Fears that fires scorching forests polluted by Chernobyl fallout may propel dangerous amounts of radioactivity 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 tainted 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 percent of it will be remobilized,” said Jim Smith, an expert on Chernobyl and a specialist in Earth and Environmental Sciences at Britain’s University of Portsmouth.

Radioactive contamination in the area has substantially diminished in the almost two and a half decades since explosions at Chernobyl’s reactor No. 4 caused the world’s worst civil nuclear disaster on April 26, 1986.