THE CARPET PROBLEM
Carpets as a source of biological stress in homes and offices have been a subject of debate over the years. The Swedish Government went so far as to ban the use of carpets in government establishments since studies indicated that they were the source of asthma and other respiratory stress symptoms. The carpet industry however has been delighted to point to an increase in such symptoms since then. They claim that the positive static charge generated by carpets attracts airborne particles and retains them until cleaned. With hard floors, those particles that settle are easily disturbed by footfalls and sweeping. Synthetic finishes add to the static and volatile organic levels.
The problem in both cases is that a conventional vacuum cleaner will put the finer particles back into the air through the weave of the dust bag. Even vacuum cleaners with hepafilters still have problems with seepage around the edges of hepafilters. The solution is either the use of vacuum cleaners that use water filters or centralised cleaning where the dust is conducted to a central container away from the area being cleaned.
The carpet is now has an opposite effect and is increasing the concentration of airborne particles. The accepted standard for a carpet to be called antistatic is a cumulative charge of up to 2-3 thousand volts. This is below the level of charge where staff experience painful discharges on metal surfaces at 3.5 thousand volts. However the static field has another effect. A computer operator with his or her hands on a keyboard that is usually well within the MPR2 standards of 50cm, close to a 21” VDU. The hands in an electric field of up to 500 volts. The feet, seat and back are in contact with charged synthetic surfaces. The combination of static, electric field and friction will produce up to 8 thousand volts of positive static charge in the chair seat and back. High positive charge on the skin surface can cause irritation, rashes and undue temperature sensitivity, affect blood circulation and contribute to general aches and pains and body discomfort.
In periods of low humidity additional discomfort can be caused by delaminated nylon fibres from the carpet becoming charged and being attracted to legs and ankles where they get into the pores and have the same effect as itching powder. The victim scratches the skin, which bleeds and can become infected and is often ascribed to ‘fleas’. The end effect is indeed similar to a flea bite. The area is sprayed and the static is dispersed and the fleas seem to go away. However the problem will return when the area has dried out and similar humidity conditions repeat themselves. The problem of carpets delaminating applies mainly to cut pile carpets where the varying staple lengths imitate the structure of wool carpets. However nylon fibres have less friction than wool and tend to delaminate more easily. The body does not seem to react to wool fibres either in the skin pores or when inhaled. One the other hand charged nylon acts like itching powder on the skin and can irritate the respiratory passages.
Carpets can act as a repository of and breeding ground for bacteria, microbes and fungus spores. These obtain an ample supply of organic nutrient from skin cells and sebum as well as drink and food spillages. Most carpets are cleaned by suction vacuum cleaners and they tend to remove only the visible surface debris. The pressure of the cleaning head also forces much of the organic material deeper into the pile. The solution is to use agitation as well as suction and to have some form of indication when the hidden dust is cleared.
Reduction of acoustic stress
The fact that bitumen based carpets have a slightly tacky surface makes the other sticky skin cells, drinks and food harder to remove. Wet cleaning that is not rigorous enough can create a dried porridge effect on the material, which makes it almost impossible to clean
Volatile Organic Compounds (VOCs)
Volatile organic compounds in carpet construction and adhesives have been identified as a hazard in the past. Present manufacturing techniques seem to have resolved most of these problems. However most synthetic materials contain organic solvents that do de-gas in minute amounts during their lifetime. These can accumulate and or combine to create problems for sensitive staff. Airborne carbon has been identified as one of the means of absorbing and concentrating VOCs. There is trend towards replacing carpets with hard floors in offices. It will be interesting to observe whether this creates more problems than it solves.
Our solution is to have carpeting removed and replaced by either the plenum flooring system or a continuous filament carpet, to prevent delamination (breakdown into particles) with the additional advantage of being sound absorbent.
Both systems utilise a chemical impregnation method that makes the flooring antibacterial, anti-fungal and also anti-static.
Further recent trials showed that expensive supposedly ‘anti-static’ carpeting still retained charges of up to 700 volts DC. Quite apart from the proven deleterious effects on humans, these levels of static also greatly reduce the working life of computers and electronic components. We therefore specify a ‘O-Volts’ anti-static carpeting with built-in anti-fungal and antimicrobial properties. Ideally there should be installation of a positive-pressure plenum (hollow) flooring systemwith either a central or cassette (localised) AC system. This system provides ducting for all cabling to be safely carried under-floor and also introduces the air-flow from below. with exhaust air being extracted from above. This reduces the circulation of gases and particulate materials and prevents cramps and chills caused by cooler air sinking from above The company also utilises a unique cryogenic system to ‘bio-remediate’ the existing environment. Frozen nitrogen ‘pellets’ are fired into the carpeting to kill any bacteria or fungi by freezing. This totally-safe system means that no chemicals are used and the building can be immediately reoccupied. Frozen CO2 gas is also squirted into the AC system, killing any moulds or bacteria lurking there. Even cryptosporidium ( one of the most dangerous and difficult bacteria to destroy – some Canadian schools were demolished because of this problem ) is totally eradicated, as is the more famous Legionella bug. Again, the gas used merely evaporates safely and the building can be back in use straight away.