OBJECTIVES

After completing this activity, the students will be able to:

$1.$ To assess the risk of manual lifting job.

$2.$ To calculate the recommended weight limit $($RWL$)$ and lifting index $($LI$)$ at both origin and destination of lift in order to identify the most stressful location of lift.

$3.$ To recommend ergonomics improvement to reduce the risk in the task condition of the worker.

DISCUSSIONS:

According to the U$.$S$.$ Department of Labor, handling is defined as: Seizing, holding, grasping, turning, or otherwise working with the hand or hands. Fingers are involved only to the extent that they are an extension of the hand, such as to turn a switch or to shift automobile gears.

Manual handling of containers may expose workers to physical conditions $($e$.$g$.,$ force, awkward postures, and repetitive motions$)$ that can lead to injuries, wasted energy, and wasted time. To avoid these problems, your organizations can directly benefit t from improving the fit between the demands of work tasks and the capabilities of your workers. Remember that worker$$ abilities to perform work tasks may vary because of differences in age, physical condition, strength, gender, stature, and other factors. In short, changing your workplace by

improving the fit can benefit your workplace by:

$$ Reducing or preventing injuries

$$ Reducing workers$$ efforts by decreasing forces in lifting, handling, pushing, and pulling materials

$$ Reducing risk factors for musculoskeletal disorders $($e$.$g$.,$ awkward postures from reaching into containers$)$

$$ Increasing productivity, product and service quality, and worker morale.

$$ Lowering costs by reducing or eliminating production bottlenecks, error rates or rejects, use of medical services because of musculoskeletal disorders, workers$$ compensation claims, excessive worker turnover, absenteeism$,$ and retraining. Manual material handling tasks may expose workers to physical risk factors. If these tasks are performed repeatedly or over long periods of time, they can lead to fatigue and injury.

The main risk factors, or conditions, associated with the development of injuries in manual. material handling tasks include:

$$ Awkward postures $($e$.$g$.,$ bending, twisting$)$

$$ Repetitive motions $($e$.$g$.,$ frequent reaching, lifting, carrying$)$

$$ Forceful exertions $($e$.$g$.,$ carrying or lifting heavy loads$)$

$$ Pressure points $($e$.$g$.,$ grasping $[$or contact from$]$ loads, leaning against parts or surfaces that are hard or have sharp edges$)$

$$ Static postures $($e$.$g$.,$ maintaining fixed positions for a long time$)$

Repeated or continual exposure to one or more of these factors initially may lead to fatigue and discomfort. Over time, injury to the back, shoulders, hands, wrists, or other parts of the body may occur. Injuries may include damage to muscles, tendons, ligaments, nerves, and blood vessels. Injuries of this type are known as musculoskeletal disorders, or MSDs$.$

Types of Ergonomic Improvements

In general, ergonomic improvements are changes made to improve the fit between the demands of work tasks and the capabilities of your workers. There are usually many options for improving a particular manual handling task. It is up to you to make informed choices about which improvements will work best for particular tasks.

There are two types of ergonomic improvements:

$1.$ Engineering improvements

$2.$ Administrative improvements

$1.$ Engineering Improvements

These include rearranging, modifying, redesigning, providing or replacing tools, equipment, workstations, packaging, parts, processes, products, or materials.

$2.$ Administrative Improvements

Observe how different workers perform the same tasks to get ideas for improving work practices or organizing the work. Then consider the following improvements:

a$.$ Alternate heavy tasks with light tasks.

b$.$ Provide variety in jobs to eliminate or reduce repetition $($i$.$e$.,$ overuse of the same muscle groups$).$

c$.$ Adjust work schedules, work pace, or work practices.

d$.$ Provide recovery time $($e$.$g$.,$ short rest breaks$).$

e$.$ Modify work practices so that workers perform work within their power zone $($i$.$e$.,$ above the knees, below the shoulders, and close to the body$).$

f$.$ Rotate workers through jobs that use different muscles, body parts, or postures.

Overview of MH Task Evaluation Tools

Introduction

Before we start a detailed description of the MH evaluation tools, it is beneficial to have a broad understanding of where the tools came from and when it is most appropriate to use them.

NIOSH Equations

The National Institute of Occupational Safety and Health $($NIOSH$)1991$ guideline consists of a series of mathematical equations developed based on historical injury data and related job data. The equations calculate recommended maximum safe weights of lift.

The $1991$ NIOSH equation is most appropriate to use when:

$$ the MH task is a lifting $($or lowering$)$ task,

$$ twisting occurs,

$$ container handle design is an issue.

In $1981,$ NIOSH incorporated epidemiological, biomechanical, physiological,