Clean How We Got to Now with Steven Johnson

In the modern world, we've become

accustomed to living in clean cities.

But imagine every time you took a drink of water from the tap,

you were playing Russian roulette with your life.

Or the streets outside your door were almost knee-deep in filth.

Well, that's what life was like in the western world

just a century and a half ago.

But over the next 100 years,

we managed to rid many cities of this waste and disease.

So, how did we get to be so clean?

Well, it took guys like the maverick railway engineer

who lifted a city to build America's first sewers.

It's a crazy idea, but it's also kind of a beautiful one.

And the doctor who added potentially-lethal chemicals

to the water supply of an entire city.

These are classic examples of the kind of people

who actually made the modern world.

People you've probably never heard of.

These were the hobbyists,

garage inventors and obsessive tinkerers.

Ordinary people doing extraordinary things.

The thing about these pioneers is

they didn't just make our world a cleaner place,

they also set off an amazing chain reaction of ideas.

The results were innovations

that would affect every aspect of our lives.

From the world of hi-tech to fashion.

Law and order...all the way to health.

I want to show how these seemingly-unconnected worlds

are linked by the unsung heroes of clean.

All my career, I've been fascinated by ideas and innovation.

From writing books about the great

British innovators of the Enlightenment,

or the Industrial Revolution,

to my work with Silicone Valley start-ups.

And what I've learned about innovation

is that the experiences of the past

are still the best road map for our future.

And that's why I want to tell you the story of How We Got To Now.

You know, you look around, today's city streets are so clean,

you could eat your dinner off of them.

A city like San Francisco spends 50 million a year

spraying and sweeping and generally keeping the streets free of filth.

But just a few feet below me,

there is a tide of highly-toxic waste.

'This deeply-unpleasant river of filth

'is one of the biggest health issues cities around the world face.

'To see it requires some serious safety gear,

'a huge team of people...'

There we go. OK. Oh, yeah.

'..and nerves of steel.

'Ironically, the story of clean

'starts in the dirtiest place imaginable.'

Another day, another sewer.

All right, here we go. OK.

I'm going in. I can already smell it from here.

It's delightful. Yeah.

All right, going down.

These are San Francisco's sewers.

There's over 1,600 kilometres of these tunnels

that run beneath the city hidden from view.

Oh, this space is incredible.

It's really hot down here and the smell is just kind of overwhelming.

There are lots of little critters walking along on the sides.

This is, er...this is the underbelly of the city.

I mean, in an incredible way, this is what makes cities possible,

is this kind of space. But we never see it, we never experience it.

It's an extraordinary thing.

'But what's even more remarkable

'is that many of San Francisco's sewers

'were constructed well over 100 years ago.

'This old infrastructure has now been expanded

'as the city above has grown.

'Which means it requires regular maintenance

'by people like Gene Chruszcz.'

So, where is all this waste...

This is pouring out of someone's apartment building right here?

This is a lateral going to the apartment building.

So people taking showers, washing their dishes,

going to the bathroom, it all comes into this sewer.

And this is... Where is this flowing to?

This is all going to flow to another big sewer

and it goes to our sanitary plant, where it's treated.

Amazing!

'The journey from homes to waste water treatment facilities

'is only made possible thanks to these amazing

'century-old sewer lines.'

This line was put in in, I think, 1868.

-1868?!

-Yeah.

The structure looks fantastic.

-It's incredible.

-Yeah.

'Today, we take it for granted

'there's somewhere for our waste to go when we flush the toilet.

'But just five generations ago,

'there were no comprehensive sewer networks anywhere in America.

'It meant much of the filth you see down here

'was on the streets and pavements.'

You made a hard job easy.

You guys done? Ready for stripping?

Strip me.

The history of clean streets is surprisingly short.

As we rewind the clock, you can rapidly see our cities

becoming ever-dirtier places to live.

And nowhere is filthier or more unpleasant

than mid 19th-century Chicago.

The place where the story of clean in American cities first begins.

It's hard to imagine it now,

but Chicago in the 1850s was a truly disgusting place.

I have a newspaper from the period, it was called,

The Gem of the Prairie, which sounds lovely,

until you actually read a description of what it was like.

"The gutters at the street crossing were clogged,

"leaving pools of an indescribable liquid

"there to salute the noses of the passersby."

Chicago has a very particular problem

when it comes to keeping clean.

Not only is it one of the fastest-growing cities in America,

but in an age before the motorcar, all these people

means there's an explosion in something else, too.

We think of horses as these symbols of natural beauty.

But imagine what it was like when all these cars were horses.

When you take thousands of these and put them on the streets

of an already-crowded city like Chicago,

things can get pretty grim.

Just imagine what this street would have been like 150 years ago.

You're walking out in your fine 19th-century outfit

and the sidewalk is literally lined with this.

I mean, it's an appalling mix of human and animal excrement

that you have to wade through on your way out to dinner.

The city is convinced the smell of this toxic waste

is causing the huge levels of disease they are experiencing.

Something has to be done.

So Chicago hires this man.

Engineering maverick Ellis Chesbrough.

Having spent a lifetime working as an engineer on the railroads,

he may seem like an odd choice to clean up the city.

But Ellis Chesbrough has a big plan.

Chesbrough makes a pilgrimage to Europe.

Now, when most Americans travel to Europe,

they're there to see Buckingham Palace or the Louvre,

but Chesbrough wants a grand tour of something else.

He wants to see the continent's new sewers.

While crowds enjoy the sights above ground...

..Chesbrough is hard at work taking notes on the underground

infrastructure of Europe's major cities.

On his trip, Chesbrough sees just how important

proper sewers are to the cities above them.

And he comes away convinced that this new technology

will keep Chicago clean.

Only the city has a problem. It's too flat.

And that means sewers can't drain properly.

You could build them deep underground,

but then the cost becomes astronomical.

Chesbrough's got an incredible idea.

If you can't dig down, why not lift the city up?

And he's got the perfect technology to do it. The jackscrew.

The jackscrew is a simple device used largely on the railways

to lift trains on and off the track.

But Chesbrough sees that it could be put to use

in his sewer-building project.

If you can use a couple of these to lift a locomotive,

why not use them to lift a building,

or a block, or an entire neighbourhood?

It's a crazy idea, but it's also kind of a beautiful one.

Using railroad technology to keep the city streets clean.

Starting in the 1850s, building by building,

Chicago is lifted by jackscrews.

The spectacle draws crowds of startled onlookers,

who watch on as a city is lifted right before their eyes.

CHEERING AND APPLAUSE

In 1868, one British visitor watches a 22,000-ton hotel be lifted.

This is what he had to say about it.

"The people were in it all the time

"coming and going, eating and sleeping.

"The whole business of the hotel proceeding without interruption."

In 1860, engineers raised an entire city block.

With super-human effort, almost an acre of five-storey buildings

weighing an estimated 35,000 tonnes

were lifted by over 6,000 jackscrews.

As the jackscrews did their work,

sewers were laid at the perfect angle to drain.

With the buildings lifted,

new foundations were built beneath

and raised streets and sidewalks were installed.

But buildings weren't just lifted in Chicago.

To make room for the sewers, some got moved altogether.

I've got a great quote.

"Never a day passed during my stay in the city

"that I did not meet one or more houses shifting their quarters.

"Going out Great Madison Street in the horse carts,

"we had to stop twice to let houses get across."

There's a lot of traffic in today's Chicago,

but at least you don't have to worry about houses

going down the street in front of you.

'By lifting these buildings, Ellis Chesbrough was able

'to build the first comprehensive sewer network in America

'and clean Chicago's streets of the muck and stench.'

But the project was destined to have some remarkable

and surprising consequences.

When you do something as ambitious as lifting an entire city,

it fires people up.

Chesbrough had proved that

even under the most difficult circumstances,

sewers could be built.

Inspired by Chicago's example, within three decades,

20 American cities have built their own networks

of underground sewer tunnels.

But building sewers is just the beginning

of a change that will transform our planet.

With the muck off the streets, attention soon turns to trash.

By 1914, over 70 cities in America

are providing municipal refuse collection.

By the 1930s, modern sanitation companies

are collecting garbage for the first time.

And American cities are becoming free of filth.

But Chesbrough and his sewers do more than just keep cities clean.

They prove that big infrastructure

is essential for making cities function.

All around the world,

new underground building projects are begun.

In 1863, in London, the first steam train travels under the city.

In Paris, the Metro opens in 1900,

followed soon by the New York subway.

Pedestrian walkways and auto freeways followed

by electrical highways and fibre-optic networks

are created around the world.

PHONE RINGS

Today, whole parallel worlds exist underground,

powering the cities above.

It's a revolution.

Chesbrough's sewers proved to be an inspirational feat of engineering.

But unfortunately, they had a bit of a teething problem.

The sewers were draining into Lake Michigan,

which was the water supply for the city.

Chesbrough may have made the streets clean,

but the water was still filthy.

And it wasn't long before the problems became apparent.

In the 1870s, this was a regular sight in the bathrooms of Chicago.

The water was so filthy with sewage

that it was regularly filled with dead fish.

One observer reported that the fish would actually come out cooked

and locals would refer to their bathroom water

affectionately as, chowder.

As you might have guessed, mixing raw sewage with drinking water

was not such a good idea.

And not just because of the dead fish, or the smell.

The problem was, the water could kill you.

But most of the Chicagoans of the time were blissfully unaware

that putting waste in drinking water was so deadly.

No-one could see the hidden killers that lurked in dirty water.

While Chesbrough's first sewers

let Chicago's waste mix with its drinking water,

today, Chicago does everything it can to keep the two separate.

I'm standing above the latest addition to Chicago's sewer network.

It's an epic project.

They've been working on it for almost 40 years

and it's cost nearly 4 billion.

But to understand the true scale of this project,

I need to go stand in this little yellow cage.

'Around five times a year, heavy storms roll in

'that can dump more than 30-billion litres of water

'on Chicago in just a few hours.

'This causes the sewer network first begun by Ellis Chesbrough

'to overflow.

'With nowhere to go, this mixture of rainwater and sewage

'can spill out into people's homes

'and pollute the waterways, causing huge problems.

'This network of tunnels are designed to store and transport

'this huge influx of dirty water and keep the city clean.

'Hidden from view, this space will keep millions of people safe.'

This is like a cathedral.

This is like the Church of Engineering right here.

Look how immense this is.

'This huge project has over 500 people working on it.

'And Kevin Fitzpatrick is one of the project managers.'

This looks like the set of a science-fiction film, right?

I mean, this is an amazing space to work in.

The air makes it feel like you're on a science-fiction set here.

We're about 300 feet underground

and it's always cool and damp here,

so you get a little bit of steam coming.

In a big storm, how much water would be in this space?

-This thing would be completely full.

-Be completely full?

-Yep.

Polluted storm water would be coming through that tunnel,

dropping right down here and shooting out into the reservoir.

'But during a major storm, so much water falls

'that even these vast tunnels are not big enough to hold it.

'So an even bigger space is required to deal with all the water.'

-So here we go into the quarry.

-Wow!

It's very hard to just tell the size of it.

You walk out of those tunnels

and then you're in this unbelievable, massive space.

And how much water can this thing hold?

7.9 billion gallons worth of water when it's done.

In a big storm, how high would the water eventually get?

The water would get 300 feet above our heads.

It'll go all the way up to the top?

Almost all the way up to ground level.

This is like the world's largest bathtub here.

It is the world's largest bathtub.

So it's basically a kind of giant buffer.

You've got a storm, you can't deal with all that water,

you've got to put it somewhere.

We need somewhere to put it that's not polluting the waterways

and that's not backing up in people's basements.

-This is the location.

-It's an amazing solution.

Ellis Chesbrough would have loved this, right?

He was all about big projects like this

and he would have loved a project like this, I'm sure.

Looking at the scale and expense of this project,

you can understand just how hard it is

to get clean water in fast-growing cities.

But today's planners have a simple, but crucial

piece of information that Chesbrough didn't.

Human waste in drinking water spreads disease.

To keep people safe, you need to do everything possible

to stop the two from mixing.

Discovering this one fact was the single

most important breakthrough in our understanding of clean.

TOILET FLUSHES

The story of how we made that breakthrough?

Well, it begins with a somewhat rock and roll choice of breakfast.

To tell you the truth, I don't normally have beer for breakfast,

but, actually, for thousands of years,

this was the healthiest way to start the day.

Our ancestors liked to have a drink or two.

Benjamin Franklin, in his diaries, recalled how his colleagues

would have a pint of beer before breakfast

and then they'd have a pint with breakfast

and a pint between breakfast and lunch.

And of course, you have to have some beer with lunch.

This is the point at which I'd need a nap.

But they would charge on and have a pint around 6:00pm

and then, of course, a pint

to celebrate the end of a hard day's work.

Now, this may seem a little excessive,

but it's not quite as crazy as you might think.

The beer-brewing process kills disease.

Although no-one realises this in the middle of the 19th century,

it means if you live in an unclean environment,

beer is a very sensible drink.

This quirky fact, that drinking beer can be safer than water,

will help transform our understanding of clean.

Ah!

Beer will prove vital in solving the mystery

of one of the deadliest killers in Victorian London.

When we think about killers

in the dark corridors of 19th-century London,

we might think of Jack the Ripper.

But the real killer that haunted the streets was cholera.

Between 1831 and 1860,

Cholera killed more than 140,000 people in Britain.

And it did so in a truly horrific way.

There's a particularly harrowing account from the time

of a cholera victim near to death.

It reads, "the mind within remains untouched and clear,

"shining strangely through the glazed eyes.

"A spirit looking out in terror from a corpse."

Cholera is a horrific disease that still kills

almost 100,000 people worldwide every year.

But in the 19th century, doctors profoundly misunderstand its cause.

The medical leaders of the time are convinced

cholera is spread through the stink in the air.

Proving them wrong will be a lifelong battle for this man.

John Snow.

A medic from the north of England whose experiences as a young man

will lead to a radical new theory about the spread of disease.

As an 18-year-old trainee doctor,

Snow spends nearly a year

in the mines of Killingworth in the north-east of England,

treating miners who have been stricken with cholera.

It's not the most pleasant way to start a medical practice,

but what he experiences in the mine

will spark an idea that will follow him for the rest of his career.

Snow is breathing in the same putrid air as the infected miners,

and yet, despite the time he spends with them,

he doesn't seem to get ill.

Looking around at the appalling sanitary conditions

that the miners worked in,

with the filth and the dirty water,

something clicks in Snow's mind.

It's just a glimmer of an idea, really.

And it might have stayed that way,

had he spent the rest of his life in a small town.

But Snow's idea is going to blossom into something truly powerful

when he moves to the city.

In 1836, John Snow arrives in Soho in the heart of London.

It's a place where beer is produced and consumed on a very large scale.

It's also a place that is ripe for big ideas.

A place that will help Snow make his breakthrough.

In the mines of Killingworth, Snow had noticed that not everyone

who breathed the air had come down with cholera.

Now in London, he attends public lectures

and learns more about the way that gases

are distributed in the atmosphere.

And he starts working on a radical new theory.

Cholera is not in the air, it's in the water.

Snow's radical idea flies in the face

of the medical establishment's view

that cholera spreads through the air.

But to convince them he's right, Snow needs irrefutable evidence.

In 1854, when a deadly cholera outbreak

begins in the heart of Soho...

..Snow realises it's an opportunity to gain the evidence that he needs.

'But to prove his theory, he's going to have to take

'a truly monumental gamble with his own life.'

While the rest of the neighbourhood is fleeing in terror...

..Snow bravely goes from door to door in Soho,

recording the deaths at each address.

And with this detective work, he assembles all the data

and he makes a map.

Now, it may not look like much,

but this is actually one of the most influential maps ever produced.

Overlaid on the map is the data John Snow has collected in Soho.

Each of the black marks represents a death from cholera.

As Snow builds up a picture of what's going on,

the map reveals that the deaths are concentrated

around a water pump on Broad Street.

But there's one group of locals who escape the outbreak.

The beer-drinking workers at the local brewery.

Unbeknownst to them, their favourite beverage

has kept them safe from the dirty water of Soho.

It's all the evidence John Snow needs.

By risking his life, Snow has proved

that cholera is spreading through the water.

It's an insight that will begin a new chapter

in our understanding of clean.

Thanks to Snow and his map,

the authorities finally come around

to one of the most important principles of public health.

Access to clean drinking water is crucial for preventing disease.

It's the principle that every relief worker in the world

now follows after a major disaster.

But Snow's map will have consequences

that extend far beyond just public health.

Snow's work helps inaugurate the new science of epidemiology.

Using maps and surveys instead of lab-based experiments

to uncover the patterns and causes of disease.

In the 1950s, these techniques will be used by

British doctor Richard Doll

to reveal that lung cancer is linked

to cigarette smoking, rather than car fumes.

In the 1980s, police forces will combine data and maps together

to reveal the previously-hidden patterns

and causes of crime in cities.

It's a technique that will revolutionise law and order.

Today, the combination of local data and maps

has become a vital tool for city dwellers all over the world.

And all these developments have their roots in a map

made by John Snow more than 150 years ago.

John Snow makes clean water

the goal for civil engineers in the rest of the century.

The irony is, Snow made his breakthrough

without actually knowing what it is in dirty water that kills us.

This little creature is what John Snow was actually up against.

It's a tiny organism that spreads through water and causes cholera.

If you are unlucky enough to ingest cholera-infected water,

there will soon be upwards of a trillion of these creatures

living in your gut.

And that spells death.

Learning how to control bacteria in water

would be one of our greatest challenges in the 20th century.

Even today, for almost one billion of us,

drinking a glass of water is like playing Russian roulette.

But one miraculous chemical

would allow us to kill these deadly creatures.

And in doing so, it would make much of modern life possible.

150 years ago in Europe and America,

the public water was so dirty,

you wouldn't have wanted to go near it.

Today, the story is a little different.

Now, we actively seek out public water,

sharing it with over 80 million other people each year,

and their trillions upon trillions of bacteria.

Whoa! Whoa!

'All these people are jostling around

'in a wonderful bacterial breeding ground of 72-degree water.

'A temperature that's ripe for superfast multiplication.'

There's a reason why we didn't have water parks like this

in the middle of the 19th century.

There was no way to keep the water clean.

Imagine what John Snow would have said about this place.

He would have been baffled by it.

Then again, I don't think he was much of a water park person.

But perhaps what would have shocked John Snow the most

is that this park operates a recycle system.

Over 11 million litres of water are used over and over in the rides.

It means keeping it clean is vitally important.

So now we're behind the scenes,

we've got this water play land up there.

This is what we need to do to keep that safe and clean.

You have to filter it and disinfect it and do all the good things

that these little magic guys do

to clean 2.5 million gallons of water here. That's a lot of water.

And what happens at the first stage of filtering?

We have some pre-filters before things go...

That is what gets trapped in the filter...?

In the pre-filter before they go on.

So this is just a small... Oh, a yummy example just for you.

That is, like, the world's largest hairball.

It is like the world's largest hairball. We are mammals!

Oh, that's what we just kind of naturally shed?

-You want to touch it?

-No!

-Are you sure?

-Seriously, don't taunt me with that.

-It's just a hairball!

-Oh, God!

It's in my contract, I'm not allowed to interact with hairballs!

It's not that scary. Some leaves, a little bracelet.

Oh, look, out of someone's shoe.

But can I ask, like, what is the weirdest thing

you've ever found in the filters?

-I think one of the weirdest things was a toupee.

-Really?

-So, what happened to the poor guy?

-Yeah.

-I assume it was a guy.

He goes onto the ride and he's, like, all Burt Reynolds

and at the end, he's, like, "Oop!"

-He's so not!

-I have a slightly different look. Sorry!

But the objects we can see make up just a tiny fraction

of what has to be cleaned out of the water.

What really keeps this place clean is chlorine.

A chemical that is lethal to microscopic bacteria.

So, what is this giant vat?

Well, this is liquid chlorine that we inject into the water,

which is our disinfection.

So, this is basically what keeps the whole park safe?

You can't have the magic up there

without this giant vat of chlorine?

That is the secret and the magic to water.

Clean water is paramount to what we do.

And we've got this amazing team of men and women

that take care of our water. They're invisible

and probably not as loved and noticed as they should be, but all day long,

they make sure our water and the magic of the water park

starts with good, disinfected, filtered, clean water.

We all know chlorine is vital in water parks, but there's a problem.

Use too much chlorine and it can be lethal to humans.

It means it was one of those innovations

that was very hard to sell.

And back when chlorine was first used to treat water,

it wasn't just for entertainment, it was a matter of life and death.

Across America and Europe at the beginning of the 20th century,

dirty water was everywhere.

And one technology in particular was causing the problem.

The humble flushing toilet.

The toilet was adopted by a lot of people

in a very short space of time.

When this happens, problems are never very far away.

Just look at the modern world of high-technology.

Think of the iPhone. This was a huge hit product.

But right after its launch, it overloaded the wireless network.

People just had no idea

how much iPhone users were going to try and get online.

People even had a hard time just making telephone calls.

New technologies can often overwhelm old infrastructure

in really surprising ways.

Please, I don't know how I got into this thing,

but I feel a little bit uncomfortable.

Guys? Can you guys get me out of here?

In the 19th century, toilets,

like iPhones, were a catastrophic success.

People bought and used them so much that they overwhelmed the system.

As many thousands of toilets

were installed in cities around the world,

there was a huge influx of dirty water.

As a result, drinking water became even more lethal.

Finding a solution to this problem

would begin a new phase in the story of clean.

What we needed was a way to kill bacteria on a truly vast scale.

And the solution wouldn't come from some genius scientist,

but instead, from a seemingly-unremarkable guy.

A passionate amateur who happened to be in the right place

at the right time.

This guy, John Leal.

He never became rich, or famous.

But his work would transform America.

'John Leal is a doctor at the beginning of the 20th century.

'But it's his special interests that mark him out as a bit different.'

Leal is obsessed with bacteria in water.

It's an obsession that had come from personal tragedy.

His father had died a slow and painful death

from drinking bad water during the Civil War.

All of which means that when he's not spending time helping patients,

he's trying to figure out new ways to kill bacteria.

Leal experiments with many ways to kill bacteria...

..but one poison in particular excites him.

Calcium hypochlorite.

The potentially-lethal chemical that's better known as chlorine.

It's a chemical that has been used in a radical one-off experiment

to treat the drinking water in the town of Maidstone in England.

But Leal is going to get to use this dangerous chemical

on a much grander scale.

Leal's passion for public health

ultimately lands him a job at a big water company.

It means he's responsible for seven billion gallons of drinking water.

And it's going to enable him to put chlorine to the test

in the most dramatic way possible.

In 1908, the New Jersey water company he works for

is suffering from an unusually high bacterial content in its water.

It's the opportunity Leal has been waiting for.

So here is where it gets really insane.

In total secrecy, without any approval from the authorities,

Leal doses the drinking water supply for a city of 200,000 people

with potentially-lethal chlorine.

To the wider world, it appears as if John Leal is a madman,

poisoning the unsuspecting citizens of Jersey City.

The public, and even many scientists, are intensely hostile

to the idea of drinking water being tampered with.

One notable chemist of the time comments,

"the idea itself of chemical disinfectant is repellent."

With public opinion against him,

it's a truly unbelievable risk,

but Leal sticks with his plan.

Three months after his experiment,

Leal gets called into court and reveals what he's done.

And the judge is shocked.

I've got the transcript here. The judge says,

"Do you drink this water?" "Yes, sir."

"Habitually?" "Yes, sir."

"Would you have any hesitation about giving it to your wife and family?"

"I believe it is the safest water in the world."

It's a bold move, but luckily for Leal,

his gamble is going to pay off in a major way.

The project is such a success that within a few years,

the chlorination of drinking water is rolled out throughout the US.

This is the graph of typhoid deaths in the US.

Look at the point where chlorination begins.

But it's not just typhoid.

In a few years, infant mortality in America is almost halved.

But Leal's chlorination project wasn't just saving lives.

It was also transforming how we have fun.

Post World War I, nearly 2,000 public baths open in America.

And a whole generation of humans learns how to swim.

Chlorinated pools become spaces

where the old rules of public decency fade.

As costumes become smaller and more revealing,

the two-piece suit is born

and women's fashion is revolutionised.

The swimming craze will go on to inspire

over a million American homes to install private pools in the 1960s.

After droughts in southern California in the '70s

leave pools empty...

..kids soon discover

they are perfect environments for their skateboards.

Helping them develop a new range of airborne tricks.

All these developments have roots

in that huge risk taken by John Leal,

one of the 20th century's most unlikely heroes.

'But the story of chlorine

'isn't just a matter of giant public health projects.

'It will also bring the clean revolution into the home

'and turn it into big business.'

Just a few years after Leal's breakthrough,

five San Francisco entrepreneurs invest 100 each

to launch a chlorine-based bleach.

And it sounds like a great idea,

but things don't turn out so well.

The bleach is aimed at big industry.

But it's such a new product

that many of the potential buyers are left baffled.

Sales are poor and the business appears doomed.

But The Clorox Company, as they will call themselves,

are destined for success.

And they will help usher in a new chapter in the story of clean.

And it will all be thanks to the wife of one of the investors

and the small shop she runs.

This is the corner of 19th and Broadway in Oakland.

In 1916, there was a charming little grocery store here

run by a woman named Annie Murray.

And like Ellis Chesbrough and John Snow,

Murray is a bit of an outsider.

And like those guys, her outsider perspective

gives her an unique take on things.

She might not have been a chemist, or an experienced entrepreneur,

but Murray understands better than anyone else

how to revolutionise the bleach business.

Annie Murray recognises that the potential for her product

is not as a cleaner for big industry, but as a household item.

Acting on her insight, Murray creates a weaker version

of the chemical and puts it in smaller bottles.

And Chlorax, America's most popular domestic bleach, is born.

People, your kitchens are disgusting, you need this product!

Kills bugs dead.

Sir? No?

No takers?

-Sir, for your home. Please take this.

-Thank you so much.

Yes. Don't drink, just...just use it on the germs.

The store is mostly empty now,

but you can imagine in 1916, this is a bustling grocery store.

And Murray is so convinced of the demand for this product

that she starts giving away free samples to her customers.

Please try this, it's very, very dangerous.

This is something that you seem like you could use.

Ah, business is booming!

This is fantastic!

And within months, bottles are flying off the shelves.

Murray might not have realised it,

but she has invented an entirely new industry.

Annie Murray created America's first commercial bleach for the home.

And soon, many other similar products will be launched.

On hard-to-get-at-places like this,

spray your cloth first, then dust.

The motor is started and now watch how each soap performs.

In the 20th century, Murray and other entrepreneurs

transform ideas about cleanliness.

Now it's not just about huge public health projects,

clean becomes truly big business.

And nowhere did the clean business take off like it did in America.

I would say that the big years for convincing Americans

that they needed to be really, really, really clean was the 1920s.

Because people were flooding into cities,

men and women were working together,

very close together in offices and in factories,

and they were also the ambitious ones.

They were the ones who had left the farm.

In this new environment, radio and television

rapidly become popular pastimes for city dwellers

with disposable incomes.

Hey, come back here! Come back here!

As advertising becomes increasingly sophisticated,

a new form of drama will be produced

to help sell cleaning products.

Something that has dominated popular culture for almost 70 years.

I don't want a baby from an adoption bureau.

I want it from here!

The soap opera.

The soaps began to sponsor little daily serials that were,

you know, hugely dramatic,

hence the term soap operas.

Because they were unsung operas and always advertised by soap.

I love the idea that we're still using that phrase, soap opera.

It was like the soap industry did such a brilliant job

sponsoring shows 60, 70 years ago

that we're still using the term

-and promoting the word soap in general.

-Yeah.

Thanks to the early pioneers and some pretty ingenious marketing,

today, the household cleaning product industry

is worth an estimated 80 billion.

But there are some who feel our obsession with cleanliness

may now have gone too far.

'Some research suggests that our ever-cleaner world

'may be linked to increasing rates of asthma and allergies.

'The explosion of cleaning products during the 20th century

'for good and for bad,

'has led to domestic environments becoming cleaner

'than they've ever been before.'

But the ultraclean revolution

didn't just help us keep our homes germ-free.

It also helped invent something new.

Something we rely on every second of our lives.

And it's manufactured in a room behind this door.

It also happens to be one of the cleanest places on the planet.

This is a Texas Instruments microchip fabrication plant.

The chips made here power everything from cars, to planes, to microwaves.

This place is a true wonder of the modern world.

Ooo, nice!

'To see inside this unique environment,

'I have to take some extreme precautions

'to make sure I don't contaminate it in any way.'

-If you're a visitor to the building, then you put shoe covers on.

-OK.

'Thankfully, clean guru Sharon Hudgens

'is leading me through the process.'

Rinse your hands under the water for a few seconds

-and then completely blow them dry.

-OK.

So I notice we didn't use any soap.

Actually, a lot of soaps have fragrances in them,

which is a contaminant.

It would give off particles.

We're trying to eliminate particles going into the clean room.

This is our first step in eliminating particles.

I like that. So, soap is too dirty for the clean room?

-Soap is too dirty.

-That's nice.

-So this is the hood.

-Right, I reverse it.

That...that's not right. There we go.

-Put another set of shoes covers on.

-Another layer of shoe covers?

-Over.

You guys are clean freaks. Has anyone told you that?

All right. Let's see if that works. Oh, yeah.

I feel incredibly clean. This is great. I'm psyched for this.

So this is John, he'll be taking you through.

Hey, John, how you doing?

-Wow!

-This is our clean room.

So this is really...this is one of the cleanest places on the planet.

We think it is, yes. It's cleaner than an operating room.

We do everything we can to ensure

that there are no particles in this air stream.

There's never a speck of dust.

To understand why dust can be so damaging,

you need to get a sense of the scale of the chips produced here.

A human hair measures about 100 microns across.

A single cell of skin is about 30 microns.

A cholera bacterium is three microns.

The intricate pathways and transistors on a microchip

can measure less than a tenth of a single micron.

A spec of household dust

landing on one of these delicate silicone wafers

would be comparable to Mount Everest landing in the streets of London.

And that is why clean is so vitally important here.

So, this is really what this is all about, right?

This is a wafer... It's in an even cleaner space here, right?

That is correct. And this is what we're trying to achieve.

This is a wafer and there are thousands

of individual microchips on that wafer.

You can sort of see them individually, but it's difficult.

So in a way, the whole digital revolution that we celebrate

that's bringing the world together

can only happen because we're able to think about cleanliness

on the level of microns,

not on the level of, you know, the planet.

That's correct.

And it's taken us a long time to figure out

everything we need to do to make sure we're as clean as we can be.

Being able to master clean at the smallest scale

has transformed our world.

But the roots of all this stem from a simple desire

almost 200 years ago...

..to keep our city streets free of dirt.

Standing here in the clean room,

I can't help but think of the sewers.

In a way, it's really the two poles of human inventiveness.

To be able to build the modern world, we had to create

this incredibly disgusting space

that we isolated from everyday life.

And at the same time, to make the digital revolution,

we had to create this hyper-clean place

and also isolate everyone from it.

We never get to visit these environments,

we don't even think about them.

But without this kind of environment

and without the incredible dirt and disgust of the sewer,

modern life wouldn't be possible.

Bit by bit, clean technologies have transformed our world.

But the story of clean has really only just begun.

Every year, millions of people die needlessly

as a result of not having access to clean, safe drinking water.

It's one of the great tragedies of the modern world.

Bringing the benefits of clean water to every human on earth

is one of the great challenges of the 21st century.

Developing ways to keep things clean has allowed cities to flourish.

And that's important because

these places are some of our most creative spaces.

Environments that drive new innovation

as ideas and cultures collide.

When clean pioneer John Snow was born,

little more than 2% of humans lived in cities.

Today, more than half of us do.

'We have become a species of city dwellers.'

The urbanisation of the planet would have never happened

without the ideas and technologies that made our cities clean.

The people behind that revolution didn't become rich or famous.

But look around at a modern, thriving, dynamic city today

and it's clear that they, as much as anyone,

invented the modern world.