Bus driving is a high risk occupation for contracting ischaemic heart disease and other cardiovascular diseases. This excess in risk has been attributed to working conditions, and several psychosocial factors have been identified as contributing to this excess risk. Furthermore, bus drivers show a profile of coronary risk factors with high serum cholesterol and blood pressure compared to other employed men in Denmark. A pilot project in the Copenhagen area including self-governing and self-management, conducted by the bus drivers and an decrease in sickness absence.

A similar trial started June 2^nd, 1996 in a bus line in Roskilde. At that time the line will be conducted by BUS Danmark. Monitoring this trial regarding coronary risk factors and stress hormones is included in this project. 25 drivers are under study. Blood samples, saliva and urine specimens will be drawn before, during and after the implementation of the trial, and 48 hours blood pressure measurements are included. Measurements of cholesterol, HDL, fibrinogen, triclycerides, HbA1c, prolactin and dihydroepiandrosteronsulfate in plasma, cortisol in saliva and catecholamines in urine will be conducted in the study. These data will be correlated to the self-reported improvement in working conditions and longitudinally as the drivers themselves serve as their own control. Three points of measurement during the first year will be conducted.

The results will be used to asses the physiological benefits of improved working conditions and to what extent physiological monitoring can be used to evaluate interventions on organization of work.