Russian authorities say wildfires are threatening a nuclear power plant in a region already contaminated by the 1986 Chernobyl nuclear disaster in Ukraine.
At least six wildfires have been put out this week in the Bryansk region - home of the Kursk nuclear power plant. Authorities have boosted the number of firefighters in the area.
The Emergency Situations Ministry said Wednesday experts have not yet found any increase in radiation levels from soil already contaminated by radioactivity from the Chernobyl catastrophe.
Elsewhere, firefighters near Moscow have begun to flood peat bogs burning outside the city. Thick smoke and choking pollution from the bogs has blanketed the capital for days, making it dangerous to go outdoors.
Officials during the Soviet days drained the bogs to harvest the peat for fuel. What remains is highly combustible. Russian environmentalists and local residents have criticized the government for what they say is its failure to properly monitor the drained bogs for fires and manage forests.
A shift in wind direction has blown some of the smoke away from Moscow, But weather forecasters say the smog could return as soon as Thursday. They warn that temperatures will continue to reach at least 34 degrees Celsius through the end of the week.
The United States has issued a travel warning for Russia because of wildfires and pollution. Authorities have also begun evacuating non-emergency workers and their families from the U.S. embassy.
The official death toll from the Russian wildfires is at 52. But Moscow health chief Andrei Seltsovsky said Monday the city's daily mortality rate has jumped from 350 to around 700.