As many as one in ten people will suffer from an allergy at some point in their lives but there are things one can do around the home to help…

Although scientists think most people would eventually react to a soup of chemicals, most of us don’t suffer allergies but for the one in ten that do life can often be uncomfortable if not threatening, so a look at what can be done to reduce allergens in the home may be helpful.

An allergic reaction is what happens when the body’s defence mechanism is triggered into action over something that is normally harmless.  The body becomes hypersensitive and forms antibodies against the normally harmless substance and these then cause certain cells in the body to release chemicals into the bloodstream, one of which is histamine.  The histamine then acts on a person's eyes, nose, throat, lungs, skin, or gastrointestinal tract and causes the symptoms of the allergic reaction.

Future exposure to that same substance (called an allergen) will trigger this antibody response again. This means that every time you come into contact with that allergen, you'll have an allergic reaction.

There are three sorts of allergies: airborne, contact and food induced. 

Food allergies are most common in infants and often go away as a child gets older. Although some food allergies can be serious, many simply cause annoying symptoms like an itchy rash, a stuffy nose, and diarrhoea. Finding out what causes the allergy is often a systematic ‘trial and error’ method but allergy specialists can test efficiently.

Most allergy specialists agree that the foods that people are most commonly allergic to are milk and other dairy products, eggs, wheat, soy, peanuts and tree nuts, and seafood.

Contact allergies are skin reactions to household chemicals, laundry detergents, metals and jewellery, cosmetics and sometimes the substances used to make rubber, reconstituted wood etc. Garden chemicals and insect bites and stings may also cause an allergic reaction by contact, injection or breathing in.

Airborne particles such as dust, grass pollen and chemicals released by both natural and synthetic materials are all included in this category. These are often called environmental allergens, and they're the most common cause of an allergy. Other examples are dust mites (tiny bugs that live in house dust), mould spores, animal dander (flakes of scaly, dried skin, and dried saliva from your pets) and pollen from flowers and trees.

For many people with asthma, especially children, an allergy to house dust mites and animal hair or fur is common.  The symptoms of asthma are caused when airways (the tubes which carry air to and from the lungs) narrow and become inflamed.

This may happen if there’s too much mucus being produced by the airways, or there is swelling or spasm in the lining of your airways. You feel breathless, wheezy, and may develop a dry cough. Symptoms tend to be worse at night or in the early morning.

The symptoms can be severe and distressing, and may require hospital treatment. Severe asthma attacks can be fatal.

In some adults, the symptoms of asthma may be a sign of heart disease, especially if wheeziness occurs when there has never been an asthma attack in the past. Heart failure can cause congestion (excess fluid) of the lungs, and have symptoms similar to asthma.

The most complete way to avoid allergic reactions is to stay away from the substances that cause them. Doctors can also treat some allergies using medications and shots.

For many allergies an antihistamine similar to that taken for hay fever will bring relief and for asthma sufferers there are inhalers, steroids and nebulisers. Nebulisers make a mist of water and asthma medicine that is breathed in. They can deliver more of the drug to exactly where it’s needed than conventional inhalers can. This is particularly critical in the event of a serious asthma attack. Nebulisers are mostly used at hospital, but some people may have them at home.

Reducing contact though remains the best approach even if difficult to achieve completely. In fact, for some people, eliminating exposure to an allergen is enough to prevent allergy symptoms and they don't need to take medicines or go through other allergy treatments.

In the home, aim to create a dry dust-free and well-ventilated house. Remove carpets and rugs opting instead for hard flooring. Even rigorously cleaned carpets harbour dust and this is released when the carpet is walked upon, taking hours to settle again. Wipe down floors with a slightly damp cloth and close windows facing a traffic carrying road.

Avoid chemical cleaners, especially those with fragrances. Many household products emit volatile aerosols even if they are not sprays.

Some studies, such as Bristol University’s Children of the 90s project, which has been following a group of children born in the Avon area in the early 1990s, have found direct links from household chemicals to lung problems in babies as early as in the womb. Bleach, paint stripper and carpet cleaners were particularly suspect.

If you like plants in the home, choose those that are normally pollinated by insects rather than type that are pollinated by the wind. The same selection should apply to your garden too.

Moulds are naturally occurring clusters of microscopic fungi, which reproduce by releasing airborne spores and it’s these spores that become the allergen. Damp is an ideal environment for moulds to grow and the big controller of damp is ventilation. These days people have well insulated homes and, in the winter particularly, don’t feel inclined to throw open all the windows. Control of damp is possible by dehumidifiers but these have to be good to work sufficiently well.  You can reduce the damp you put into the house by using ventilation fans in the kitchen, and bathroom, cleaning up water from pans below self-defrosting refrigerators and emptying rubbish bins frequently. Don’t store firewood or other damp materials indoors and cut down on the number of indoor houseplants.

Humidity in rooms and bedding leads to one of the biggest offenders of all - dust mites. It’s long been known that dust mites and asthma are closely related, even though a number of studies have not been conclusive on the matter.

However study by Wright State University, USA has directly linked a large number of dust mite species to the allergens that affect humans and there are studies that link dust mite reduction in the home to a reduction of allergies and asthma.

Dust mites thrive in carpets and bedding by feeding on human and animal skin that accumulate there. The mites are so small they cannot be seen with the naked eye but they have sticky feet that cling on to bedding and carpets so that vacuuming them up or even washing is not effective. It is actually the faeces of the mite that cause the allergy and this can be vacuumed however.

The cleanliness of the home or the presence of animals has nothing to do with the number of mites in a home. Their population is determined by the humidity of the home, the temperature of the home, and the amount of fabric or upholstery in the home. They do not survive on vinyl or hardwood floors but are everywhere that dust accumulates.

However tenacious the little critters are, there is one thing that they cannot do without and that is water. An option that recently was shown to be effective and practical in homes in temperate climates is to reduce relative humidity to below 51%. Below this point the mites cannot absorb moisture and they die. Once dead, their sticky feet dry up and they can be successfully vacuumed up.

Keeping the humidity low may pose a problem however. Some studies using low-efficiency dehumidifiers (mostly in single rooms) showed a benefit, while others showed no benefit at all. 

The problem seems to be keeping the humidity low for a long enough period. As soon as the system is turned off or the room opened to outside air the humidity returns. Even so, a substantial reduction in mites will occur from a short period of humidity below 51%.

A recently completed study in the USA clearly showed that by using high-efficiency dehumidifiers coupled with air conditioning, it was possible to maintain low relative humidity.

The Scandinavians have learnt another trick. By washing and drying bedding, then hanging it outside to air overnight in the cold they have found that the freezing temperatures kill the little mites.  You can achieve the same result by putting pillows and duvet covers in the freezer overnight!

As mentioned above ventilation is an important factor in reducing many allergens and their ideal growing conditions. A forced air heat-exchanger type of ventilation system may allow good ventilation and still retain much of the heat in the home.

A whole-house vacuum system will also be a benefit as the air taken in by the vacuum is expelled to the outside of the house rather than back to the room as in conventional vacuum cleaners.

• Keep pets out of certain rooms, like your bedroom, and bathe them if necessary.
• Remove carpets or rugs from your room (hard floor surfaces don't collect dust as much as carpets do).
• Don't hang heavy curtains, and get rid of other items that allow dust to accumulate.
• Clean frequently (if your allergy is severe, you may be able to get someone else to do it or you could try using a mask)
• Take care emptying the vacuum cleaner.
• Use special covers to seal pillows and mattresses if you're allergic to dust mites. The mites are kept out of the pillow, so are easier to wash off.
• If you're allergic to pollen, keep windows closed when pollen season's at its peak, change your clothing after being outdoors - and don't mow lawns.
• Avoid damp areas, such as basements, if you're allergic to mould, and keep bathrooms and other mould-prone areas clean and dry.
• Do not give furry toys to children to take to bed. An excellent substitute is a little cotton blanket that can be washed regularly at 60 degrees centigrade or higher.
• It may be possible to wash the toy well enough to remove the dust and then freeze the toy for 24 hours to kill the mites.
• Washing bedclothes at temperatures higher than 56% will kill mites, but you will have to find suitable bedclothes that will stand up to this temperature.
• Damp-dust instead of vacuuming.
• In winter, it is relatively easy to open the bedroom windows and pull back the bedclothes, and keep the heating turned off in these rooms.