Different standards used by municipal governments are exacerbating the confusion among residents over safety levels of radioactive fallout from the Fukushima No. 1 nuclear plant and how to deal with possible dangerous areas.
Different standards used by municipal governments are exacerbating the confusion among residents over safety levels of radioactive fallout from the Fukushima No. 1 nuclear plant and how to deal with possible dangerous areas.A group of mothers in Tokyo's Arakawa Ward has repeatedly visited the ward office since June to ask government officials to measure radiation in the atmosphere, citing programs that have started in other wards.The group has submitted two petitions to Arakawa Ward containing the signatures of about 6,000 residents asking for such measurements.Ward officials said they were awaiting instructions from the central government on the radiation standards to be used. Other officials said going ahead with the measurements could trigger negative publicity if high levels were detected.The ward in June did ask the central and Tokyo metropolitan governments to establish safety standards and measure radiation levels. Finally, in October, the education ministry released guidelines defining local hot spots as areas where radiation levels 1 meter above ground were 1 microsievert or more per hour than in surrounding areas.Those guidelines allowed Arakawa Ward to start taking its own radiation measurements at schools and day-care centers a month later. But it was the last to do so among Tokyo's 23 wards.In contrast, neighboring Adachi Ward came up with its own standards in July and began taking measurements and replacing sand at schools and parks."By blaming the central government for the delay in taking action, Arakawa Ward has been slow in responding to all matters," said Akemi Mori, 39, a member of the Arakawa Ward mothers' group who has children aged 5 and 8.Local governments, including Adachi Ward, have come up with their own standards by turning to various existing standards.One is the 2007 recommendation by the International Commission on Radiological Protection (ICRP), which set maximum annual radiation exposure levels for citizens at 1 millisievert (1,000 microsieverts), excluding background radiation and radiation from medical treatment.Using the ICRP recommendation, many local governments have taken into account the amount of time spent outdoors and established a standard of 0.23 microsievert per hour.The Environment Ministry used the ICRP recommendation for a guideline in September for the standard to be used in deciding whether central government money should be spent to decontaminate an area. Under that guideline, areas with annual radiation levels exceeding 1 millisievert (which translates into 0.23 microsievert per hour) would be subject to decontamination.But in October, the education ministry came up with the hot spot standard of 1 microsievert per hour.According to education ministry officials, the 1-microsievert standard was intended to deal with localized hot spots, while the 0.23-microsievert standard was designed to determine which areas needed decontamination. Those areas would be much wider, covering entire towns and cities.Officials said a wide area with average radiation levels of 0.23 microsievert per hour would undergo decontamination, while a single hot spot with radiation levels of 1 microsievert per hour would receive a different response.But the existence of those two standards has led to confusion among local governments about which one to use.Local governments that were quick to act have continued to respond in stronger ways.For example, Kawasaki city in Kanagawa Prefecture established a standard of 0.19 microsievert per hour in June. That standard was not relaxed even after the education ministry guideline was released in October.Kawasaki city officials used 14 radiation detection devices to measure levels at 2,689 locations in the city, including 450 schools. Eighteen locations were found to have radiation levels above 0.19 microsievert, and sand in those areas was replaced.Shinjuku Ward established a standard of 0.25 microsievert in June and changed that to 0.23 microsievert. If reports are received about an area with levels above the latter standard, ward workers are dispatched to conduct measurements.In contrast, Suginami Ward set its own standard of 1 microsievert after the October guidelines were released by the education ministry. Ward officials are dispatched when reports are received about radiation levels above 0.7 microsievert per hour.* * *Editor's note: An earlier version of this article carried a graphic that misstated the radiation measurement unit. A corrected version is attached.