What is Impairment?

Impairment is the reduction in physical and /or mental ability of persons to carry out their work in safe manner. Fatigue stress chemicals. Medication illness, drugs and alcohol are causes of impairment; the major causes of impairment are fatigue and stress.


Fatigue is tiredness that results from physical and or/mental exertion. OR fatigue is the temporary inability, or decrease in ability, or strong disinclination to response to situation, because of inadequate recuperation from previous over-activity, either mental, emotional physical. Fatigue describes a variety of symptoms ranging from muscle pain to difficulty in concentration and sleepiness. The level of fatigue experienced will depend on the balance between the demands of work (workload imposed by a job, the length of shift, previous hours and days worked, and the time of day or night) and the opportunity to recover or recuperate from these demands through rest, sleep and relaxation.

The lack of recuperative rest, disruption to normal sleep routines and a lack of sufficient sleep lead to what is called sleep debt. (After the urge to breathe, the urge to sleep is the most powerful physiological urge.) Without enough sleep, the human brain may spontaneously shift into sleep in order to meet its need. Lasting from a few seconds to several minutes, these can have disastrous effects particularly if they occur while driving or operation machinery. One recent study showed that 17 hours of sustained wakefulness leads to a decrease in performance equivalent to a blood alcohol content of 0.05 per cent.

Lack of sleep and fatigue in combination, or separately, can adversely affect job performance, risking individual health and safety and the safety of others.

The risk factor is increased with any of the following:

Shift work, particularly extended shifts and night work;
Long hours of work and/or high levels of overtime;
Unpredictable work schedules. Particularly if there is a continual possibility of recall to duty;
Jobs which requires standing for lengthy periods, frequents manual handling or repetitive movements, and /or heavy work which is physically demanding;
Monotonous work or work where a high level of attention and alertness is required; and
Night work combined with extended hours.

Stress Top Page

Stress may be the result of exposure to a wide range of hazards in a work environment. Signs of worker stress (such as inability to concentrate) are very often also going to be conditions that impair a worker.

Stress is essentially a misfit between a worker’s needs and capabilities and what the workplace offers or demands. A ‘good job’ usually involves a measure of positive stimuli, which encourages the worker to perform well and gain job satisfaction as a result. On the other hand, many jobs involve negative factors that put unwanted pressure on the worker, leading to adverse consequences.
This is the ‘stress process’

Work related stressors can include:

Physical Organisational Industrial Social
Poor tool design
Poor lighting
Poor air conditioning
Too hot
Too cold
physical security
Deadline pressures
Excessive workload
Meaningless work
Lack of control
Inability to match
family/social needs
with job demands
Lack of recognition
Job insecurity
Poor career
Long hours
Inadequate pay
Client hostility
conflict with
Conflict with co-workers

Different workers may respond differently to exposure to these hazards.????

Once the causes of stress have been identified, the process then of assessing and controlling the identified, the process then of assessing and controlling the identified causes should then be followed (See: ‘How to Prevent Impairment at Work’ section).

See also: ‘Stop Stress at work a Guide for Workers (draft), ACTU OH&S Unit, October 2001

Information on the OH&S Rep website www.ohsrep.org.au


Many industrial chemicals, especially organic solvents, can have immediate as well as long term effects. Significant amounts of solvents are used throughout a range of industries including manufacturing, printing, construction, education, agriculture and services.

Solvents act on the nervous system in a similar way to alcohol and can cause headaches, dizziness or giddiness, weakness of the limbs, forgetfulness, nausea and abnormal tiredness.

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