Ergonomic risk factors are conditions of a job process, work station or work method that contribute to the risk of developing a WMSD. For an example, see the Hazard Zone Checklist*.

1. Awkward/Static postures

Posture is the general position of your body in space or the position of any body part/joint with respect to adjacent body parts. Body posture determines which joints and muscles are used in an activity and the amount of force or stresses that are generated. An awkward posture is any body position that overloads muscles, tendons, or joints. The more a joint deviates from the neutral position the more the posture is considered to be 'awkward' and the greater the risk of injury.

2. Exertion of force - manual handling (including lifting, pushing and pulling)

When doing work the body uses muscles to generate force to allow for movement of body segments. Tasks that require forceful exertions place higher loads on the muscles, tendons, ligaments and joints that can result in fatigue and WMSDs.

3. Work procedures

Work procedures determine rest periods, shift work and work pace. They determine the duration, frequency or severity of exposure to ergonomic risk factors and consist of work methods, training, job rotation, job design and equipment maintenance.

4. Contact stress

Contact stress occurs when pressure is exerted on soft tissue of the body, for example resting the arms on the hard edge of the work surface and when gripping tools or materials. Pressure on the soft tissue can result in musculoskeletal disorders due to inhibition of nerve function and blood flow.

5. Repetitive work

Repetition refers to a series of motions performed repeatedly with little variation over an 8-hour day this may produce fatigue and muscle-tendon strain eventually leading to tissue damage and musculoskeletal problems. The severity of the risk depends on how often the action is repeated, the speed of the movement, the required force and the awkwardness of the posture. If motions are repeated frequently without adequate time for recovery, fatigue and muscle tendon strain can accumulate, which can result in permanent tissue damage.

6. Vibration

Exposure to local vibration occurs when a specific part of the body is exposed to a vibrating object, for example, a power hand tool. Whole body exposure occurs whilst standing or sitting on and object that is vibrating, such as. vehicles or large machinery.

7. Duration

Tasks that require use of the same muscles or motions for long periods increase the risks of acquiring a MSD.

Note: Workplace conditions that can increase the risk of WMSDs include cold environments, insufficient rest breaks, machine paced work. Jobs that combine risk factors will increase the risk for musculoskeletal problems. The level of risk depends on how long an employee is exposed to these conditions, how often they are exposed and the level of exposure. Jobs that have multiple risk factors have a higher probability of causing a WMSD.


Based on NIOSH elements of an Ergonomic Program, which can be found at:

Ergonomic risk assessment is proactive approach to occupational health and safety, which includes identifying the hazard, estimating the risk (likelihood and severity of harm) and making recommendations to control the risk where necessary.

A risk assessment is the process of risk analysis and risk evaluation. Risk analysis is the use of available information to identify hazardous tasks and to estimate the risk. Risk evaluation is the process based on the risk analysis but taking into account other factors, such as economic and social, in which judgements are made on the acceptability of the risk.

The process is carried out in a number of steps, which will be discussed in the following pages.

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General Introduction to Occupational Health: Occupational Hygiene, Epidemiology & Biostatistics by Prof Jonny Myers is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 South Africa License