A small capsule containing highly radioactive caesium-137 was found inside the concrete wall of an apartment building, with a surface gamma radiation exposure dose rate of 1800 R/year.

[1] The capsule was detected only after residents requested that the level of radiation in the apartment be measured by a health physicist.

[1] The capsule was originally part of a radiation level gauge and was lost in the Karansky quarry in the late 1970s.

Doctors, unable to identify the root cause of the illness, attributed the diagnosis to poor heredity.

By the time the capsule was discovered, four residents of the building had died from it and 17 more had received varying doses of radiation.