All you need to know about the house dust mite
For the Curious

Best fabrics to exclude dust mites

A clinical study looked at the effectiveness of 53 anti-dust mite pillow protectors or pillowcases purchased from 10 different countries. The aim was to help manufacturers to produce medical textiles of quality and to provide consumers with a suggested standard when reviewing anti-mite packaging information. The major finding of the study was that plastic, and a selection of tightly woven covers, completely prevented mite penetration and blocked more than 99% of allergen movement through the fabric.
House dust mites, a major cause of disease worldwide, are tiny, barely visible creatures living indoors in colonies in damp, dark, and still conditions. The most common methods for controlling mites and their allergens involve physical means such as covering bedding with anti-mite covers. Several products claim 'mite-proof' protection but very few have been evaluated for their anti-mite properties. To help in this respect scientists from Thailand and the USA put various anti-mite pillow protectors through rigorous tests to report on their efficacy and to note fabric wear and tear.

The study divided the products into eight separate categories:

1. tightly woven - 30 samples

2. non-woven- 10 samples

3. film/membrane-coated woven - 4 samples

4. membrane-coated non-woven - 3 samples

5. acaricidal-coated woven - 1 sample

6. acaricidal-coated non-woven - 1 sample

7. plastic -1 sample

8. combination of woven and non-woven - 3 samples

Three normal cotton bed sheets were included for comparison but did not qualify as protection against mites and allergens.

The fabrics were then investigated to see how they blocked the movement of allergens, stopped the penetration of live mites, sustained air permeability for comfort, dust leakage and measured the thread count per square inch where applicable. Each product was repeatedly tested using established clinical procedures.

The highest quality of anti-mite fabrics were identified as being:

tightly woven

thread count greater than 246/in2 . (per square inch)

pore size of between 2-10 micron

allergen impenetrability >99%

resistance to live mite penetration

dust leakage of <4%

air permeability between 2 and 6cm3/sec/cm2 (cubic centimetre per second per square centimetre) 'breathability'

Please note:

Tightly woven fabrics are derived from twisted cotton or synthetic fibres perpendicular to each other and having either a regular, systematised bi- or tri-axial weaving pattern. To block dust mites from entering a fabric a thread count greater than 246/in2 (per square inch) is advised.

Thread count represents the coarseness or fineness of a fabric and is defined by the number of horizontal (warp or lengthwise) and vertical (weft or widthwise) threads in one square inch of the fabric. Tightly woven fabrics, measured by pore size, allow little space for mites to penetrate, but if the pore size is measured between 2 - 10 m the fabric will act to block dust mites and the majority of allergens.

The report also touched upon evidence of wear and tear following months of use and washing. With the exception of plastic structural changes and efficacy will change after use. ??In one study two brands of non-woven covers exhibited warn and matted surfaces threads, easily providing access points for mites. From clinical studies using tightly woven anti-mite fabrics indications are that structural integrity is not compromised even after one year of continual useage.

This study's findings followed another successful clinical report investigating tightly woven covers in anti-mite bedding materials. Authors from both studies expressed hope that their findings will help set standards for consumers when purchasing anti-mite fabrics.


References

Anti-mite Covers: Potential Criteria for Materials Used Against Dust Mites. Vanna Mahakittikun , John Joseph Boitano Chulaluk Komoltri , Prapakorn Ninsanit, Teerapong Wangapai 'Textile Research Journal', 2009, 79: 436,443

Mite penetration of different Types of Material Claimed to be Mite-proof by he Siriraj Chamber Method, Mahakittikun V., Boitano J. J., Tovey E., Bunnag C., Ninsanit P., Matsumoto T., Andre C., 'J. Allergy Clin, Immunol.', 118, 1164-1168 (2006)