" (Applications Manual for the Revised NIOSH Lifting Equation) This is an update and contains information on the physiological, biomechanical, psychophysical, and epidemiological aspects of manual lifting. This led to the recommendation by the ad hoc committee of the criteria for defining the lifting capacity of healthy workers. Since the basis of the previous calculation changed, the new criteria were used to formulate the revised lifting equation. (Applications Manual for the Revised NIOSH Lifting Equation) At the same time, it should be clear that the NIOSH lifting equation is only one of the tools in the effort for prevention of work-related low back pain and related disability. It should also be realized that lifting is only one of the reasons for work-related low back pain and disability. Other reasons for back pain are "whole body vibration, static postures, prolonged sitting, and direct trauma to the back." (Applications Manual for the Revised NIOSH Lifting Equation) Psychosocial factors, correct medical treatment, and job demands are also significant in the development of acute low back pain and may even lead to chronic disabling pain. (Applications Manual for the Revised NIOSH Lifting Equation)

6. The parameters:

The RWL is the new development in the NIOSH lifting equation. The RWL has been defined for a specific set of task conditions and that is the weight of the load that most healthy workers could perform over their duty hours, up to 8 hours and this should not increased chances of their developing lifting-related LBP or lower back pain. Here the workers should be free of adverse health conditions that would increase their risk of musculoskeletal injury. The estimate of the level of physical stress has been defined by the relationship of the weight of the load lifted and the recommended weight limit for the weight to be lifted. The lifting equation has been devised assessing the physical stress of two-handed manual lifting tasks. Thus, the application of the equation is limited to those conditions for which it was designed. In short, the lifting equation is meant to meet specific lifting-related criteria that cover all aspects of biomechanical, work physiology, and psychophysical assumptions and data. (Applications Manual for the Revised NIOSH Lifting Equation)

7. Other methods:

Another method is the ACGIH method and in general has the same assumptions as described for the NIOSH equation and adds some more. The specific definition given is that the method applies only to "two-handed, mono-lifting tasks within 30 degrees of the sagittal plane" (Faville; Shulenberger, 2004) What this means is that the body should not turn more than 30 degrees from the central plane. It also mentions that other factors based on judgment should be included when there is high frequency lifting or more than 360 lifts in an hour, enhanced periods of lifting that is more than 8 hours of lifting in a stretch, high twisting during the lifting exercise, lifting with one hand, lifting with the body in a seated or kneeling position, lifting in conditions of high heat and humidity, lifting items with shifting center of gravity like liquids, incorrect or unstable holding of the item or being in an unstable position with both feet not fully supported. (Faville; Shulenberger, 2004)

The third set of tables as designed by Snook and Ciriello take into account biomechanical and physiological stressors and based on the concept of a discreet population. The tables are designed to provide the maximum acceptable weight of lift, and the maximum possible frequency for lifting. This method accepts that there is no single maximum weight that is applicable for everybody as the capacity for lifting depends on the strength and endurance of the person concerned. Thus the best method for evaluating safe lifting or lowering is in terms of weights that most of the persons will be able to handle. The correct evaluation would be through determination of the percentage of population that would be able to handle the weight. The higher the percentage that would be able to handle the weight, the lower will be the risk. These tables apply to two handed symmetrical lifts and in situations where minimum force is required. At the same time, the limitations due to psychophysical responses and limitations due to coupling, floor coefficient, posture, etc. are also not considered. In terms of environment, the figures here have to be reduced by 20% when individuals have to work in hot areas. The greatest advantage of these tables is that they provide...

(Faville; Shulenberger, 2004)
8. Analysis for job on hand:

Some methods were being used for the purpose of having to perform calculation of some factors for the person that we have been talking about. The first question points to the maximum amount of weight that the person should be able to handle. By analyzing and following the three methods, the maximum amount of weight which is being permitted was being given as 51 pounds by NIOSH whereas for the other methods, it was 70.5 pounds and 90 pounds. The recommendation was being chosen by keeping the issue of safety in focus, and thus it was being decided that the maximum amount of weight that any individual should be able to handle/manage was that of 51 pounds. Since it is considered difficult in order to judge the amount of weight of the individual parcels, the packages which are to be handled/managed were being defined in terms of the items that would come. The second question was in relation to taking the material from the truck, and for the purpose of protection, it was being made sure that the amount of height from which the material would be accrued or received is never considered to be higher or being greater than that of 70 inches, as that is being considered to be the amount of the safe height. (Comparison of Three Lifting Guidelines: Whom Do They Protect?)

For this purpose, one should ensure that suitable ramps had to be constructed. Another question is with regard to getting the material from the truck, and it was being decided that there workers would be available inside the truck in order to push the material towards the side parts of the truck. Hence it could be in a position to be safely collected from a maximum amount of a distance of 25 inches. The company which was sending the material was being asked to improve or better the quality of the grips and thereby mark the packages which were exceeding the quantity of 51 pounds shown in red, which would make the lift to become a combined total effort of the two lifters and not just of one single person. The area wherein the trucks which came for loading and unloading was being resurfaced by means of rough tiles; this was done so that adequate friction was to be developed in that particular area. These suggestions are being based on NIOSH and that is only considered as a recommendation and it cannot be legally enforced upon. (Comparison of Three Lifting Guidelines: Whom Do They Protect?)

9. Other tasks:

There are different sets of work conditions in which the application of the lifting equation could result in under or overestimation of the physical stress connected with a particular work-related activity. Some of the following task limitations noted now need of further research before it is possible to extend the application of the lifting equation. First, the revised NIOSH lifting equation is focused on the assumption that activities which involve manual handling are mainly for lifting and those activities do not require significant efforts as compared to repetitive lifting tasks. Examples of such tasks are inclusive of holding, pushing, pulling, carrying, walking, and climbing. When such non-lifting activities account for more than 10% of the activity of the worker, then measures of workers energy expenditures or heart rate might be needed to find out the demands of the other tasks. The existing revised lifting equation are not inclusive of risk factors that account for unforeseen conditions, like unexpectedly heavy loads, slips, or falls by the individual carrying the load, etc. Additional biomechanical analyses are probably needed to evaluate the physical stress that will be placed on joints from such from traumatic incidents. (Applications Manual for the Revised NIOSH Lifting Equation)

Again, if the environment is unfavorable, and what that means is if the temperature is outside the range of 19 degrees to 26 degrees Centigrade -- 66 degrees to 79 degrees Fahrenheit or humidity not within 35% to 50% of relative humidity, then independent metabolic assessments would be made to judge the effects of these changes on heart rate and energy consumption. The other consideration is that revised lifting equation was not designed to evaluate tasks which involved one-handed lifting, lifting not in a standing position but while sitting or kneeling, or lifting while being within a constrained or restricted work space. Another question is of the equation not applying while lifting unstable loads. Here an unstable load would be defined as an item in…