Hazard Category - Vibration

​Whole-body Vibration

The movement that occurs when oscillatory motions are transmitted to the entire human body through contact with a vibrating source at the feet for a standing individual, at the buttocks for a seating individual, and along an entire side of the body for a supine individual.

Data Requirements
Collect WBV test data according to MIL-STD-1472H, ISO 2631-1, and TOP 01-1-014A^1,2,3. Ensure data are representative of the use scenario, including test conditions for all terrains, speeds, occupied seat locations, and vehicle loads. Measurements should include the frequency weighted root mean square acceleration, crest factor, and vibration dose value for each of the three orthogonal axes (X, Y, and Z) at the seat pan.

Health Protection Criteria

MIL-STD-1472H describes three categories of environments to evaluate vibration and shock ¹. The majority of Army vehicles fall into Category A where data are processed IAW ISO 2631-1^1,2. Exposure within the health guidance caution zone of ISO 2631-1 should be avoided or minimized².  Some Army exposures are considered Category C, or multiple shock, and are evaluated IAW ISO 2631-5^1,4. Engineering controls and design features are available to control Soldier exposures to WBV (e.g., adding active vibration damping systems, replacing current seating with air ride seats, modifying suspension systems, isolating the engine and/or cab from the vehicle), and should be applied to the maximum extent feasible to the design.  

Hand-arm Vibration

The mechanical vibration that, when transmitted to the human hand-arm system, causes risks to the health and safety of workers.

Data Requirements

Provide detailed use scenario information (e.g., exposure duration and frequency, number of operators, and work/rest schedule). Collect HAV field data according to ISO 5349-2⁵. These frequency-weighted vibration magnitude data must be representative of the equipment's intended operating conditions. Alternatively, provide manufacturer specification's with tools tested according to ISO 8662 or ISO 28927^6,7. These manufacturer values are laboratory values and require use of a safety factor when determining field exposure.

Health Protection Criteria
ANSI provides exposure limit values for the control of HAV^2,8. The upper limit of the health risk zone is defined as the daily exposure limit value equal to 5 meters per second squared. The lower limit of the health risk zone is defined as the daily exposure action value equal to 2.5 meters per second squared. 

For more information and guidelines for assessing vibration health hazards, see Technical Guide 351C, Health Hazard Assessor's Guide.

References

^{(1) ISO 2631-1: 1997. Mechanical Vibration and Shock. Evaluation of Human Exposure to Whole-body Vibration. Part 1: General Requirements.} 

^{(2) DOD. 2020. MIL-STD-1472H, Department of Defense Design Criteria Standard: Human Engineering.} 

^{(3) ATEC. 2011. Test Operations Procedure (TOP) 01-1-014A, Ride Dynamics and Evaluation of Human Exposure to Whole-Body Vibration.} 

^{(4) ISO 2631-5: 2018. Mechanical Vibration and Shock. Evaluation of Human Exposure to Whole-body Vibration. Part 5: Method for Evaluation of Vibration Containing Multiple Shocks.} 

^{(5) ISO 5349-2: 2001. Mechanical Vibration. Measurement and Evaluation of the Vibration Transmissibility of Gloves at the Palm of the Hand.} 

^{(6) ISO 8662 Series, Hand-held Portable Power Tools - Measurement and Evaluation of the Vibration Transmissibility of Gloves at the Palm of the Hand.} 

^{(7) ISO 28927 Series. Hand-held Portable Power Tools - Test Methods for Evaluation of Vibration Emission.} 

^{(8) ANSI/ASA S2.70-2006(R2020). Guide for the Measurement and Evaluation of Human Exposure to Vibration Transmitted to the Hand.}