A preliminary investigation on the traumatic accidents of farmers engaged in mechanized agricultural work was carried out from the viewpoint of epidemiology.
The incidence of traumatic accidents was higher in the group of machine operators than of non-operators, the male group than the female group, and the middle-age group and the group with over 4 years' career.
It was found from the cohort study that for the recent several years the male operators have been constantly in the traumatizing risk, but in the case of female oprators the traumatizing risk is increasing in the recent few years.
Traumatic accidents occured frequently during the busiest farming season and during 10-11 o'clock in the morning and3-5 o'clock in the afternoon.In the subjective symptoms a marked sign of fatigue
From these facts, the high incidence of traumatic accidents might be attributed to the great strain of mechanized agricultural work. was found.
Authors keenly feel the necessity of ergonomic case-study on each traumatic accident.

Vibration and noise of three types of tractors were measured under various conditions of operation from the viewpoint of occupational health. The other hand, daily records of operation time of tractors were collected from 135 households and exposure time to tractor vibration were estimated from these data.
Vibration spectra are showed in Fig. 1 and noise spectra in Fig. 2. The peaks of vibration spectra of tractor's seats are in the high frequency range corresponding to rev count of the engines. However, components of the low frequency range become often hygienic problem, when compared to ISO's Standard 2631-1974 (E) “Guide for the evaluation of human exposure to whole-body vibration.”
Vibration acceleration levels of the tractor operating with various accessories are higher in the low frequency range than those without accessories.
Acceration levels of Y and Z directions are higher than that of X direction and unfavorable hygienically. Antivibration countermeasure should be taken to the Y direction not only to the Z direction.
Noise level of tractors exceed the hearing conservation criteria for daily 8 hour exposure, when they run at high speed. More serious problem is that the noise disturb speech communication between the driver and his co-workers or among co-workers. To prevent labor accidents tractor noise should be controlled.