For instance, as a result of increased humidity. Or due to the presence of metal objects, metal piping, metals dispersion in cinders, silver, gold, and many other.
Kwa mfano, kama matokeo ya kuongezeka kwa unyevu. Au kutokana na kuwepo kwa vitu vya metali, kusambaza chuma, metali utawanyiko mwaka makaa, fedha, dhahabu, na wengine wengi.