Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Machine timber harvesting makes it possible to reduce substantially factors which have adverse impact on human health and which accompany manual-machine timber harvesting, presently predominating in Poland. The ergonomic factors classified into four following groups may be recognised as the main preconditions related to work with multi-operation machines: physical load – small energy expenditure, a very high value of repetitiveness and static efforts; mental load – high level of monotony, aesthenopia, a high level of stress; environmental load – significant limitation of hazard to operator’s hearing, work under conditions of thermal comfort, reduced vibration hazard; organisational load – a relatively low risk of work – related accidents, making it possible to perform work operations throughout the year, continued employment, high work autonomy, independence in decision making, a possibility for workers to organise themselves and form work teams. The paper presents subjective perceptions and opinions of fifty operators of specialised machines with respect to their work load. Almost a half of the respondents worked over 50 hours per week. One third found their work conditions difficult. Work pace was recognised as particularly challenging to their well-being as merely 6% of respondents found it relatively low. Additionally, the selected elements of assessment of workstations under study in terms of energetic costs and noise load is discussed The maximum energy expenditure of a machine operator is related to operations performed outside a cab: tuning up, routine maintenance, and repairs. Energy expenditure related to work inside a cab did not exceed 14 kJ/min. Noise level in a low-noise cabin was lower than sixty dB(A). Use of machines to a large degree eliminates important health-adverse factors accompanying combined machine-driven and manual timber harvesting, however, it creates conditions favouring occurrence of new ailments and diseases, totally different from those which have been recorded so far in forestry.