It is the most important allergy in western countries, both for its widespread diffusion (modern homes create an ideal microclimate for the growth of mites at nearly all latitudes) and, above all, for the mite’s strong allergising power. It has been demonstrated that sensitisation to mites is the greatest risk factor for the development of asthma and that, by creating microscopic fissures in the mucosa of the respiratory apparatus, mite allergens favour the passage of other allergens, facilitating the onset of new allergies which aggravate the clinical picture. Despite these aspects, it is the easiest allergy to control with simple measures of environmental prophylaxis. It is easy to defend yourself against dust mites because their allergens are not scattered in the air, but build up in mattresses, pillows, blankets and duvets. Scientific studies have shown that, by covering these sites with certified anti-mite covers, it is possible to reduce the exposure to allergens from 100 to 1000 times in one month, with objective and appreciable benefits for allergic persons.
What are mites
Dust mites, or Dermatophagoides, are microorganisms similar to spiders and invisible to the naked eye, much smaller than one millimetre in diameter (they measure about 250 micron, a quarter of a mm). Although they are commonly called “dust mites”, they live almost exclusively in beds, where more than 94% of their allergens can be found. Only there do they find the conditions necessary for their survival:
1) Absence of sunlight:
light kills mites, that is why they nest in the internal layers of the mattress, the pillow and the duvet.
2) Temperature around 20°C and relative humidity between 60 and 80%,
conditions which are guaranteed by our body, which constantly loses humidity and warmth.
3) Plenty of food
As their name says, Dermatophagoides mites (skin eaters) feed on dandruff and flakes of skin which are continuously shed by our body (the skin detritus that we leave in the bed every night is enough to feed one thousand mites for a month).
What are mite allergens?
Mite allergens are the enzymes present in the mite’s excretions. They are relatively heavy, measuring from 10 to 30 micron, and they are not dispersed in the air, but remain deposited inside the mattresses, pillows and duvets where they are produced, accumulating in enormous quantities.
We come into contact with the allergens through our airways, because the weight and movements of the human body raise them just enough to let them reach our nose.
ADVICES TO REDUCE THE EXPOSURE TO DUST-MITE ALLERGENS
1) Cover mattresses and pillows with certified anti-mite encasings
That’s the golden rule for environmental prophylaxis and should have top priority: following other rules and neglecting this one would make any action useless. The encasings must completely encase the mattress and pillow and must be washed with the frequency indicated by the manufacturer at 60°C, because mites die only at temperatures higher than 55°C. Every week, when changing the sheets, wipe the encasings with a well wrung damp cloth to eliminate surface dust. It is important to keep them on the bed for very long periods, because it has been demonstrated that, after using them continuously for 20 weeks, less than 1% of the mites survive.
- if there are other beds in the room where the allergic person sleeps, these too must be fitted with anti-dust mite encasings;
- if an allergic child sleeps even for just part of the night with its parents, their bed too must be fitted with anti-dust mite encasings.
2) Cover duvets and blankets with anti-mite encasings, or replace them with blankets that ca be washed at 60° C
High concentrations of mites can also be found in duvets and blankets (especially merino woollen blankets) which should be exposed to the sun daily and washed every 2-3 weeks at 60°C (dry cleaning does not remove allergens). If this is not possible, use a waterproof and breathing blanket cover or duvet cover. As an alternative it is suggested to use blankets that can be washed at 60°C. Sheets and pillow cases must be washed weekly at 60°C.
3) Wash sheets and pillowcases every week at 60 ° C
4) Remove rugs and carpets from the allergic person's room
It is very difficult to remove mites from those sites. If this is not possible, clean them at least once a week using a vacuum cleaner with cyclone technology fitted with a HEPA filter, which is able to block more than 99% of the allergens that are sucked up. Other vacuum cleaners send the allergens, which had previously been deposited, back into the air where they can be breathed. Although steam (100°C) can kill part of the mites and destroy the allergens, its use on carpets (and on mattresses) is not recommended, because the humility retained by the fibres favours the uncontrolled growth of mites, mould and fungi; steam can also damage the colours and fibres of fine-quality carpets. The use of acaricides on carpets has proved to be partly useful, but its clinical efficacy has not yet been sufficiently documented.
5) Make the space in the bedroom easy to clean
Avoid padded upholstery, replace heavy drapes and venetian blinds with lightweight curtains that can be washed at 60°C. Plush toys should also be washed at this temperature, every 2-3 weeks, or put in the freezer for 24-48 hours and then washed in cold water. Clothes should be kept closed in wardrobes, possibly in waterproof breathing bags.
6) Prefer couches and armchairs covered with leather, alcantara or other allergen-impermeable material
If you already have fabric-upholstered armchairs and couches, their cushions can be covered on the inside with waterproof anti-mite fabrics that allow the passage of air.
7) An allergic child should not jump on beds and couches and "fight" with pillows or cushions if they have not been protected with anti-mite encasings
These movements spread an enormous amount of allergens in the air. For the same reason the child should also avoid crawling about on carpets.
8) Clean the house with a damp cloth or use a vacuum cleaner with cyclone technology fitted with a HEPA filter
HEPA filters are the only ones able to block more than 99% of mite, dog and cat allergens. Vacuum cleaners using a bag, air or water, disperse part of the allergens in the air where they can be breathed.
9) Keep the relative humidity (R.H.) below 50%
If not in the whole house, at least in the bedroom of the allergic person. With 50% R.H. the number of mites is 10 times lower than with 60% R.H. and even 100 times lower than with 80% R.H. It is possible to measure the value of the relative humidity with a good hygrometer, better if equipped with a memory of the minimum and maximum recorded values. It may also be useful to use a good dehumidifier in rooms with very high humidity (basements, rooms or the ground floor or facing north, etc.), in particular where there is mould on the walls, humidity behind the furniture or condensation on the windows.
- Avoid using electrical household appliances that produce humidity
- Ventilate the rooms when producing humidity (bathroom, kitchen, etc.)
- Air the rooms frequently, even for just a few minutes.
10) Take the anti-dust mite encasings with you when staying away from home
Particular care is needed in holiday homes, which remain closed for many months of the year; they are damp and poorly ventilated, offering the ideal terrain for the development of mould, fungi and mites. (see Microair Travel Set).
11) Use the covers right from the first months of the child's life
If the parents are allergic, it is advisable to use anti-dust mite encasings right from the first months of the child’s life. The children of allergic parents have 75% probability of developing an allergy, while the risk is 50% if only one of the parents is allergic.
12) Periodically clean the filters of the air heating system or of the air conditioner
13) Do not smoke
Active and passive smoking are a much more dangerous source of pollution than industrial activities and heavy motor traffic.
Bad habits, ineffective and expensive remedies
- Cleaning doesn't solve the problem. Continuously vacuuming, washing the floor, getting rid of rugs and carpets, heavy drapes and plush toys from the bedrooms of allergic children are excellent means of maintaining hygiene, but they do not solve the allergy problem. Dermatophagoides mites are not in house dust, which can be seen with the naked eye, deposited on floors, furniture or ornaments, because they are photophobic and die rapidly if exposed to sunlight. The only dust in which they may be found in large quantities is the dust that falls from the mattress, and that lies under the bed.
- It is no necessary to buy new mattresses or pillows frequently. It is of no use, because in just a few months they will be colonised by mites anyway. The important thing is to cover them with certified anti-mite encasings.
- Do not vacuum the mattress. This removes only the few mites that live on the surface and not the ones nesting in the internal layers.
- Do not use acaricide products on mattresses, pillows and couches. This eliminates only the few mites that live on the surface. Moreover, these products contain chemical substances that may have a toxic and irritating effect on the skin and mucosa, especially in the case of prolonged contact such as occurs in bed.