NIOSH VIBRATION
MAY 2018 • E&MJ; 43 www.e-mj.com
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levels of vibration exposure in three directions: X (fore-aft),
Y (side-to-side), and Z (vertical). The term a
w
(8) represents lev-
els normalized to an 8-hr shift. The results presented in this
paper focus on vibration in the Z direction, since it is typically
of greatest interest and can be associated with the greater risk
for back injury/pain.
Vibration dose value (VDV) is a cumulative measure of vibra-
tion received by a person during the measurement period. This
measure is more sensitive to peak levels and transients and is
expressed in m/s
1.75
. The term VDV (8) represents levels normal-
ized to an 8-hr shift.
Health guidance caution zone (HGCZ) is a metric that uses
vibration level and duration to evaluate when a subject is
at risk of overexposure to WBV. The boundaries expressed in
frequency-weighted acceleration and VDV are shown above
for both the International Standards Organization/American
National Standards Institute (ISO/ANSI) and European Union
Good Practices Guide (EUGPG) for Directive 2002/44/EC.
These boundaries represent the minimum health and safe-
ty requirements for exposure of workers to the risks arising
from physical agents, such as vibrations. The exposure action
value (EAV) is the level below which health effects have not
Standard/EU Directive Lower Boundary—EAV Upper Boundary—ELV
ISO/ANSI 0.45 m/s
2
0.90 m/s
2
EUGPG 0.50 m/s
2
1.15 m/s
2
Table 1—Health guidance caution zone limit in frequency-weighted acceleration (a
w
).
Standard/EU Directive Lower Boundary—EAV Upper Boundary—ELV
ISO/ANSI 8.2 m/s
1.75
16 m/s
1.75
EUGPG 9.1 m/s
1.75
21 m/s
1.75
Table 2—Health guidance caution zone limit in vibration dose value.
