges in the 20th century.
0:32:21 > 0:32:24Even today, for almost one billion of us,
0:32:24 > 0:32:27drinking a glass of water is like playing Russian roulette.
0:32:32 > 0:32:34But one miraculous chemical
0:32:34 > 0:32:37would allow us to kill these deadly creatures.
0:32:37 > 0:32:41And in doing so, it would make much of modern life possible.
0:32:44 > 0:32:48150 years ago in Europe and America,
0:32:48 > 0:32:50the public water was so dirty,
0:32:50 > 0:32:52you wouldn't have wanted to go near it.
0:32:52 > 0:32:55Today, the story is a little different.
0:33:04 > 0:33:07Now, we actively seek out public water,
0:33:07 > 0:33:10sharing it with over 80 million other people each year,
0:33:10 > 0:33:13and their trillions upon trillions of bacteria.
0:33:16 > 0:33:18Whoa! Whoa!
0:33:24 > 0:33:26'All these people are jostling around
0:33:26 > 0:33:30'in a wonderful bacterial breeding ground of 72-degree water.
0:33:33 > 0:33:36'A temperature that's ripe for superfast multiplication.'
0:33:47 > 0:33:49There's a reason why we didn't have water parks like this
0:33:49 > 0:33:51in the middle of the 19th century.
0:33:51 > 0:33:53There was no way to keep the water clean.
0:33:54 > 0:33:57Imagine what John Snow would have said about this place.
0:33:57 > 0:33:59He would have been baffled by it.
0:33:59 > 0:34:02Then again, I don't think he was much of a water park person.
0:34:06 > 0:34:08But perhaps what would have shocked John Snow the most
0:34:08 > 0:34:12is that this park operates a recycle system.
0:34:12 > 0:34:16Over 11 million litres of water are used over and over in the rides.
0:34:18 > 0:34:22It means keeping it clean is vitally important.
0:34:25 > 0:34:27So now we're behind the scenes,
0:34:27 > 0:34:29we've got this water play land up there.
0:34:29 > 0:34:33This is what we need to do to keep that safe and clean.
0:34:33 > 0:34:35You have to filter it and disinfect it and do all the good things
0:34:35 > 0:34:37that these little magic guys do
0:34:37 > 0:34:40to clean 2.5 million gallons of water here. That's a lot of water.
0:34:40 > 0:34:43And what happens at the first stage of filtering?
0:34:43 > 0:34:45We have some pre-filters before things go...
0:34:45 > 0:34:47That is what gets trapped in the filter...?
0:34:47 > 0:34:49In the pre-filter before they go on.
0:34:49 > 0:34:52So this is just a small... Oh, a yummy example just for you.
0:34:52 > 0:34:55That is, like, the world's largest hairball.
0:34:55 > 0:34:58It is like the world's largest hairball. We are mammals!
0:34:58 > 0:35:00Oh, that's what we just kind of naturally shed?
0:35:00 > 0:35:02- You want to touch it? - No!- Are you sure?
0:35:02 > 0:35:05- Seriously, don't taunt me with that. - It's just a hairball!- Oh, God!
0:35:05 > 0:35:08It's in my contract, I'm not allowed to interact with hairballs!
0:35:08 > 0:35:11It's not that scary. Some leaves, a little bracelet.
0:35:11 > 0:35:13Oh, look, out of someone's shoe.
0:35:13 > 0:35:15But can I ask, like, what is the weirdest thing
0:35:15 > 0:35:17you've ever found in the filters?
0:35:17 > 0:35:19- I think one of the weirdest things was a toupee.- Really?
0:35:19 > 0:35:22- So, what happened to the poor guy? - Yeah.- I assume it was a guy.
0:35:22 > 0:35:25He goes onto the ride and he's, like, all Burt Reynolds
0:35:25 > 0:35:26and at the end, he's, like, "Oop!"
0:35:26 > 0:35:29- He's so not!- I have a slightly different look. Sorry!
0:35:31 > 0:35:34But the objects we can see make up just a tiny fraction
0:35:34 > 0:35:37of what has to be cleaned out of the water.
0:35:37 > 0:35:41What really keeps this place clean is chlorine.
0:35:41 > 0:35:45A chemical that is lethal to microscopic bacteria.
0:35:47 > 0:35:48So, what is this giant vat?
0:35:48 > 0:35:51Well, this is liquid chlorine that we inject into the water,
0:35:51 > 0:35:53which is our disinfection.
0:35:53 > 0:35:56So, this is basically what keeps the whole park safe?
0:35:56 > 0:35:58You can't have the magic up there
0:35:58 > 0:36:00without this giant vat of chlorine?
0:36:00 > 0:36:02That is the secret and the magic to water.
0:36:02 > 0:36:04Clean water is paramount to what we do.
0:36:04 > 0:36:06And we've got this amazing team of men and women
0:36:06 > 0:36:09that take care of our water. They're invisible
0:36:09 > 0:36:12and probably not as loved and noticed as they should be, but all day long,
0:36:12 > 0:36:14they make sure our water and the magic of the water park
0:36:14 > 0:36:18starts with good, disinfected, filtered, clean water.
0:36:21 > 0:36:26We all know chlorine is vital in water parks, but there's a problem.
0:36:26 > 0:36:30Use too much chlorine and it can be lethal to humans.
0:36:30 > 0:36:33It means it was one of those innovations
0:36:33 > 0:36:34that was very hard to sell.
0:36:34 > 0:36:37And back when chlorine was first used to treat water,
0:36:37 > 0:36:42it wasn't just for entertainment, it was a matter of life and death.
0:36:44 > 0:36:48Across America and Europe at the beginning of the 20th century,
0:36:48 > 0:36:50dirty water was everywhere.
0:36:50 > 0:36:54And one technology in particular was causing the problem.
0:37:01 > 0:37:03The humble flushing toilet.
0:37:14 > 0:37:17The toilet was adopted by a lot of people
0:37:17 > 0:37:19in a very short space of time.
0:37:19 > 0:37:23When this happens, problems are never very far away.
0:37:23 > 0:37:25Just look at the modern world of high-technology.
0:37:28 > 0:37:32Think of the iPhone. This was a huge hit product.
0:37:32 > 0:37:36But right after its launch, it overloaded the wireless network.
0:37:36 > 0:37:38People just had no idea
0:37:38 > 0:37:41how much iPhone users were going to try and get online.
0:37:41 > 0:37:45People even had a hard time just making telephone calls.
0:37:45 > 0:37:50New technologies can often overwhelm old infrastructure
0:37:50 > 0:37:51in really surprising ways.
0:37:55 > 0:37:57Please, I don't know how I got into this thing,
0:37:57 > 0:37:59but I feel a little bit uncomfortable.
0:37:59 > 0:38:02Guys? Can you guys get me out of here?
0:38:08 > 0:38:10In the 19th century, toilets,
0:38:10 > 0:38:14like iPhones, were a catastrophic success.
0:38:14 > 0:38:18People bought and used them so much that they overwhelmed the system.
0:38:20 > 0:38:21As many thousands of toilets
0:38:21 > 0:38:23were installed in cities around the world,
0:38:23 > 0:38:26there was a huge influx of dirty water.
0:38:28 > 0:38:32As a result, drinking water became even more lethal.
0:38:32 > 0:38:34Finding a solution to this problem
0:38:34 > 0:38:37would begin a new phase in the story of clean.
0:38:40 > 0:38:46What we needed was a way to kill bacteria on a truly vast scale.
0:38:46 > 0:38:50And the solution wouldn't come from some genius scientist,
0:38:50 > 0:38:54but instead, from a seemingly-unremarkable guy.
0:38:54 > 0:38:57A passionate amateur who happened to be in the right place
0:38:57 > 0:39:00at the right time.
0:39:00 > 0:39:02This guy, John Leal.
0:39:02 > 0:39:06He never became rich, or famous.
0:39:06 > 0:39:08But his work would transform America.
0:39:13 > 0:39:17'John Leal is a doctor at the beginning of the 20th century.
0:39:17 > 0:39:20'But it's his special interests that mark him out as a bit different.'
0:39:29 > 0:39:33Leal is obsessed with bacteria in water.
0:39:33 > 0:39:36It's an obsession that had come from personal tragedy.
0:39:36 > 0:39:39His father had died a slow and painful death
0:39:39 > 0:39:42from drinking bad water during the Civil War.
0:39:42 > 0:39:45All of which means that when he's not spending time helping patients,
0:39:45 > 0:39:49he's trying to figure out new ways to kill bacteria.
0:39:57 > 0:40:00Leal experiments with many ways to kill bacteria...
0:40:02 > 0:40:05..but one poison in particular excites him.
0:40:07 > 0:40:09Calcium hypochlorite.
0:40:09 > 0:40:14The potentially-lethal chemical that's better known as chlorine.
0:40:16 > 0:40:20It's a chemical that has been used in a radical one-off experiment
0:40:20 > 0:40:23to treat the drinking water in the town of Maidstone in England.
0:40:26 > 0:40:29But Leal is going to get to use this dangerous chemical
0:40:29 > 0:40:31on a much grander scale.
0:40:37 > 0:40:39Leal's passion for public health
0:40:39 > 0:40:43ultimately lands him a job at a big water company.
0:40:43 > 0:40:48It means he's responsible for seven billion gallons of drinking water.
0:40:48 > 0:40:52And it's going to enable him to put chlorine to the test
0:40:52 > 0:40:54in the most dramatic way possible.
0:41:00 > 0:41:03In 1908, the New Jersey water company he works for
0:41:03 > 0:41:08is suffering from an unusually high bacterial content in its water.
0:41:08 > 0:41:10It's the opportunity Leal has been waiting for.
0:41:17 > 0:41:20So here is where it gets really insane.
0:41:20 > 0:41:24In total secrecy, without any approval from the authorities,
0:41:24 > 0:41:29Leal doses the drinking water supply for a city of 200,000 people
0:41:29 > 0:41:31with potentially-lethal chlorine.
0:41:35 > 0:41:39To the wider world, it appears as if John Leal is a madman,
0:41:39 > 0:41:42poisoning the unsuspecting citizens of Jersey City.
0:41:46 > 0:41:48The public, and even many scientists, are intensely hostile
0:41:48 > 0:41:51to the idea of drinking water being tampered with.
0:41:53 > 0:41:56One notable chemist of the time comments,
0:41:56 > 0:42:01"the idea itself of chemical disinfectant is repellent."
0:42:03 > 0:42:05With public opinion against him,
0:42:05 > 0:42:08it's a truly unbelievable risk,
0:42:08 > 0:42:10but Leal sticks with his plan.
0:42:19 > 0:42:21Three months after his experiment,
0:42:21 > 0:42:25Leal gets called into court and reveals what he's done.
0:42:25 > 0:42:28And the judge is shocked.
0:42:28 > 0:42:30I've got the transcript here. The judge says,
0:42:30 > 0:42:32"Do you drink this water?" "Yes, sir."
0:42:32 > 0:42:35"Habitually?" "Yes, sir."
0:42:35 > 0:42:39"Would you have any hesitation about giving it to your wife and family?"
0:42:39 > 0:42:43"I believe it is the safest water in the world."
0:42:43 > 0:42:47It's a bold move, but luckily for Leal,
0:42:47 > 0:42:49his gamble is going to pay off in a major way.
0:42:57 > 0:43:01The project is such a success that within a few years,
0:43:01 > 0:43:04the chlorination of drinking water is rolled out throughout the US.
0:43:08 > 0:43:12This is the graph of typhoid deaths in the US.
0:43:12 > 0:43:15Look at the point where chlorination begins.
0:43:21 > 0:43:22But it's not just typhoid.
0:43:22 > 0:43:26In a few years, infant mortality in America is almost halved.
0:43:29 > 0:43:33But Leal's chlorination project wasn't just saving lives.
0:43:33 > 0:43:36It was also transforming how we have fun.
0:43:38 > 0:43:43Post World War I, nearly 2,000 public baths open in America.
0:43:44 > 0:43:47And a whole generation of humans learns how to swim.
0:43:50 > 0:43:52Chlorinated pools become spaces
0:43:52 > 0:43:55where the old rules of public decency fade.
0:43:55 > 0:43:58As costumes become smaller and more revealing,
0:43:58 > 0:44:01the two-piece suit is born
0:44:01 > 0:44:03and women's fashion is revolutionised.
0:44:06 > 0:44:09The swimming craze will go on to inspire
0:44:09 > 0:44:13over a million American homes to install private pools in the 1960s.
0:44:15 > 0:44:18After droughts in southern California in the '70s
0:44:18 > 0:44:19leave pools empty...
0:44:21 > 0:44:22..kids soon discover
0:44:22 > 0:44:25they are perfect environments for their skateboards.
0:44:26 > 0:44:28Helping them develop a new range of airborne tricks.
0:44:34 > 0:44:36All these developments have roots
0:44:36 > 0:44:40in that huge risk taken by John Leal,
0:44:40 > 0:44:43one of the 20th century's most unlikely heroes.
0:44:50 > 0:44:51'But the story of chlorine
0:44:51 > 0:44:54'isn't just a matter of giant public health projects.
0:44:54 > 0:44:58'It will also bring the clean revolution into the home
0:44:58 > 0:45:01'and turn it into big business.'
0:45:02 > 0:45:05Just a few years after Leal's breakthrough,
0:45:05 > 0:45:09five San Francisco entrepreneurs invest 100 each
0:45:09 > 0:45:12to launch a chlorine-based bleach.
0:45:12 > 0:45:14And it sounds like a great idea,
0:45:14 > 0:45:17but things don't turn out so well.
0:45:22 > 0:45:24The bleach is aimed at big industry.
0:45:24 > 0:45:26But it's such a new product
0:45:26 > 0:45:29that many of the potential buyers are left baffled.
0:45:29 > 0:45:33Sales are poor and the business appears doomed.
0:45:35 > 0:45:38But The Clorox Company, as they will call themselves,
0:45:38 > 0:45:40are destined for success.
0:45:40 > 0:45:43And they will help usher in a new chapter in the story of clean.
0:45:43 > 0:45:48And it will all be thanks to the wife of one of the investors
0:45:48 > 0:45:50and the small shop she runs.
0:45:55 > 0:45:59This is the corner of 19th and Broadway in Oakland.
0:45:59 > 0:46:03In 1916, there was a charming little grocery store here
0:46:03 > 0:46:05run by a woman named Annie Murray.
0:46:05 > 0:46:08And like Ellis Chesbrough and John Snow,
0:46:08 > 0:46:11Murray is a bit of an outsider.
0:46:11 > 0:46:13And like those guys, her outsider perspective
0:46:13 > 0:46:16gives her an unique take on things.
0:46:16 > 0:46:20She might not have been a chemist, or an experienced entrepreneur,
0:46:20 > 0:46:23but Murray understands better than anyone else
0:46:23 > 0:46:25how to revolutionise the bleach business.
0:46:27 > 0:46:31Annie Murray recognises that the potential for her product
0:46:31 > 0:46:36is not as a cleaner for big industry, but as a household item.
0:46:37 > 0:46:40Acting on her insight, Murray creates a weaker version
0:46:40 > 0:46:44of the chemical and puts it in smaller bottles.
0:46:44 > 0:46:49And Chlorax, America's most popular domestic bleach, is born.
0:46:50 > 0:46:54People, your kitchens are disgusting, you need this product!
0:46:54 > 0:46:55Kills bugs dead.
0:46:55 > 0:46:57Sir? No?
0:46:57 > 0:46:59No takers?
0:46:59 > 0:47:03- Sir, for your home. Please take this.- Thank you so much.
0:47:03 > 0:47:07Yes. Don't drink, just...just use it on the germs.
0:47:07 > 0:47:09The store is mostly empty now,
0:47:09 > 0:47:14but you can imagine in 1916, this is a bustling grocery store.
0:47:14 > 0:47:18And Murray is so convinced of the demand for this product
0:47:18 > 0:47:22that she starts giving away free samples to her customers.
0:47:22 > 0:47:24Please try this, it's very, very dangerous.
0:47:24 > 0:47:27This is something that you seem like you could use.
0:47:27 > 0:47:29Ah, business is booming!
0:47:29 > 0:47:31This is fantastic!
0:47:31 > 0:47:35And within months, bottles are flying off the shelves.
0:47:35 > 0:47:36Murray might not have realised it,
0:47:36 > 0:47:40but she has invented an entirely new industry.
0:47:45 > 0:47:49Annie Murray created America's first commercial bleach for the home.
0:47:49 > 0:47:53And soon, many other similar products will be launched.
0:47:53 > 0:47:55On hard-to-get-at-places like this,
0:47:55 > 0:47:58spray your cloth first, then dust.
0:47:58 > 0:48:02The motor is started and now watch how each soap performs.
0:48:04 > 0:48:06In the 20th century, Murray and other entrepreneurs
0:48:06 > 0:48:10transform ideas about cleanliness.
0:48:10 > 0:48:13Now it's not just about huge public health projects,
0:48:13 > 0:48:15clean becomes truly big business.
0:48:20 > 0:48:24And nowhere did the clean business take off like it did in America.
0:48:31 > 0:48:35I would say that the big years for convincing Americans
0:48:35 > 0:48:39that they needed to be really, really, really clean was the 1920s.
0:48:39 > 0:48:42Because people were flooding into cities,
0:48:42 > 0:48:44men and women were working together,
0:48:44 > 0:48:47very close together in offices and in factories,
0:48:47 > 0:48:50and they were also the ambitious ones.
0:48:50 > 0:48:52They were the ones who had left the farm.
0:48:53 > 0:48:56In this new environment, radio and television
0:48:56 > 0:48:59rapidly become popular pastimes for city dwellers
0:48:59 > 0:49:00with disposable incomes.
0:49:02 > 0:49:05Hey, come back here! Come back here!
0:49:05 > 0:49:08As advertising becomes increasingly sophisticated,
0:49:08 > 0:49:11a new form of drama will be produced
0:49:11 > 0:49:12to help sell cleaning products.
0:49:14 > 0:49:18Something that has dominated popular culture for almost 70 years.
0:49:18 > 0:49:21I don't want a baby from an adoption bureau.
0:49:21 > 0:49:23I want it from here!
0:49:23 > 0:49:25The soap opera.
0:49:25 > 0:49:30The soaps began to sponsor little daily serials that were,
0:49:30 > 0:49:31you know, hugely dramatic,
0:49:31 > 0:49:33hence the term soap operas.
0:49:33 > 0:49:37Because they were unsung operas and always advertised by soap.
0:49:37 > 0:49:40I love the idea that we're still using that phrase, soap opera.
0:49:40 > 0:49:44It was like the soap industry did such a brilliant job
0:49:44 > 0:49:46sponsoring shows 60, 70 years ago
0:49:46 > 0:49:47that we're still using the term
0:49:47 > 0:49:50- and promoting the word soap in general.- Yeah.
0:49:50 > 0:49:54Thanks to the early pioneers and some pretty ingenious marketing,
0:49:54 > 0:49:57today, the household cleaning product industry
0:49:57 > 0:50:00is worth an estimated 80 billion.
0:50:02 > 0:50:05But there are some who feel our obsession with cleanliness
0:50:05 > 0:50:07may now have gone too far.
0:50:13 > 0:50:16'Some research suggests that our ever-cleaner world
0:50:16 > 0:50:20'may be linked to increasing rates of asthma and allergies.
0:50:22 > 0:50:25'The explosion of cleaning products during the 20th century
0:50:25 > 0:50:26'for good and for bad,
0:50:26 > 0:50:30'has led to domestic environments becoming cleaner
0:50:30 > 0:50:32'than they've ever been before.'
0:50:42 > 0:50:45But the ultraclean revolution
0:50:45 > 0:50:48didn't just help us keep our homes germ-free.
0:50:48 > 0:50:51It also helped invent something new.
0:50:51 > 0:50:55Something we rely on every second of our lives.
0:50:55 > 0:51:00And it's manufactured in a room behind this door.
0:51:00 > 0:51:03It also happens to be one of the cleanest places on the planet.
0:51:09 > 0:51:13This is a Texas Instruments microchip fabrication plant.
0:51:15 > 0:51:20The chips made here power everything from cars, to planes, to microwaves.
0:51:22 > 0:51:25This place is a true wonder of the modern world.
0:51:31 > 0:51:33Ooo, nice!
0:51:34 > 0:51:36'To see inside this unique environment,
0:51:36 > 0:51:39'I have to take some extreme precautions
0:51:39 > 0:51:42'to make sure I don't contaminate it in any way.'
0:51:42 > 0:51:46- If you're a visitor to the building, then you put shoe covers on.- OK.
0:51:46 > 0:51:49'Thankfully, clean guru Sharon Hudgens
0:51:49 > 0:51:51'is leading me through the process.'
0:51:51 > 0:51:54Rinse your hands under the water for a few seconds
0:51:54 > 0:51:56- and then completely blow them dry. - OK.
0:52:01 > 0:52:03So I notice we didn't use any soap.
0:52:03 > 0:52:05Actually, a lot of soaps have fragrances in them,
0:52:05 > 0:52:07which is a contaminant.
0:52:07 > 0:52:09It would give off particles.
0:52:09 > 0:52:12We're trying to eliminate particles going into the clean room.
0:52:12 > 0:52:14This is our first step in eliminating particles.
0:52:14 > 0:52:17I like that. So, soap is too dirty for the clean room?
0:52:17 > 0:52:19- Soap is too dirty.- That's nice.
0:52:20 > 0:52:23- So this is the hood. - Right, I reverse it.
0:52:23 > 0:52:25That...that's not right. There we go.
0:52:25 > 0:52:29- Put another set of shoes covers on. - Another layer of shoe covers?- Over.
0:52:29 > 0:52:31You guys are clean freaks. Has anyone told you that?
0:52:31 > 0:52:34All right. Let's see if that works. Oh, yeah.
0:52:35 > 0:52:39I feel incredibly clean. This is great. I'm psyched for this.
0:52:39 > 0:52:41So this is John, he'll be taking you through.
0:52:41 > 0:52:43Hey, John, how you doing?
0:52:46 > 0:52:48- Wow!- This is our clean room.
0:52:48 > 0:52:54So this is really...this is one of the cleanest places on the planet.
0:52:54 > 0:52:57We think it is, yes. It's cleaner than an operating room.
0:52:57 > 0:52:59We do everything we can to ensure
0:52:59 > 0:53:03that there are no particles in this air stream.
0:53:03 > 0:53:05There's never a speck of dust.
0:53:07 > 0:53:10To understand why dust can be so damaging,
0:53:10 > 0:53:14you need to get a sense of the scale of the chips produced here.
0:53:17 > 0:53:21A human hair measures about 100 microns across.
0:53:24 > 0:53:27A single cell of skin is about 30 microns.
0:53:30 > 0:53:33A cholera bacterium is three microns.
0:53:35 > 0:53:39The intricate pathways and transistors on a microchip
0:53:39 > 0:53:42can measure less than a tenth of a single micron.
0:53:47 > 0:53:49A spec of household dust
0:53:49 > 0:53:52landing on one of these delicate silicone wafers
0:53:52 > 0:53:56would be comparable to Mount Everest landing in the streets of London.
0:54:00 > 0:54:02And that is why clean is so vitally important here.
0:54:04 > 0:54:07So, this is really what this is all about, right?
0:54:07 > 0:54:11This is a wafer... It's in an even cleaner space here, right?
0:54:11 > 0:54:14That is correct. And this is what we're trying to achieve.
0:54:14 > 0:54:16This is a wafer and there are thousands
0:54:16 > 0:54:19of individual microchips on that wafer.
0:54:19 > 0:54:22You can sort of see them individually, but it's difficult.
0:54:22 > 0:54:26So in a way, the whole digital revolution that we celebrate
0:54:26 > 0:54:28that's bringing the world together
0:54:28 > 0:54:34can only happen because we're able to think about cleanliness
0:54:34 > 0:54:37on the level of microns,
0:54:37 > 0:54:38not on the level of, you know, the planet.
0:54:38 > 0:54:40That's correct.
0:54:40 > 0:54:43And it's taken us a long time to figure out
0:54:43 > 0:54:46everything we need to do to make sure we're as clean as we can be.
0:54:50 > 0:54:53Being able to master clean at the smallest scale
0:54:53 > 0:54:55has transformed our world.
0:54:55 > 0:54:58But the roots of all this stem from a simple desire
0:54:58 > 0:55:00almost 200 years ago...
0:55:02 > 0:55:04..to keep our city streets free of dirt.
0:55:10 > 0:55:12Standing here in the clean room,
0:55:12 > 0:55:15I can't help but think of the sewers.
0:55:15 > 0:55:20In a way, it's really the two poles of human inventiveness.
0:55:20 > 0:55:22To be able to build the modern world, we had to create
0:55:22 > 0:55:24this incredibly disgusting space
0:55:24 > 0:55:26that we isolated from everyday life.
0:55:26 > 0:55:28And at the same time, to make the digital revolution,
0:55:28 > 0:55:31we had to create this hyper-clean place
0:55:31 > 0:55:34and also isolate everyone from it.
0:55:34 > 0:55:36We never get to visit these environments,
0:55:36 > 0:55:37we don't even think about them.
0:55:37 > 0:55:39But without this kind of environment
0:55:39 > 0:55:43and without the incredible dirt and disgust of the sewer,
0:55:43 > 0:55:45modern life wouldn't be possible.
0:55:54 > 0:55:58Bit by bit, clean technologies have transformed our world.
0:56:03 > 0:56:06But the story of clean has really only just begun.
0:56:11 > 0:56:14Every year, millions of people die needlessly
0:56:14 > 0:56:18as a result of not having access to clean, safe drinking water.
0:56:19 > 0:56:22It's one of the great tragedies of the modern world.
0:56:22 > 0:56:25Bringing the benefits of clean water to every human on earth
0:56:25 > 0:56:30is one of the great challenges of the 21st century.
0:56:36 > 0:56:42Developing ways to keep things clean has allowed cities to flourish.
0:56:42 > 0:56:44And that's important because
0:56:44 > 0:56:46these places are some of our most creative spaces.
0:56:48 > 0:56:50Environments that drive new innovation
0:56:50 > 0:56:51as ideas and cultures collide.
0:56:57 > 0:56:59When clean pioneer John Snow was born,
0:56:59 > 0:57:02little more than 2% of humans lived in cities.
0:57:05 > 0:57:07Today, more than half of us do.
0:57:12 > 0:57:15'We have become a species of city dwellers.'
0:57:29 > 0:57:33The urbanisation of the planet would have never happened
0:57:33 > 0:57:38without the ideas and technologies that made our cities clean.
0:57:38 > 0:57:43The people behind that revolution didn't become rich or famous.
0:57:43 > 0:57:48But look around at a modern, thriving, dynamic city today
0:57:48 > 0:57:52and it's clear that they, as much as anyone,
0:57:52 > 0:57:54invented the modern world.