Q&A: Health effects of radiation exposure

Concern remains over the potential effect on human health from radiation leaks at the stricken Fukushima Daiichi nuclear plant.

A 20km (12 mile) evacuation zone affecting about 70,000 people has been imposed around the plant, and is being extended to five communities outside the zone to the north west of the plant, where radioactive contamination is most significant.

Residents living within 30km (18 miles) have been advised to leave the area, or to stay indoors, and try to make their homes airtight.

Experts believe that swift action of this sort should have minimised the risk to human health, but there are worries about the level of radiation to which emergency workers have been exposed, and about possible contamination of food and water supplies.