UCLA

In the United States, whole body vibration (WBV) affects approximately 6 million workers who regularly operate trucks, buses, heavy equipment, forklifts, planes, helicopters, small marine craft, high-speed crafts, and ships. Continuous exposure to excessive levels of vibration can cause irreversible damage to the human body. Prolonged exposure to whole body vibration has been linked to various adverse health outcomes including physiological effects, musculoskeletal disorders, as well as diseases of the nervous, digestive, and circulatory systems (Byeon et al., 2013).

There is a high prevalence of back pain among aircrew in the MH-60S community that can potentially jeopardize operational readiness and safety in the military. Questionnaire data for 884 aircrew personnel sitting on the left and right gunner seats of the MH-60S helicopter were collected from 11 September 2017 to 11 September 2018. 854 of the 884 aircrew (96.6%) responded that they experienced back pain. The average pain reported by aircrew personnel experiencing pain on a scale from 0 to 9 was 4.79 with a standard deviation of 1.84. Vibration data collected, using tri-axial seat pad accelerometers, showed that 89% of the flying events that were evaluated exceeded the American Conference of Governmental Industrial Hygienist (ACGIH) action level, defined as half of the threshold limit value, with 22% of the events exceeding the threshold limit value. The threshold limit value is the maximum level to which a healthy worker can be exposed day after day for a working lifetime without adverse effects.

Per the ISO 2631-1 standard, since each of the flying events had crest values greater than nine, the vibration dose value was calculated for this study. After calculating the vibration dose value for each of the flying events it was found that all 18 (100%) of the flying events exceeded the action limit and of those 44% of the flying events exceeded the limit value. Aircrew sitting in the current gunner seats have the potential to be exposed to whole body vibration exceeding both current ACGIH TLV and AL as well as ISO 2631-1 Limit and Action values.