Hand-arm vibration and terrain vehicles.

Hand-arm vibration was measured on the handlebars of terrain vehicles (N = 36) and a postal inquiry was made among N = 2705 reindeer herders (snowmobile drivers). Since many subjects had also used other vibrating tools the snowmobile group proper (N = 334) was established. In the whole group 19% of the subjects reported having experienced white finger attacks and 48% numbness of the hands. The frequency-weighted acceleration of snowmobile vibration was 3.5 m/s2, and risk evaluation using the ISO 5349 standard predicted the prevalence of white finger well in the snowmobile group proper. The vibration levels were 1.6-7.9 m/s2 on snowmobiles, 5.5-11.8 m/s2 on all-terrain vehicles and 6.9-12.7 m/s2 on terrain motorcycles. The most critical points for damping the vibration were the motor mounting and resonance in the steering yoke. There is need for health care, technical improvements, and other protection means to reduce the symptoms of vibration in driving terrain vehicles.