Russia denies that there is a radiation hazard anywhere in the country after higher levels of radioactive materials have been measured in the air above Northern Europe.

The particles are said to come from Western Russia.

Sensors in Sweden, Norway and Finland had measured “minimal” elevated levels of radionuclides, man-made nuclear substances, in the air at the beginning of this month.

According to an international organization that supervises compliance with a treaty that prohibits nuclear testing, these are substances that result from nuclear fission.

Kremlin spokesman Dmitri Peskov assured Monday that Russia has “a very sophisticated radiation monitoring system” and that no alarms have been triggered.

“We do not know the source of this information,” was Peskov’s comment on the claim that the particles came from Western Russia.