I received an e-mail which warned all people to stay indoor for the next 24 hr as radiation from Fukushima reactor explosion can spread across nearby nations. Even some friends also were seen discussing about the same. I do not know how is it possible when the incident is not like what happened in Chernobyl in 1986. A search in the internet reveals that this advise is for people staying within 30 km of the nuclear plant and not for everybody on the globe. The denial at BBC website is available here.
Sometimes, rumours can cause more harm than the real incident. There may be vested interests to create panic and then loot the property from abandoned houses.
We have to salute Japanese people who are braving the worse conditions caused due to earth quake, tsunami and explosions at the nuclear reactors. There were no reports of any chaos or property looting or trading charges on the government. They demonstrated their support to the authorities inspite of hardships they are facing and this is what is required in emergency so that concerned agencies can concentrate on their work to control the situation.