The heightened levels reportedly lasted approx. 30 minutes. The increase may have been up to 20 times higher than the normal background levels.
Such an increase, however, does not represent any health impacts for the locals in Severodvinsk.
Health impacts for the local community would only be possible if the levels had increased more than 1000 times the normal background values, in the short time the spike lasted.
DSA has not measured any increase in radioactivity so far.
DSA has observed the available Russian monitoring stations, which report to the European Commissions data Center.
The results show no abnormal mean for the 24-hour interval after the accident.