[Spectrum character of vibration and clinical form of vibration disease]

300 workers of metalurgical plant exposed to vibrations were divided according to the chief work tool into the three groups: 1) moulder, 2) mould cleaner and 3) ironworker--grinder. The velocity of vibration was measured and the spectrum of vibrations examined. The product of vibration velocity excesses was evaluated within the following three bands of frequency: 16--63 Hz, 125--250 Hz, 500--2000 Hz and the frequency of occurrence of the two main forms of vibration disease, i.e. angioneurosis and osteoarthrosis was calculated. The osteoarthretic form of vibration disease was significantly more frequent when the multiplicity of surpassing the velocity of vibration occurred with low frequencies (moulders), and angioneurotic form was more frequent at high and very high frequencies. It seems, that "the safe limit" of vibration frequency should be transferred to frequencies higher than 500 Hz.