It made the national news ONE MONTH AFTER a private citizen measured the air radiation level on his own and had the dirt tested with his own money.
According to TV Asahi's "Morning Bird" news variety show on September 19, 63,000 becquerels/kg of radioactive cesium was detected from the dirt sediment on the rooftop of a 5-story apartment building in Kohoku-ku in Yokohama City. It is the same Kohoku-ku where 42,000 becquerels/kg of radioactive cesium was found near the side drain on the road.
The person who measured the radiation tweeted the result as early as August 15.
The air radiation at the spot was 1.8 microsievert/hour. The result of the soil analysis:
Cesium-134: 29,775 becquerels/kg
Cesiu-137: 33.659 becquerels/kg
Total cesium: 63,434 becquerels/kg
The show's commentators are saying "Oh... what about Tokyo? I thought we're safe."