Heinz Smitai, a nuclear physicist, Greenpeace campaigner and participant in the radiation monitoring mission, told foreign journalists at an October 30 press conference in Tokyo that radiation hot spots exist as far as 60 kilometres from the site of the disaster.
For instance, one street in front of a hospital in Fukushima City “is quite contaminated”, Smitai said, measuring 1.1 microsieverts of radiation per hour. Although this was one of the highest readings, Greenpeace found 70 other places in the city where the amount of radiation recorded exceeded the Ministry of Environment’s long-term target of 0.23 microsieverts per hour.
A sievert is the standard unit for measuring the risk of radiation absorbed by the body. A millisievert is equal to one-thousandth of a sievert, while a microsievert is one-millionth of a sievert. A typical CT scan can deliver from 2 to 10 millisieverts of radiation, depending on the area being scanned.
Radiation ‘hot spots’
Greenpeace also monitored contamination in Miyakoji and Kawauchi, the first two locations in the 20-kilometre exclusion zone around the Daiichi plant where the government has lifted its evacuation advisory.
Nevertheless, Greenpeace found numerous points on roads in these areas that exceeded the target of 0.23 microsieverts per hour.
“And when you leave the roads and go into the fields and surrounding forests, the radiation levels go up very strongly,” said Jan van de Putte, a radioactivity safety advisor in Greenpeace who also participated in the Fukushima monitoring mission. Most of these areas therefore have “not been decontaminated, and cannot be decontaminated because, for instance, a forest can’t be decontaminated, practically speaking”, he added.
Japan’s Ministry of Environment (MOE) disputes Greenpeace’s claim that it is underestimating radiation contamination and its risks. It points out that radiation in Fukushima has steadily diminished over time, as indicated by the most recent Nuclear Regulation Authority (NRA) airborne monitoring survey, conducted in December 2013. An MOE spokesperson told Al Jazeera that radiation rates “around Fukushima have significantly decreased [compared to October 2012 NRA survey] due to physical decay, weathering, and decontamination efforts”.
Critics, however, charge that these results were found by averaging the radiation measurements, meaning that individual “hot spots” such as those Greenpeace claims to have found could go unstated.
Read more at Study: Fukushima health risks underestimated