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House dust mites and especially their pellets are held responsible for certain allergies and asthma.
What is known ?
Claims that carpets were breeding grounds for dust mites have proven false.
In carpets, dust mites can easily be kept under control with regular ventilation and proper cleaning.
Carpet is not the ideal habitat for mites. Carpet prevents the allergic material from being released into the atmosphere by holding the fine allergen particles in the pile until next vacuuming. Hard surfaces, on the contrary, allow the allergens to become easily airborne with the slightest draught or vibration. Thus, carpet improves the quality of life of allergic persons.
It is not the floor covering, but the temperature and humidity that make the difference.
The map on the next page shows that conditions in northern Europe do not favour mite growth, and yet, that’s where carpet has been considered wrongly a problem. In southern countries mites do survive, even on hard floors and tiles. Despite this, no problems have been reported.
(Source: Bronswijk J.E.M.H. van, Schober G. Geoklimatische Verteilung von Innenraumallergenen. In: Jorde W., Schata M., eds. Mönchengladbacher Allergieseminar Band 5. Innenraumallergene. Dustri-Verlag, München-Deisenhofen. 1993: 69-84.)
Distribution of mites in houses of mite-allergic patients
Bedding offers ideal living conditions for dust mites, because they are not dependant upon the relative humidity of the bedroom itself: bedding is warm, dark, and damp after sleep and contains discarded skin scales. Dust mite allergen in mattresses can be 1.5 times greater than in dust from bedrooms placed carpet.
Dust mites are almost not found in offices.
In a study comparing carpets in 27 randomly selected offices with 30 bedrooms in homes, mite allergen levels were found to be 0.32 μ/g in offices vs. 18.4 μ/g in bedrooms. It was concluded that mite exposure in offices does not seem to be a risk for neither allergic (atopic) nor for non-allergic (non-atopic) employees.
(Source: V. Freund, F.Lieutier-Colas, M. Ott, A.Vrot, G. Pauli, F. De Blay H pitaux universitaires de Strasbourg, France 2002)