Avoid the allergens

Avoid the allergens

House Dust Mite Allergy – Avoid the Allergens

It is possible to achieve a healthy, allergen-free home without expensive equipment, risky chemicals or major renovations.

With a few adjusted habits, you can maintain a comfortable, allergen-free lifestyle, making your home a safe haven for you or your child with house dust mite allergy.

With our scientific background, we have tried below to explain and describe the correct guidance.

The most important allergens are found in house dust mite faeces.

For Dermatophagoides pteronyssinus, nine allergen structures are now known: Der p 1, Der p 2, Der p 3, etc.

Under normal living conditions, these allergens are quite stable.

Avoid the allergens

House dust mites love your home. You provide their favourite food – flakes of dead skin cells – every day. They also like your home because it is warm and humid.

They love moisture because they cannot drink; instead, they absorb water through their legs. This is why they thrive in bedrooms – your bed retains moisture.

That is where you should focus your primary efforts.

Although you should focus on the bedroom, you should also keep an eye on the rest of the home.

If you have house dust mite allergy, you should at least:

  • Keep humidity low during the colder months
  • Ensure ventilation in the kitchen and bathroom
  • Limit fitted carpets as much as possible
  • Ask yourself whether you really need the old upholstered sofa or chair

TOP 10 ADVICE – How to avoid house dust mite allergens

  • Keep the humidity in bedrooms as low as possible. Aim for 35–50% RH during the cooler months.
  • Wash bedding in hot water (60°C) once a week and dry it in the tumble dryer.
  • Use a recognised house dust mite-proof cover on mattresses and pillows in the bedroom.
  • If symptoms are severe, duvets should also have covers.
  • Use a mattress protector.
  • If you have allergies – consider replacing your mattress if it is 6–8 years old or older. Without allergies – 8–10 years.
  • Do not make the bed or use a bedspread after sleeping.
  • Only use a bed on legs.
  • Aim for the same temperature in the bedroom as in the rest of the home during the day, and make sure all internal doors are slightly open so air can circulate. You can turn the temperature down at night.
  • Avoid fitted carpets – especially in the bedroom.
  • Clean your home regularly and use a vacuum cleaner with a HEPA filter.
  • If this does not help – seek medical advice and discuss which treatment is best suited to you.

Allergen-proof mattress cover

Physical protection of mattress, duvet and pillows.

Cotton and non-woven microfibre are not suitable.

Only use products that are CE marked in accordance with the regulations for Class I medical devices.

Only use allergen-proof covers that are guaranteed for a minimum of 50 washes at 60°C.

Always use a mattress protector.

If possible, choose fully enclosing covers with a zip.

Use:

  • Mattress cover
  • Pillow cover
  • Duvet cover

Leave it on permanently (remove and wash approximately 4–5 times a year).

Combine with a correct bedding routine

Use a washable cotton cover outside the allergen-proof layer.

This reduces wear.

If you have allergies – wash cotton sheets and pillowcases weekly.

Wash allergen-proof covers 4–5 times a year.

Always wash all bedding at 60°C. This kills house dust mites.

Change cotton pillowcases twice a week if the user sweats heavily.

If you have allergies – replace the mattress every 6–8 years.

Source: ALK-Abelló

Consider replacing your mattress

A new mattress can contain unacceptable levels of mites after only four months and up to 1 million mites after one year.

Manufacturers recommend replacing mattresses every 6–8 years for allergy sufferers – earlier if symptoms worsen.

Using allergen-proof covers from the first day can significantly extend the life of the mattress.

Do not make the bed

People release between ½ and 1 litre of fluid every night while sleeping.

If you make the bed with a blanket or duvet over the mattress so that it looks inviting, you ensure that the moisture remains in the mattress and bedding.

Instead, find a way of making the bed that allows the mattress to breathe.

Only use a bed on legs

When you release ½–1 litre of water every night, it is important that the mattress can breathe.

It cannot do this if it lies directly on the floor, so it should have legs and be raised so that air can circulate freely underneath and around the mattress.

This necessary ventilation is stopped if you store bedding, for example, in a drawer under the bed, so you should avoid this.

Difference between mattresses?

Mites thrive on all types of mattresses, even waterbeds, if the temperature and humidity conditions otherwise allow it.

Control the indoor climate 

House dust mites and mould thrive in high humidity, so keep humidity below 40–50%. House dust mites do not survive humidity below 50%.

  • Get a hygrometer
  • Keep the same temperature in the bedroom as in the living areas during the daytime
  • Air the home at least twice a day for 10 minutes with through-draught
  • Install fresh-air vents in external walls or windows
  • Keep internal doors open as much as possible to ventilate the home
  • Ensure effective mechanical extraction in the kitchen and bathroom/utility room
  • Use a bed on legs so that the mattress is raised above the floor
  • Do not cover the bed with a bedspread. Fold the duvet to the side and allow the mattress to air

Humidity

Source: ALK-Abelló

House dust mites are extremely sensitive to moisture and die when relative humidity falls below 50% RH.

People release 0.5–1 litre of moisture during the night, so it is essential to remove this moisture from the bed.

If your bedroom is cold, it is more difficult to lower the humidity.

Remember: humidity falls when cold air is heated – a natural and free effect that you can use by keeping your home evenly warm when the outdoor temperature is below 20°C and ventilating well.

Think of your home as a person – it needs to breathe freely, both in and out.

Ventilation systems with heat recovery are ideal, but where this is not possible, you can achieve a great deal with natural ventilation.

About house dust mite-proof covers

Because it can be difficult to reduce the humidity in the home, allergen-proof covers for your bed are a must. Good, recognised brands made from tightly woven and tested microfibre are the only type that effectively protects you.

The use of allergen-proof covers has been shown to result in up to 47% fewer hospital admissions due to house dust mite allergy compared with not using allergen-proof covers, and after one year the dose of inhaled steroids can be expected to be reduced by at least 50%.

Many companies try to make money from the “allergy market”. Advertisements often offer “allergy covers”, “allergy-friendly covers”, “hypoallergenic” products, etc.

The vast majority are not serious products, and covers made from cotton and, for example, non-woven polyester are NOT allergen-proof after use and washing. They may not contain substances that cause allergies, but they do not protect against allergens either.

Allergen-proof covers must at least cover:

  • The top and edges of the mattress
  • The pillow where the head and upper body are
  • The mattress seams and zip
  • The duvet or blanket

Several studies by independent institutes indicate that most allergen-proof covers on the market have major shortcomings. Even if the fabric itself may be good, most overlook the fact that seams and zips are a major source of contamination.

About mattress protectors

Most house dust mites are found near the top of the mattress, where the humidity is highest and the temperature is suitable.

Many studies show that allergen density is reduced by up to 30% when using a mattress protector, probably because it can be washed at 60°C.

Electric blankets that are left switched on during the day can, at best, reduce the house dust mite concentration by 30–50%.

Air OUT: Remove indoor moisture through heating and good ventilation, especially in bedrooms. A ventilation rate below 0.2 per hour increases the risk of house dust mites, while rates above 0.5 per hour greatly reduce mites and allergens.

Keep doors open so that air can circulate through extractor fans in the kitchen and bathroom. Use fans during cooking and bathing.

Air IN: It is best if rooms are fitted with fresh-air vents in walls or windows, which help draw outdoor air in without causing draughts. Also ensure cross-ventilation at least twice a day. But no more than 10 minutes at a time, to avoid cooling the surfaces.

Regardless of how you reduce the humidity, this will only be possible during the colder months.

If the outdoor temperature is above 20°C, it is not possible. During these periods, you must rely on allergen-proof covers and your medication to protect you.

The example here shows that in Scandinavia it is difficult to reduce humidity in the home from May to September, when the outdoor temperature is above 15°C, but it will be possible during the rest of the year.

Source: ALK-Abelló

In warm areas, air-conditioning systems are often used. These systems reduce the water content of the air because the indoor coils are cold and water condenses on them. This can reduce the allergen concentration during the summer months.

A study in Denmark showed that mechanical ventilation and heat recovery were sufficient to reduce absolute humidity significantly and thereby reduce or completely eliminate house dust mites in mattresses.

When the same tests were carried out in other countries where building standards were lower and homes were less airtight, such as the United Kingdom and southern European homes, the results were completely different.

Mechanical ventilation and heat recovery are therefore not recommended as a general solution for reducing house dust mites and allergens in these countries.

Temperature

Humidity

Survival/Activity

Comment

10–15°C

70–80%

💤 Low activity

Slow reproduction

20–25°C

70–80%

🌿 Optimal growth

Best for breeding

26–30°C

60–70%

⚖️ Moderate activity

Gradual decline

35°C

60%

⚠️ Stressed

Few survive

>38°C

<60%

☠️ Fatal within hours

Eggs and adults die

≥55°C

—

💀 Total mortality

Bedding wash

All temps

<50% RH

🚫 No reproduction

Air too dry for eggs/larvae

Exception: House dust mite allergens are quite stable under normal living conditions. However, new studies may indicate that the Der p 1 allergen from Dermatophagoides pteronyssinus is not greatly affected by heating to 60°C, and that allergen activity remains unchanged after storage for four years at 5–25°C.

D. pteronyssinus thrives in warm and humid climates and is most widespread in Western and Northern Europe – for example Denmark, the United Kingdom, the Netherlands, Germany and France.

It is also found in coastal areas and regions with high humidity, such as Southern Europe (Portugal, Spain) and parts of the Mediterranean region.

Avoid Wall-to-Wall Carpets

Fitted carpets trap mites and allergens.

Smooth, washable floors are best – vacuuming removes 80% of mites from hard floors but only 30% from carpets.

Small washable rugs are acceptable alternatives.

Not having fitted carpets makes cleaning easier and reduces the number of house dust mites. You can remove 80% of mites when vacuuming a smooth floor, but only 30% when vacuuming a carpet.

There are almost four times as many mites on floors with fitted wall-to-wall carpets as on other floors. This may be because vacuuming does not remove many mites from carpets and because the humidity conditions in a carpet can be particularly favourable for mites.

The mite concentration on the mattress is largely independent of the floor covering.

House dust mite allergens are widespread in the home and are found particularly in carpets, furniture, mattresses, pillows, duvets, mats, curtains, soft toys, clothing and furry animals – and can even, to a lesser extent, be detected in hair, on the skin and in umbilical cord blood.

A large study from New Zealand showed that the level of Der p 1 in dust samples from floors, beds and seats in hotels, hospitals, nursing homes, primary schools and nurseries, cinemas, churches, ski lodges, banks and aircraft was significantly lower in these public places compared with the home environment.

Although the level was significantly lower, it was found that carpets in public spaces still represent an important source of house dust mite allergens, and that lower Der p 1 levels are related to how frequently they are cleaned.

Cleaning

Maintain a good standard of general cleaning in your home. Vacuum your bedroom at least once a week and frequently wipe all horizontal surfaces with a damp cloth.

Thorough vacuuming of mattresses that have otherwise simply been cleaned can temporarily reduce allergen levels by half, but it is difficult to reduce them further after that.

Dust in your bedroom can trigger allergic reactions such as a blocked nose, breathing difficulties and postnasal drip – the unpleasant sensation of mucus running down the back of the throat. This can lead to coughing and persistent sneezing. These are your body's natural ways of removing dust from your airways.

If you sleep in a dusty room, you are likely to inhale dust particles. If these particles contain substances to which you are sensitive, they can trigger an allergic reaction.

In some cases, house dust mite particles that pass through the nasal cilia (the nose's filter) can reach the lower airways and cause bronchitis, or in the worst case – bronchitis or asthma.

Remove dust deposits

  • No wall-to-wall carpets or heavy curtains that are difficult to wash, primarily in bedrooms.
  • Carpets are reservoirs for dust and house dust mites.
  • Only use a bed on legs so that the mattress is raised above the floor.
  • Use a HEPA filter in the vacuum cleaner 1–2 times a week on floors and monthly on the mattress.
  • Vacuum weekly.
  • Keep clean rather than cleaning.

HEPA filter

Make sure your vacuum cleaner has a HEPA filter. This means that the air returned by the vacuum cleaner has been cleaned of most microparticles such as allergens.

Most studies show that even the most thorough vacuuming leaves behind up to 30% of impurities.

Faecal particles and mite fragments are stirred up, particularly during cleaning, vacuuming and other activities, but after only 20–30 minutes the concentration in the air is quite low again, unlike, for example, cat allergens, which remain suspended for hours.

When damp, faecal particles are 10–40 µm in diameter, i.e. the same size as pollen. But when dry, they break down and are then only 1–4 µm in diameter and are therefore normally airborne and easy to inhale.

As much as 20% of house dust mite allergen in the air is found on particles smaller than 10 µm, probably fragments of house dust mites or faeces that can easily reach the large and small airways.

It is therefore highly advisable to ventilate the home during and immediately after vacuuming. This can be done as part of regular airing.

Carpet cleaning

It is a myth that chemical or dry carpet cleaning removes all dust and allergens.

Although these cleaning agents use surfactants that loosen dirt, they also damage the protective mucous membranes in the nose, throat and lungs – weakening resistance to allergens.

Even after professional cleaning, up to 15% of the dirt remains.

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