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Carpet and Airborne Mold

By Michael Hilton

Fungi Allergies and Carpet

Fungi is present everywhere; daily in the air we breath, on all horizontal surfaces, indoors and outdoors, and in every environment. Individuals who exhibit allergic tendencies to fungi receive no refuge from its presence. Carpet has been identified as a suspected "source" of airborne fungi, but this assumption is based on the presence of fungi in carpet dust, rather than direct evidence of carpet releasing fungi into the breathing zone.

Fungi (mold and mildew) as a Primary Allergen

Numerous studies have been initiated over the past few years in an attempt to identify carpet as a primary source of airborne fungi, but few studies have been able to establish a direct correlation. The fact that carpet contains high levels of fungi does not, in itself, definitively label carpet as a source for airborne fungi. Airborne investigations in which speciation of fungal types have been identified and speciation of fungal types in carpet dust are identified, rarely provide the same results. Carpet acts as a trap or filter for airborne fungi. Those types of fungi present in the air today may be found in carpet dust 2-3 days later. This occurrence, while it runs contrary to commonly held beliefs, indicates carpets usefulness in trapping airborne fungi as a result of deposition rather than as a source. Often, results of airborne investigations labeling carpet as source of airborne fungi are misinterpreted. In one study of adjacent modular classrooms in the Tampa FL area, one carpeted classroom and one hard surface classroom were sampled simultaneously to establish a comparison of airborne fungi levels. Despite high levels of fungi in carpet dust, airborne fungi levels and species were virtually the same for the two classrooms. Indoor air constitution for both classrooms reflected the content of outdoor air. Because indoor air is a reflection of outdoor air, field studies provide very few definitive answers.

The lack of complete environmental control necessitates the use of environmental chambers to positively identify the source of airborne fungi. Room size environmental chambers control the purity of the air introduced into the test area. In this environment, airborne fungi can be definitively traced to the source material within the chamber.

In a recent environmental chamber study, ten heavily contaminated carpets were removed from a south Florida classroom and evaluated within the chamber. Results showed that carpet did not release fungi held within its pile into the breathing zone. These results were surprising considering the high degree of contamination that existed.

Several of the carpets in this study were incubated at 85%-90% humidity for four weeks and retested. After the incubation period, under extreme conditions, fungi actively growing on the surface of the pile were released into the breathing zone. However, similar findings could be expected from any flooring surface. Studies further show that vacuuming is very effective in removing surface contamination from carpet.

Unfortunately, surface levels are rarely used to evaluate fungi levels in carpet. Most investigations extract dust held within the carpet pile to enumerate fungi levels in carpet. Since environmental chamber studies indicate that those contaminants held with the pile do not provide an exposure risk, this sampling technique provides no direct evidence that fungi in carpet dust can contribute to airborne levels.

Other studies have demonstrated the ease of fungi removal through routine carpet cleaning activities. These studies indicate fungi levels can be reduced by more than 99% with wet extraction carpet cleaning and levels can be continually reduced through a regular carpet care program.

Carpet and Allergies

While allergists typically recommend that carpet be removed, carpet removal in itself has never eliminated allergic reactions by allergic/sensitive individuals. Some short term benefits have been noted following carpet removal, but allergic reactions return to normal several weeks after carpet replacement. In some cases, allergic reactions worsen due to increased airborne particle levels with hard surface flooring. Carpet, like any other fabric, could possibly become a problem without yearly cleaning and regular vacuuming. Carpet acts as a filter to trap airborne allergen. Once filled with allergen, carpet assumes the characteristics of a hard surface floor, releasing untrapped allergen with every foot step or wind current.

Did you know?

Mold allergy is among the most common causes of allergic symptoms anywhere and mold is present everywhere, daily in the air we breathe. Carpet can actually have a positive impact on mold allergies if proper carpet cleaning is performed. Dust mites, mold, mildew, fungi, and allergens are easily removed with proper carpet cleaning.

About the Author
Michael Hilton was the original creator of Carpet Buyers Handbook. Having owned and operated a carpet wholesale company, Hilton has a vast knowledge about all-things carpet related as well as other types of flooring.

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