Asthma Breath Easier!

Discover The Truth About Asthma, & Why Hard Floors Are Unhealthier Than Carpets

Recently we have been fed a diet of sensationalist scare stories about carpets and dust mites and their alleged links to asthma. This stream of anti-carpet propoganda has advised, indeed urged, you to switch to wooden floors ostensibly 'in the interests of health'. It must be pointed out, however, that this was an orchestrated anti-carpet campaign that was part funded by a Swedish laminate flooring producer. Thus the advice to 'rip up the carpet' was far from independent and impartial as it purported to be.

The Carpet Foundation, the UK carpet manufacturing industry's lead body, in conjunction with the European Carpet Association, GuT, the German Association for environmentally friendly carpets, the Wool Research Organisation of New Zealand and the Carpet and Rug Institute of the USA, has conducted a detailed review of the key scientific papers on asthma and floorcoverings. It proves conclusively that there is no scientific validity for suggesting that carpet is a major threat to your health, even those sensitive to the dust mite allergen.

Asthma is a very complicated condition and experts cannot agree on a single cause for the illness. Dust mite allergen is only one of the causes of sensitisation and triggers for asthma attacks which is influenced by a wide range of other factors.

The main site for dust mites to live and to thrive in UK houses is in bedding and bedrooms.

The environment in UK carpet is rarely suitable for large populations of dust mites to live and thrive. Temperature and humidity are too low.

The live dust mite does not pose a problem for asthma sufferers, but their faecal pellets contain the allergen which, on inhalation, triggers asthma attacks in sensitised individuals.

The filter like properties of carpets hold allergen materials in the pile and significantly limits its chances of becoming airborne again. Hard floors allow allergen on the surface to re-circulate readily in the atmosphere through vibrations or movement of the air.

Fresh air ventilation together with temperature and humidity control will significantly reduce dust mite populations and regular vacuum cleaning will remove most of the allergen load from the carpet.

There is no scientific evidence to support the advice that the removal of carpet is clinically beneficial to asthma sufferers. No studies have ever been carried out which conclusively links a carpet free environment to clinical benefits for asthma sufferers. In fact in Sweden where health hysteria led to a 77% reduction in carpet use, there was a corresponding 300% increase in asthma in the same 15 year period to 1990

All materials emit gasses from V.O.C’s. (Volatile Organic Compounds) but tests have shown that carpet emits significantly lower levels than other indoor finishes and furnishings and as such, these pose no threat to UK consumers.

On the contrary wool pile carpet absorbs common gaseous airborne pollutants and generally improves indoor air quality. Carpet also traps other particulate pollutants, deposited through foot traffic or airborne settlement, holding them in the pile of the carpet, away from its surface until they can be removed by regular, normal vacuum cleaning.

10. The manufacture of carpets in the UK is controlled by environmental legislation and manufacturers recognise their responsibility towards the environment. All process emissions have to meet stringent regulations policed by the environment agency. As with every other industry, where new evidence points to the undesirable effects of a process or chemical it is phased out to an agreed timescale. The UK carpet industry has an excellent record of compliance and improvement.

11. It can be of no surprise that a manufactured product such as carpet will contain traces of the chemicals used in its production or the production of its raw materials. Some are applied deliberately, such as the mothproofing treatment Permethrin, and are essential for the carpet to be functional in the home. Others may be a residual, by-product or contaminant from raw material processing. In either case, the traces are minute and represent no health hazard to the consumer whatsoever. However, the industry is not standing still and is continually working to find processes and material suppliers capable of reducing or eliminating even these insignificant traces.

12. Regular, normal vacuum cleaning will significantly reduce the amount of any allergen or toxic pollutants already held safely in the carpet pile away from the surface.

13. Carpet continues to offer consumers a wide range of practical and safety benefits

• heat insulation
• comfort
• noise absorption
• ease of cleaning and maintenance
• obvious aesthetic benefits
• positive impact upon indoor air quality

14. The safety benefits of carpet must also be clearly recognised. Carpet is seen as beneficial in hospitals particularly those specialising in orthopaedic care where its’ non slip and cushioning properties in case of falls are particularly beneficial. Smooth floors in contrast are considered quite dangerous in this respect.

ALLERGIC REACTIONS, DUST MITES AND ASTHMA

Between 5 and 10% of the population of Western Europe in general and 6% of the UK population suffers from allergic diseases and 90% of these are sensitised to the dust mite allergen Der p1. These allergic diseases are eczema, dermatitis, hay fever, rhinitis and asthma (1). Although there has been a great deal of concern about asthma in children a recently published work shows that there is evidence that over a 10 year period ending in 1998, the rate of occurrence of asthma in the UK is on the decline and that asthma attacks are reducing in number. (2)

There are two main allergens - dust mite allergen and cat allergen, which can sensitise certain people who can subsequently have an allergic reaction when particular substances or situations are encountered. These “triggers” which give rise to allergic reactions in sensitised people include: -

Main triggers for allergic reactions

• Pets
• Pollen
• Moulds
• Dust mite allergen
• VOC.’s - Poor air quality
• Cigarette smoke - Poor air quality
• Cooking emissions - Poor air quality
• Workplace emissions - Poor air quality

Other factors which influence allergic reactions

• Emotion and Stress
• Colds and viral infections
• Exercise
• Weather
• Certain foods and Medicines
• Genetic predisposition
• Diet

Contrary to the popular view published in many papers and emphasised by the anti-carpet press there is now evidence that exposure to environmental allergens (dust mite and cat) does not cause childhood asthma. (4) A study in Germany recording the medical history and exposure to allergens of approximately 1000 children drew the conclusion that the data recorded did not support the hypothesis that exposure to environmental allergens causes asthma in childhood, but that the induction of specific IgE responses and the development of childhood asthma are determined by independent factors.

Since allergic illnesses are a complex subject influenced by the interaction of various factors it is dangerous and scientifically invalid to isolate just one factor as the sole cause of the UK asthma problems.

Other new scientific developments which should be considered

Scientists seeking to explain the increase in childhood asthma have to ask the question do people live in a more toxic environment (with greater exposure to more allergen) or are individuals more susceptible to sensitisation for some reason. In the case of the dust mite humans have cohabited with them since prehistoric times and there are proportionally no more mites now than there ever were. Mites existed in bedding in large numbers in the 60’s and 70’s when asthma incidence was lower and there is no evidence to suggest cat populations are on the increase. There has to be another explanation.

Research has recently highlighted the effect of the modern westernised diet on the propensity for an individual to become sensitised. The reduction in the intake of anti-oxidants, (which suppress inflammation) in the form of fresh fruit and vegetables is linked to the rise in allergic diseases, and has resulted in the population in the modern Western world becoming increasingly susceptible to sensitisation to allergic disease, including asthma (5).

Professor Seaton of Aberdeen University, who has carried out this work, has further quoted the example of Saudi Arabia which shows similar levels of Asthma to the West but, as a country is one where the use of wall to wall carpets is very rare and where the climate is hot and dry, conditions which prevent dust mite survival. Its move towards a more westernised diet of convenience foods is thought to be the cause.

A further report, by Professor K H Carlsen of the Vokentoppen Children’s Asthma and Allergy Centre in Oslo, has suggested that the presence of chlorine in (swimming) pools is a major cause of asthma attack and chronic stress has been also been shown to be a major factor in triggering an asthma attack. (6)

In his report Industrial Air Pollution and the Country Doctor, quoting a large number of references, Dr D Van Steenis argues that the increase in asthma is closely associated with high levels of pesticide and fine airborne particulates resulting from industrial processes and combustion products, particularly of waste oil based fuels. He further argues that the U.K’s asthma epidemic is limited to areas of high pollution by fine particulates (PM2.5) and that unpolluted areas having asthma incidence as low as 1%.

A great deal of research has been carried out on the subject of asthma and major differences exist between scientists on the many factors which influence the illness. There is common agreement between the world’s top scientists that carpet is not a major factor, which influences the illness.

THE DUST MITES AND WHERE TO FIND THEM

In order to thrive, dust mites require food (flakes of human skin), moisture (in the presence of some species of mould such as Aspergillus Penicilloides) and a dark warm habitat. Dust Mites need a narrow range of high temperature and humidity conditions to thrive. Dust mites populations show optimal growth at conditions between 18ºC to 25ºC and 60% to 70% relative humidity, conditions of temperature and humidity rarely found in carpet in homes in the UK. Furthermore, when the relative humidity falls below 50% the dust mites desiccate and die (7).

The dust mites feed on the dead scales of skin, which the human body constantly sheds at a rate of 5g per day. The scales are too dry and horny when they flake off the human body for the mites to eat and they need to condition in a moist atmosphere for a few days to absorb water from the air, and to promote the growth of miniature surface moulds, before they are suitable as mite food. Since water is not readily available in carpet the mites depend upon the absorbed moisture for their entire water needs (8). Since the dust mites require such an extreme range of conditions to survive it is common to find carpet completely free of mites or with very low concentrations. Hysterical claims that, as many as 100,000 dust mites ‘may’ be found in a square metre of carpet have no scientific validity.

Bedding on the other hand offers ideal conditions for dust mites to live and thrive which are not dependent upon the ambient relative humidity of the bedroom. We spend approximately one third of our lives in bed during which time the body loses approximately one litre of water each night through perspiration and breathing.

During this period the body continues to shed skin scales which are concentrated in a relatively confined area and so the bed provides a dark, warm, humid and food rich environment for the dust mite with long periods of intimate contact between bedding nose and throat.

In a Dutch study it was found that the level of dust mite allergen in dust taken from mattresses was more than 78 times greater than in dust taken from wall to wall carpet in school rooms, almost 3 times greater than dust taken from carpet in living rooms and 1½ times greater than in dust taken from bedroom carpet. (9) This illustrates the importance of beds and bedding as the main environment for dust mite to thrive and produce allergen.

Surveys of households in Germany have shown that whilst almost 30% of all houses were mite free, 50-60% of mattresses, blankets and upholstery fabrics contained mites (10,11) but only 16% of wall to wall carpets in living rooms and 45% of bedroom carpets contained them. (12). Most researchers have shown that the main centre for dust mites to breed is in bedding and following agitation during bed making the airborne dust mites and their allergen then settle on the bedroom floor and soft furnishings. Migration of the dust mites to other areas of the home then slowly takes place through air changes, agitation and vibration. In schools (where there are no beds) the allergen level in dust taken from carpet is very low. In a study, which examined the health of 98 asthmatic children in Holland, it was found that those children who were exposed to wall to wall carpets suffered no poorer health than children exposed to uncarpeted floors. (9)

Live dust mites do not themselves cause allergic reactions but their faecal pellets are the cause of sensitisation and can trigger allergic reactions in some people. These faecal pellets are extremely small measuring about 10-15 microns (1 micron is 1/1000th of a millimetre). When these are held trapped in the pile of carpet they do not pose a hazard to sensitised persons. It is only when they are airborne that they pose a problem by being available for inhalation. Airborne allergen settles on all surfaces but whilst hard surfaces, including floors, allow the allergens to become easily airborne through the slightest draught or vibration (13) carpet retains the allergen deep in the pile. It has been found, for example, that the velocity of air over a carpet surface is required to be ten times greater than that over a smooth surface if the same number of particles were to be released into the air. (14).

There is no direct link between the number of mites in a carpet and the amount of allergic faeces present. Production of allergen is very slow and it takes a long time for a significant build up to occur. (8) In a residential environment, wall to wall carpet prevents the allergic material from being released into the atmosphere by holding the fine allergen particles in the pile and can thus improve the quality of life of allergic persons. (15) This has been confirmed by research, which showed that measurements of the level of dust mite allergen in the in the room air above the surface of carpets, even those containing high levels of dust mite allergen, failed to detect the presence of allergen. These measurements were made over an extended period at only 24” above the carpet surface. This study, quotes other research (Air Quality Sciences, An Indoor Air Quality Study of Alafia Elementary School, (1994-95) Atlanta, Georgia, U.S.A.) which also found no detectable dust mite allergen above carpet. (16)

In a further study which compared the flooring in fourteen Swedish town halls, it was found that whilst more dust could be collected from carpeted floors than uncarpeted floors no greater amount could be found in the (still) air indoors over carpeted floors. (17) This again confirms the inherent property of carpet to hold dust, including allergen, in the pile preventing it from becoming airborne.

Dust mite expert, Dr John Maunder, Director of the Medical Entomology Centre at Cambridge University is certain that carpet cannot be blamed for allergic reactions. “Only in poorly ventilated humid dwellings can large populations of mites build up in carpets. In dry well ventilated places either no mites exist or they are in such low numbers that no significant production of allergen occurs.” (8)

SIMPLE STEPS TO REDUCE DUST MITE POPULATIONS

It is well recognised that carpets filter like properties hold dust including allergen, and as previously discussed, it carries out the important function of holding and preventing it from circulating in the air. Most importantly it holds the dust until it is removed, by regular and efficient vacuum cleaning, (18) typical of a regime in a well maintained home in the UK.

The real key to controlling dust mite populations is to control the temperature and relative humidity indoors to prevent the warm, humid conditions that dust mites need to live. The easiest way to achieve this is to ensure good ventilation in the home, particularly in bedrooms, which is the critical zone, and also avoid excessive temperatures. (8)

Cleaning of carpets

The accumulation of dust mite allergen in carpet depends upon the balance between its production and its removal. Production of allergen is very slow and it takes a considerable period for a significant allergen build-up to occur. Although allergen is a very stable compound some is removed from carpet by natural biological or chemical breakdown, most remains until removed by cleaning through normal vacuum cleaning.

The very fine allergen particles and minute flakes of skin, which comprise the food source of the mite, are easily removed from carpet by a proper cleaning regime. A carpet cleaned regularly, in a well-ventilated environment, will not contain enough allergen to affect most people. The vacuum cleaner will ideally have a powerful suction and, have efficient filtration to ensure the retention of the allergen within the cleaner and preventing its release into the air. The British Allergy Foundation has an evaluation and accreditation scheme for vacuum cleaners and asthma sufferers are recommended to use a machine approved by them.

The physical action of vacuum cleaning will probably provide sufficient agitation of the carpet surface to allow allergen particles to be stirred up into the atmosphere. The action of opening windows during and, for a period after, vacuum cleaning will ventilate the room and effectively remove the allergen from the air. (8)

One additional benefit of regular vacuum cleaning is to remove skin flakes from the surface of the carpet before they condition (i.e. absorb moisture) to the point that they become edible for the dust mite. This reduction in available food supply will reduce mite populations.

Studies involving 13 classrooms in the U.S.A. showed that a single dry extraction carpet cleaning operation reduced the average level of dust mite allergen in carpet dust by 51%. (16) A further study involving 57 homes in Georgia and Wisconsin showed that a single dry extraction cleaning operation reduced the average level of cat allergen (Fel d 1) by over 85%. (19)

Occasional wet extraction cleaning of the carpet is also to be recommended (20) to reduce deep seated dusts and steam cleaning has also been found to be particularly efficient at removing a high proportion of allergen and completely killing the dust mite population. (21).

Summary

When a household is ventilated and vacuum cleaning of a normal frequency and intensity is carried out, carpet in UK homes: - - Will not hold sufficient food for dust mites to survive, - Will contain minimal allergen loads on the surface waiting to become airborne. - Will not provide an indoor environment for dust mites to live.

WHAT CARPET DOES FOR YOUR HOME?

Some organisations have recommended that carpets be removed from the home, particularly in the bedroom and replaced by wood floors in order to produce clinical benefits for asthma sufferers. A paper has been published however, which examines the effect of dust mite control measures (22) and which concludes that “Current chemical and physical methods aimed at reducing exposure to allergen from dust mites seem to be ineffective; these methods cannot be recommended as prophylactic treatment for asthma patients who are sensitive to mites.

Furthermore, it needs to be recognised that carpets have a very important function in creating a comfortable, safe and easy to clean living environment whilst improving air quality. It has been suggested that wood floors constitute a safety hazard since they are smooth and allow slips to occur. Approximately 15,500 injuries requiring hospital treatment occur in the UK each year as a result of falls caused by slipping on wood floors. (23)

Whilst research has shown conclusively that bedding contains a significantly higher level of allergen and dust mites than carpets (9) no one appears to advocate the removal of bedding. Similarly there is a list of factors known to influence asthma, yet there are no recommendations, for example, that smoking is banned, pets not kept and food not cooked in the home. With regard to dwellings it had been shown that the removal of wall to wall carpeting has no clinical effect on patients who show allergy reaction to dust mites (24). Even the anti-carpet Healthy Flooring Network admit in their report that no scientific studies have been carried out which solely deal with the effect of carpet removal on asthma patients. (25)

What happens when a Nation stops using carpet?

In the 1970’s in Sweden there were intensive discussions with some claiming that carpet was a serious breeding place for allergens and a source of harmful contaminants. As a result of considerable publicity supported by various interest groups this debate became a national issue.

Not surprisingly the bad press given to carpet started to affect consumers’ confidence in the product and sales began to fall.

In fact, from 1975 to 1990 the carpet share of the floorcoverings market fell from 40% to 2% as hard floor sales grew by 50% and carpet usage fell by 77%.

And what happened to the incidence of asthma in Sweden during this 15-year period? Well, as carpet usage declined dramatically, allergy cases in Sweden increased by 300%. (26)

his massive study carried out on a national scale in a health aware country like Sweden has shown a dramatic increase in asthma cases in the same 15-year period that carpet sales declined!

Other studies in Sweden have shown that there is no difference in the incidence of asthma between carpeted and uncarpeted schools. (27)

A recently published paper (28) reporting on a specific study involving homes which are carpeted and homes with hard floors shows that there is no difference in the level of airborne particulates between homes with and without carpets. The report concluded that airborne particulates, which include allergens, are suppressed by carpet. 6.0

CARPETS AND INDOOR AIR QUALITY

Typically all manufactured materials and products emit gasses from VOC’s (Volatile Organic Compounds) for a period of time. These may have a distinct odour and are, therefore, perceived as dangerous. There are a great number of VOC’s and different materials emit different mixes and concentrations of VOC. The distinctive smell of the interior of a new car, for example, is the result of VOC emissions, and is perceived as desirable to many people. All too soon the distinctive smell diminishes and disappears as the VOC’s are released into the atmosphere.

The new carpet smell is the result of VOC emissions, usually from the backcoating material and it too will diminish and disappear in time dependent upon the level of ventilation in the room.

According to studies by leading research organisations in the US and Germany, the contribution made by carpet to indoor air pollution is minimal compared with many other indoor finishes and materials. Taking paint as being rated as 100, relative emissions are adhesives 72.5, wall coverings 8.5, plywood 1 and carpet 0.5. (i.e. a carpet emits 1/200th of the VOC gasses given off by paint). Such a low level of emissions from carpet does not constitute a health risk for consumers. (29)

Some adhesives used for the installation of some carpets may contribute to VOC levels and should be used in well ventilated areas which should continue to be ventilated for some days after installation has been completed. Modern adhesives, which have been recently introduced, have significantly lower emission levels.

Many people are concerned about indoor air quality. An analysis of the air in a new office building in the USA where the workers were complaining of discomfort and illness found that the enclosed heated and air conditioned environment recirculated rather than dispersed emissions from the indoor wall, ceiling, floor, and furnishings. Ventilation, introducing fresh air removed any problems.

Many key research papers show that carpet, in fact, contributes significantly to cleaner indoor air. Three major pollutants of indoor air quality are formaldehyde which is emitted from a wide range of building products, oxides of nitrogen and oxides of sulphur both of which are by-products of combustion processes (e.g., gas cookers and heaters).

Research has shown that wool is particularly effective absorbent of these gases (30,31). A study in the US has shown that wool has one of the highest rates of removal of nitrogen dioxide from the atmosphere. (32) Because of the 3 dimensional nature of carpet with the wool fibres in the pile standing vertically from the backing, the wool fibres present a considerable fibre area for the absorption of gases. One square metre of carpet containing 1Kg of wool will present a fibre surface for gaseous absorption of 100 square metres. (33)

Other studies have shown that large amounts of sulphur dioxide are also absorbed and held by wool fibres in carpet. (34)

Summary

Carpet, therefore, contributes significantly fewer emissions than other building materials, indoor furnishings and finishes do. The capacity for carpet to absorb airborne pollutants and to hold these makes it a significant contributor to good indoor air quality.

CHEMICALS IN CARPETS

Carpet manufacturers in the UK recognise their responsibility towards the environment and do not generally add dangerous materials to their products during manufacture. The requirements of the OSPAR convention are recognised and understood and those chemicals listed under this agreement which might find their way into carpet are being phased out within the required time scale. (The OSPAR convention is the main inter-governmental agreement to regulate and control marine pollution in the North Sea and the North Atlantic.)

Generally speaking the occurrence of minute traces of toxic pollutants in carpet will almost certainly be there as a constituent of one of the raw materials used in carpet manufacture, particularly those which may be sourced outside the modern western world.

The results of a recently published Healthy Flooring Network study would have you believe that carpet manufacturers include a range of dangerous chemicals in their products but it must be clearly understood that their small sample of carpet tested was not in the least representative of the wider range of products made by British carpet producers and that they were chosen carefully for analysis so that many of the chemicals found were indeed likely to be present in the products. There was, furthermore, no information relating to acceptable human exposure levels of such chemicals or comparisons with background levels of these chemicals in the everyday environment.

Not surprisingly, two carpets tested, advertised as being treated with Ultrafresh (an Organo-tin known to be applied to apparel, particularly socks and sportswear), were found to contain Organo-tins. Those carpets containing a high proportion of wool in the pile were found, also not surprisingly, to contain Permethrin a chemical treatment used to impart insect (moth) resistance. There is no evidence to suggest that the very low levels found in these carpet samples have any adverse effect upon human health.

Brominated Fire Retardants were found in 3 products, two of which were not produced in the UK and were constructed with polypropylene fibre, a product with less inherent fire retardancy properties than other popular carpet fibres.

Formaldehyde was found in small amounts in a number of samples, which is also not surprising when wool is known to absorb formaldehyde from the atmosphere (contributing to cleaner air).

It is possible that some of these chemicals may have been included in raw materials down the supply chain and therefore present in the carpet without the knowledge of the carpet manufacturer.

Organo - tins and Brominated fire retardant are two of the chemicals in the OSPAR list of 32 chemicals which are to be phased out, by agreement, by 2020 at the latest.

The report concludes that these potentially toxic chemicals were found in some (but not all) samples and goes on to say "although the consequences of long term exposure to chemicals such as these, in the indoor environment is uncertain, the above chemicals have properties which make them potentially hazardous to human health and the environment”. (35) The words potentially and uncertain should be noted!

A recent article published in New Scientist magazine (5th May 2001) alleged that living indoors exposes us to much higher levels of toxins than being outdoors. This article is based on US experience and is not directly comparable to experience in Britain.

As pointed out above carpet is acknowledged as a reservoir for dust, which sinks to the base of the pile. The dust may well contain minute traces of toxins and absorb others but, clearly, the toxins did not originate in the carpet and in any event they would have contaminated other indoor surfaces to some extent. More importantly the carpet holds these alleged toxins at the base of the pile, away from the surface, until they are safely removed by vacuum cleaning. Research has shown that only 1% of dust in a carpet is available on the carpet surface. (36) The remainder being held in the pile until such time as it is removed by normal cleaning 

Ian Harper MBICSc

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REFERENCES

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