[Relations between working conditions and occurrence of vibration disease in forestry workers. I]

The level of mechanic vibrations intensity of 20 motor saws of the BK-3a type and 5 saws of the Partner R-11 type was determined and the evaluation of 460 motorsawers' vibration exposure--in case of working on these types of saws--was performed. The evaluation covered saws of various technical conditions, with which felling, cross-cutting and trimming of soft and hard timber were performed. The vibration measured exceeds 3--5 times Soviet hygienic normatives and ISO, especially in octave frequencies of 63 and 125 Hz. The intensity level of vibrations was significantly dependent on the technical conditions of the saw, activities performed with it and the hardness of timber. The evaluation of the woodcutters' exposure to vibration in a day, a year and the whole employment period was performed on the basis of the test-checking, the ammount of timber produced, fuel used for the saw and days of saw-work. Daily exposure to vibration was 2,4 +/- 1,2 hours and was of intermittent, irregular character. Motor-sawers worked with saws from 31 to 296 days a year, producing yearly from 973 to 10.503 m3 of timber as m3 of timber felled.