Visual Display Units are often blamed for causing headaches, eyestrain and an assortment of other ills but how much of this is really true and how much is just office myth?

The simple fact is that there is very little evidence VDUs actually cause any permanent eye damage.

Most people experience some discomfort or eye fatigue after working at a computer monitor for a prolonged period of time but this is perfectly normal and can generally be avoided by good working practises.

The most important thing is for the VDU to be positioned where it can be seen without discomfort. Adequate workplace lighting should be available so that the constantly flickering light of the VDU does not provide the main source of illumination. Remember that flickering lights can trigger epilepsy and migraine headaches.

Contact lens wearers may find working with a VDU causes their eyes to feel dryer than usual.

This is usually because the heat from the VDU dries out the atmosphere in a room and also because VDU users tend to stare at their monitors for abnormal periods of time. The answer is to use eye drops to keep the eyes moist or wear ordinary glasses for work.

Some users may see a coloured "after image" after prolonged VDU work. This is perfectly normal and does not harm vision but can be a little disconcerting. Other users may experience headaches but these headaches are rarely caused by the use of a computer monitor.

The cause is usually stress, tension, eye strain from extended periods of work, poor working posture or a combination of these things.

Users should be careful of using a monitor that has excessive flicker or appears to be out of focus. This indicates a fault and should be checked by an engineer.

Computer monitors have been at the centre of several scares concerning unacceptable levels of radiation. Simply, modern VDUs do emit both visible light and other forms of electromagnetic radiation but these levels should be set well below the safe levels ordained by international watchdogs to safeguard computer users.

This means employers do not need to check radiation levels and employees are quite safe without needing protective goggles, aprons or additional monitor screens.

Pregnant women have nothing to be afraid of, according to many experts in the VDU industry. evolution's advice is to contact your doctor if you have any concerns.

A small number of people have experienced irritation and skin rashes whilst working with VDUs.

The exact cause is not known but it would seem possible an electrostatic charge in the room combined with dry air and the individual's own susceptibility may be a part of the problem.

It is possible increasing humidity levels and reducing the electrostatic charge may help.

If you have any concerns then contact your equipment supplier for more information or speak to Nick Wilmot at the environment and housing department of Brighton and Hove Council on 01273 291799.

So what can you do to make sure you are not affected by VDU strain?

Adjust your chair and VDU to find the most comfortable working position.

A broad guide is the top of the VDU should be at the level of your eyes.

Don't sit in the same position for long periods.

Make sure you have enough work space.

Make sure you do not have bright lights reflected in your screen.

Do not sit facing windows or bright lights.

Make sure the characters on your screen are in focus and do not flicker.

Make sure finger marks and layers of dust are removed.

Adjust the brightness control to suit the level of light in the room and ensure a comfortable level of on-screen brilliance.