Is Fukushima's exclusion zone doing more harm than radiation?
The exclusion zone around the Fukushima nuclear plant has a strange beauty to it. The small town of Okuma, just two kilometres from the plant, looks unreal to my human eyes - so conditioned to the bustle of urban life.
There are houses and shops, cars parked neatly in driveways, a traffic light flashing orange in the distance. But, apart from me, there is not a single human. Wait long enough and you can see a racoon dog scurry across the street; a group of monkeys wanders nonchalantly along a nearby riverbank.
I look down at my radiation monitor. It's reading 3 microsieverts per hour - not enough to get me worried on a short visit, but more than ten times above what the Japanese government has declared "safe" for people to return.
Because of that, this place has been declared off limits for the foreseeable future. That means the people who once lived here are now permanent exiles.
Think about that for a minute. Think about the town or village you grew up in, a place your family may have lived in for generations. Now think about never being allowed to return there.
That is the reality facing the Shiga family. They come from the small village of Obori a few kilometres north of Okuma. The village sits in a delightful little valley backed by pine-covered mountains.
The village was famous for its beautiful ceramics. Almost every single house has a pottery workshop. Mr Shiga is descended from 16 generations of pottery masters.
Before coming back here with me, Mr Shiga had to apply for special permission. He can stay a maximum of five hours, and he has been told he must wear a white "Tyvek" suit and mask at all times. In his hand he carries a large radiation spectrometer.
It's a cliché to say Japanese people find it hard to display emotions. It is also often true. To understand how upset Mr Shiga is you have to ignore his polite smile and listen to the pain in his voice.
"I hope my ancestors will forgive me for leaving here," he says. "It is not my fault I cannot come back. This place was stolen from us. I want to come back, I have a deep attachment to my home, but if I admit that to myself it is too painful, so I try not to think about it."
But perhaps Mr Shiga should be allowed to come home, if he wants to. Of course it would not be easy. Mr Shiga's house is now a mess. Wild Boar have broken in and turned it upside down.
The roof is leaking and water damage means the house would probably need to be rebuilt. There is no electricity or water supply and roads are still broken from the earthquake. But all that is fixable. The problem is the radiation.
Radiation is a hugely emotive subject. There is massive disagreement even in the scientific community over how much radiation is "safe". But there are now a number of scientists who are calling for a more "rational" discussion of the dangers.
One of them is Professor Geraldine Thomas of Imperial College, London. She is one of Britain's leading researchers on the effects of radiation on the human body. She visits Japan several times a years to advise the government. Gerry has become a passionate advocate of the right of people around the Fukushima plant to return to their homes.
Walking with me through the streets of Okuma, Professor Thomas eschews the government-provided safety suit and mask as entirely unnecessary.
"People have to feel safe to come back," she says. "Many will now not want to come back because they've made a life elsewhere. But in terms of radiation, the amount we are getting now is very small, and if you were inside a building you'd be getting even less than standing in the open air."
So, I ask, has the world's media been getting this story completely wrong?
"In my opinion yes it has," she says. "The radiation has not been the disaster. It's our response to the radiation, our fear that we've projected on to others, to say this is really dangerous. It isn't really dangerous and there are plenty of places in the world where you would live with background radiation of at least this level."
Writing these words I can already hear the cries of indignation. That Professor Thomas is an "outlier", and that plenty of other eminent scientists disagree with her. But let's look at the facts for a moment.
On recent visits to the towns of Okuma and Namie inside the radiation exclusion zone I measured a "received dose" of around 3 microsieverts of radiation per hour. These are in areas that are off-limits and have had no remediation work done. If I were to stand outside here for 12 hours a day, every day of the year, I would receive an annual extra dose of radiation of around 13 millisieverts.
That is not insignificant, but it is far below what the data suggest is dangerous to long-term health.
In most countries nuclear industry workers are allowed to receive up to 20 millisieverts a year. There are places in Cornwall in the UK where background radiation levels reach 8 millisieverts a year.
The world's highest background radiation rate is found in the city of Ramsar in Iran, which has the astonishing rate of 250 millisieverts a year.
Of course this is a ferociously complex issue, and many will argue that I am ignoring the dangers of "hot spots" and from ingesting radioactive Caesium particles in food or water or dust. But five years after the meltdowns at Fukushima 100,000 people are still unable to go home. That is a massive human tragedy.
If, as professor Thomas asserts, the science shows the dangers from radiation are being exaggerated, then it is possible that human tragedy is being made much worse than it need be.