A.The fire at Fukushima’s Daiichi reactor 4 is thought to have released the most radiation so far, with readings after the blaze showing 400 millisievert (mSv)
per hour.
For comparison, a chest X-ray will give a 0.2 mSv dose and the legal limit in the UK for nuclear workers is 20mSv per year.
The levels later dropped to 0.6 mSv per hour but radiation is believed to have entered the atmosphere.

Q.Who has been affected so far?
A.The International Atomic Energy Agency (IAEA) said 23 people near Daiichi have tested positive for radiation and have been decontaminated. 140,000 people within 30km of Fukushima have been ordered to stay indoors, but one expert said the risk is limited to a small area. “Radioactive material will reach Tokyo but it is not harmful to human bodies because it will be dissipated by the time it gets to Tokyo,” said Koji Yamazaki, professor at Hokkaido University.

Q.could more radiation be released?
A.Fukushima’s reactor 2 is the most pressing concern, with authorities unsure about whether the reactor’s casing is damaged. Reactor 4’s status is still unclear. But Fukushima Daini, Onagawa and Tokai plants are now in a safe condition, authorities say.

Q.how are humans affected by radiation?
A.In the short term, exposure to radiation can cause temporary radiation sickness, with vomiting, bleeding, burns and diarrhoea. Large doses of radiation or a long exposure can increase the risk of certain cancers.
• Sources:?IAEA, Reuters, TEPCO, Nuclear and Industrial Safety Agency, NHS