Office safety

To reduce the risk of injury offices should comply with ergonomic principles. See attached poster for display in workplaces.

Desks

(a) The work surface area should be adequate for the tasks to be performed at the workstation. It should be large enough to accommodate a screen, keyboard and associated equipment, and leave enough room for writing and for the resting of hands and arms. The workstation should also be large enough to permit items used regularly to be within easy reach of the operator from the normal operating position.

(b) For single task operations (eg keyboard work), the work surface shall have minimum dimensions of 1200 mm X 800 mm.

Height requirements include:

Adjustable including a range from 610 to 760mm
Fixed height, 700-720 preferred but can be as low as 680mm
Sufficient space should be provided under the work surface to allow free leg movement without obstruction.
- The minimum knee space shall be 650 mm wide and 450 mm deep. For fixed height work surfaces the minimum height of the knee space shall be 645 mm.
- Leg space depth front to back measured at a distance above the floor of 120 mm shall be a minimum of 600 mm. Leg space depth should be available over the full 650 mm width.

The layout should permit the employee to adopt an upright and forward facing posture.

Keyboard working positions should follow these fundamental principles:

The feet must be firmly and comfortably supported either on the floor or on a footrest
There must be ample room to move the legs
The thighs must be adequately supported and the underside of the thighs should not be compressed by the seat edge
The natural curvatures of the spine should be maintained and excessive twisting and bending of the spine should be avoided
Frequent or continuous bending and rotation of the neck should be avoided
Shoulders should be comfortable and relaxed
Elbows should be close to the body and the elbow angle should be around 90 degrees
Frequent or continuous bending of the wrist (upwards, downwards or sideways) should be avoided.

Office Chairs

Office chairs should comply with the Australian Standard (AS/NZS 4438:1997). NOHSC (Ergonomic Principles and checklists for the selection of office furniture and equipment, Ergonomics Unit, NOHSC) makes the following recommendations:

Chairs and seating should be primarily designed to provide adequate support for the user, without placing unnecessary stress on any part of the body. They should encourage a posture, which allows for comfort, efficiency, and minimal muscle fatigue.

There are three major anatomical/ physiological factors, which need to be considered in sitting posture:

The posture of the spine
The type and amount of muscle work required to maintain comfortable postures
Compression of the tissues (particularly blood vessels and nerves) at the back of the thigh and behind the knee)

Chairs, considered suitable for the duties completed at the office, are classified as multi task chairs or keyboard operator chairs (AS/NZS 4438:1997, p 10). They should have the following features:

Adjustable seat height
Adjustable back rest height
Adjustable lumbar support
Seat tilt
A medium back rest, unless otherwise specified
No arm rests
The chair should have gas adjustments rather than manual adjustments. Lever adjustments are preferred and should be easily operated from the seated position

Chairs should be adjusted easily from the seated position. Lever gas lift adjustment is preferable. Armrests should not be used unless requested specifically by the user, as they can restrict access to the workstation. If armrests are requested, height adjustable armrests would be preferable. Executive type chairs with no option for separate backrest adjustment are not suitable for screen-based work. They may be suitable where mixed tasks are complete with only a small amount of screen based tasks.

Footrests

When working at a non-height adjustable desk, footrests should be used. Some but not all staff observed at the review, were using footrests. Staff who are not using a footrest and have insufficient foot support while seated at their desk should be supplied with one according to the criteria listed below.

The footrest should have the following features[1]

Wide enough to support both feet and allow change of position
Stability
Upper and lower surfaces should not be slippery
A variety of heights should be available

Other factors to consider:

Temperature, Humidity and Ventilation

The preferred work temperature in Australia is 20-26 degrees Celsius but 2 degrees lower in winter. Humidity refers to the amount of water vapour in the air. The optimum comfort range ofr relative humidity is 40-60 per cent. Ventilation refers to the movement of air and rate of fresh air input. Air movement should be between 0.1 and 0.2 metres per second. For each person a minimum rate of 5-10 litres per second per person for general office space or 10 litres per second for every 10 square metres of floor space is recommended.

Lighting

Illumination is measured in units of LUX – lumens per square metre. Suitable light levels based on AS 1680.1:1990: Interior lighting – General principles and recommendations are:

General background 160-240 lux
Routine office work (typing, filing) 400 lux
Work with poor contrast (proof reading) 600 lux

Light should fall from the side rather than from the front to avoid reflections on the work surface. The sides of desks should be parallel with fluorescent strip lighting. Avoid strongly contrasting lighting levels. Lights deteriorate with age and accumulate dirt over the surface. It is advisable to ensure that lights are cleaned at regular intervals, at least every 6-12 months.

Noise

The legal requirements are that workers are not exposed to more than 85 dB(A) of noise over an either hour period. Noise in an office environment is not likely to exceed 65-75 dB(A) but can have an adverse effect at this level.

Exposure to noise produces, raised blood pressure, acceleration of heart rate, contraction of blood vessels of the skin, increase in metabolism, slowing down of digestive organs and increased muscular tension.

Background noise levels have been shown to have a detrimental effect on complex mental activities as well as the performance of activities requiring high levels of skill and the interpretation of information as well as the ability to learn certain kinds of dexterity.

Working from home

Where staff are able to work from the home the employer is responsible for ensuring the safety of the home office and may undertake an assessment of same. A sample assessment form and employee informaiton is attached. More information on working from home is available from WorkCover.

[1] Guidance note for the prevention of occupational overuse syndrome in keyboard employment