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- 2005 No. 1093
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Regulations 4(1) and 6(5)

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

where:

*a*_{hv}is the vibration magnitude, in metres per second squared (m/s^{2};);*T*is the duration of exposure to the vibration magnitude*a*_{hv}; and*T*_{0}is the reference duration of 8 hours (28,800 seconds).

To avoid confusion between vibration magnitude and daily exposure to vibration, it is conventional to express daily exposure to vibration in m/s^{2} A(8).

The vibration magnitude, *a*_{hv}, is ascertained using the formula:

where:

*a*_{hwx},*a*_{hwy}and*a*_{hwz}are the root-mean-square acceleration magnitudes, in m/s^{2}, measured in three orthogonal directions, x, y and z, at the vibrating surface in contact with the hand, and frequency-weighted using the weighting W_{h}.

The definition for the frequency weighting W_{h} is given in British Standard BS EN ISO 5349-1:2001.

Where both hands are exposed to vibration, the greater of the two magnitudes *a*_{hv} is used to ascertain the daily exposure.

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*_{hvi}is the vibration magnitude for operation*i*; and*T*_{i}is the duration of operation*i*.

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).

Regulations 4(2) and 6(5)

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};*T*_{0}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/s^{2} 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 weightings 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*.

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).

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