NHK TV announcers which now includes even a solid white plume representing the water out of the fire hoses. (An earlier version featuring the helicopter water-drop is shown here. Japanese TV still often prefers the hand-written or model graphic to computer ones.) All are attempts to explain radiation and the current situation in an overall situation in which people have just been introduced to the term "microsieverts" and have no idea what a dosage let alone dosage per hour means and in a week when people have only just found out how nuclear power works.
The best I've seen yet is the above, which I'll leave the interested to work out.
Via the Facebook Tokyo Radiation Levels page, who sourced it via the xkcd comic blog (from a cartoonist with a degree in physics and who worked at Langley), who complied it from information from a friend, Ellen, who's a senior reactor operator in the States: just one indication of how people are trying to get information to base informed decisions on and from more than one source. And I'm in Tokyo, and have pretty much felt safe from radioactivity since the event happened, I just wanted to confirm for myself – not via an ill-informed media – what the scenario was. My situation is nothing like those affected closer or evacuated from the Fukushima area, as reported here by colleague Justin McCurry in The Global Post.