The typical house contains a toxic soup of chemical organic compounds, electromagnetic fields, combustion gases and other pollutants. Here’s how to minimise the harmful pollutants in your home.

We spend an estimated 90 per cent of our lives indoors, and much of that time inside our own homes. Once we’ve shut our front door, we tend to see our living space as a refuge, imagining it to be a safe haven from the world outside and certainly less polluted. But surprisingly it’s not; in fact, quite the reverse. A recent report by the normally conservative US Environmental Protection Agency (EPA) stated: ‘Indoor air pollution in residences, offices, schools and other buildings is. . . one of the most serious potential environmental risks to health.’Ever since the oil crisis of 1973, when ‘save energy’ became the new mantra, houses have been made increasingly airtight. At the same time, many new materials have found their way into our homes, developed by the building and home furnishing industries. These new substances are all synthetic and many are potentially toxic, causing one industry expert to describe our indoor air quality as a ‘chemical soup’.

‘Consumers are largely ignorant of the health threat posed by these new materials, relatively few of which have been tested for toxicity,’ says environmental architect Paula Baker. ‘But there is growing concern that chronic, low level toxic exposure is on the increase, resulting in symptoms that are often falsely attributed to the normal ageing process’ (P Baker et al, Prescriptions for a Healthy House, Sante Fe, NM: Inword Press, 1998).

One long term study found that indoor air often contains more hazardous chemicals than outdoor air even in highly industrialised areas. Between 1979 and 1995, the EPA compared indoor and outdoor pollution in three different locations: industrialised Bayonne, New Jersey, semi industrialised Greensboro, North Carolina, and rural Devils Lake, North Dakota. By means of an automatic pump attached to their chests, the air of some 355 people was sampled as they went about their daily activities.

In a typical day at work and at home, these people were found to breathe at least two to five times more hazardous chemicals when indoors than if they had sat in their gardens. This was true even if the people lived within a mile of a source of industrial air pollution, as in New Jersey. In North Carolina and North Dakota, the results were even more striking: indoor air chemicals were between five and 10 times higher than the levels outside (Environmental Research, 1987; 43: 290-307).

In Britain, related studies by Dr Geoffrey Llewellyn and colleagues at the Building Research Establishment (BRE) came to similar conclusions, finding that in semi rural Avon, air quality was on average 10 times worse indoors than outdoors. His team found over 200 indoor chemicals,

of which 80 were judged to have significant adverse health consequences (BRE report no 299, Construction Research Corporation Ltd, 1996).

As a result, the BRE now recommends that houses should have a complete air change every two hours. In today’s well sealed, energy efficient dwellings, air changes average less than half that.

Chronic exposure to toxins in the indoor environment has now been linked to a vast spectrum of illnesses, ranging from asthma, chronic sinus infections, headaches, insomnia, anxiety, fatigue and joint pain, to full blown multiple chemical sensitivities (Public Health Rep, 1998; 113: 398-409). The authors of this particular study, two doctors from the prestigious Massachusetts General Hospital in Boston, lay the blame on ‘the explosion in the use of chemicals in building construction and furnishing materials over the past four decades’.

Indoor air pollutants can be classified into five main categories: volatile organic compounds, toxic by products of combustion, pesticides, electromagnetic field pollution and naturally occurring substances.


The biggest group is volatile organic compounds. Derived from petrochemicals, VOCs readily release vapours at room temperature in a process called ‘outgassing’. VOCs are found in a multitude of materials that are used in the building and furnishing of today’s average home plywood, particle board, wood panelling, insulation, adhesives, carpets, paints, finishes and synthetic fabrics. Even many of the modern cleaning materials we use contain VOCs. The distinctive smell of a new house is primarily caused by VOCs outgassing from the building materials, paints and furnishings.

As with other pollutants, the extent and nature of the effects on your health depend on many factors, including the level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to VOCs.

Benzene and formaldehyde are the two major toxic VOCs. Indoor formaldehyde is gradually becoming recognised as a severe health hazard, even by such august bodies as the American Lung Association, which now recommends that formaldehyde levels should not exceed 0.1 parts per million. However, it is estimated that about half the US population is exposed to concentrations above this figure (J Thrasher and A Broughton, The Poisoning of our Homes and Workplaces, Seadora, 1989). In Europe, the situation may not be much better. A recent study of Austrian homes found indoor air concentrations of formaldehyde above the US threshold, and in some houses 10 times higher (Cent Eur J Public Health, 1997; 5: 127-30).

Formaldehyde is a colourless gas emitted by many construction materials and related products such as glues, resins and preservatives. In the fabric of buildings, the most significant sources of formaldehyde are likely to be in plywood and the adhesives used to bond pressed wood building materials. Urea formaldehyde resins are found in wood products that are intended for indoor use which, paradoxically, emit more formaldehyde gas than the phenol-formaldehyde resins contained in products intended for exterior use. Certain foam insulating materials, once widely used in housing construction, also contain large amounts of formaldehyde. They were banned in the US in 1985, and so, with the passage of time, they are unlikely to still be outgassing.

Although formaldehyde has been shown to cause cancer in animals, there is no definitive evidence linking it to cancer in humans. Other health hazards attributed to formaldehyde include skin rashes, watery eyes, breathing difficulties and burning sensations in the eyes, throat and nasal passages. It can also trigger asthma attacks. Most people will react to formaldehyde when the levels are in the range of 0.1 to 1.1 parts per million. If the initial exposure is relatively high, some people may acquire a reduced tolerance to formaldehyde, so that even low level exposure at a later date will cause reactions.

People who develop permanent health problems as a result of formaldehyde exposure often relate the onset of their symptoms to a flu like illness, which is usually misdiagnosed as a viral infection. Because formaldehyde is an immune system sensitiser, it may cause multiple allergies and sensitivities to entirely unrelated substances if exposure is chronic.

Benzene is a known human carcinogen, a major source of which is paint. Oil based paints are generally considered to be more hazardous than water based paints, although both contain VOCs. Some manufacturers have now responded to public concern by developing very low VOC paints at prices comparable to the conventional variety.

A recent meta analysis of mortality rates among painters and decorators in Britain showed significantly elevated deaths from cancer, compared to the rest of the population. This was largely attributed to benzene in paint (Cancer Detect Prev, 1998; 22: 533-9).

Cigarettes contain benzene, but in the non smoking home, benzene is primarily found not only in paints but also in carpets. In fact, carpets are one of the major sources of both formaldehyde and benzene, as well as many other chemicals. A typical carpet may contain over 120 chemicals in its fibre bonding material, dyes, backing glues, fire retardant, latex binder, fungicide and anti static and stain resisting treatments. Outgassing is at its peak when the carpet is new, but it can persist for up to three years after installation.

In the US, the carpet industry has been put on the defensive after a rash of complaints from consumers about respiratory and neurological reactions to new carpets. Ironically, in 1987 some of the most adverse reactions occurred in the very heart of the top American regulatory body, the EPA, when over a thousand employees complained of symptoms after new carpeting was installed in their Washington headquarters. Although the agency publicly denied any link between these health symptoms and the new flooring, over 25,000 square yards of carpet was removed.

In 1992, in response to public concern, the US carpet industry began the Green Tag programme a PR initiative to reduce VOCs in its products. However, recent animal experiments by an independent laboratory has shown that supposedly low VOC carpets can still be highly toxic (Anderson Laboratories Report, August 1992).

Combustion gases

A second cause of pollution in the home arises from the by products of combustion. Open fires, ranges and stoves, space heaters and central heating boilers and furnaces are all sources of potentially toxic gases, such as nitrogen oxide or dioxide, hydrogen cyanide and carbon monoxide. In a study of 47,000 chemically sensitive patients, it was found that the most adverse reactions were caused by gas stoves, hot water heaters and furnaces and boilers (W Rae, Chemical Sensitivity Vol 2, Lewis Publishers, 1994: 706). However, even a tiny, unvented gas pilot light produces a significant amount of fumes, mainly nitrogen dioxide. Such gases have recently been shown to cause problems even in non chemically sensitive children (Int J Epidemiol, 1997; 26: 788-96), resulting in ‘significant increases in sore throat, colds and absences from school’. As one might expect, children with asthma react more adversely (Am J Respir Crit Care Med, 1998; 158: 891-5).

Carbon monoxide is a colourless, odourless gas which, as is well known, will cause death at fairly modest levels. Less well known, however, is how toxic carbon monoxide can be at much lower doses, where it can have serious effects on higher cognitive functions, such as memory, concentration and reasoning, according to a study at Israel’s Hadassah University (Arch Neurol, 1998; 55: 845-8). Chronic exposure to carbon monoxide can also result in multiple chemical sensitivities, as it interferes with the detoxification pathways in the liver, causing toxic overload.

In the recent book Why Your House May Endanger Your Health, author Dr Alfred Zamm describes how gas kitchen ranges have been the hidden culprit in many cases of what he calls ‘housewife’s malaise’. Zamm says that a gas oven operating at 350 degrees F for one hour, because of the inevitable incomplete combustion, can cause levels of carbon monoxide and nitrogen dioxide three times higher than typically found in a Los Angeles smog. This is consistent with the recent findings of two doctors at Boston’s Brigham Young Hospital, who discovered links between the use of domestic gas appliances and the incidence of lung disease (Thorax, 1997; 52 (Suppl 3): S58-62).


Insecticides and fungicides number among the major health hazards in the home. These are found mainly in carpets, paints and wood. Many such pesticides were developed as offshoots of military nerve gases. We tend to assume that, because they are licensed for use in the home, they have been rendered safe for humans and domestic animals. However, a recent US government report admitted that less than 10 per cent of the hundreds of pesticides in common use have been adequately tested for safety. A recent study showed that combining pesticides can add considerably to their toxicity, making them up to 1600 times more potent (Science, 1996; 272: 1489-92). For instance, pyrethroids, actually become extremely toxic to humans as well as insects when combined with the petroleum derived piperonyl butoxide, even causing severe liver damage.

In older houses, insecticides are often sprayed in roof spaces to control woodworm, and householders are now cautioned about venturing too soon into the area after spraying. But there are also significant amounts of pesticides in the living areas particularly in carpets. Not only are carpets sprayed to keep away moths, but they also tend to collect residues of pesticides that are tracked in from the outdoors. In fact, an EPA study in Florida found some of the highest household pesticide residues in carpet dust (Environ Science Technology, 30: 3313-20).

Because of their proximity to the floor, this makes infants and young children particularly vulnerable, with potentially serious long term consequences. In one study, children who had been exposed to insecticides had a greater risk of developing brain tumours and other cancers (Am J Epidem, 1979; 109: 309-19).

Electromagnetic fields

Only recently have electromagnetic fields in the home become a cause for concern. Studies have concentrated on the adverse effects of high tension power lines, where the evidence, although hotly debated, has tended to demonstrate a carcinogenic effect.

In animal studies, frequencies between 15 to 60 Hz have been shown to alter cellular protein synthesis, disrupt RNA synthesis and reduce immune response (R W Adey in B Norden and C Ramel, Interaction Mechanisms of Low level Electromagnetic Fields in Living Systems, Oxford: Oxford University Press, 1992).

As a precaution, Paula Baker recommends that magnetic fields be kept to a minimum in the area we spend most of our time around our beds.

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Written by What Doctors Don't Tell You

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