The Cable-bug phenomenon

In Chester there have been a number of incidents concerning large organisations where employees have been 'bitten' by insects.

Some standard characteristics include:

• A staff-intensive situation usually within a large organisation.
• A modern building with modern equipment.
• A high percentage of women employees in sedentary occupations.
• A comprehensive heating and ventilation system.

However, the possibility of finding an insect or mite responsible for the outbreak is to say the least remote. For what you will have on your hands, in most cases, is the phenomenon known as 'the cable bug' and that the irritation of the skin felt by members of staff was caused by environmental factors of one kind or another which would need further investigation.

The term 'cable bug' was coined originally because the earliest 'outbreaks' occurred in telephone exchanges when cables had outer coverings of fabric. Telephone cables are now made of copper conductor with pvc sheath and are pressurised to keep out water or moisture. There is therefore, no potential source of minute sharp particles likely to cause skin irritation.

The environmental problems, however, have gone on from there as our buildings and their furnishings become increasingly modernised and synthetic. Sharp paper dust particles cause skin irritations, and in Chester the culprit has usually been pig-hair carpeting. In addition, certain combinations of temperature and relative humidity seem to set the stage for itches. The skin becomes hypersensitive and then contaminants irritate it.

Whenever someone walks across a carpet or other floor covering the friction between their soles and the flooring generates an electrostatic charge. This passes onto their skin and accumulates with each step. The charge drains slowly from the body back to the floor, but, when walking quickly or for a long distance, people accumulate static electricity on their bodies faster than it can drain away. Problems arise, if someone takes 20 or 30 paces across the floor and then touches or passes very near another object.

Although the discharge occurs unnoticed, it is often sufficient to cause localised skin irritations and leave a tiny red rash similar to an insect bite. Temperature and relative humidity influence the magnitude of the discharge, while sweat, oils and other materials on the skin improve the electrical conductivity of the body surface and aggravate the situation.

The other prime suspect for phantom 'bites' can also be traced to carpets. Carpeting subjected to heavy wear in a hotel, hospital or a commercial premises sheds millions of fragments of fibre as the pile is constantly being damaged.

Vacuum-cleaner samples collected in such premises contain large numbers of tiny fragments of carpet or textile fibres. Coming from materials designed for heavy duty wear, many of these fragments are sturdy and, seen under the microscope, are like minute, inflexible spikes.

This particular matter is too small to be visible to the naked eye and is carried around the building on air currents or in the ventilation system. The fragments can pass easily through the mesh of nylon or other clothing material, assisted by normal body movements. When they reach the skin, these minute spikes can cause rashes and localised irritation which exactly mimic insect bites.

The situation is made worse on days of high relative humidity. Perspiration evaporates more slowly, providing a site where it is ideal for particles to adhere and be lubricated into the skin to cause an irritation. Wearing tight-fitting clothing reduced the rate at which perspiration
evaporates and similarly aggravates the problem.

Sometimes cleaning the filters and grills in the ventilation/air conditioning systems resolves the problem. Sometimes lowering or raising the temperature a few degrees has a beneficial effect. Sometimes 'misting' also helps by settling out the invisible particles. Sometimes none of these has any effect.

In premises where we have been called in some improvement has resulted.

• Standards of cleanliness had to be sharply improved in several instances.
• Heating and ventilation systems have been checked, overhauled or cleaned.
• Anti-static has been incorporated in cleaning products.
• Worn synthetic floor carpeting has been replaced.

Operators have been discouraged from sitting for prolonged periods on synthetic chair fabric on phone switchboards.

Animals have been excluded from office buildings.

Indiscriminate storage of large amounts of paper has been discouraged

Taken from a paper given by
Mr R D Hutchison, former Environmental Protection Manager.