Pre war-II buildings were made on the whole with natural materials, mainly because that was all there was within the limits set by the simple existing technologies, transport dificulties and cost. An aditional factor was the availability of relatively cheap labour, which made the choise of materials more a matter of quality than of speed of construction. But with the development of modern transport and an abundace of fosil fuel power after the war, these restrictions dissapeared. Cheap energy gave a new freedom to the manufacturing process, while an increase in labour costs due to rising standarts of living added the new criterion of speed of construction. The advance of chemical technology and the advent of plastics and other man-made materials meant that the whole new type of construction emerged. These new products, most of which had never been seen on Earth before, were used to replace traditional materials like timber, brick and stone. 40 years later, the number of synthetic substances and chemicals used in the building industry has grown from a few dozen to over 5.000. And the numbers are still increasing. with over a quarter of a million new compounds worlwide being invented each year. Without long-term testing and understanding of how these materials operate in practice, no one can know the effect they will have on human beings or indeed on the rest of the natural world. Many will be beneficial but many may not be and will have effects that will be known only after decades of use.

Already, however, some understanding is emerging with evidence of the outgassing of unstable compounds which causes serious toxicity of indoor air; the adverse health effects of modern sealed, non-breading buildings which concentrate the toxins even further; stress from artificial electromagnetic fields; radon gas poisoning; and the effect of the many other household chemichals and substances that are used to make our clothes, cleaning products, paints, furniture, carpets, flooring, and even cosmetics.

The potentially crippling reaction to the accumulated chemicals trapped in homes and offices has been recognised as a condition called "sick building syndrome" . The symptoms off SBS do not fit the pattern of one particular illness and cannot be associated with as single cause, but are the result of a complex synergy among low level contaminants. New medical practitioners/professionals, known as clinical ecologists, have emerged to treat these patients. Symptoms include eye, nose and throat irritation, congestion, lethargy, respiratory difficulties, fatige, irritability, head aches, dizziness and dificulty with concentration. In some extreme cases buildings had been temporarily abandoned or even demolished when toxins could not be traced or controlled. In most cases symptoms desappear when the person is removed from the cause, ie. the building, although some materials, asbestos being one of the worst offenders, have long-term and /or permanent negative effects.

It is clear that we cannot continue randomly to manufacture new buildings and home products without looking fully at other considerations, including health and overall ecological concerns, in addition to cost and convenience.

Although criteria is no easily found, from the point of view of human health there has been a considerable amount of research and writting done to date, and more is going on all the time. Because we spend nearly 90% of our time indoors, half of that in our homes, the quality of indoor air is vitally important to our health. The American Enviromental Agency is so concerned with the detiriorating quality of indoor air in homes that it has called it "the most significant enviromental issue we have to face now and into the next decade. Exposure to toxic materials in the home can occur in several ways. We can ingest them in our food, off our hands or in our drinking water, and absorb them through our skin or by being splashed in the eyes. But where we receive our greatest exposure to toxic substances in building products is from air pollution. The EPA has identified five causes of indoor polution:

1 . Biogenetic particles (mould and bacteria).

2 . Combustion products (from tobacco, gas appliances etc).

3 . Organic chemicals (like benzene and formaldehyde used in building materials).

4 . Naturally occurring health hazards (like radon and lead).

5 . Fibrous materials and airborne particles (asbestos,fiberglass and pollen).

Biogenic particles can be controlled by preventing the conditions in which they thrive. Mould and mildew like damp, moist or humid conditions and can often form on the cold surfaces of poorly insulated walls, the cold wall, ceiling or floor providing the condensing point for airborne moisture. Through proper detailing of insulation to avoid these cold spots and ensuring adequate ventilation to reduce humidity, most problems with fungal growth can be eliminated.

Danger from combustion products inside the house can be minimised by avoiding the use of unvented gas appliances and providing good ventilation. By far the greatest danger in this category is cigarette smoke.

The third category, organic compounds, is where the greatest opportunity for improvement lies in the building materials area and we will return to it shortly.

Naturally occurring health hazards can usually be avoided in new buildings through careful design, as in the case of radon. Radon is one of the most serious health problems in many homes but it can be remedied. As for other natural health hazards, it pays to be somewhat familiar with which ones are prevalent in your particular area and how to avoid them.

The final category, fibrous materials and airborne particles that are a mixture of man-made materials and other naturally occurring particles, can be dealt with in new builduings firstly by avoiding their use, as in the case of asbestos, and then by good detailing to eliminate loose particle ingress, for example, mineral wool fibres with air barriers, etc. Substances like pollen are more difficult to control and, depending on the sensitivity of the residents, special filtering of fresh air might be required if the problem is severe.

The third category still needs to be addressed. Volatile organic chemicals (VOCs), solvents, chlorocarbons, formaldehyde, phenol and many other chemicals are all fairly rampant and are present in a myriad of different building materials, paints, decorating products and furnishings. These various compounds are unstable and to a varying degree make their way tinto the air we breathe. Solvents in oil-based paints for example, including substances like toluene and xylene, both classed as narcotic and severe irritants, and benzene, a recognised carcinogen, are given off relatively quickly in the first few weeks after appplication. On the other hand the formaldehyde found in most particle boards and compressed wood products can continue to outgas over a period of years.

Formaldehyde is perhaps the most common of this category of pollutants. It is classed by the EPA as a potential human carcinogen, but it will make you sick years before it will cause cancer. Low levels of exposure to formadehyde can cause dizziness, nausea, eye and respiratory irritation and more serious long term effects if exposure continues. It is found in upholstery, furniture, some types of foam insulation, permanent press clothing, carpets, curtains, glues and adhesives, and moulded plastics, to name just a few. But the biggest problem in building materials is in the particle boards and plywoods. In the form of urea-formaldehyde resin can constitute up to 10% of the average sheet of compressed wood board. It is through the choice of non-toxic building products that the danger of VOCs and other synthetic chemicals can be avoided.

It is possible to have a healthy and enviromentally friendly home inspite the obstacles presented by the dominance of chemicals and synthetics in modern building products. No doubt as the evidence continues to emerge in favour of the non toxic, low energy and low -enviromental-impact approach it will became easier. Eventually it may even become the norm for all houses. We hope so.

back