As Japan continues to recover from the earthquake, tsunami and nuclear explosion at the Fukushima Daiichi power plant, it’s still unclear how much radiation people in the area were actually exposed to over time.
One report following the aftermath of the quake suggests that human exposure to nuclear radiation was relatively low. Until now, researchers and health officials lacked data on exposures during the days and weeks immediately following the event.
Following the explosion in March until June, 13 research teams from Hirosaki University in Japan collected data from more than 5,000 people by using Geiger counters. They found that the vast majority had external contamination levels (radioactive particles on their clothes and body) below the “no contamination” level. On average, people registered at levels lower than 13 kilo counts per minute, which isn’t known to be harmful.
Ten individuals, however, showed higher levels of radioactivity, but they were still too low to warrant decontamination. Researchers also found a trend among the safety shelters, with locations closer to the plant showing higher exposures in the air. As expected, outdoor air was linked to higher radiation levels than indoors. All levels declined with time.
Though the report is preliminary, it puts forth estimates that may be representative of the area. It’s also worth mentioning that scientists measured radiation exposure indirectly — through detectable particles on a person’s body rather than internally, or measuring how much material a person has accidentally inhaled or consumed. Even so, radioactive particles on a person’s clothes likely serve as a good indicator of how much radiation was present in dust particles in the air.
Overall, the team thinks long-term studies will be needed to establish whether these low-exposures add up over time, especially in newborns and fetuses, which are more sensitive to the negative effects of radiation.
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