Air pollution may be a bigger risk to health than exposure to radiation, such as that after the Chernobyl disaster, a study suggests.
The damaged reactor at Chernobyl
Researchers examined the health impact of the meltdown of the Chernobyl nuclear power plant, and the atomic bombs dropped on Japan in 1945.
They concluded the risks were probably no greater than those posed by obesity, smoking and urban pollution.
However, a radiation expert cast doubt on the BMC Public Health research.
He said the risks posed by radiation were not comparable to those from other sources.
Researcher Dr Jim Smith, from the Centre for Ecology and Hydrology, said exposure to radiation took fewer years off life expectancy than heavy smoking or severely obese.
He calculated that someone who was exposed to radiation after the Chernobyl incident had around a one in 100 chance of contracting a fatal cancer in later life as a direct result - in effect the mortality risk was increased by 1%.
Dr Smith estimated that exposure to air pollution, or passive smoking had a similar impact.
He conceded that the exact risk linked to pollution or passive smoking was harder to pin down.
But he said people living unofficially within the Chernobyl exclusion zone may have a lower health risk than if they were being exposed to the air pollution in a large nearby city such as Kiev.
Dr Smith said: "The perception is that there are big risks to public health from radiation exposure.
"This study shows that for the population exposed to significant doses of radiation from the Chernobyl incident, the risks of premature death are no greater than those of being subjected to prolonged passive smoking or of constantly over-eating.
"We can all face such health risks just going about our daily lives."
Fears and perceptions
He said people's fears or perceptions of the health risks they were exposed to after Chernobyl could prompt people to behave in ways which would actually have more impact on their health - such as becoming a heavy smoker.
But Dr Michael Clark, a radiation expert at the Health Protection Agency, said: "Comparing risks can give a helpful perspective but it needs to be done with care.
"Comparing the radiation risks of living near Chernobyl with the risk from air pollution in nearby Kiev may be relevant.
"However I'm not sure that it helps to compare the health risks from radiation among survivors of the atomic bombings in Japan with the risks from obesity or smoking.
"One is an extreme involuntary risk, the others are self imposed."
A UN report estimated around 9,000 people exposed to radiation in the Chernobyl incident in 1986 would die from cancer, although Greenpeace has said the number of deaths linked to the incident could be closer to 90,000.
The atomic bomb dropped on the Japanese cities of Hiroshima and Nagasaki are estimated to have killed a combined total of more than 200,000 people.