4.2 NIOSH Lifting Guide
NIOSH
National Institute for Occupational Safety and Health
Human Limits Considered
• In NIOSH Lifting Guide
Epidemiology
Based on risk injury potential
Biomechanical
Based on compression limits for L5/S1 disk
Physiological
Based on Energy Expenditure Levels
Psychophysical
Based on muscle-strength  capabilities
Data
The greater the predicted compressive forces, the greater the number of lower back pain incidents
Compression Data
• Looks at existing studies on dead bodies
• 20 studies reporting disc endurance
• Studies are old because it is a trade-off protecting dead people's rights.
• Findings:
NIOSH Action Limit
• Below this line there is no problem/no need to worry about injuries
NIOSH Max. Permissible Limir
• Above this line it can be very very dangerous
1. Injury potential increases for some people
Description
1. Injury potential increases for most people
Description
2. A 350 kg (770 lb) compression on the L5/S1 disc
Description
2. A 650 kg (1430 lb) compression on the L5/S1 disc
Description
3. A metabolic rate of 3.5 kcal/min
Description
3. A metabolic rate of 5.0 kcal/min
Description
4. 75% of females are capable of exerting the necessary muscle strength
Description
4. 25% of females are capable of exerting the necessary muscle strength
Description
NIOSH LIfting Guide Equations
To figure out safety standards.
Recommended Weight Limit (RWL)
RWL = LC x HM x VM x DM x AM x FM x CM
• No discounting factor can be greater than 1
• If factor = 0 you should never do this activity
• Optimal conditions: symmetric lifting position with no torso twisting, occasional lifting, good coupling, <= 25 cm vertical distance of lifting
RWL =
FM x
AM x
DM x
VM x
HM x
LC x
CM
Horizonal Location
• Distance of the hands away from the midpoint of the ankles.
• How far away the load is from horizonal center of mass (point between the ankles)
• Maximum weight under ideal conditions
• LC = 23 kg OR 51 lbs
Assymmetric Lifting
• Angular measure of how far the object is displaced from the front (mid-sagital plane) of the worker's body at the beginning or ending of the lift, in degrees.
Vertical Travel Distance
• Absolute value of the difference between the vertical heights at the destination and origin of the lift
• How much is lifted UP
Vertical Location
• Distance of hands above the floor
• Harder to lift if it is on the floor
Coupling Multiplier
• Classificaation of the quality of hand to object coupling (Ex; handle cut out, grip)
Lifting Frequency
• Average number of lifts per minute over a 15 minute period
Lifting Index (LI)