Do not panic. This is the main message from a team of scientists who conducted a global survey on the radiation exposure caused by the meltdown of the Fukushima-Daiichi nuclear plant reactors.
The team’s conclusion: Everyone on Earth received the equivalent of an X-ray’s worth of radiation from the Fukushima accident. This risk is negligible. Every year, millions of patients receive CT scans in hospitals with higher doses than the exposure induced by the Fukushima event.
The nuclear reactor meltdown occurred after a 9.0-magnitude earthquake off the coast of Japan triggered a tsunami on March 11, 2011. During this event, large amounts of radioactive material were released, with about 80 percent deposited in the ocean and poles. The main source of radiation was the radioactive element cesium-137.
However, “we don’t need to worry,” said Nikolaos Evangeliou of The Norwegian Institute for Air Research at the annual meeting of the European Geosciences Union in Vienna, Austria, according to New Scientist. “What I found was that we got one extra X-ray each.”
The team conducted the first global survey of the radiation exposure caused by the Fukushima meltdown. Most of their data came from the Comprehensive Test Ban Treaty Organization, which uses a global network of stations to measure radiation levels in the environment.
To quantify the biological effect of radiation levels absorbed by human tissue, scientists use a unit called sieverts. After the Fukushima disaster, the average person received 0.2 millisieverts (mSv) of radiation.
This, the team says, is little compared to the annual background level of radiation in the UK, which is around 2.7 mSv a year. A standard chest X-ray is about 0.1 mSv, while a typical CT scan produces 15 mSv. To put this in perspective, it takes 1,000 mSv (1 Sv) for radiation sickness to occur.
If you were to be zapped with 1 Sv of radiation right now, you would likely experience an extreme case of nausea and vomiting, but you would not immediately die. However, you would be at an increased risk of conditions linked to radiation exposure.
The locals who lived near the Fukushima power plant received a slightly higher radiation dose at between 1 and 5 mSv. Further away in Japan, the average radiation dose was 0.5 mSv.
The ecosystem surrounding the Fukushima site took a much harder hit, with a decline in diversity reported for birds, insects, and mammal populations. On top of that, around 160,000 people were forced to flee their homes after the event, thousands of which are still displaced. Cleanup of the site continues to this day – and will for decades to come.