I have always been interested in garbage: What it says about us. What in there embarrasses us, and what we can't bear to part with. Where it goes and how much of it there is. How it endures. What it might be like to work with it every day.

I don't believe in objectivity. I observe the observer's paradox every moment I'm filming. Your presence is changing everything; there's no mistaking it. And you have a responsibility.

Why is nobody questioning the sanity or suicidal tendencies of Everest ascenders? It's kind of a question of framing: How do you frame these activities? We frame them as freedom-loving, exciting, progressing sports and they are. But there are other ways to frame it. It's also true that these young men, neurologists say that their frontal lobes aren't developed yet - the long-term planning part of the brain.

Extreme sports tricks are becoming increasingly complex, the courses ever more challenging and crashes all too common.

The world of extreme sports is also one of the big businesses. Kids might think that snowboarding is the ultimate freedom, but this freedom is being marketed to them by commercial sponsors.

I have always been interested in garbage: What it says about us. What in there embarrasses us, and what we can't bear to part with. Where it goes and how much of it there is. How it endures. What it might be like to work with it every day.

I can't help seeing 'Waste Land' as the third in a triptych with my earlier films 'Devil's Playground' and 'Blindsight,' and not least in the awe and gratitude I feel for the group of people who were courageous enough to share their stories with us - and to live lives so rich in inspiration for us all.