تهیه کننده : دکتر مسعود مطلبی

NIOSH Lifting Guidelines Scientific Evidence from: Epidemiological Physiological Psychophysical Biomechanical

NIOSH Load Constant LC = 23 Kg Acceptable load to 75% of women and 99 % of men Recommended Weight Limit will be LC discounting factors due to less than optimum task

Loading Factors Horizontal Location (HF) Vertical Location (VF) Distance of Lift (DF) Asymmetry (AF) Coupling (CF) Frequency (FF)

NIOSH Lifting Equation RWL = LC x Hf x Vf x Df x Af x Cf x Ff H D V 23 Kg

NIOSH: The Factors D V H HF = 25/H H [horizontal distance] mid-point of the line joining the inner ankle bones to a point projected on the floor directly below the mid-point of the hand grasps (ie., load center).

NIOSH: The Factors V [vertical distance] vertical height of the hands above the floor V is measured vertically from the floor to the mid- point between the hand grasps, as defined by the large middle knuckle D V H VF = (1-(0.003*abs(V-75))

NIOSH: The Factors D [distance in vertical travel] vertical travel distance of the hands between the origin and destination of the lift. D V H DM= (0.82+(4.5/D))

NIOSH: The Factors A [Asymmetry Angle] defined by the location of the load relative to the worker's mid- sagittal plane, as defined by the neutral body posture, rather than the position of the feet or the extent of body twist NIOSH assumes that no pivoting or stepping occurs. AM = (1-(0.0032A))

NIOSH: The Factors Frequency Factor (by Table)

NIOSH: The Factors FM based on F, D, V

NIOSH: The Factors 1.defined as handles or hand-hold cut- outs of optimal design 2.For loose parts or irregular objects, (not containerized) a "Good" hand-to- object coupling would be defined as a comfortable grip in which the hand can be easily wrapped around the object 1.as handles or hand- hold cut-outs of less than optimal design 2. For containers of optimal design with no handles or hand- hold cut-outs or for loose parts or irregular objects, a "Fair" hand-to- object coupling is a grip in which the hand can be flexed about 90 degrees (see note 4) 1.Containers of less than optimal design or loose parts or irregular objects that are bulky, hard to handle, or have sharp edges (see note 5 below). 2. Lifting non-rigid bags (i.e., bags that sage in the middle. GOOD = 1.0 POOR=.90FAIR =1.0 or.95 Coupling Factor[CF]

1991 NIOSH Equation RWL = LC x Hf x Vf x Df x Af x Cf x Ff LI = L / RWL H D 23 Kg V

Successes (Waters, 1993; Garg, 1989)   Combined 4 disciplines of science  Asymmetry incorporated  Easy to use  Measure factors independently  Conservative estimates  Focuses on the biggest problem  Growing scientific literature review

Compromises Single equation for all populations AL not necessarily suit all people (advanced age, gender, weaker spines) Not include many variables Variables are not independent therefore, challenge multiplicative model.