Principles of House Dust Mite Reduction
Raised ambient temperature, ultra-violet light and a relative humidity of less than 55% are all lethal to house dust mites.
These can be achieved as follows:
- Wash bedding, pillows, duvets and mattress covers in HOT water of greater than 55oC.
- Expose the mattress to the sun's UV light for a few hours each month.
- Turn an electric blanket on to HIGH for a few hours each month. Many mites will be killed near the mattress surface.
- Where available, use an air conditioner or dehumidifier to maintain bedroom humidity below 50%.
- Chemical agents which kill mites are available in New Zealand, but these have not been found to be very effective.
Remove Mites & Mite Protein
Even if mites are dead, their bodies and excreta can still cause allergic reactions.
Removal can be achieved as follows:
- Intensive vacuuming of mattress, carpets and furniture is needed once a week. The more vigorous and effective the cleaner the better. It is vitally important that housedust mite and other allergenic particles once sucked up into the vacuum cleaner are prevented from leaving the cleaner through its exhaust opening. The most effective way of controlling this efflux is undoubtedly the HEPA (High Efficiency Particulate Air) filter. HEPA filters retain 99.9% of particles in the range of 0.3 to 0.5 micrometers and will retain housedust mite, cat and mould allergens. Vacuum cleaners which incorporate both a double dust bag and HEPA filters are the best choice for allergy sufferers.
- Weekly hot water washing (55oC) will kill mites and remove bodies and excreta. Curtains should be laundered at regular intervals.
- House dust mites and their excreta accumulate on dusty surfaces, in drawers and on clothes. Using a damp cloth, dust all exposed surfaces in the bedroom daily. Clean out the drawers regularly.
Mite – Impenetrable Barriers for Bedding
Mites are mobile, crawling through beds and carpets. Plasticised fabrics provide an impenetrable barrier to mites and their excreta.
Washable mite-protective covers for the mattress, bed base, pillows and duvet are available. The modern versions are water permeable and so do not cause sweating.
Bedding & Furnishings
Any furnishings with soft, fluffy surfaces provide growing sites for house dust mites. Similarly they will grow in dust allowed to accumulate about cluttered surfaces and books.
- All bedding should be washable. Synthetic materials, sometimes described as "allergy free" are best. Pillows, blankets and duvets in particular should be washable.
- Soft mattress covers or underlays such as sheepskins should not be used. Kapok or down duvet fillings should be avoided.
- Curtains should be of the type which can be laundered.
- Avoid soft covered furniture in the bedroom.
- Keep all surfaces uncluttered and store books outside the bedroom.
- Carpets are a problem as they can act as a continuous reservoir of mites. While regular vacuuming is helpful it is not as successful as having shiny surfaces such as wood or vinyl.
- Sheepskin rugs provide an ideal haven for house dust mites and so should be avoided.
N.B. MITE PROTEIN REDUCTION MEASURES ARE NOT A REPLACEMENT FOR APPROPRIATE MEDICAL MANAGEMENT OF ALLERGIC DISEASE BUT DO PROVIDE COMPLEMENTARY AND SOMETIMES CRITICAL ADJUNCT TO ONGOING TREATMENT WITHOUT ADDING TO THE DRUG BURDEN.
Environmental allergy avoidance in allergic asthma