House Dust Mite Allergy and Asthma
You often hear people talking about being allergic to dust or that dust triggers their asthma symptoms. You might notice you have more symptoms when dust is disturbed – for example, when you’re cleaning, moving furniture or making a bed. Or you might simply find your asthma symptoms are often worse indoors.
However it’s actually dust mites rather than dust itself that are troublesome for most asthmatics with 90% of people with asthma being sensitive to them. Dust mite allergy is also implicated in eczema and rhinitis.
Dust mites are 200-300 microns long, but their allergen, which is found in its droppings, is a microscopic 4-20 microns in size. It can crumble into fragments of 1-3 microns and the tiniest bits are only 0.5 microns across.
It’s relatively heavy compared to cat or mould allergens for example and though some of it becomes airborne when dry and floats around, the most significant exposure is inhaling it close to the source.
Dust mites live mainly inside mattresses, pillows, upholstery, cushions and soft toys. This is where their food source of human skin scales that have been broken down by the moulds created by humidity is found.
Dust mite allergen is blasted out into the air when you sink into the sofa or an armchair, but it is when you get into bed or turn over in the night that you inhale the biggest dose of allergen, from a pillow, mattress or teddy bear.
Carpets also contain dust mites but the numbers are generally lower. Dust mites are also carried around in clothing.
What’s the best way to reduce the risk of dustmite allergy triggering your asthma?
Take your asthma medicines as your doctor prescribed them. "If your asthma is triggered by dust mites, the best way to reduce asthma symptoms is to look after your asthma and make sure it’s well managed, as this reduces the likelihood of you reacting to the dust mite droppings when you come into contact with them – they are impossible to avoid," says Dr Samantha Walker, Asthma UK’s Research Director. Your preventer inhaler works by reducing inflammation in your lungs, meaning they’re less sensitive, so less likely to be triggered by dust mite droppings.
Help ensure your asthma is as well controlled as possible by taking your preventer inhaler as prescribed, and using a written asthma action plan to help you work out if your symptoms are getting worse, and what to do about it if they are.
How to combat dust mites in the home
Getting rid of dust mites is only the start in the battle to reduce their presence in your home as their allergen will remain and continue to cause asthma attacks and allergic reactions for years.
The goal is therefore not only to remove the dust mites but also to inactivate their allergen - denature its DNA so that your immune system no longer recognises it.
• Washing pillows, duvets and sheets at 60⁰C and above kills mites and removes dust mite allergen. Try bestselling anti-allergy brand Featherfresh (natural-fill) or Spundown (synthetic) pillows and duvets.
The Dermatherapy brand of sheets, pillow cases and sleepsacs (synthetic) are dustmite-proof as is the Dreambag sheet sleeping bag (natural cotton).
• Adding a capful of FabriCleanse to the laundry when washing at lower temperatures will kill dustmites and denature their allergen.
• Cooler washes without FabriCleanse will not kill mites but will remove the allergen as it is water soluble. This is useful if you have killed the mites before with a spray of HomeCleanse.
Regular cool washes of clothing and sheets will also reduce the dust mites’ food supply.
• Dry cleaning duvets and pillows kills dust mites but only removes 20-70% of the allergen.
• Enclosing an in-use mattress, pillow and duvet in dustmite-proof barrier covers will keep any dustmite allergen inside. Enclosing a new one will prevent dust mites from colonising your mattress, pillow or duvet from the beginning.
• An upholstered bed base will have its own smaller population of dust mites. A wooden or metal bed frame will not.
• Putting soft toys and pillows into a freezer for more than six hours kills dust mites, but the allergen will remain unless you then wash them.
• Hanging rugs and woollen blankets outdoors in strong direct sunlight for three hours on a dry day will kill dust mites living in them but will not remove the allergen.
• Dust mites cling to carpet fibres when a vacuum cleaner passes over them and about 65% will remain. An ordinary vacuum cleaner sprays dust mite allergen into the air as it goes, leaving three times as much in the air to be breathed in than before. Medivac vacuum cleaners are certified to retain the allergen.
Dust mites, asthma and humidity
Dust mites do not drink, but absorb water from the air, so they prefer humid conditions. When the relative humidity falls below 50%, the mites gradually dry out and are killed.
In today’s drive to make our homes energy-efficient with good insulation, one crucial thing has been overlooked – ventilation. Huge amounts of water vapour are generated in a house, creating the moist conditions ideal for dust mites and moulds. As well as steam from cooking and showering, each person in a home gives off about a litre (2 pints) of water in sweat each night. In any one week a household of four puts 70-140 litres (130-250 pints) of water into the indoor atmosphere around them. This, combined with draught-proofing, double glazing and modern insulation results in an indoor environment that is much too moist.
However, dry air can make an asthma attack worse, so the challenge is to monitor the relative humidity (RH) in the home and maintain a level of no more than 50% - moist enough for asthmatic airways, but not so moist as to encourage dust mites.
• Check the RH in the room with a hygrometer (humidity gauge.) Aim for an RH of 50% or, even better, less than 40%.
• Use a Dehumidifier such as the Combined Dehumidifier & Air Purifier with its ‘Set-& Forget™’ feature. This reads the temperature and level of humidity in your home every thirty minutes, every day, and automatically adjusts the performance so that you don't have to be constantly changing the controls.
• Buy an electric blanket with a dustmite-killing setting. This will keep the bed free of moisture and prevent dust mites from setting up home in your mattress and bedding. Brand leader Beurer have a good one.
• Fit a powerful extractor fan in the bathroom, particularly if your bathroom is en suite to the bedroom.
• Dry clothes outside or use a tumble dryer. Avoid draping wet washing on radiators.
The information AllergyBestBuys provides should not be considered medical advice, nor is it intended to replace consultation with a qualified physician