Comparison of whole-body vibration exposures in buses: effects and interactions of bus and seat design.

Bus and seat design may be important for the drivers' whole-body vibration (WBV). WBV exposures in buses during actual operation were assessed. WBV attenuation performance between an air-suspension seat and a static pedestal seat in low-floor buses was compared; there were no differences in WBV attenuation between the seats. Air-suspension seat performance in a high-floor and low-floor bus was compared. Relative to the pedestal seat with its relatively static, limited travel seat suspension, the air-suspension seat with its dynamic, longer travel suspension provided little additional benefit. Relative to the measurement collected at the bus floor, the air-suspension seat amplified the WBV exposures in the high-floor bus. All WBV exposures were below European Union (EU) daily exposure action values. The EU Vibration Directive only allows the predominant axis of vibration exposure to be evaluated but a tri-axial vector sum exposure may be more representative of the actual health risks. PRACTITIONER SUMMARY: Low back pain is common in bus drivers and studies have shown a relationship with whole body vibration. Relative to a pedestal seat with its limited travel seat suspension, the air-suspension seat with its longer travel suspension provided little additional benefit. Exposures were below European Union daily exposure action values.