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Carpet and Allergies

Carpet has become the floor covering of choice by most consumers because of the many benefits that carpet offers. In addition to ease of carpet care, comfort, warmth, and outstanding acoustical value, carpet enhances any decor or matches any color scheme. Carpet continues to become a better value, when compared to other floor coverings, because the cost of carpet has not kept pace with inflation. The cost of carpet has only increased at a yearly rate of 1.5 per cent over the past thirty years; whereas, the average rate of inflation has been 5.5 per cent over this time period.

Despite all the benefits that carpet provides, many people have begun to question the impact of carpet and other renovation materials on allergies and people who consider themselves to be overly sensitive to chemicals. The role of indoor air quality has become an important environmental issue to many people. Various construction materials, surface finishes, interior furnishings, renovating and cleaning agents, and even office furniture, impact the indoor environment. Many of these materials, including carpet, give off chemical emissions. Because of concerns about chemicals, the carpet industry initiated an ambitious program to categorize and lower the number of chemical emissions from new carpet. In addition, studies were performed to develop an understanding of the type of allergens contained in older carpet and how to reduce the effects of these allergens. In each case study, some surprising results were discovered.

In categorizing the number and types of chemicals emitted from new carpet, it was discovered that carpet was found to be one of the lowest emitters in the indoor environment. The emission levels from carpet were determined by the Environmental Protection Agency (EPA) and several independent researchers to be well below recommended guidelines. With fresh air ventilation, carpet emissions are almost undetectable within 72 hours after carpet installation. This applies to carpet made with natural as well as synthetic materials. Following common sense ventilation recommendations after installation of new carpet can reduce the occurrence of most allergic symptoms. For those who consider themselves to be allergy prone or overly sensitive to chemicals, it may be advisable to avoid the area or leave the premises.

The second area of concern for many individuals is the number of allergens contained in existing carpet. An exhaustive study was initiated to classify the types of allergen contained in existing carpet and methods for the removal of these allergens. Many consumers purchase carpet with the impression that carpet cleaning should only take place when the carpet appears soiled. Today's carpet fibers have been engineered to withstand soiling and stains as never before. Carpet should be cleaned before it begins to exhibit signs of soiling. Failure to regularly clean carpet could allow soil and allergens to build-up within the pile. However, one positive attribute of carpet is that these allergens are trapped within the carpet pile rather than released into the breathing zone. As noted in a "Design Review on Carpets" published in Architectural Review " ...the fact that carpet may collect more lint and dust than a hard surface floor covering may be considered an advantage, as it is better to have dirt and bacteria-carrying particles held down in the carpet until it is vacuumed, than to have it stirred up and airborne by continual shuffling of shoes--as is the case with smooth surfaces." This allergen is only released into the breathing zone when the carpet pile has become filled with allergen.

The studies verified that each time carpet is extraction cleaned, most of the allergen contained in carpet is removed. The key to preventing allergen release into the breathing zone, and maintaining low allergen levels, is to regularly clean carpet. Carpet should be cleaned a minimum of every twelve (12) to eighteen (18) months in normal situations. Cleaning carpet more often can reduce the number of allergens in the home and prolong the life of the carpet.

Carpet, Bacteria, Fungi, and Allergen

Synthetic floorcoverings such as carpet, ceramic tile, and sheet vinyl do not provide a food source for biological growth, although airborne biologicals do collect on these surfaces. Studies comparing the amount of surface biologicals on each flooring surface indicate no difference in biological levels among these surfaces. However, results revealed, due to contaminated cotton mops and ineffective maintenance procedures, hard surfaces could have higher biological loads, if mops are not carefully dried and disinfected after each use and cleaning solutions are not replenished frequently to limit the spread of infectious organisms. Recent studies also suggest that airborne particulates and other allergens may be higher above hard surface floorcovering due to its inability to collect and hold these airborne contaminants.

It has been suggested that carpet may be a source for airborne biologicals and allergen based on the assumption that these contaminants can be found in carpet dust. No direct relationship has been established to confirm this suspicion. In fact, the body of good science available suggests that carpet is a very effective trap, which removes these pollutants from the breathing zone. Environmental chamber studies have revealed that these contaminants are not released during normal activities. Carpet cleaning studies reveal that more than 99% of biologicals and allergen collected by carpet can be removed with one carpet cleaning. The key to limiting the biological load on any flooring surface is a regular, carefully planned carpet care regimen.

Carpet Bacteria, is it Harmful?

While many people constantly ask if carpet contains bacteria and whether this Bacteria is harmful, the answer is yes and no. Most of the bacteria that is found in carpet is gram negative bacteria, a component of human skin scales (dead skin). A microbiologist would tell you bacteria is our friend. Not all bacteria is harmful and bacteria plays a key role in keeping our environment clean and healthy. Many of the harmful bacteria species require a wet environment to proliferate. A constant water source is critical to keep these bacteria alive.

Legionaires (Legionellosis) disease, one of the most notable and commonly known diseases caused by bacteria, is caused by Legionella bacteria, which is most often found in air conditioning drip pans where a constant water source is available. Legionellosis can present as two distinct illnesses; Pontiac fever, a flu-like illness; and Legionnaires’ Disease, the more severe form involving pneumonia. The severity of the illness can be mild or result in pneumonia. Most cases occur as single isolated events, however outbreaks have been noted. Legionella bacteria are ubiquitous (everywhere) in natural and manmade water environments, and multiply in the presence of warm water. Without an active water source, these colonies die within hours.

While carpet may contain some bacteria, you may be shocked to know that the chances of contracting a bacteria borne disease is much higher from door knobs than carpet (If this helps you sleep any better).

The contents of this section provide a review of some of the work that suggests carpet’s positive environmental impact. While some allergists continue to recommend that carpet be removed, the fact remains that carpet removal has never eliminated allergic reactions.

As you will see in this section, numerous countries including Sweden, China, and East Germany have some of the highest allergy rates in the world, yet these countries do not use carpet. After the fall of the Berlin wall, researchers were surprised to learn that East Germans, who could not afford carpet, had a far higher allergy rate than West Germans who use carpet extensively. The same holds true for China, where a recent investigation revealed more than 49% of China’s population suffers from allergies, yet carpet is rarely found in any indoor environment.

Dust Mites, Allergies and Carpet

Allergists routinely recommend carpet removal due to allergy concerns based on an allergen avoidance theory. Allergists believe that if all possible places where allergen can be held are eliminated, allergic reactions will disappear. However, the removal of carpet has never produced a reduction in allergic reactions. The incidence of allergy sufferers that use carpet is about the same as for those who avoid carpet. Numerous studies have been performed in cultures that do not use carpet and allergy rates per capita are very similar to the U.S. culture where heavy carpet use is the norm.

In 1973, based on anecdotal evidence that carpet contributed to allergic reactions, the Swedish government banned the used of carpet in all public facilities. Carpet was replaced with hard surface flooring materials in homes, commercial environments, government buildings, and carpet market share fell from approximately 20% of the market share to less than 2% of the total flooring market share. Follow-up studies by the Swedish Central Statistics Bureau indicated a dramatic increase in reported allergies by the Swedish population following carpet replacement. As carpet was removed and hard surface flooring was installed, the incidence of allergy increased among the Swedish population. This alarming increase was in direct proportion to the amount of hard flooring materials installed. This ban was removed after 17 years when the dramatic increase in allergic reactions was confirmed.

In recent years, numerous investigations have begun to question the practice of avoidance and began to look at routes of exposure for allergens that are impossible to avoid. Researchers understand that allergic reactions are caused by exposure to specific allergens, but these respiratory allergens typically must be inhaled or ingested to produce a respiratory response.

Dust mite allergen has been a concern since its initial discovery as a primary allergen in the 1960’s. Allergists routinely test for mite allergen sensitivity and historical data reveals that a significant number of their patients reveal a low tolerance to this allergen. However, allergists stop short of stating that allergic reactions have been caused by a specific allergen, because of an inability to trace reactions to a specific cause.

In microscopic terms, Dust mites are extremely large. The allergen (fecal pellets, body parts etc) is quite heavy as well. Numerous scientific evaluations have failed to produce airborne dust mite allergen from carpet during periods of activity, despite heavy occupant activity. Since dust mite allergen is difficult to disturb, reactions may only be exacerbated by direct surface contact or direct inhalation from surfaces, such as pillows or mattresses, or hand to nose. Hence, mite allergic individuals rarely suffer a reaction when entering a carpeted room containing heavy dust mite infestations. Most of the mite allergen in the home can be found in pillows, mattresses, or upholstered furniture. In fact, 30% of the weight of the average pillow is comprised of dead human skin scales (dust mite food source) and dust mite allergen. The average mattress can weigh as much as 100 pounds more than when originally purchased due to the accumulation of the matter. While carpet is typically mentioned in connection with allergies, pillow and mattress accumulations of these allergens pose a far greater exposure risk.

Dust mite allergen should be distinguished from cat allergen or various types of fungi (mold and mildew). These allergens can easily be detected in air samples and, because of their small size, they can easily be aerosolized. To examine the propensity of dust mite allergen to become airborne, a project conducted in a south Florida school was undertaken to assess the airborne exposure risk of mite allergen contained in carpet. This study failed to identify airborne dust mite allergen in a carpeted classroom despite heavy mite allergen concentration in the carpet and questions the universal assumption that carpet contributes to allergic reactions stimulated by mite allergen content in carpet.

For those who remain unconvinced that carpet does not exacerbate dust mite allergy, but prefer the comfort of carpet, there is good news. Recent investigations show that carpet cleaning reduces the amount of mite allergen in carpet by more than 90% with each carpet cleaning. Dust mites tend to have seasons in which they proliferate. Due to elevated humidity, dust mite populations tend to increase during the spring and summer and the population diminishes during the heating season when the air becomes much drier. By scheduling carpet cleaning in bedrooms, media rooms, or other rooms, where time is spent on the floor, during September and October, allergen can effectively be removed before accumulation of allergen becomes an exposure risk.

In addition to regular carpet cleaning, new treatments have become available which have been proven to be effective in eradicating dust mites. Some products containing benzyl benzoate have received mixed scientific reviews relating to their efficacy. To date, the most effective product brought to market is a product produced by The Ecology Works (1-888-353-2649 http://www.dustmitex.com/). This EPA registered product, (Dust Mite Control) can be added to the rinse water of a portable extractor (Rug Doctor, Etc) and applied during the carpet cleaning process, or it may be applied as a separate treatment on a regular basis to prevent the accumulation of dust mite populations and their associated allergen.

Fungi (mold and mildew), also a primary allergen, is found in every environment. Numerous studies indicate there is no difference in airborne fungi levels above various flooring surfaces regardless of contaminant levels on/within the flooring surface. Other studies show that hot water extraction (steam cleaning) of carpet is much more effective in removing fungi from within the carpet pile than wet mopping of hard surface flooring materials.

Cat Allergen is less often blamed for allergic reactions in homes, schools and commercial environments because they rarely reside in these environments, but air sampling inevitably reveals the presence of cat allergen in most instances. Cat allergen is extremely small and remains airborne for long periods. It is introduced into homes, school, and commercial environments that do not house these pets on the clothes and garments of cat owners. Cat allergen can be an extreme irritant for those who demonstrate sensitivity to the allergen.

Cockroach allergen has recently come to the forefront in allergy investigations and has come to be recognized as another extreme irritant and respiratory allergen. Recent studies performed in low income housing units have revealed an abundance of cockroach allergen and may explain the high incidence of allergic disease among children residing in these units. Like cat allergen, cockroach allergen can be found in almost every indoor environment. Cockroach allergen easily becomes airborne and requires an extraction method, such as vacuuming or steam cleaning, to remove. Wet mopping and especially dry mopping of hard surfaces is not an effective extraction technique for these allergens.

In examining the relationship of carpet and reported allergic reactions in schools, it is important to examine historical data related to flooring use and reported reactions. Sixty-six percent of all schools report allergic-type symptoms related to the building environment. Yet only 36% of available floor space is carpeted. In homes where allergic individuals reside, a closer examination reveals there is no difference in the incidence of allergies in homes predominately carpeted and homes without carpet.

It also must be noted that even though all carpet is characterized under one classification, there are numerous qualities of carpet with numerous construction characteristics. Residential carpet is very different from commercial carpet in its release characteristics. Loose constructions, have the tendency to release far more contaminants than tighter constructions.

Cleaning and Occupant Wellness

For any flooring surface, effective maintenance and utilizing the philosophy of cleaning for health is a primary element in ensuring occupant wellness. Carpet acts as a trap for airborne allergen. Once allergen becomes trapped within the pile of the carpet, it must be removed. Without carpet to act as a filter, allergen tends to remain airborne or may become airborne with each footstep. Studies reveal carpet is very effective in trapping this allergen without releasing it into the breathing zone. Carpet cleaning has proven to be very effective in extracting this allergen and removing it from the indoor environment. In homes that utilize hardwood flooring or other hard surface flooring material, you will typically find a heavier loading of surface dust on tables, chairs, lamp fixtures, and other horizontal surfaces. A good common sense approach for people with allergies is to install carpet and perform regular carpet cleaning to remove the allergen.

In comparing the allergen removal efficiency of carpet and wood or tile flooring, allergen removal is much more effective with carpet than with hard surfaces. Vacuuming of hard surfaces can be initiated as an effective extraction tool, but vacuuming of hard floors is rarely performed. Long-term studies have shown that proper carpet selection, along with an adequate carpet care program, can reduce the amount of allergen in carpet and provide a suitable living environment. In one such study, dust mite allergen levels in carpet were significantly reduced over the course of one year. The study involved 12-year old carpet that had received neglectful carpet care. Despite heavy concentrations of mite allergen, levels were continually reduced over the course of the study. Hot water extraction (steam cleaning) alone produced a 92% reduction, while vacuuming continued to reduce allergen levels on a daily basis. No airborne dust mite allergen was detected during the two-year study. This study was performed using regular carpet care only. The use of acaricidal treatments may enhance the results of routine carpet care.

Key Points to Consider

The replacement of carpet with a smooth flooring surface does not produce the results expected by allergy patients. Allergy rates per capita in cultures that do not use carpet are very similar to the U.S. culture where heavy carpet use is the norm.

In 1973, based on anecdotal evidence that carpet contributed to allergic reactions, the Swedish government banned the used of carpet in all public facilities. Follow-up studies by the Swedish Central Statistics Bureau indicated a dramatic increase in reported allergies by the Swedish population following carpet replacement. This alarming increase was in direct proportion to the amount of hard flooring materials installed.

While a majority of allergy suffers exhibit sensitivities to dust mite allergen, allergists stop short of stating that specific allergic reactions have been caused by mite allergen.

Numerous scientific evaluations have failed to produce airborne dust mite allergen from carpet during periods of activity, despite heavy occupant activity.

Cat allergen, fungi, and cockroach allergen may produce more allergic reactions than any other allergen because of their small size and tendency to become airborne.

Because of the lack of an effective “extraction” method for cleaning of hard surface flooring materials, allergen, especially fungi, is not removed from the facility.

Also See Decision to Purchase carpet.

Did you know?

Carpet can actually have a positive impact on allergies if proper carpet cleaning is performed. Dust mites, mold, mildew, fungi, and allergens are easily and effectively removed with proper carpet cleaning. Prior to removal these allergens are trapped out of the respirable breathing zone within the carpet pile fibers. Other flooring surfaces allow allergen to become airborne with each footstep.

In This Section
Chemical Health Scares
Mold Allergies
Carpet and Airborne Mold
Airborne Mold
Animal Allergies
Dust Mites
Mite Allergen Exposure
Humidity and Allergies
Carpet Allergy FAQ
Airborne Particles