Whole-body vibration (WBV) comprises the transfer of relatively low-frequency environmental vibration to the human body through a broad contact area. These frequencies are in the range of 0.5 to 80 Hz (ISO, 1997; ANSI, 2002). Transmission occurs through the feet when standing, the buttocks when sitting (most common scenario) or the entire body length when reclining in contact with the vibrating surface. WBV exposures exist in many occupational settings. The body as a whole and each individual organ have natural frequencies that can resonate with vibration energy received at their natural frequencies. Resonance of the body or its parts due to WBV is suspected to cause adverse health effects, primarily with chronic exposure. Presently, most evidence supporting this relationship is epidemiological. Direct medical evidence is scarce, especially when compared to the greater amounts of data available for hand-arm vibration (HAV) illnesses that occur at higher frequency ranges. HAV exposures occur with higher vibration frequencies applied to the fingers and hands using powered hand tools, resulting in known adverse health effects such as "white finger" (Janicak, 2004). In the U.S., standards are available for reference, however, no specific regulations (such as the Code of Federal Regulations) mandate WBV identification, monitoring and control. In Europe, WBV monitoring and exposure limits have been addressed in mandatory standards and regulatory directives. The methodology used to monitor WBV is similar to that used to monitor occupational noise. Accelerometers are used in place of a microphone, and recording the direction of vibration waves is critical. WBV level is measured as oscillation about a fixed point and recorded in m/s2; noise energy is measured as rapid variations in air pressure and is recorded in decibels. Assessing noise and WBV exposure levels relative to mandatory levels (noise) or ISO/ANSI guidance levels can be fairly simple using devices such as a dosimeter and a human vibration meter/data logger, which are available from various manufacturers. Identifying probable sources of adverse noise and WBV exposure levels can be more difficult and tedious, and involves more complex data collection procedures with more sophisticated instrumentation and data-logging capabilities. A 2006 survey of U.S. safety and health professionals was conducted to determine knowledge and awareness of WBV. Analysis of the data revealed a relatively low knowledge of the topic. Of the respondents, 69.5 percent self-reported less than a basic understanding of WBV (Paschold, 2008). Many positive steps can be taken to eliminate or reduce harmful WBV exposure. These methods can include engineering redesign, procedural changes and employee training. However, before these corrective actions can be undertaken, WBV exposure must be identified and assessed.
Vibration; Vibration-effects; Vibration-exposure; Humans; Body-regions; Vibration-exposure; Epidemiology; Biological-effects; Chronic-exposure; Acceleration; Vibration-monitors; Data-processing; Measurement-equipment; Exposure-assessment; Exposure-levels; Health-surveys; Standards; Monitoring-systems
Helmut W. Paschold, School of Public Health Sciences and Professions, College of Human and Health Services, Ohio University, Athens, OH 45701, USA