Allergen Avoidance

Allergy is widespread and affects approximately one in four of the population in the UK at some time in their lives. Each year the numbers are increasing by 5% with as many as half of all those affected being children.


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Allergen avoidance is an essential step in managing allergies. Identifying the allergen causing symptoms is a vital part of treating allergic diseases. Once the causes are correctly identified, the following practical advice on avoiding or minimising your exposure to allergens should help. Sometimes, the offending allergen may be obvious. However, in other cases your doctor will need to consider your medical history together with the results of allergy tests in order to give you advice as to what allergen avoidance measures to take.

While there may be no cure for your allergy, there are positive steps that can be taken to reduce the number of allergens in your home that can cause the allergic symptoms. It has been shown that the severity of allergic symptoms and the amount of medication needed to control allergic conditions can both be reduced dramatically by reducing the number of associated allergens around the home.

One way of understanding how allergen avoidance might work is to think of a level of allergen which causes symptoms. In some people, a high amount of allergen is needed to cause symptoms, so anything which reduces the allergen in the environment can be very effective in reducing symptoms. In more sensitive people, a lower level of allergen will trigger symptoms, and allergen avoidance strategies may not be as successful. The only way to find out is to try.

Understanding common allergens

The way in which we live has changed dramatically over the last century, with new building methods and luxuries giving us more comfort, but increasing the number and levels of allergens in our homes. Modern homes have been built and adapted to keep us warm and draught-free, but those very conditions have also improved the environment for two particular allergens to increase in number; house dust mites and moulds both thrive in warm, humid conditions.

In the past, housing was not consistently warm in the same way that ours is today, nor were houses particularly well insulated. The constant flow of air with fluctuation in temperatures meant that the conditions for house dust mites and moulds were much less favourable.

Central heating and double glazing, together with other modern building methods have meant that the air flow from outside has reduced dramatically and, combined with the cooking and other household items that emit heat, everyday living creates a warm, humid atmosphere ideal for moulds and house dust mites.

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House dust mites

House dust mites are microscopic creatures related to spiders and ticks, which live off dead skin cells found in house dust. They have become a serious problem for many people due to the number of allergic symptoms that are associated with them, including breathing problems, asthma, rhinitis and itching eyes. Some cases of eczema are also linked to house dust mite allergy.

House dust mites are very difficult to remove completely from the home since they move down into the lower parts of carpets and cling onto material fibres. Typical cleaning methods do not remove all house dust mites, and allergy symptoms are actually caused by the mites' digestive enzyme mainly found in its excreta. The allergen particles are invisible to the naked eye and are about the same size as a pollen grain, easily becoming airborne when we sit on a sofa or move around in bed. These mites particularly thrive in carpets, curtains, mattresses, pillows and duvets.

To avoid or minimise allergen exposure:

  • Wash bedding and pillow cases at least weekly, in hot water (more than 50°C). This will kill dust mites and wash away the allergen they produce. Another way to kill mites is to tumble dry the sheets on ‘hot’ for at least 10 minutes. Dry cleaning is not as effective as it will kill house dust mites but won't remove the allergen they produce.
  • Cover mattresses, pillows and quilts with dust mite resistant covers, and wash these every 2 months.
  • Consider replacing carpets with hard floors such as wood, tiles, linoleum or concrete, where practical and affordable. Carpets can contain large amounts of house dust mite and animal allergens which cannot be completely removed by vacuuming.
  • Damp dust hard surfaces (including hard floors) weekly.
  • Vacuum carpets weekly, but be aware that vacuuming increases the amount of house dust mite allergen in the air for up to 20 minutes. So if possible, ask someone else to do the vacuuming and wait for 20 minutes before re-entering the room. High efficiency particulate air (HEPA) filter vacuum cleaners may remove more allergen than other vacuum cleaners, but they still increase the amount of allergen in the air after vacuuming.

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Moulds

In modern, clean homes moulds are generally not considered to be serious threats to health. However, to individuals who suffer allergy that is triggered by mould spores, even in the most modern homes these can still be hazards. The body of a mould releases thousands of microscopic spores into the air which have the potential to cause allergic reactions when inhaled.

Moulds commonly form in the rooms where moisture is created, such as the bathroom and kitchen. In addition, it is common for black mould to form around window frames or at points where the warm indoor air meets cold external surfaces.

Old foods such as fruit, vegetables, cheese and bread grow moulds easily and fridges are often home to moulds. House plants readily provide a breeding ground for moulds in the soil and on the plants themselves, and at Christmas time sufferers should be aware that a real Christmas tree will bring a large number of mould spores into the home.

Mould spores in the environment are consistently everywhere but have peak seasons, like pollen. In the UK, for most moulds, this is in the autumn, in damp and mild conditions.

Like the house dust mite allergy, mould allergy may cause symptoms such as breathing problems, a constantly runny nose and sneezing. These rhinitis symptoms can lead to more serious health problems such as asthma.

If you are allergic to mould, you may consider:

  • removing visible mould by cleaning with bleach or anti-mould cleaners
  • ensuring adequate natural ventilation including the use of extractor fans
  • removing indoor pot plants (which promote mould growth)
  • drying or removing wet carpets
  • avoiding working with garden compost

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Pollen

Pollen is perhaps the best known allergen due to its potential to cause seasonal allergic rhinitis (hay fever). It is now known that hayfever is caused by an allergy to a specific pollen, or group of pollens, rather than pollen in general. Knowing this can help in the control of the allergic condition by reducing exposure to that particular allergen. However, as with almost all allergens, total elimination is impossible.

Pollen ‘season’ can alter slightly each year, but it is known when the different types of pollens are generally released from each plant type. How pollen affects an individual on a daily basis differs depending on weather conditions, such as humidity and temperature, as well as the time of day.

However, pollen is not limited to outside; these microscopic particles are often brought into the home on clothes, skin and hair. This remains a potential problem once inside the home, and although it is a fairly heavy substance and will fall to rest on surfaces quite quickly it can still be disturbed and cause ongoing symptoms.

Pollen can be hard to avoid, but the following advice can be helpful:

  • Remain indoors (when possible) during the pollen season
  • Avoid activities known to cause exposure to pollen, such as mowing grass
  • Shower soon after activities where there is high exposure to pollen
  • Use re-circulated air in the car when pollen levels are high (many cars are fitted with pollen filters)

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Pets

Allergen particles from pets, found in saliva, sweat and urine can linger for a long time and be easily spread. Pet dander is formed from the skin of animals and is often the most common cause of pet allergy, easily collecting on their bedding, and is distributed in the air as they move. Even with constant cleaning and vacuuming it is hard to remove all these allergen particles and they can cause a constant problem for allergy sufferers.

Pet allergy sufferers may also find that while not having a pet themselves, visiting others who do still causes them problems once they have returned home, as any hair and pet dander can easily be transported on clothing. Even when moving into a new home where there has previously been a cat or a dog, it can be simpler to replace the carpets rather than waiting for the allergens to go away. Cat dander, in particular, can linger for 12 months or more on soft furnishings, despite the cat no longer being present.

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Dust

Dust is comprised of a mixture of tiny particles of materials found in the home. It very often includes mould spores, pollen, fabric fibres, animal dander, dried food particles, and insect parts (including house dust mites). Due to the size and amount of dust that gathers in the home it is very difficult to eliminate completely and is easily inhaled. It collects on the skin of those cleaning or working in dusty environments. Associated allergy symptoms include asthma attacks, rhinitis and dermatitis.

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Last updated: March 2012
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