Have you ever wondered what happens to those Sars health declaration forms, the ones every traveller completes either entering or leaving Hong Kong?
About 100,000 passengers pass through Chek Lap Kok each day, and at least double that number cross via Lowu and the Macau and China ferries. That's 1.5 million forms every 10 days, or 45 million since they started handing them out last April.
Somewhere there must be a giant godown, staffed by gnomes furiously trying to sort them out, praying they are never needed.
So what does happen to them?
A call to the Health Authority reveals that the forms are kept for only 10 days, 'after which they will be systematically and properly disposed of to ensure that all personal data collected would not be leaked out'.
But the World Health Organisation website says Sars has an incubation period of up to - you've guessed it - 10 days, or longer. That's the time from exposure to the virus to developing symptoms.