Safety Basics

The vast majority of people don’t actively think about safety when using a computer or other devices, although most automatically use common sense to deal with the problem. Unfortunately, there are those, who, through ignorance or sheer carelessness, put themselves and other people at risk.

By necessity, this document only skims the surface of the subject. If you have doubts about any other aspects of safety you should consult the appropriate expert.

The Legal Position

Apart from a moral responsibility, those within a ‘place of work’ who ignore safety issues leave themselves open to prosecution. For example, legislation in the United Kingdom’s Health and Safety at Work Act (HASAWA) and its subsequent additions make both employer and employees accountable to the criminal courts for any death or injury at a place of work.

In recent years there has also be an increase in litigation for damages, which are carried through the civil courts. Unlike a criminal prosecution, however, a lower level of proof of negligence is required and the amounts paid in compensation can often be astronomic. Although some protection can be provided by using a public liability insurance policy or a special policy, the insurance company can refuse to pay out if the owners of the policy have been criminally negligent.

Generally speaking, an employer can usually avoid criminal or civil prosecution if proof is provided that reasonable care was taken to avoid damaging the health or safety of employees. This usually involves the setting up of a safety regime, with regular safety checks being made and recorded, as well as appropriate safety training. Unfortunately, such practices often stifle the natural instincts of those at work, ironically compromising safety in the process.

Although a ‘place of work’ is normally a factory or building used by some kind of business, under some circumstances it can be your own home. You should check your legal position.

Safety Aspects

Safety risks are divided into physical, electrical and chemical hazards, any of which can be connected with the greatest danger of all, fire. Although there’s a legal requirement to consider all of these aspects at a place of work, there’s also a moral aspect in the domestic environment.

Physical Safety

This aspect is primarily concerned with objects that could impede movement, perhaps during evacuation in an emergency, or that could cause physical injuries. Examples include:

Sharp edges: these must be reported to an assigned person and corrected.
Obstructions: any blockages to doors and gangways must be removed.
Precarious objects: items must sit ‘four square’ on a stable surface at a sensible height.
Loose items: any items that are improperly fitted, such as shelves, equipment stands, fans, loose ceiling tiles or ventilation diffusers should be removed as soon as possible.
Trip hazards: extra electrical sockets should be provided or cables extended to prevent ‘bow string’ wiring. Also, floor coverings must have safe edging at joins or doorways. In addition, equipment and materials shouldn’t be stored on the floor, except within marked areas.
Tools: these should be stored in an appropriate manner. Single-sided razor blades, as used for traditional tape editing, should be disposed of safely, usually via a special metal box.
Machinery: must only be operated by those trained and authorised to do so.

To summarise this in a rather trite phrase: ‘a tidy workplace is a safe workplace’.

VDU Safety

This is an area of safety that’s often neglected: most people simply place a computer and screen on a table and then proceed to use it, without any consideration of posture and eyesight. By making a few simple changes you can improve your general comfort and avoid harming your health.

Lighting

This shouldn’t result in any glare or reflections on the screen, which might otherwise cause eye strain. Only indirect light should reach the screen, which can provided by:-

Using adjustable blinds or curtains at windows.
Adjusting the angle of the VDU to be at 90˚ to windows or fluorescent lighting tubes.
Using flicker-free virtual daylight tube (VDT) lights fitted with suitable diffusers.
Ensuring a lighting level of between 300 and 500 lux, resulting in a contrast between the ‘white’ level on the screen and the room’s ambient light level of between 3:1 and 5:1.
Providing additional lighting, such as an angle-poise lamp, where extra light is required. This can be used where the overall lighting isn’t compatible with that necessary for a VDU.
Adjusting the VDU contrast to make the ratio between ‘white’ and ‘black’ less than 3:1.
Minimising reflectivity of surfaces by, for example, using a matt finish on walls, to give:-

Area	Reflectivity
Walls	0.2 to 0.8
Ceilings	Less than 0.6
Floors	0.2 to 0.4

Posture

The positioning of a screen, keyboard, seating and work surface should be tailored to suit the individual concerned. The following general guidelines apply:-

You should view the VDU correctly, usually square-on. If you need to tilt it to avoid reflections then the lighting requires improvement (see above). Your eyes should be between 350 and 600 mm from the screen with your head inclined downwards by 15 to 30˚. However, you may need to incline your head a further 30 to 60˚ in order to look at the keyboard.
The seating at a VDU position must:
1. Have a five-wheel base.
2. Be adjustable in height between 340 and 520 mm.
3. Have an adjustable backrest to support the lumber region.
4. Not exert pressure the thighs, back of the knee or calf.
You must be in a comfortable position. For example, a foot rest must be provided if necessary for good posture. In addition, your thighs shouldn’t be under pressure from the underside of the desk but should be in an roughly horizontal position. Similarly, your forearms should be almost horizontal, with the elbow at the same height as the computer’s Home key.

Radiation

The amount of ionising radiation (X rays) produced by traditional CRT-based displays has been a contentious subject for years. Generally speaking, most modern display devices produce very little radiation, although if a user is concerned about this it may be easier to install an LCD screen.

Having said this, the amount of radiation produced by a display must be tested, and should be found to be less than 0.75 mrem/h (EMSC Guidance Paper 8 - Ionising Radiation applies). The amount of ultra violet (UV) radiation produced by CRTs is generally accepted as harmless.

Display Quality

A VDU shouldn’t exhibit any of the following problems:-

Flicker: although subjective, this shouldn’t be apparent where appropriate lighting is used.
Jitter: this is most noticeable when a TV receiver, which has ‘interlaced’ scanning is used as a VDU. It can also occur if other mains equipment is in close proximity to a CRT screen. Two adjacent VDUs can also have problems, in which case the backs of the monitors should be angled away from each other.
Swim: this appears as a slow drift of the image up and down or from side to side and can be caused by a fault in the VDU’s power supply circuitry.
Resolution: The display should be adequate to clearly differentiate between the following pairs of characters:-
X - K O - Q T - Y S - 5 B - 8 q - g y - g j - g

Lasers

Some laser devices produce a large amount of optical power, which has the potential to damage eyesight. Those used inside modern devices such as CD players are classified as follows:-

Class 1: considered harmless
Classes 2 to 4: increasing degrees of danger to the eyes

Note that these classes refer to the leakage of laser light from equipment as a whole, which means that, for example, a Class 1 device can contain a Class 3 laser, making the equipment far more dangerous when it’s partly dismantled.

Many lasers operate in the invisible infra red region of the spectrum, which means that you can’t actually see the light, although it can still damage your eyesight,

Sound Levels

Exposure to a high sound pressure levels (SPLs), as produced in a recording studio, can cause long-term hearing damage. In some instances, ear defenders are used, although these are unsuitable in a sound studio where high-powered loudspeakers should carry a safety warning.

Headphones are also a potential hazard, often generating surprisingly high levels of sound. It is of course possible to ‘hard wire’ headsets to a special amplifier that has SPL indicators, although these need to be calibrated on a routine basis.

Electrical Safety

The electrical system within a area can be separated into the electrical installation, forming part of the fabric of the building, and individual devices, usually in the form of portable appliances.

Generally speaking, modern installations and devices conform to a host of international standards, which makes them intrinsically safe, but only when used in the manner for which they were designed. For example, if you threw a heater into a swimming pool to warm it up, the device would either blow the fuse or circuit breaker, or you’d be electrocuted, since water often conducts electricity.

Both the installation and the separate devices must be checked for compliance with safety requirements and then rechecked on a regular basis.

Chemical Safety

Chemicals are covered by the Control of Substances Hazardous to Health (COSHH) regulations. Any substances whose package carries an orange rectangle comes under these rules. Such a rectangle (or rectangles) can contain one of the following:-

Flame: indicates a flammable chemical, usually harmless in other respects. Such chemicals, including aerosols, should be stored in a flammable storage area. Smoking is not permitted whilst such substances are in use. The chemicals must also be disposed of in a safe manner.
Skull and crossbones: indicates a substance that acts as a poison when taken by mouth. You should always wash your hands after using such chemicals.
Cross: indicates a substance that causes harm by inhalation, although it may or may not be a carcinogen. The situation can be made worse if the ‘victim’ is smoking at the same time!
Nothing: the substance is a danger due to more than one of the above reasons.

Small quantities of COSHH substances, such as correcting fluid, can be held in an office environment, but larger amounts must be locked into a designated cabinet. Safety information sheets must be provided for all chemicals in the workplace, allowing users to assess the risks, if any, associated with each substance. The following terms sometimes appear on such COSHH data sheets:-

OEL (occupational exposure level): the actual amount of a substance to which you have been exposed.
MEL (maximum exposure level): a level that must not be exceeded. There may be concern or uncertainty over the long term effects on your health.
OES (occupational exposure standard): an acceptable level which may be initially exceeded providing that steps are taken to reduce it.
SUP (suppliers standard): probably set to avoid action at law.
mgm^-3 (milligrammes per cubic metre): a measure of solvent vapour in air.
PPM (parts per million): an alternative measure of solvent in air.

Fire

The causes of a fire can include:-

Arson: often best avoided by cultivating good staff relations.
Smoking: ash trays to be used where provided and smoking stopped in ‘No Smoking’ areas.
Electrical: faulty devices should be switched off, if possible, and reported immediately.
Combustible material: unwanted material, such as packaging, must be removed.

The following should always be in good order:-

Fire point: has to be within less than 30 metres.
Fire evacuation notice: must be clearly visible in each room.
Exit route: must be clear of obstructions and be at least 3 feet wide.
Emergency lighting: has to provide adequate illumination for escape.
Door closers: these must actually work, so as to prevent the spread of fire.
Cable entries: these must be ‘pugged’ to prevent fire spreading.

The following shouldn’t be present:-

Dangerously hot surfaces: kettles and heating rings are a serious risk.
Flammable material: film or tape waste must be disposed of via designated bins.

In the Event of Fire

The following things are essential:-

Fire wardens: these people should be known to everyone on the site. They should understand their area of responsibility and during a fire evacuation must guide everyone out of the building in an orderly manner. Wardens must wear high visibility vests during evacuation.
Fire alarm: if this sounds, you must leave the building immediately. Don’t worry about your personal possessions, although you should turn off the power, if possible. If you discover a fire yourself you must set off the alarm before attempting to fight it.
Fire exits: always use the routes shown by the green signs, which must be provided. These should indicate the shortest way out. Fire exit doors must never be locked or barred.
Fire extinguishers: you should only attempt to fight a fire after setting off the alarm and you shouldn’t try at all if you’re uncertain about what to do. You should aim the extinguisher jet towards the base of the fire with a sweeping action. Two types of extinguisher are commonly used:-
1. Water (H2O, coded red): although very effective, this kind of extinguisher must not be used on electrical equipment or fires that involve flammable liquids.
2. Carbon Dioxide (CO2, coded black): suitable for use on electrical equipment or where the nature of the fire is unknown.