These day's environmental radiation level in Tokyo is the same of that of Beijing
Beijing 78.4 nGy/h (average 2011/04/14 9:00-15:00)
Tokyo 77.6 nGy/h (average 2011/04/14)
No iodine-131 or cesium-137 in fallout was detected at 14th April.
Radioactive material level in tap water is acceptable level according to WHO guideline.
I was happy to know these data this morning.
Beijing's data url:
Tokyo's data url:
But it does never mean tokyo become free from radioactive contamination.
For example, The measuring device which is used to measure above tokyo data looks equipped on the roof of the building according to the photos. It is said that radioactive materials are fallen on the ground gradually. I hear some data which are sampled near ground shows higher number than above number. This means small children or dogs would be effected much more than adult.
And it was not only iodine-131 and cesium-137 that leaked from Fukushima nuclear plant.
By the way, when the fist testing result of fallout on the nuclear plant ground was announced, I heard very curious words. "Plutonium was detected in 2 samples, they were thought to be from the accident, other 3 samples included the plutonium too, these were average level for ground." Common quantity level of plutonium? Plutonium is one of the most feared isotope to Japanese. A few days after this announce, I heard that they were legacy of '60, cold war encourage nuclear development and nuclear bomb test. Half-life of Plutonium-239 is 24,000 yeas.
Half-life of iodine-131 is 8.1 days. So if Fukushima nuclear plant stop leaking, iodine-131 will disappear soon. But even if Fukushima nuclear plant stop all of nuclear leaking asap, many long half-life radioactive things will remain and spread to the food.