The philosophical saying that fear springs from ignorance is especially apt with the nuclear crisis in Japan. Concern about radioactive contamination has led some Hong Kong people to avoid Japanese food and products. There has been a marked fall in business at Japanese restaurants and the country's popular cosmetics suddenly are not so sought after. Vigilance is necessary, but a lack of understanding can create irrational behaviour.

We have seen that already with the run on iodised salt. Rumour that the potassium iodide it contains wards off the thyroid cancer that results from exposure to high levels of radiation caused panic buying and hoarding. Fortunately, common sense prevailed after Food and Health Secretary York Chow Yat-ngok pointed out that salt contains such a minute trace of the mineral as to be ineffective against contamination.

Never mind that we are 3,000 kilometres from the crippled nuclear power plant in Fukushima prefecture, making the risk of fallout of dangerous particles negligible, or that we face everyday health risks from our own air pollution. Now that the government has found radiation in three food samples and banned fruit, vegetables and dairy products from five prefectures, more such assurances are needed. The radiation level in one sample of spinach tested by the Centre for Food Safety was found to be 10 times above what is acceptable. That sounds bad, but the vegetable would have to be eaten every day for a year before being dangerous to health. The bans were a precaution, not a wholesale alert that Japanese produce is to be avoided. No bar is in place, for example, on meat, poultry and seafood from the prefectures or anywhere else in Japan.