Choosing the right anti-dust mite encasing is fundamental, because it is decisive for the efficacy of treatment and prevention. Unfortunately, many of the “anti-dust mite” covers on the market have proven to be totally ineffective and even potentially harmful in the light of scientific studies. The Journal of Allergy and Clinical Immunology, one of the most prestigious journals on allergology, has published a series of comparative studies on the efficacy of the anti-dust mite covers sold in various countries in the world, demonstrating that the only ones that are really efficacious and valid are those made of fabric with a very tight weave (Pristine® patent). These studies revealed that all the other types of cover (waxed; unwoven fabric or polypropylene; waterproofed fabric, for example with Teflon; fabric with a polyurethane membrane; fabric with anti-mite treatment, for example triclosan or silver ions) are penetrated and/or colonised by mites within a few days, losing all effective barrier power.
Encasings made of nonwoven fabrics
Encasings made of nonwoven fabrics have proven to be particularly harmful as they are not only rapidly colonised by mites, but they retain and accumulate large quantities of allergens among the fibres which are then inhaled by the allergic person. This is due to the fact that nonwovens do not have a regular structure (warp and weft), but are formed by countless numbers of microfiber filaments intertwined in a disorderly fashion. The mites can manage to find their way into this tangle of filaments and remain trapped there (see photo).
Enlarged 200 times
The same applies to allergens, which are retained by the tangle of microfibers, accumulating layer upon layer. The problem is also due to the fact that, once the mites and allergens are captured, they remain trapped between the fibres and are not removed, either by machine-washing or by wiping with a damp cloth (cleaning with a cloth even makes the situation worse, because instead of removing the dirt it makes it penetrate deeper down).
Thanks to their “dust capturing” properties, nonwovens have been used for years to make filter bags for vacuum cleaners and disposable dusting cloths.