Fears that fires scorching forests near Chernobyl may reawaken dangerous amounts of radioactive fallout and propel it into the air are overblown, scientists say, and the actual health risks are very small.
Even firefighters tackling the blazes, which officials say have hit forests in Russia's Bryansk region polluted by radioactive dust from the 1986 Chernobyl reactor disaster, are unlikely to run any added nuclear contamination risks. The amount of radiation in smoke would be only a fraction of the original fallout, they say.
"Of the total radioactivity in the area, much less than one per cent of it will be remobilised," said Jim Smith, an expert on Chernobyl and a specialist in Earth and Environmental Sciences at the University of Portsmouth.
Bryansk, which borders Ukraine, was among the regions worst affected by the Chernobyl disaster on April 26th, 1986, the world's worst civilian nuclear disaster, which dumped radioactive dust across Ukraine, western Russia and Belarus.
Radioactive contamination in the area has substantially diminished since the explosion.
"Most of the radioactivity is in the soil, which will not be affected by the fires, and only a small proportion is in the vegetation," Mr Smith said. "And of that only a very small proportion of that will get re-suspended in the smoke from the fires."
Russia's worst heatwave since records began has set ablaze thousands of hectares of forest, killing 54 people and leaving thousands homeless. The Kremlin declared a state of emergency in seven regions last week. President Dmitry Medvedev today cancelled a state of emergency in three out of seven regions affected by forest fires.
A statement from Russia's forest protection agency said fires covering an area of 39 square km had been registered in radiation-polluted regions. The deputy head of the agency said yesterday most of the fires had been extinguished.
The overall area of Russia's forest fires decreased by 100 square km today from 927 square km a day ago, the Emergencies Ministry statement said. More than 50,000 people were putting the fires out.
Weather forecasts for the next four to five days may favour the eruption of new fires but temperatures will cool gradually from next week, Russia's weather service said today.
Both France's Institute for Radiation Protection and Nuclear Safety and Germany's Federal Office for Radiation Protection said today that while some radiation was likely to be remobilised in smoke, the health risks were minimal and would have no impact on either Russia or neighbouring countries.
"The fires do not have any radiological consequence for the rest of Europe and Germany since the dispersion of the radioactive substances is regionally limited," the German organisation said on its website.
According to experts, the types of radioactive isotopes that might still be active in the Bryansk area include strontium 90 and caesium 137. These substances have half lives of about 30 years, meaning that only about half the radioactive material emitted by Chernobyl is still around now.
"Even though the contaminated territories are affected by the fires in Russia, the situation would not lead to health concerns for the population, locally and in other countries in Europe," said France's Institute for Radiation Protection.
It said there may be a slight increase in radioactivity in the nearby environment due to re-suspension of caesium-137, "but it would be very much lower than the natural radioactivity."
Stig Husin, an analyst in emergency preparedness at the Swedish Radiation Safety Authority, said the main threat from the fires both locally and nationally in Russia was the choking smoke from forest and peat fires, and the smog which is clouding the air in Moscow - all of which can cause lung and heart problems.
He said those living near the Chernobyl-contaminated areas where fires have been reported would be wise to protect themselves by staying inside or wearing masks.
"Naturally it would be good if you are living close to the fires to protect yourself from the smoke itself. If you do protect yourself then naturally you protect yourself from the radioactive substances that may be in the smoke."