MOSCOW  As if things in Russia were not looking sufficiently apocalyptic already, with 100-degree temperatures and noxious fumes rolling in from burning peat bogs and forests, there is growing alarm here that fires in regions coated with fallout from the Chernobyl nuclear disaster 24 years ago could now be emitting plumes of radioactive smoke.

Several fires have been documented in the contaminated areas of western Russia, including three heavily irradiated sites in the Bryansk region, the environmental group Greenpeace Russia said in a statement released Tuesday. Bryansk borders Belarus and Ukraine.

“Fires on these territories will without a doubt lead to an increase in radiation,” said Vladimir Chuprov, head of the energy program at Greenpeace Russia. “The smoke will spread and the radioactive traces will spread. The amount depends upon the force of the wind.”

Officials from Russia’s federal forest protection service confirmed that fires were burning at contaminated sites on Tuesday, and expressed fears that lax oversight as a result of recent changes in the forestry service could increase the chances that radioactive smoke would waft into populated areas.