Relation of digital arterial dysfunction to alternative frequency weightings of hand-transmitted vibration

This study compared the relative performance of alternative frequency weightings of hand-transmitted vibration (HTV) to predict the extent of cold-induced vasoconstriction in the digital arteries of HTV workers. The cold response of digital arteries was related to measures of daily vibration exposure expressed in terms of r.m.s. acceleration magnitude normalised to an 8-hour day, frequency weighted according to either the frequency weighting Wh defined in international standard ISO 5349-1:2001 (Ah(8) in ms-2 r.m.s.) or the hand-arm vascular frequency weighting Wp proposed in the ISO Technical Report 18570:2007 (Ap(8) in ms-2 r.m.s.). The measure of daily vibration exposure constructed with the frequency weighting Wp (Ap(8)) was a better predictor of the cold response of the digital arteries in the HTV workers than the metric derived from the conventional ISO frequency weighting Wh (Ah(8)). This finding suggests that a measure of daily vibration exposure constructed with the vascular weighting Wp, which gives more weight to intermediate- and high-frequency vibration (31.5 – 250 Hz), performed better for the prediction of cold induced digital arterial hyperresponsiveness than that obtained with the frequency weighting Wh recommended in ISO 5349-1 which gives more importance to lower frequency vibration (≤ 16 Hz).