The air, over the past few days, has been vile. Back to pre-Olympic smog, despite regulations to keep twenty per cent of the cars off the road Monday to Friday (we can't use our car on Friday, and the inconvenience is already stretching my committment to the environment). You can smell the dirt in the air. I had been toying with the idea of buying an extra air purifier for the house, and looking out of the window convinced me that the time was right. I made the call to Mike, the genius who realised a couple of years ago that there might be quite a market here for IQAir units – the gold standard of the air purifier industry. I asked what discount he might give me as an old customer (just about any purchasing conversation goes like this in China), and he offered me a little piece of history. Instead of an entirely new machine, I could have – at 15% off full price – a machine used for just five weeks by the Olympic delegation. And now here it sits, humming in our sitting room, gently blowing nice clear air over us, just as it might well have blown nice clean air all over Michael Phelps! Or at least over a junior coach.