The Control of Vibration at Work Regulations (Northern Ireland) 2005

Regulations 4(2) and 6(5)

SCHEDULE 2 WHOLE-BODY VIBRATION

PART I daily exposure to vibration

The daily exposure to vibration (A(8)) of a person is ascertained using the formula:

where:

• a_w is the vibration magnitude (root-mean-square frequency-weighted acceleration magnitude) in one of the three orthogonal directions, x, y and z, at the supporting surface;

• T is the duration of exposure to the vibration magnitude a_w;

• T₀ is the reference duration of 8 hours (28,800 seconds); and

• k is a multiplying factor.

To avoid confusion between vibration magnitude and daily exposure to vibration, it is conventional to express daily exposure to vibration in m/s² A(8).

Daily exposure to vibration (A(8)) is evaluated separately for the x, y and z directions of vibration.

For horizontal vibration (x and y directions), k = 1.4 and a_w is obtained using the W_d frequency weighting. For vertical vibration (z direction), k = 1.0 and a_w is obtained using the W_k frequency weighting.

Definitions for the frequency weighting are given in International Standard ISO 2631-1:1997.

If the work is such that the total daily exposure consists of two or more operations with different vibration magnitudes, the daily exposure (A(8)) for the combination of operations is ascertained using the formula:

where:

• n is the number of individual operations within the working day;

• a_wi is the vibration magnitude for operation i; and

• T_i is the duration of operation i.

PART II exposure to vibration averaged over one week

The exposure to vibration averaged over one week (A(8)_week) is the total exposure occurring within a period of seven consecutive days, normalised to a reference duration of five 8-hour days (40 hours). It is ascertained using the formula:

where:

• A(8)_j is the daily exposure for day j.

The exposure to vibration averaged over one week is for use only for the purposes of regulation 6(5).