Encasement material to stop house dust mites from entering a pillow, mattress or duvet, can be made from plastic, vapour-permeable materials, finely woven fabrics, or nonwoven synthetics. Pore size is important when considering the material. Access to most mites will be prevented by fabrics rated as having pore size less than 10 microns. Ideally, to be comfortable, encasements should be manufactured from breathable fabrics; be vapour permeable, and be able to block both dust mites and their allergens.
Care must be taken to regularly wipe down with a damp cloth the mite-proof material because, if left alone, in dark, damp conditions with plenty of food and moisture, the mites will breed on top of the fabric. Referring to the debate about feather versus non-feather pillows, recently researchers from several sources found that non-feathered pillows accumulate mite allergens five times faster that feathered pillows. They speculate that these results are due to the tighter weave on the fabric encasing feathers and down.
'The biology of dust mites and the remediation of mite allergens in allergic disease', Larry G Arlian, Thomas A E Platts-Mills, 2001, J. Allergy Clin. Immunol. Vol. 107, Number 3, S406-413