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 Health and Safety



Ergonomics for users of computers

Overview

This page is largely about posture - if you sit for long periods hunched over a PC, tablet, or laptop computer you may develop musculoskeletal disorders.

Typing for very long periods in front of a screen can cause temporary eye strain, sore dry eyes, headache, aching shoulders,  inflammation of the tendons of the fingers and wrist, pain in the legs and potentially Deep Vein Thrombosis (DVT).

Much of this can be avoided by getting up and taking short breaks every 20 to 40 minutes, blinking and focusing on distant objects.

Tips for users of desktop PCs

Ideally your chair height should be adjusted so elbows are level with the top of the table, the back rest adjusted to fit the small of the back, and the screen height adjusted so that the top is approximately level with the eyes.

Short people may require a foot rest if their feet do not touch the ground whilst very tall people might require the desk to be raised eg on blocks. Alternatively height adjustable desks can be purchased from specialist suppliers.

Wrist rests are generally considered unnecessary and liable to do more harm than good.

Overuse of the mouse scroll wheel should be avoided eg use up and down arrow keys instead.

If one shoulder aches, moving the mouse from the right to the left hand side and vice vecan can occasionally help, especially if you want to hold a pen or phone in the other hand.

Eyesight

Any deficiencies in your sight are going to be highlighted by spending long periods in front of a screen.

Ideally you should have your eyes tested every two years or so to check that your sight is not being affected by health problems such as diabetes, cataracts and glaucoma, and that your sight, if necessary wearing glasses or contact lenses, still meets the requirements for driving (which is to read a number plate at 22 metres).

If you are having trouble reading the screen, your eyes ache, or you are suffering from headaches, your first step should be to visit your optician.

If you have to wear reading glasses these might well suffice for working with PCs, but your optician might prescribe glasses which focus slightly further away eg at arms length.

If glasses won't resolve the problem, for example due to early stage cataracts or macular degeneration, you could  try adjusting the screen resolution (eg to 800 X 600 px) or by adjusting the zoom to make the characters bigger. Also consider buying a larger eg 21" monitor, adjusting the lighting and repositioning the screen to avoid glare.

Microsoft Windows offers a high contrast mode which allows a high contrast display to be selected such as white characters on a black background. This can be accessed by clicking Control Panel, Accessibility Options, Display, and can be toggled on and off by holding down Shift+Alt and pressing the Print Screen key. You may need to try various settings to find the one that suits you best.

Windows 7 has a magnifier mode which can greatly enlarge characters.

If your vision is impaired to the extent that the keyboard is not very clear, you may want to consider a high visibility keyboard with larger lettering and/or larger keys and a low wattage desk lamp to illuminate the keyboard.

Note that if you change the screen resolution, you may experience problems with some programs such as when the OK and Cancel buttons 'fall off' the bottom of the screen and no scroll bars are provided; in high contrast mode some webpage colours can be  difficult to read.

You may blink less when staring at a screen for long periods and this may cause the surface of the eye to become dry which can lead to sore eyes and possibly blurred vision. Blinking now and again may help prevent this.

Laptop computers

Laptop computers present their own problems. They are invaluable for giving presentations or working at home, but the keyboard and screen do not meet the ergonomic requirements described above.

The solution, at work, can be to insert the laptop into a docking station with a separate display, keyboard and mouse.

At home, or in a hotel room, ideally a riser should be used to raise the height of the laptop screen, and a separate keyboard and mouse used. At home the latter can be pushed under the riser when not in use.

Obviously if you are on the move this may not be possible, but then there could be other issues to consider such as backing up your files and encrypting the hard drive in case the computer is dropped, mislaid or stolen.

Tablet computers

Tablet computers, such as the Apple iPad are typically hand held devices, more likely to be used in informal situations and only used for short periods of time. Therefore the above provisions are less likely to apply, but should not be ignored completely.

A protective case is a good idea, and many of these can be folded so that the screen can either be used flat, or at an angle of about 20 degrees for typing, or at 70 degrees eg for video calls using Skype or Facetime. See the range of cases from Kavaj for example.

When using the touch sensitive virtual keyboard at the bottom of the screen your eyes may be nearer the screen than when using a desktop PC, so you might find your reading glasses work better than computer glasses used for PC work.

At close of day

It is a good idea to rest your eyes for ten minutes before driving home, particularly in the dark.

Further information

Posture guidance is available free from Osmond Ergonomics but you may need to create a username and password to log on and gain access.

HSE guide on Working with VDUs


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