Dust Mite – know the enemy

This is the house dust mite (also known by it’s latin nameDermatophagoides). It is a few fractions af a millimetre long and cannot be seen with the naked eye. It lives off dead skin. This sounds revolting but dead skin is all over the house, in nearly everybody’s house. A lot of household dust is dead skin. 10-20% of the weight of old pillows may be dead skin. The bed is full of it, and although the dust and mites are everywhere, you spend more time in bed than in any other room, and you are in very close contact with the mites throughought the night.

As if this is not revolting enough, the dust mites, having eaten the dead skin, then leave droppings / excrement everywhere which contains some of their stomach enzymes. It is these stomach enzymes that we are allergic to; these allergies can lead to asthma, excema, but most importantly for us, rhinitis – a blocked, itchy, runny or sneezy nose. This in turn can cause sinusitis and ear problems.

What mites like

Dust mites like warmth, humidity and dead skin. Lots of it. The ideal room for them to grow in is a bedroom, over centrally heated, under ventilated, with lots of fabric:

• thick curtains
• long pile carpet – ideal for trapping dust
• lots of bedding
• cuddly toys like teddy bears
• infrequent laundry, especially using warm washes only.

What mites don’t like

Cold and dryness. Good ventilation, being exposed to the atmosphere to dry up, direct light. Temperatures over 60 degrees centigrade and under freezing will kill them. Some chemicals will also kill them. The dust mites worst possible room is:

• somewhere with a dry climate – like the Alps or Arizona
• no carpet (stone, wood or linoleum)
• no soft furnishings at all
• window wide open
• no heating

Obviously the above may be a bit impractical, but there are more realistic steps you can take to make a difference to your home.

Reducing the mite population in your home

Before you start:

• ensure that you are actually allergic to house dust mite. Although the following measures will not actually harm your health, they may harm your wallet and cause you a lot of fuss you may not need. Allergy testing is the usual way of determining this and it is undertaken at ENT outpatient visits. This can be discussed with your GP or ENT surgeon.
• Don’t go into this half heartedly. You need to reduce the mite population by a minimum of 90% to make any real difference and a few occasional measures will not achieve a lot. This is a laborious process.
• Generally speaking, although killing mites is initially very desirable, if the dust is left in place, the mites will soon come back, so take action against the dustand the mites.
• Aim most of the serious attention at the bedroom, this is where the problem is biggest.
• There is little point doing any of this if you are going to smoke inside your house as well. Smoking makes asthma worse, causes rhinitis and other problems and increases the risk of glue ear and tonsillitis in children exposed in the home.
• Many people who are allergic to HDM are also allergic to furry pets. Having made your bedroom hell on earth for dust mites, don’t go and ruin it all by letting the cat sleep on the bed all day.

Step by Step Around the House

Floors

Carpets are an ideal place for dust to settle. When you walk on them the dust is thrown into the air and even the best vacuum cleaners leave some dust. The best thing is to get rid of them and either have bare floorboards, which when polished up actually look very nice, of lino or stone. People in flats may not be able to do this for reasons of noise. In this instance a short pile carpet is a good idea and a very good vacuum cleaner used regularly.

Curtains

Much the same applies. Wooden blinds or plastic curtains are ideal. Damp dust them regularly (weekly) to stop the dust building up.

Bedding

Wash all bedding regularly (weekly) in temperatures above 60 degrees centigrade. This gets rid of dust and kill mites.

Mattresses

Mattresses harbour lots of dust. Turn the mattress over regularly and vacuum it with a good vacuum cleaner. An old mattress should really be replaced.

Mattress and Pillow covers

Probably the single most important item to get. They stop the dust getting at the mattress and pillows and stop the mites under them getting out. The cheapest are available from Argos (mediguard) at around Ј12-15 for a single mattress cover and pillowcase, more for a double. These may not last very long. A variety of more expensive ones are available (ask at a department store, Boots or other chemists, or look on the internet) and can cost Ј100 or so. The mattress and pillow covers will also need to be washed at 60 degrees regularly. Plastic sheets are great because they are so impermeable, but a bit sweaty and uncomfortable in long term use, and there is a risk of suffocation in children.

A lot of pillows and some duvets are sold as ‘Anti allergic’ or non – allergic. This normally only means that they are non feather. In fact dust can still build up inside these pillows, so they are not as effective on their own as you might think. You will still need to use dust proof pillow cases on them.

Just get rid of very old pillows, regardless of type. They will be heaving with dust.

Making the Bed

Instead of making the bed normally, turn the duvet down to expose the mattress and underneath of the duvet every morning and leave it like that until bedtime. This will expose the mites to light, cold and ventilation and dry them out.

Furniture

Upholstered furniture traps dust. Ban all upholstered chairs and sofas from the bedroom. Plastic, leather or wood is fine. In the rest of the house this helps, but is less important.

Furry toys

Unfortunately many children go to bed clutching bears, rabbits and a wide variety of other wildlife. Sadly, this is bad news as they will be full of mites and dust. The best thing is to get rid of them completely and if your child wants something to cuddle, a blanket (especially a cotton one) is ideal, as long as you can regularly wash it at 60 degrees. If parting with teddy is a worse prospect than the underlying problem, then regularly wash it in the machine (when your child is looking the other way). Tumble dry on hot to be extra sure.

Freezers

Putting teddy into the chest freezer for 24 hours sounds a bit bizarre, and you may find it difficult to explain this satisfactorily to your 3 year old. However, this will kill all the mites in it, so it will help. Unfortunately, the dust will still be there, so the mites will come back quite quickly. Pillows can be treated this way too, if you have freezer space. It would be a good idea to put the items into a plastic bag first however.

Vacuum Cleaners

You want a vacuum cleaner to keep the dust inside it and not spray it back out all over the room. Get the best one you can realistically afford.

It may sound obvious, but get someone other than the allergy sufferer to empty the bag.

Chemicals

A variety of chemical preparations to kill mites are available. These certainly kill mites, but in practice, the evidence that they make a lot of difference to the overall picture is less convincing. I am also a bit skeptical of putting any insect killing chemicals too near the bed, despite the safety guarantees, so I would personally not advocate the use of these formulas.

Humidity

Mites certainly like humidity and centrally heated homes usually have plenty of it. Don’t be too tempted to buy an expensive de-humidifier. The expert view is that they will reduce the humidity, say from 60% to 50%, but this is nowhere near enough to make any difference to the mites. Better to make sure that the room is well ventilated and cool.

Temperature

Don’t have your heating on too high. Better to be a bit cooler and put on a jumper. This sounds old fashioned but it will make a difference.

Summary

You could obviously end up spending a fortune on this so take it carefully. Here is a suggested order in which to go about things, you may not need to take up all of the suggestions.

1. Make sure the room is cool and well ventilated
2. Regular laundry above 60 degrees for bedding
3. Wash / remove soft toys
4. Regular turning of mattress, vacuuming it as well
5. Dust mite proof mattress and pillow covers, new pillows
6. Vacuum once a week damp dust all surfaces
7. Remove fabric curtains and furnishings
8. Remove carpet