Allergy to house dust mites is very common and can trigger allergic reactions such as asthma, eczema and rhinitis. Cutting down mite numbers may reduce these reactions. Hopefully this information sheet will answer a few questions and point you in the right direction to reducing mite numbers in the home.
What are house dust mites?
House dust mites are creatures which are so small that they cannot be seen with the naked eye. They live in all our homes and feed mainly on the scales of skin that we shed. They are most common in warm, damp areas where dust containing skin scales gathers. These areas include pillows, mattresses, carpets, soft furnishings, soft toys and even clothing.
The mites are harmless to most of us but they can cause allergic symptoms in some people. These symptoms are caused by breathing in substances known as allergens which are contained within the mites droppings. The droppings are so small that they become airborne and then may be breathed in. There are other allergens as well as house dust mite which can trigger allergic reactions e.g. moulds, cats and dogs or pollen from trees and grasses.
Why do house dust mites need to be controlled?
Drugs can treat and control the symptoms of allergic asthma, eczema and rhinitis but do not provide a cure. Although it probably won’t stop the need to use them altogether, cutting the numbers of house dust mites in the home may reduce the amount of drugs required and help to control symptoms.
A step by step guide to controlling house dust mites in the home
If you have had a positive skin or blood test to house dust mites and you feel that your symptoms are caused by the house dust mite, here are a few steps to reduce house dust mites in the home. Try them and see if there is any improvement.
For best results the steps should be carried out over the whole house. If this is not practical, concentrate on the rooms where the person with the allergy spends most of their time i.e. the bedroom or sitting room.
The first steps mentioned are the easiest and cheapest, the later steps are more expensive. Bear in mind that although they will reduce exposure to mites, there is no guarantee that these steps will reduce symptoms. The number of steps needed to give an effect will differ from person to person and it may take at least two months before the effects of carrying out the steps are noticed.
Step 1. Reduce dampness in the home
- House dust mites prefer warm, damp homes. Dampness can also lead to the growth of moulds which can cause allergic reactions too. These are some ways of avoiding dampness:
- Open windows or vents in kitchens and bathrooms during and after cooking, washing and bathing. To stop dampness spreading to the rest of the house, keep the door to these rooms closed
- Avoid drying clothes indoors, especially in the bedrooms and living rooms, unless using dryers which are vented outdoors. If you have to dry clothes indoors, open a window and close the door to the room where the damp clothes are
- Air bedding before remaking beds
- Open windows or vents in bedroom
- Run central heating a few degrees lower (especially in the bedroom)
Step 2. Prevent build up of dust
- Removing dust is important in the homes of allergy sufferers. To help prevent dust building up in the home:
- Reduce the number of items on which dust can build up, especially if they are difficult to clean e.g. keeping ornaments in display cabinets, placing books in closed cases and putting clothes and other objects in cupboards or drawers
- Regularly clean surfaces/objects where dust collects using a damp cloth. (Dry cloths will not pick up all of the dust and will let a lot of it back into the air)
- Regularly wipe down window blinds with a damp cloth
- Vacuum clean soft furnishings and curtains as well as carpets/floors. Replace the air filter or dust bag in the vacuum cleaner regularly
- Vacuum clean mattresses every two weeks
Step 3. High temperature washing
Washing fabrics at a minimum of 60° centigrade kills house dust mites therefore:
- Use sheets, pillowcases and duvet covers that can be washed at 60°C and wash them at this temperature at least every two weeks
- Use curtains that can be washed at 60°C and wash regularly at this temperature
Step 4. Bedding and soft toys
House dust mites are found in large numbers in mattresses and pillows where there are lots of skin scales. To reduce the number of mites in these areas:
- Replace pillows with new ones every six months (unless the pillows have special covers)
- Replace blankets with duvets which are made of synthetic material
- Cover all mattresses, duvets and pillows in the sufferer’s bedroom with micro-porous membrane covers. These covers need to be wiped clean with a damp cloth each time the bedding is changed
- Stuffed soft toys can also contain house dust mites so try to reduce the allergy sufferer’s contact with these toys. Keep the toys away from the bed if possible otherwise, about once a month, put soft toys in the freezer for six hours to kill the house dust mites
Step 5. Carpets
- Carpets also contain a lot of house dust mites. Replacing carpets can be expensive but if you are going to change your carpet anyway these are some options which will reduce the number of mites present:
- Replace carpets with linoleum/vinyl flooring or sealed natural flooring such as cork, tiles or wood.Make sure that the new floor does not have cracks in which dust may build up
- Choose very short pile, synthetic carpets as they tend to hold fewer mites than long piled wool carpets
- Use cotton rugs that can be washed at high temperatures (60°C) and wash them regularly
Step 6. High efficiency filter vacuum cleaners
There are vacuum cleaners on the market which are better at collecting dust than ordinary vacuums so:
Consider buying a high efficiency filtered vacuum cleaner and use regularly on floors, carpets, soft toys and soft furnishings
Step 7. Replace furnishings
When you buy new furnishings you should consider
Replacing woven fabric covered chairs and sofas with cane, canvas, leather-like or leather covered furnishings which are easy to clean and do not harbour dust mites
Other possible measures
Products such as air filters, ionisers, dehumidifiers and mechanical devices for ventilation with heat recovery are available. These may also help to reduce allergic symptoms but their effectiveness has not been fully tested as yet.
British Society for Allergy and Clinical Immunology