Archive for the ‘Allergens’ Category

Allergens and irritants at work
Some workplaces have very high concentrations of allergens in the air, especially if proper safety procedures are not being followed. Occupational allergies can begin with symptoms in the nose, such as sneezing, blockage or constant streaming (allergic rhinitis). You may also suffer with itchy or watery eyes (conjunctivitis), a cough, sweating and a feverish feeling. Alternatively, direct contact with the allergen can produce a skin rash (dermatitis) or itchiness and swelling (contact urticaria/nettle rash and angioedema).
If you work somewhere with an allergy risk (see pp. 133-4), be vigilant for such symptoms and see your doctor immediately. These symptoms can be the forerunners of occupational asthma, which is a serious and potentially irreversible problem. Some allergens, such as latex, can even produce anaphylactic shock (a life-threatening allergic collapse).
Skin-prick tests (see p. 91) can show if you have an allergy to a substance encountered at work.
Acting promptly gives you the best possible chance of recovery and is vital if you have occupational asthma. Only if exposure to the allergen stops promptly do you have a good chance of shaking off the asthma. See your doctor as soon as possible and ask for a referral to a chest specialist, so that a definite diagnosis can be made. This is essential if you are going to make a claim for compensation.
Far too many people with occupational asthma are just sent off with an inhaler when they first see their doctor. By delaying the moment when work is identified as the source of the problem, and the exposure to the allergen is stopped, drug treatment can turn occupational asthma into a disabling lifelong problem. Although drugs can be helpful in speeding your recovery once exposure to the allergen
Latex allergy
Sensitisation to latex usually occurs at work (see pp. 133-4), or as a result of having many surgical operations. But latex allergy sometimes occurs in allergy-prone people even though they don’t work in a high-risk job and haven’t had many operations. Some doctors think that if a child with severe allergies needs surgery, this should be done in latex-free conditions, even though the child has no allergy to latex, because of the risk that the operation will sensitise.
Latex can cause either contact dermatitis (see p. 55) or a Type I allergy, whose symptoms can include urticaria, asthma and anaphylaxis. Latex allergy often goes undiagnosed. Once sensitised, you may react to balloons, elastic bands, condoms and household gloves. Latex in the air,
due to powdered latex gloves being used, can be a hazard for someone who is highly sensitive, as can latex traces in food (see box on p. 175). Medical treatment may be problematic (see p. 98 and box on p. 249). Cross-reactions to certain foods can occur (see p. 15 and p. 51).
For those avoiding latex, there are non-latex gloves (see p. 57), and non-latex condoms. Immunotherapy (see pp. 164-9) may be useful in severe cases: it can reduce sensitivity and eliminate cross-reactions to foods.
Other hazards
This article (pp. 132-5) deals mainly with allergens at work, that is, substances which provoke classical allergies (Type I reactions). In addition, there are skin irritants and antigens in workplaces which can provoke contact dermatitis (see p. 56) or contact urticaria (see p.50).
Some of the most dangerous workplace substances are those that bring on asthma but are not allergens. These are usually called low-molecular-weight asthmagens. The most notorious of these are platinum salts, isocyanates (used in cement, in the manufacture of foam, plastics and varnishes, and for spray-painting cars, aeroplanes and boats), colophony (used as a solder in electronics), glutaraldehyde (used in hospitals for sterilisation procedures), and persulphate (used in hairdressing). Powerful respiratory equipment, supplying air from outside the area (see p. 135) is needed if you work with some of these substances, e.g. isocyanates for spray-painting cars.
has ended, they should not be seen as a way of allowing you to go on working with the offending allergen or asthmagen.
If it seems plausible that your allergies or your asthma are related to your work, your doctor should be able to give you a sickness certificate, so that you can have some time away from the workplace, to see if you recover. The medical service at your workplace may be better at diagnosing occupational asthma than your own doctor, but be cautious. In some workplaces they do operate as they should and offer genuinely confidential treatment. But there have also been cases of information being passed to the management, and workers with the early signs of occupational allergies and/or asthma being dismissed on a pretext, or made redundant, to avoid a possible compensation claim. Most occupational health services claim to be independent, but they actually have to earn the trust of the workforce. Before you make any move, ask your colleagues for their views, especially those who have worked there for many years.
Choosing a job
If you have any tendency to allergies, or come from an allergy-prone family, you should be very choosy about where you work. Try to avoid workplaces where there is heavy exposure to allergens, especially airborne allergens which can provoke asthma:
• Bakeries and flour mills, where the allergens concerned may be wheat proteins in the flour, or enzymes added to the flour mix. These allergies can take years to begin.
• Other food-processing works, particularly those dealing with tea, soyabeans, other beans (e.g. gram flour), shellfish and fish (especially if automated gutting machines are used without adequate ventilation). Food preparation and sandwich-making can cause contact urticaria, if there is prolonged contact with a particular foodstuff (e.g. tomatoes).
• Farms, docks and cotton mills – or any other workplace generating dust from plant products. On farms, it is the dust from grain and hay that is often responsible, although mould spores (see p. 121) can also be the culprit. Allergies to mites (found in hay, grain and flour) sometimes occur and eczema is the most common symptom – often called simply ‘grain itch’.
• Saw mills and joineries, because of the wood dust, especially that from hardwoods and from red cedar (Thuja plicata).
• Paper recycling plants, if there is a lot of paper dust in the air.
• Detergent and pharmaceutical factories handling enzymes – these are added to ‘biological’ washing powders and are potential allergens. The risks are less these days, as the enzymes are in granule form rather than powder.
• Factories processing natural products such as psyllium or ispaghula, which are used as laxatives. Anyone who has been sensitised should avoid taking medicines containing the offending substance in the future, because these can sometimes provoke a dangerous anaphylactic reaction.
• Hospitals, clinics and dental surgeries, mainly due to latex rubber, used in gloves and equipment. Although nursing staff and surgeons are most susceptible, other staff including hospital administrative workers can occasionally be affected. Fears about the spread of the HIV virus has led to a huge increase in the use of latex gloves in medicine and dentistry, and a consequent epidemic of latex allergy. The main problem is with powdered latex gloves, which release 15,000 times as much allergen into the air as unpowdered gloves. Unpowdered, low-allergen gloves greatly reduce the risk of latex allergy developing, and non-latex gloves are even better. There are moves to ban the import of powdered latex gloves into Britain. They are already being phased out in hospitals and other medical facilities, but progress is slow in some areas.
• Other workplaces where powdered latex gloves are used, including
Making the workplace safe for everyone
Note that these choices about employment are for the individual employees to make for their own protection - an employer cannot refuse to take anyone on because they have allergies or come from an atopic (allergy-prone) family.
The reasoning behind this is that the workplace should be safe for everyone, as far as possible. As many as one in three of the population may be susceptible to allergies, and it is clearly wrong to bar all such people from major industries. Current thinking, in most countries, is that the focus should be on getting allergens and asthmagens out of the air, not keeping the more vulnerable workers out of the workplace.
hairdressers, dental surgeries, pathology laboratories and police stations. Construction workers wearing rubber gloves are also at risk. Someone who has been sensitised by powdered latex gloves may then react to other items (see box on p.132). Those severely affected can have great problems in daily life and with medical treatment, so anyone with a strong tendency to allergy should strenuously avoid becoming sensitised.
• Factories making or using rubber items may also expose workers to the risk of latex allergy. Anything made by the ‘dipping method’ (e.g. balloons, condoms, elastic bands and gloves) is highly allergenic. Moulded rubber items, such as tyres, are much less of a problem. Neoprene and other synthetic rubber items are not allergenic.
• Chiropody and podiatry clinics, where there is a risk of allergic reactions to the fungus that causes athlete’s foot. It is inhaled on skin flakes from the patients’ feet.
• Laboratories and other workplaces where animals are kept. In the case of mice, rats and other rodents, the allergen is found in the animals’ urine, and becomes airborne as the urine dries. Insects and spiders (e.g, those reared for biological pest control), are also allergenic due to small airborne particles from their bodies. Those working closely with bees (either honeybees or bumblebees, now reared for pollinating glasshouse crops) are liable to be stung frequently, and this can lead to sting allergy (see pp. 60-61).
• Hairdressing salons, where many different items are used that are potentially allergenic, including latex gloves (see above), permanent-wave solutions and henna. The risks of contact dermatitis are also high (see p. 55).
• Greenhouses, where the enclosed conditions can lead to high levels of allergens from plants, moulds and insect pests. There may also be exposure to pesticide sprays or their residues, which can greatly aggravate any underlying tendency to allergies.
If you have ever suffered from atopic eczema, work situations that can bring on contact dermatitis should also be avoided (see p. 55).
Taking a risky job
If circumstances force you to take a job with an allergy risk, observe all the safety procedures that are in place, and where you have the option of turning on extractor fans, wearing protective gear, or simply opening doors and windows, always do so. If the safety procedures seem inadequate, talk to your trade union Safety Representative, or the local Health and Safety Executive which can run a check on safety procedures in your workplace. This will be presented to the employer as a routine check, so they need never know that a member of the workforce has contacted the HSE.
Whatever you do, if you are in a risky job, don’t smoke. At a salmon processing plant in Scotland, 40% of the smokers developed allergies (resulting in asthma) to the fish allergens in the spray from the fish-gutting machine. Non-smokers - who formed the overwhelming majority of the workers - were not affected at all. In United States cotton mills, smokers are affected by levels of cotton dust in the air that are legally defined as ’safe’, while nonsmokers remain unaffected.
Passive smoking at work is also an important issue. A recent US study showed that non-smokers were more likely to develop asthma if they worked alongside a smoker. Your employer has a duty to provide you with clean air. This includes ensuring that other employees do not impose their cigarette smoke on you.
Respiratory equipment
Where respiratory equipment is needed, your employer must provide this, and it must be the right equipment for the job. It should be inspected, tested, cleaned and repaired after each use, and filters should be replaced regularly. All this is your employer’s responsibility, but check that it is being done, and always look the mask over before you put it on.
Two different types of respiratory equipment are currently in use:
• Those that give you a supply of air from outside the work area, either from a compressed-air cylinder, or via an air-hose (airline) supplied with fresh air. In Britain these are called breathing apparatus.
• Those that use the surrounding air but filter it to remove allergens and asthmagens. In Britain these are called respirators. (In some countries this term describes any kind of respiratory equipment.) Ordinary respirators may pose problems for some asthmatics because they cannot breathe in strongly enough to draw sufficient air through the filter. Powered respirators can be the answer: they have a battery-powered unit to help with pulling in the air.
There are government regulations concerning the type of equipment required for each type of allergen and asthmagen. Large companies generally follow these regulations, but small businesses, such as local sawmills, joineries and car-repainting workshops, may not even know about them.
Any respiratory equipment that has a face mask must form a tight seal with your face. Facial hair will prevent this, and so will stubble, so shave carefully. Faces vary enormously in shape, and if your face mask does not fit, ask for a different type of mask or a different type of respiratory equipment. Persist until you get one that’s right for you.
Carry out a ‘fit check’ each and every time you wear the mask. For example, with respirators, you can check the fit by covering the air intake completely with your hand and breathing in sharply: if the mask fits properly, it should collapse onto your face, and remain stuck to your face for several seconds. Look at the manufacturer’s instruction booklet as there may be a specific fit check recommended for the equipment you are using.
If there is any difficulty in breathing through the respiratory equipment, the replaceable filter cartridge or the equipment itself should be replaced. You should also take action immediately if you can smell the substance being handled – but never rely on this as a danger sign, because an extremely small amount, way beyond the detection capacity of the human nose, may be very damaging indeed to your health.
Keep your mask on throughout the work period. If you find this impossible, talk to your employer or
line manager about getting a different kind of respiratory equipment – a powered device, for example, that assists the inflow of air.
No form of respiratory equipment provides complete protection against allergens and asthmagens: there is always the chance of some small amount getting through. This is why respiratory equipment should not be used by those who have already developed occupational asthma but want to stay in their job.
Those who really cannot change jobs (e.g, farmers) are sometimes able to use a powered respirator helmet, which allows them to go on working despite the allergen. But this is not an ideal solution from a purely health point of view. Farmers can also improve matters, where moulds are the source of allergens, by keeping all harvested crops dry and thoroughly ventilated.
A lasting problem
As long as you catch the problem early, and are no longer anywhere near the allergen, your symptoms should disappear completely, but remember that you may still be highly sensitive to the allergen, even years afterwards. For a year or two at least, avoid contact with it again, even in tiny amounts. If someone else in your family works at the same place, they may bring home traces of the allergen on their clothes and hair: ask them to leave their workclothes outside the house and shower on arriving home.
With occupational allergies to airborne food particles, it is possible that the affected individual will later react to the same food when eaten. Experiment very cautiously, especially if the allergen is fish or shellfish.
The allergy may persist long after the job has ended. In one case, doctors found that a woman who had developed ‘baker’s asthma’, while working briefly in a bakery when young, was still allergic to the enzyme additive in bread 20 years later. She suffered an asthma attack whenever she ate bread.

Air Pollution and Allergy

Air pollution plays a variety of roles in allergic reactions. Some pollutants irritate the nose and airways (and sometimes the skin) making them more sensitive to allergens. These pollutants can worsen existing allergic symptoms and may promote the development of allergies in children, by making the airway membranes more permeable. Other chemical pollutants may affect the immune system directly, increasing any existing tendency to allergic reactions.
Indoor pollution
For many of us, the air in our houses is much more polluted than any outdoor air. Several of the indoor pollutants irritate the nose and airways, and some can trigger asthma attacks. A few of the pollutants found indoors can also make allergies and asthma more likely to develop in young children.
Background pollution
One of the worst irritants in indoor air is tobacco smoke. Other people’s cigarette or pipe smoke can trigger asthma attacks in the short term, and makes asthmatics generally worse in the long run. Passive smoking might also affect the immune system making allergies more likely to develop, though this is not proven. Do whatever you can to eliminate tobacco smoke from your home.
Everyone is different
This article considers air pollution from the point of view of someone with classical allergies (e.g. hayfever or asthma). Those with chemical intolerance (see p. 84) may well be more severely affected by air pollution.
If you smoke yourself, there are many good reasons for giving up:
• If individuals from atopic families (see p. smoke, they have a far greater chance of developing allergies and/or asthma when exposed to an allergen in the air.
• For those who had asthma as children and have since grown out of it, cigarette smoking doubles the chance of it coming back.
• Parents of asthmatic children who smoke indoors make their children’s asthma worse. Teenagers can be just as badly affected by passive smoking as young children.
• Smoking during pregnancy significantly increases the risk of a woman’s baby developing allergies and asthma. (Smoking also leads to more prematurity, still-births and cot deaths.)
If possible, have an electric cooking stove rather than a gas one –or fit a powerful extractor fan. Cooking with a gas stove generates a lot of nitrogen dioxide, a gas that you can’t smell or see but which affects the airways. This same gas also comes from motor traffic, but peak levels of nitrogen dioxide in kitchens with gas cookers are often ten times the average level on city streets, and frequently exceed standards for outdoor air set by the world Health Organisation. Other sources of nitrogen dioxide include cigarettes, gas fires and kerosene-burning stoves.
For some people with allergies, nitrogen dioxide enhances their response to the allergen. So if you inhale dust-mite allergen together with nitrogen dioxide, it may have more effect than the Smoke screen
Smoke particles from coal or wood do not seem to make allergies more likely to develop - in fact, quite the reverse. In rural areas of Germany, researchers have found that children with coal or wood stoves in their homes were less likely to have allergies or asthma. An Australian study made a similar finding. Bronchitis and pneumonia are more common in those children with wood and coal stoves and these infections may stimulate the immune system in such a way that allergies are less likely to develop later. However, wood smoke may be a cause when asthma begins in an adult.
allergen alone. Breathing sulphur dioxide (see below) and nitrogen dioxide together boosts the reaction to allergen more powerfully than either gas alone.
Nitrogen dioxide might also make asthma attacks more likely, but the evidence on this is conflicting.
For young children, a high level of nitrogen dioxide at home may make the development of allergic reactions more likely. A recent Canadian study showed that children exposed to high levels of nitrogen dioxide in the home - usually from gas cookers - were ten times as likely to develop asthma as those breathing low levels of nitrogen dioxide. If a dog, cat or other furry pet was kept, and there were high nitrogen dioxide levels, the risk of developing asthma shot up even higher, to 25 times that of children with low nitrogen dioxide and no pets. (Other studies have not produced the same spectacular results, but their methods of measuring nitrogen dioxide exposure were less precise.)
Try to eliminate materials that produce formaldehyde fumes, or seal the items with a good coat of paint. Formaldehyde is given off by chipboard and to a lesser extent by MDF (medium-density fibreboard). Injected cavity wall insulation can also produce persistent formaldehyde fumes, and is very difficult to get rid of -moving out is often the only option. A recent study from Australia showed that children exposed to formaldehyde, especially in the bedroom, were more likely to develop allergic reactions: the higher the level of formaldehyde exposure, the more severe the child’s allergic sensitisation.
Those with asthma have more frequent symptoms if exposed to high formaldehyde levels. A recent study from Finland shows that easy-to-clean plastic wall-covering and flooring increases the risk of asthma in children.
A Canadian study found that children whose first home was less than 20-30 years old were 50% more likely to develop asthma than children living in older houses. One possible explanation for this lies with the materials used in the construction and fitting of new houses, especially the plastics, wood preservatives and insulation materials. Solvents, and chemicals such as formaldehyde, are still being given off by these materials some years later.
Air fresheners provoke asthma attacks in some people. For a few individuals they can cause general symptoms of ill-health that are similar to those described for mild chemical intolerance (see p. 84). Those affected generally don’t realise that the air freshener is the source of the trouble. This malign effect is not entirely surprising, since air fresheners work by giving off a chemical that targets part of the brain - the part involved in processing sensory input from your nose. The chemical ‘freshens the air’ by partially disabling your sense of smell. Better to open a window.
Cleaning products, furniture polish and deodorant were never intended to go into the nose and airways, but that’s what happens when they are sprayed from an aerosol, and they can trigger asthma attacks. Steer clear of aerosols as much as possible - there are usually alternatives.
Pollution peaks
Read the instructions and ingredients lists on all products carefully. It is not just a question of what’s in them, but also what gases they might give off when used. One asthmatic died within minutes when the de-rusting agent she was using on her dishwasher produced a large amount of sulphur dioxide gas: her airways tightened up so much that she couldn’t even use an inhaler to save herself. ‘Sulphuric’, ’sulphate’ or ’sulphite’ in the list of ingredients should ring warning bells if you have asthma: sulphur dioxide gas could be given off by this product.
Bleach, and other chlorine-based cleaning products, such as toilet cleaner and scouring powder, should be used sparingly, and with plenty of ventilation. These products release chlorine gas which, in large amounts, can irritate the airways of asthmatics. Never allow bleach or toilet cleaner to become mixed with any other product. Take care with any product containing hypechlorte, chloramine, ammonia, acids or morpholine and with the chemicals used for swimming pool water. All these can trigger asthma attacks.
If doing repairs or DIY work about the house, take special care. Always ventilate the work area well, and wear a dust mask if sawing or drilling.
The smell of paint is due to solvents, and these can act as irritants to the nose and airways. When decorating, ventilate well, and use low-odour water-based paint. Some of the best low-odour paints, tested and shown to be safe for paint-sensitive asthmatics, are only available by mall order: see p. 255.
‘Instant foam’ kits sold for DIY insulation can provoke asthma in those who were not asthmatic previously. Two different substances are mixed to create the polyurethane foam, and during the mixing process, isocyanate is released – this is one of the most powerful asthmagens known (see box on p. 132). The level of isocyanate can breach the safety limit set for factories.
Avoid using fly spray or other insecticides: look for other methods of pest control. A study from Ethiopia showed that people using an insecticide in their houses were twice as likely to develop allergies. A study of Canadian farmers suggested that asthma might be linked to the use of carbamate insecticides (e.g. carbofuran). The sprays used for cockroaches can act as irritants for those with allergic rhinitis or chronic sinusitis.
If advised that your house needs spraying with insecticide, for woodworm or other wood-boring pests, ask for more information before you go ahead. Is the spraying really necessary? What will happen if the house isn’t sprayed? How quickly will it happen? Is there any other method of eradicating the pest? Spraying is often done when it is not really essential – houses remain standing even with woodworm holes all over them. Unless you have a heavy infestation that is threatening the structure of the house, you are probably better off not having the house sprayed. The heavy and ongoing exposure to insecticide that spraying of a house involves is something you and your family should avoid if at all possible. All the sprays used are toxic to some extent – don’t believe those who tell you otherwise. A heavy exposure to pesticides can sometimes make allergic symptoms worse or precipitate chemical intolerance (see p. 85).
The garage, workshop or garden shed can also be very polluted. Petrol, kerosene and paraffin can affect some people with rhinitis or asthma, and can bring on their symptoms. These fuels should always be kept in airtight containers. Paints sold for cars often contain isocyanates, among the most common causes
of work-related asthma (see box on p. 132). If using such paint, wear a mask with an activated carbon filter and make sure the area is well ventilated. Avoid prolonged or repeated exposure.
Outdoor pollution
Some of the pollutants in outdoor air can make allergic reactions worse and can trigger asthma attacks in people who are already asthmatic. A study of hospital admissions in London, Paris. Barcelona and Helsinki found that high levels of pollution increased hospital admissions for asthma by about 3%.
The pollutants that matter to those with allergies are:
• ozone, which soars to high levels on sunny days, mainly in country areas that are near large cities. The reason for this is a chemical reaction which occurs when car exhaust fumes are exposed to sunlight, producing ozone, a highly reactive form of oxygen. Further chemical reactions, involving another ingredient of exhaust fumes, then break the ozone down again. Thanks to this second reaction, there is usually little ozone in city air. But in a relatively rural area 20 miles or so upwind of the city, the pollutants are too dispersed for the second reaction to occur, and the ozone from the urban traffic can accumulate.
Ozone levels in the air tend to peak in the late afternoon and early evening – but it takes 4-24 hours for ozone to produce its effects on the airways. Indoors, ozone breaks down very quickly because of contact with other gases inside the house.
Ozone can increase the effects of allergens, such as pollen, on the nose and airways.
In addition, ozone makes the airway muscles contract, even for people without asthma. Healthy people tend not to notice these effects, whereas some asthmatics may have more symptoms, and may need more drugs, on days when ozone levels are unusually high.
• diesel particulates, which can become a problem in town centres, and close to main roads used by vans and lorries. Unlike ordinary petrol, diesel fuel contains oil, so when it burns it produces tiny black particles. These consist of flakes of carbon (soot), coated with complex chemicals that are produced by the
But what about the ozone layer…?
Is ozone good for us or bad for us? People often get confused about this, because of all the discussion about
‘the destruction of the ozone layer’. But that ozone layer (which screens us from harmful ultraviolet light) is a natural phenomenon and it is thousands of feet up, well away from our lungs. At ground level, in the air we breathe, ozone is unnatural and potentially damaging .
The size of the particles
Diesel particles are 1-10 microns in size, with most smaller than 2.5 microns. Tobacco smoke, coal smoke, fumes from oil-burning boilers, and the smoke from frying food all contain very much smaller particles, down to a hundredth of a micron (.01 microns) in size. (A micron is a thousandth of a millimetre.)
In pollution reports, counts for particles in the air (mostly diesel particles these days, except in heavily industrialised areas) will often appear as ‘PM1 0′, meaning ‘Particulate Matter less than 10 microns in diameter’. This particle size is chosen because larger particles tend to settle in the nose and throat, and not reach the airways of the lungs. The term ‘Small Particles’ is sometimes used to mean PM10.
To deal with air pollution, you need a really good mask with two filters: a dust filter that can take out very small particles and an activated carbon filter that absorbs irritant fumes and gases. Note that while activated carbon filters remove most pollutants, they do not take out nitrogen dioxide unless they have been specially treated.
partial combustion of the oil. It is probably these surface chemicals, rather than the soot particles themselves, that have such bad effects on the nose and airways.
Some research suggests that diesel particulates might increase the risk of allergies developing – to pollen for example. Additionally, when levels of diesel particulates are high, asthmatics tend to have more symptoms. If levels rise above 50 micrograms per cubic metre there is a sharp increase in asthma attacks – and a recent study in Birmingham showed that such levels are regularly reached at roadsides.
• sulphur dioxide, which often reaches high levels in areas of heavy industry, particularly near coal-fired power stations and coking plants. It acts as an irritant to the airways and can trigger attacks in asthmatics, who are far more sensitive to sulphur dioxide than healthy people (see box on p. 207). However, at the sort of concentrations normally encountered, even in quite polluted air, sulphur dioxide does not have any effect on most asthmatics.
• nitrogen dioxide, which is produced by all types of vehicles, and by power stations and some factories. In towns and cities with heavy traffic, nitrogen dioxide can build up to high levels. This gas is also found indoors (see p, 128) – often at far higher levels.
Oil refineries and cement works
In addition to these widespread pollutants, there are localised areas of air pollution, around industrial sites, that are frequently accused of causing health problems, including high rates of asthma. The kinds of industrial sites regularly mentioned include:
• oil refineries and oil-burning power stations
• cement works that use waste solvents for fuel
• dock areas where oil is loaded into tankers.
None of these accusations has been investigated in any detail, so it is impossible to say if there is a real link with asthma.
Avoiding outdoor air pollution
If you live in the kind of area that experiences high levels of ozone (see p. 130), plan your outdoor activities, especially jogging or playing sport, to avoid summer afternoons and early evenings.
Those who live very close to a main road, with a lot of lorries going past, would probably improve their own health, and reduce the chance of their children developing allergies and asthma, by fitting air conditioning or high-quality HEPA air filters – or by moving house. However, the benefits, in terms of decreased risk, are not enormous, and it is important to take other preventive measures as well (see Chapter 8).
When driving, if you stop behind a lorry or bus, keep your distance, close the window and turn off the fan. Diesel vehicles often emit a thick cloud of particles as they set off, and this can come straight into your car, setting off severe attacks for some asthmatics.
A car with air conditioning will reduce your exposure to diesel particulates while driving. When buying a new car, you can make a contribution to air quality by choosing a non-diesel vehicle, preferably one with a catalytic converter fitted. Alternatively, buy a diesel vehicle with a particle filter on the exhaust (now fitted as standard in Germany).
In Britain, the Vehicles Inspectorate of the Department of Transport encourages the public to report lorries and buses seen pumping out black smoke (look in the phone book for the number).
If you are asthmatic, breathing through your nose may help as this can filter out some damaging pollutants before they reach the airways in your lungs. (If your nose is usually blocked, try the exercises on pp. 230-31).
When levels of ozone or sulphur dioxide are high, taking a supplement of Vitamin C and eating plenty of foods that contain Vitamin E and beta-carotene (see p. 207) can protect your airways.

If you or your child are allergic to your pet, you should really find it another home. But a survey in the United States showed that more than a third of people with cat allergy still keep their cat - so there is detailed advice below for those who want to keep the pet, as well as those who decide to part company.
Often people with severe allergies find that, although they miss their pet badly at first, the vast improvement in their symptoms makes that difficult decision seem like a good one in the long run. Finding a home for an adult pet is often difficult, as most people want kittens or puppies, but try advertising locally, and explaining in your ad exactly why the pet needs a new home. Family and friends may be happy to help by offering your pet a home. Ask around among your older neighbours too – they may value having a mature pet that is calmer and already house-trained.
Cats
You can’t see cat allergen – many people wrongly assume that it is cat fur that is allergenic, or flakes of skin. The main allergen is a protein found in the sweat and saliva of the cat, which wafts about in the air in microscopic specks. These lightweight allergen particles are carried throughout the house.
So small are these particles that they remain airborne for six hours or more, however still the air. If they do finally settle, they are easily made airborne again by the least little breeze. Simply walking around a room is enough to disturb them.
Parting with the cat
After your cat has gone, there will be allergens everywhere – on and in the armchairs, sofas and cushions, on shelves and lampshades, in the carpets and even stuck to the walls and curtains. They will also be inside the mattress if the cat once slept on the bed, and will shoot out every time you lie down.
Once the cat has gone, air the house very thoroughly to shift all the allergen that is just hanging in the air. Wait a couple of
weeks, and see how much your symptoms improve, before going further. If you still have troublesome symptoms that are worse at home, then you need to:
• Buy a high-suction vacuum cleaner that retains allergen particles (these are marketed for dust mites – make sure it is a good one) so that you can vacuum your furnishings without redistributing the allergen everywhere.
• Wash anything that can be washed: duvets, sheets, curtains, loose covers, cushions and their covers, duvet covers, pillow cases, bedspreads etc. Cat allergen is not affected by heat, so a cool wash is as good as a hot one – but you must wash all the allergen away, so run the rinse cycle twice. No one knows if dry-cleaning removes cat allergen.
• If the cat ever slept on your bed, then consider buying new pillows and duvet. Covers designed for dust-mite avoidance (see p. 115) are an alternative option. They will keep some of the cat allergen from escaping into the air, but not the very smallest particles.
• The seat cushions of sofas and armchairs can be sprayed with tannic acid or a polysaccharide (see box on p. 116) to deactivate the allergens. Vacuum clean very thoroughly first to remove as much allergen as possible, then spray repeatedly for a few weeks or months.
A clean getaway
The allergic individual should go out while this work is done, and stay out for at least six hours afterwards (see p. 109).
The size of the allergen particles
Cat allergen is the tiniest allergen - most of the particles are less than 2.5 microns, and the smallest may be only 0.05 microns. (A micron is a thousandth of a millimetre.) You would need a really good dust mask or HEPA air filter (see pp. 108-9) for these particles. It probably won’t remove the very smallest particles, but will certainly reduce the allergen load.
Even after the cat has gone, and you have cleaned up meticulously, you may still sometimes have symptoms. Unfortunately, cat allergen is carried about on the clothes of cat-owners and gets into schools, cinemas, buses, banks and even the padded seats in hospital waiting rooms. However, only the most highly sensitised people are affected by these low levels of allergen.
Keeping the cat
Bear in mind that keeping the pet will result in significant continued exposure however hard you try with the methods described.
• Improve the ventilation in your house as this will reduce the amount of allergen in the air. If your house is tightly sealed against draughts at the moment, this will actually make a huge difference. Air the house regularly. Always keep a window slightly open whenever the cat and/or the allergic person is indoors. You could use a HEPA filter to clean the air, instead. These work fairly well for cat allergens because these are very small lightweight particles which easily become airborne, so there is quite a lot of allergen in the air most of the time. Of course, an air filter cannot do anything to protect you from a cat sitting on your lap (though advertisements have sometimes implied that they can!).
• Put the cat outdoors when it begins washing itself, as this generates a lot of airborne allergen. Provide the cat with a shelter outside where it can sleep and wash, to reduce the amount of allergen in the house. Make it as warm and comfortable as possible, feed the cat there, and provide a little catnip to make it more attractive.
• If your cat is still allowed indoors, remove all soft furnishings and fitted carpets. Buy leather- or vinyl-covered armchairs which can be wiped clean of cat allergen.
• Keep the cat out of the bedroom entirely. If it has been in the habit of sleeping there, wash all the bedding and buy new pillows. The mattress and duvet should be replaced or covered with anti-mite covers (see p. 124).
• If you have an un-neutered tom, consider having him neutered: the amount of allergen produced declines when male cats are neutered.
The following measures are sometimes recommended, but in fact they don’t work:
• treating the cat with acepromazine, an animal tranquilliser
• using a spray called Allerpet-C, which, so it is claimed, reduces the amount of allergen released. Scientific trials by a research group in Detroit have shown that it does not work.
• giving the cat a shower - i.e. drenching it in water. After a cat has had such a shower, the washing water contains a lot of cat allergen, so everyone assumed that this meant less cat allergen in the air. New research shows that the amount of allergen in the air around a cat after showering is no less than before. However, actually immersing the cat for three minutes followed by rinsing in clean warm water does reduce the allergen level in the air considerably. Unfortunately, the cat probably renews its stocks of allergen very fast, as a washed dog does (see below), so you need to repeat the wash at least once a week to reduce the allergen level in the air.
Dogs
Most of the advice given above, for cats, applies to dogs too because their allergens are also small and lightweight. Dogs produce less allergen than cats, and it seems to be less potent. However, you would still need to clean up thoroughly after the dog has gone, assuming you decide to find it another home.
If you decide to keep your dog, HEPA filters can be very useful, although you need also to take other measures, such as excluding the dog from bedrooms and keeping it outside for more (or most) of the time. Washing dogs thoroughly in a bath, using dog shampoo, reduces the amount of allergen in the air, but it builds up again to its former level within three days. You would need to wash the dog twice a week to achieve a useful reduction in allergen levels.
Other pets and domestic animals
Horses produce very powerful allergens, and those with allergies to horses are often so sensitive that even clothing that has been worn while riding and then brought indoors can elicit symptoms. Old furniture or mattresses stuffed with horsehair can sometimes cause problems too.
In the case of small mammals, such as mice and guinea pigs, it is usually the urine that causes allergic reactions. Proteins in the urine become airborne, and are carried around the house. You may be able to keep the pet if it is in a well-ventilated utility room or caged outside.
With snakes, lizards and other reptiles the allergens are found in tiny skin particles that float in the air. The same is true of stick insects and other insect pets.

Bees, wasps and other stinging insects

`Know your enemy’ is always a good motto, but particularly for those with insect-sting allergy. Being allergic to wasps or hornets, for example, is enough of a problem without panicking every time you encounter a hoverfly as well. If your reaction to this is ‘What’s a hoverfly?’ then you need a good field guide or a friend who knows a little about natural history. These common insects have yellow-and-black stripes to mimic those of wasps, giving them some protection against predatory birds. They fool a lot of people as well as birds, but it isn’t difficult to tell the two apart — hoverflies are a different shape from wasps, hold their wings differently at rest, and fly in a completely different way (for one thing they hover, unlike wasps). Being able to tell one from the other will make life much more relaxing.
If you did not see the insect that stung you, ask the doctor which skin tests came up positive (see p. 61), and use a field guide to check exactly what the insect(s) looks like.
As well as knowing what your problem insect looks like, you need to know a little about its habits and tastes.
These are the general characteristics of stinging insects that you need to know about:
• The most dangerous thing you can do is to disturb the nest – all stinging insects go into attack mode when this happens. If there is a nest in or around your house, call in a pest control expert to destroy it. Never tackle this job yourself, nor allow anyone else to do it while you are in the vicinity.
• If you think there may be an insect nest in or around your house, call in a pest control expert to do a survey. Regular annual checkups of your property are advisable if insects have nested before.
• Insect repellent works only for biting insects, such as mosquitoes. It does not repel wasps, bees or other stinging insects.
• Insecticide spray can be useful, but make sure the insect is really dead before you touch it. A groggy poisoned insect may well sting.
• A small but thick blanket can be useful for catching bees or wasps that have flown into cars. Don’t try to do this yourself unless there is no alternative. Ask a passer-by to help you if you are alone.
• Always stay as calm as possible.
Wasps and hornets (vespids)
• If you react to one species of vespid, you may well have a cross-reaction to other species in this group, so take care.
• Wasps like sweet foods (e.g. jam, honey, cakes) and you should avoid taking these on picnics. They will also crawl into open cans of beer or soft drinks. Never ever drink from the can, as you can get a mouthful of cross wasp with your drink.
• In spring and early summer, wasps collect protein-rich food for their young, and may be attracted to meat. If eating outdoors, as far as possible keep food covered.
• Wasps come to fallen fruit in the autumn. They get very sluggish and bad-tempered late in the year, and will sting with little provocation. They may crawl into crevices or hollow logs as winter approaches. Be very careful about picking up fruit or dead leaves, or working in the garden –always wear thick gloves.
• Wasps are often on the ground, especially in late summer and autumn. Wear shoes and socks for protection. If working outside where there may be wasps, long trousers and long-sleeved shirts are also advisable.
• Rubbish bins and litter bins are also very attractive to wasps. Make sure your own bin has a tightly fitting lid, and that no rubbish accumulates around it. Ask neighbours to do the same. Keep away from litter bins, and from picnic sites, orchards and tea gardens, all of which are havens for wasps.
Cross-reactions between insect stings
There are cross-reactions between the venoms of wasps, hornets and related insects (vespids), so if you are allergic to one, you may react to another. Cross-reactions are very unlikely between bee and wasp venoms.
Honeybees and bumblebees have very similar venom and these cross-react (but honeybee immunotherapy does not work for bumblebee allergy – see p. 168). Surprisingly, there is some cross-reaction between honeybee venom and snake venom.
The usual suspects
Wasps (yellow-jackets in the United States), hornets and bees are the most common source of allergic reactions worldwide. Locally, there are allergic reactions to various other stinging or biting animals. Fire ants are a particular problem in the southeastern United States. Hopper ants are a cause of anaphylaxis in Australia, and allergy to leech bites has been reported from Tasmania. A few people are allergic to the kissing bugs (Triatoma spp.) – also called cone-noses, ‘big bed bugs’ or ‘Mexican bed bugs’ – that are found in South and Central America, as well as rural areas of North America. These large insects creep into beds and bite painlessly, by night. In urban areas of Italy, where large numbers of pigeons live in some old buildings, pigeon ticks that find their way indoors have sometimes caused anaphylactic shock by biting during the night. Localised reactions to earlier bites had occurred in all cases.
Honeybees and bumblebees
• When it stings, a bee loses part of itself – the stinger and venom sac – and therefore dies. So stinging is very much a last resort. Most honeybees are not aggressive, and only sting if their nest is attacked, or if they are threatened when feeding.
• Bees feed on nectar from flowers. They may be attracted by brightly coloured clothes, especially red, orange and yellow, and flower-prints, mistaking these for flowers. Wearing dull colours is advised.
• Some perfumes, shampoos and scented cosmetics or lotions may also attract bees. If bees do approach you, never swat at them, and don’t panic. The best thing is to brush them away very gently.
• Bees often feed on clover, which grows in lawns and other grassy places, and it is easy to tread on them in this situation. Walking barefoot outside is therefore dangerous.
• Bees are attracted by water, including swimming pools and paddling pools.
• Although large, bumblebees are also very placid and rarely sting.
• Swarming bees are dangerous because they have the queen with them. If you see a swarm, keep well away.
Africanised honeybees
If travelling abroad, you should remember that Africanised honeybees – found in South and Central America, Texas, Arizona and parts of California – will sting with much less provocation than ordinary bees.
They are hybrids between domestic honeybees and an aggressive variety of wild African bee mistakenly introduced to South America. While they are much more pugnacious than ordinary bees, Africanised honeybees are only intent on defending their hive, and do not maliciously hunt people down as some horror movies have implied! They inject slightly less venom with each sting than a normal bee, but multiple stings are more likely because more than one bee is usually involved.

Pollen

Do you ever wake up in the middle of the night with an attack of hayfever or pollen asthma? And do you ever wonder why this should happen? The explanation is that warm air, rising up from ground level on a summer’s day, takes pollen with it high into the Earth’s atmosphere. When the air cools down after sunset, this pollen slowly descends again — an invisible ‘pollen shower’.
This pollen shower falls quite quickly in the countryside, reaching ground level between 8 p.m. and 10 p.m., but hot city pavements and buildings keep upward air currents going, and pollen stays aloft for longer. Most pollen lands on the city between about midnight and 2 a.m. That’s why you wake up sneezing or wheezing – especially if you sleep with the windows open.
Understanding facts like these about pollen can help you to reduce exposure substantially. Pollen is by far the most difficult allergen to avoid, but don’t believe the defeatists who tell you ‘You can’t do anything about pollen.’
Pollen counts and forecasts
Pollen counts are based on the amounts of pollen collected at specific sites earlier in the day, or on the previous day.
Forecasts for the coming day are really just informed guesswork, based on the present pollen count, the time of year, the temperature and rainfall over the last few days, and the weather forecast for the next day. At best, pollen forecasts are only as good as the weather forecast.
Forecasts of pollen can be useful in deciding when to start taking antihistamines for hayfever or when to Increase your asthma preventer drugs (steroid or cromoglycate inhalers). The start of the grass-pollen season is now predicted quite accurately.
Avoiding pollen outdoors
One thing that really can help here is an air-conditioned car. In an ordinary car, closing the windows (and perhaps fitting a filter to the air intake) helps a lot, but the heat is terrible.
The size of the allergen particles
The pollen grains that cause allergies are between 10 and 40 microns in size, with the majority between 20 and 35 microns. An ordinary dust mask takes out particles larger than 5 microns, so it will be adequate for most pollens. However, a few plants — including rye grass — produce tiny allergenic fragments, some no bigger than half a micron. These are about the same size as cat allergen and will therefore need much better masks. For these fragments, it is worth using a HEPA air filter, and getting a high-quality vacuum cleaner.
A cycle mask, or special nose filters sold for hayfever, will keep out pollen at peak pollen times. Just wearing a scarf over the mouth and nose will also give some protection. Another option is to smear a little Vaseline just inside each nostril and breathe through your nose only. Much of the pollen coming into your nose will stick to the Vaseline. If you ’suffer symptoms in the eyes, sun- glasses will keep some pollen out. Even better are wrap-around shades, or safety goggles with side panels sold in DIY stores.
Pollen release occurs at different times of day for different plants. Grasses release pollen from about 7.30 a.m, onwards, but if the ground is damp the release will be delayed until the moisture has evaporated. Unfortunately, a few grass species wait until the afternoon, so there will be some pollen entering the air all day. If you get up at 6 a.m. for a walk or run, you can be safely home by 7.30 a.m. Alternatively, go out In the early evening, after grasses have finished releasing pollen, and before the ‘pollen shower’.
Birch is an afternoon pollen: release peaks between noon and 6 p.m. Unfortunately, there is no information at present for other types of plants.
All types of plants favour warm sunny days for releasing pollen, and they all avoid rainy weather. On cloudy days there is a build-up of pollen in the flowers, so a massive release of pollen occurs on the next day of good weather.
Avoiding pollen indoors
Pollen grains have one huge point in their favour: compared to other allergenic particles, they are big and heavy. This means that they settle more quickly from the air. In a room with 3m- (1 Oft-) high ceilings, all the pollen will settle within four minutes, as long as the air is completely still. In other words, if you close all the doors and windows, block off any draughts, and sit fairly still, within four minutes you will be breathing pollen-free air.
This does not mean that all your symptoms will instantly vanish, because the ‘Late Phase Reaction’ (see p. 13) can go on for up to 24 hours. But you should feel better and, by not starting a new cycle of allergic reaction, you are improving the prospects for the next day. Escaping from pollen for a few hours every day should produce a general improvement in the long run, with your nose and airways becoming less inflamed.
The bad news is that some plants produce allergenic fragments much smaller than the pollen grains themselves. Various grasses do this, as do birch trees and certain plants not generally found in Britain, such as ragweed. These tiny particles take much longer – up to six hours – to settle from the air.
Some plants even produce ‘volatiles’ – airborne chemicals that provoke symptoms. Birch trees release volatiles from their buds in early spring, weeks before the pollen itself is released, and they affect a great many people, including some who are not allergic to birch pollen. Volatiles can only be removed by masks or air filters if they contain an activated carbon filter (see p. 109).
The notorious effects of oil-seed rape on the nose are also due to volatiles, not pollen. These volatiles are simply irritants and there is no allergic reaction.
To cut down on the amount of pollen you inhale at home:
• Dry all your laundry indoors during the pollen season, to stop it collecting pollen.
• Pets bring in pollen on their fur, so keep them outdoors during the pollen season, and avoid stroking them or getting too close. Brushing them thoroughly before they come in is another option, but the allergic individual should not do this.
• Close the windows when your offending pollen is being released, and during the evening ‘pollen shower’ (see p. 126).
• Change your clothes when you arrive home, since they will be coated with pollen, and wash or rinse your hair. Keep some clothes for indoor use only.
• Aim for still air (no draughts, no fans and no vigorous movement) in the rooms where the allergic individual studies, sits or sleeps. Air currents stir up pollen from the floor and furnishings. (No draughts means poor ventilation, of course, which is acceptable during the pollen season – but ventilate again afterwards, to discourage moulds and dust mites.)
• If tranquil air is an impossibility, consider getting a high quality air cleaner, or air conditioning. Alternatively, wet-dust and vacuum every day (using a vacuum cleaner that keeps allergen particles in – see pp. 116-17) to reduce the amount of pollen residue. Those who are very sensitive may need to do this as well as having an air cleaner.
• Cover your armchair and bed with a dust sheet during the day. In the evening, fold this up very gently and wash it. This removes the layer of pollen that accumulates on furniture during the day, before it is disturbed and inhaled. If you are studying, cover your desk and books when not working.
Places to go, places to avoid
• For the grass-sensitive, mown grass is usually fine (it won’t flower) although some people react to skin contact with grass (see p. 43). Unmown grass does flower, and will cause symptoms. Wheat, barley and oats, although they are grasses, release little pollen and rarely cause problems. Rye and sugarcane do release pollen, and may affect some people, but maize (corn) has heavy pollen that does not travel far, so it rarely causes much trouble.
• The levels of most pollens do not differ much between town and country. In fact, high up in a tower-block may be one of the worst places, because of pollen rising on warm air.
• The seaside is often pollen-free thanks to onshore breezes. Mountain peaks and ridges are also good, but deep mountain valleys can be pollen traps.
Roses are not the problem
The pollens that cause allergic reactions almost all come from plants with inconspicuous greenish flowers. These plants are pollinated by the wind, which is why there is so much of their pollen wafting about in the air. Colourful and scented flowers are pollinated by insects and have big sticky pollen grains that don’t float about and rarely cause allergies. However, strong scents can irritate the nose of those who already have hayfever, and make their symptoms worse.

Because house-dust mites are a major source of allergic reactions they have been studied intensively, and various ways of killing them devised. But simply killing the mites is not enough. Their allergens will remain, and continue to cause allergic reactions for years. The allergens have to be either removed or inactivated — that is, changed chemically so that they are no longer recognised by the immune system.
Tackling dust mite is easier if you know certain key facts:
1 Dust mites prefer humid conditions. They do not drink, but absorb water from the air. When the relative humidity falls below 50%, the mites gradually dry out and are killed.
2 Mites feed on our skin scales, but only if they have been broken down first by moulds. High humidity (70-90% relative humidity) is a particular problem, for anyone with an allergy to house-dust mites, because it favours the mould that suits dust mites best.
3 Dust mites live inside mattresses, pillows, upholstery, cushions and soft toys. The allergens are blasted out when you settle into an armchair, get into bed, or turn over in the night.
This is when you inhale the biggest dose of allergen, or get the maximum dose to your skin. Carpets also contain dust mites, but the numbers are generally lower.
4 Dust-mite allergen is relatively heavy, compared to cat or mould allergens for example. Little of it floats around in the air, and the most significant exposure is inhaling it close to the source — from a pillow, mattress or teddy bear. This is why air filters are of little value for anyone with dust-mite allergy.
5 Dust mites are everywhere, and are carried around in clothing. Even if you could eliminate all the mites from your house, new ones would soon appear. A new mattress will usually be colonised by dust mites within four months.
The size of the allergen particles
The droppings of the dust mite, not the mites themselves, are the main cause of symptoms. The droppings are 4-20 microns in size, but they can crumble into fragments of 1-3 microns, and the tiniest bits are only 0.5 microns across. The pores of mite-proof covers (which really means mite-allergen-proof) should be less than one micron across, and preferably less than 0.5 microns. Dust masks (see p. 109) should also filter out particles of this size to be effective. The mites themselves are much bigger, 200-300 microns long, (A micron is one thousandth of a millimetre.)
The basics of mite warfare
• A temperature just above boiling point kills dust mites and inactivates Der pl, which is the troublesome allergen for most asthmatics. However Der p2, the other mite allergen, is not affected by heat. (Note that the carpet treatments advertised as ’steam cleaning’ generally just use hot soapy water, not steam. Because they leave the carpet very damp, they can increase the numbers of dust mites.)
• Washing with detergent at 55′C (130′1 or above (i.e. a 60′C wash cycle) kills mites and removes the allergen.
• Cooler washes will not kill mites, but will remove the allergen. This can be useful if the mites have already been killed by some other means. Regular cool washes of clothing or sheets will also remove human skin scales, reducing the mites’ food supply. (This is beneficial if you have eczema, because flaking skin adds to the problem by giving dust mites even more to eat.)
• You can buy mite-killing substances (see p. 255) to add to cooler washes, so that the mites are killed - the chemicals are rinsed out at the end of the wash, so are pretty safe.
• Dry-cleaning kills mites and it removes some of the allergen, but the amount removed is variable (20-70%).
• Freezing for more than six hours kills mites. Three hours’ strong direct sunlight in dry air will kill mites living in rugs and blankets. Neither treatment removes allergen.
• Mites hang on to the carpet fibres when the vacuum cleaner passes overhead, and about 65% of them remain afterwards. An ordinary vacuum cleaner sprays mite allergen into the air as it goes. The amount in the air - and therefore available to be inhaled - is three times higher after vacuuming.
Combating mites
Bear in mind that mites are the enemy - not dust itself. A house may be thick with dust but, because the windows are open a lot and the air is dry, it will have few mites. Another house may look perfectly clean, but be seething with mites because it is thoroughly draught-proofed, warm and slightly humid. The mites will be thriving in the carpets, beds and upholstery. Vacuuming and dusting every day, if done with an ordinary type of vacuum cleaner and a dry duster, will stir up the allergens and ensure that the air is full of them. So a person with mite allergy would feel far worse in the apparently very clean house than in the dusty one.
One crucial aspect of a mite-reduction programme is making the air drier - see p. 119 - so that mites no longer flourish.
Most of the other measures - described below - will involve stirring up dust-mite allergens, so the allergic person should not do the work, nor be in the house (see p. 109).
Too dry or too moist?
It is a well-established fact that the air in most modern houses is too humid, encouraging dust mites and moulds. Yet many people fit humidifiers because they believe that the air is ‘too dry’ and that this irritates the nose. Some very good scientific studies have shown it is indoor pollutants plus overheating that is the problem here, not dryness - even very dry air is not irritating as long as it is clean. Should your nose feel dry and ticklish, try to reduce indoor pollution (see pp. 128-9).
It is true that during an asthma attack, dry air does make matters worse, and very moist air helps. Inhaling steam from a bowl of hot water can be used to ease the attack.
The bed
Begin with the bed because this is the main exposure zone. A Danish study showed that just fitting mite-allergen-proof covers to the mattresses and pillows of dust-allergic children worked well. After a year the children had much less asthma at night, used half as much inhaled steroid, and gave better peak-flow readings.
The best approach is to buy a new mattress and new pillows before putting anti-mite coverings on them. These covers keep skin scales and mites out, which should prevent a new mattress or pillow becoming recolonised. The modern covers have tiny pores which allow perspiration to evaporate - this makes them comfortable to sleep on.
These pores are small enough (see box on p. 114) to keep any mite allergens inside, so they will also work with an old mattress, keeping the existing allergen inside. But the mites themselves will also thrive inside (there’s enough old skin there to keep them in business for years) and there is always the risk that, if a small tear develops, the stores of allergen in the mattress will come pouring out again. So start with a new mattress if you can.
Another possible option is to arrange for a contractor to heat-treat the bed, the mattress and all bedding. This is a new specialist treatment (see p. 255), where the bed is enclosed in a plastic tent and heated to very high temperatures. It is designed to kill all mites, even those right inside the mattress, and inactivate the allergen. (The contractor can also do your living room suite.)
If the covers are for a small child, check with the manufacturer that they pose no threat of suffocation. Mattresses and bedding with built-in covers may be safer.
Buy a new duvet (or wash or dry-clean your existing one) and put an anti-mite cover on it. Alternatively, buy a duvet and pillow that can be washed at 60′C (130′F), and wash them once a month. You must have the use of a tumble dryer, because mites will flourish if bedding is not completely dry.
An upholstered bed base will have its own (much smaller) population of mites. Buy a simple wooden or metal bed frame if possible. Or you could enclose the upholstered base in a mite-proof cover, or in plastic sheeting completely sealed with heavy-duty tape.
Wash all sheets and blankets at 60°C or more, or have blankets dry-cleaned – or buy new ones. From now on, wash sheets once a week and blankets once every two weeks.
Get rid of any other bedding such as patchwork quilts or fleecy underblankets. Alternatively, you can wash or dry-clean them regularly.
Electric blankets can be cleared of mites by washing them, and are very useful in keeping the bed free from moisture. This prevents mites from setting up home in the outer surface of your new mite-proof covers, so that you don’t need to wash the covers, sheets and underblankets so frequently. Leave the electric blanket on at a high setting, with the bed made, for at least twelve hours (check that there is no fire risk first). Note that some mite-proof covers might be damaged by this procedure – check with the manufacturer. If you have not yet purchased mite-proof covers, there are some made from Egyptian cotton which can tolerate this level of heat without damage (see p. 255).
Children’s beds and toys
Where children share a room, all the beds and bedding should be dealt with. Even then, an asthmatic child should never sleep in the lower half of a bunk bed, because mite allergens will shower down from the bed above.
Ali soft toys should spend at least six hours in the freezer once a week, to kill the mites. The first time, wash the toys
immediately afterwards to remove any existing allergen and dry thoroughly in a tumble dryer.
A hot wash, or the freezing/washing treatment, should also be used for ‘comfort blankets’, dressing-up clothes, dolls’ clothes and any other fabric items.
Sheepskins, sometimes used for babies’ cots, especial,. New Zealand and Australia, contain huge amounts of dust-mite allergen. It is advisable to discard these.
The next steps
Clothing is often full of mites, especially sweaters, coats and woollen trousers. Dry-clean all such items, or wash using a m –e-killing wash, then store them in a well-heated place so that they are always very dry.
Dandruff consists of skin flakes, and may help to feed mites Using an anti-dandruff shampoo may help. Semen also gives mites nourishment.
From now on, be careful about exposing your airways to dust. Get someone else to empty the vacuum cleaner bag – and they should, of course, do it outdoors. If you are stripping wallpaper, wash it down first to remove dust. Moving house, going into the attic, spring cleaning, turning out cupboards or moving furniture should all be avoided – unless you have a good mask on.
Do not use fan-heaters or convector heaters which churn up mite allergens from the carpet. Seal off any hot-air ducts from centralised heating systems, as these blow mite allergens around the room.
If possible, invest in a vacuum cleaner that keeps in all the allergens, or vents them outside, rather than spraying them out into the air. Make sure that the vacuum cleaner you buy really
What about sprays?
Chemicals that kill mites (known collectively as acaricides) are sometimes useful but have various limitations. They do not penetrate inside upholstered furniture, cushions or mattresses, so make little difference to the total population of dust mites. Even on carpets, sprays won’t reach most of the mites unless you rub the spray in really hard. (And ‘anti-mite’ carpet shampoos are completely ineffective.)
The safest chemical is benzyl benzoate — so safe that it is used directly on the skin for treating scabies infections. It can cause skin irritation at these doses, but rarely does so at the concentrations used in anti-mite sprays.
However, the idea of constant spraying, over a period of months or years, is worrying. Doctors generally advise against spraying bedding, and carpets or furniture where babies or small children play, to avoid close and prolonged contact with the spray residue.
Even more alarming are sprays containing a pyrethroid (pyrethrum) compound. The latter is derived from a plant and is therefore sold as ‘natural’, but pyrethroids are potentially toxic with prolonged exposure, and they quite often provoke allergic reactions too. They should definitely be avoided.
Sprays that inactivate allergen (rather than killing mites) sometimes have their uses. There are two kinds and both should work against a variety of allergens, not just dust mite. Polysaccharide sprays stick the allergen particles together, so that they don’t float about and get inhaled. Tannic acid sprays change the allergen chemically, making it non-allergenic. Because tannic acid is found in tea it is assumed to be harmless, but the sprays available vary a lot and often contain many impurities, so it is hard to be sure about their long-term safety. Don’t use these sprays on bedding.
Carpets and bedding covers with built-in pesticide are also on sale, but are probably best avoided.
does its job well – a lot of machines now claim to be ‘allergy’ vacuum cleaners but they are not all equally good. Very few have been adequately tested (see p. 255). Alternatively, cover the bed with a clean sheet and open the windows whenever you vacuum, leaving them open for half an hour afterwards. After closing the windows, allow the dust to settle for another half hour, then carefully remove the dust-cover from the bed.
For dusting, use a damp cloth and add a few drops of eucalyptus oil which deters mites. Alternatively, use a special anti-mite duster with an electrostatic charge that holds the dust.
Above all, keep the moisture levels in your house down. Ultimately, this is the key to eliminating dust mite. Look at p. 119 and check you are doing everything possible.
The bedroom in particular should be kept dry. Air your bedroom whenever it’s dry and sunny. Remove pot plants and fish tanks. Don’t dry clothes in the room and don’t shampoo the carpet. Avoid using Calor gas heaters, as these produce a lot of moisture. If your bedroom has an en suite shower, fit a powerful extractor fan, or open a window wide during and after showers – or just stop using this shower. En suite basins may also generate moist air.
Do you need to do more?
Give it some time before deciding if you have done enough. In one study, it took eight months for the full benefits of an anti-mite campaign to be seen.
If you are still not as much improved as you hoped, then you could try a more drastic mite-elimination programme.
Thoroughly clean the bedroom, getting rid of any dust along skirting boards or picture rails, on top of wardrobes or behind furniture. Remove anything stored under the bed, so that vacuuming is easier in future. During this cleaning operation, completely cover the bed.
Get rid of the bathroom carpet, if you have one. In the bedroom, either remove the carpet or buy a special anti-mite steam cleaner that kills mites in the carpet and inactivates the allergen. To work properly, the device must produce steam at a temperature above boiling point, by means of high pressure. Make sure you are buying the right kind of device.
If you take out the carpet, you will need to mop the floor, with a wet or oiled mop, several times a week, as the dust will quickly build up, and is easily made airborne from an uncarpeted floor. One of the advantages of carpet is that it ‘holds’ dust at floor level.
Wash the curtains, or dry-clean them, or replace them with blinds of a kind that can be easily wet-dusted. If you have bought an anti-mite steam cleaner for the carpet, use this on the curtains every 2-3 weeks.
Remove dirty clothes from the bedroom, clean out drawers and shelves, and dry them thoroughly. Only store freshly laundered clothes in the room.
Remove all upholstered items from the bedroom, such as padded headboards, cushions, armchairs, or stools with padded seats. Draught excluders, fabric lampshades and anything covered in velvet should also go.
A different approach
If you are even more allergic to housework than you are to dust mites, consider buying a really powerful dehumidifier, designed for killing mites. This makes the air too dry to breathe (its relative humidity or RH goes down to 25%), so you leave it on in the bedroom during the day, with the bedroom door closed. You must eliminate all sources of moisture that will counteract the dehumidifier, and have fairly tight seals around your windows and doors for it to work. In the evening, turn the dehumidifier off and leave the bedroom door open for an hour or so before going to bed.
Of course, all the allergen which was already there in the bed, carpet, curtains, clothes and soft toys will still be present. You need to either eliminate or inactivate this allergen using the methods described above. But once you have got your daily dehumidifier routine going, you do not need to rewash everything regularly because mites will be a thing of the past, so no new stocks of allergen will be produced.
The rest of the house
A completely mite-free house is hard to achieve, but if you are determined, you can come close. Everything so far described for the bedroom, such as reducing moisture in the air, and dealing with carpets and curtains, is applicable to the rest of the house.
The exception – and the toughest nut to crack – is the upholstered furniture in the living room. Fixed upholstery (i.e. everything other than removable cushions) is a safe haven for mites that is especially hard to deal with.
One option is to give all such furniture a specialist heat-treatment, if this is available locally (see p. 115). The mites inside will be killed, and the allergen inactivated. If you drastically reduce moisture levels at the same time – with a powerful dehumidifier used at night, perhaps – you should avoid serious reinfestation.
Alternatively, you could replace all your existing upholstered furniture with leather-covered or vinyl-covered furniture. Both are impenetrable to mites. Furniture made of wood or bamboo with loose cushions and no fixed upholstery can also work. Fit the cushions with tailor-made mite-proof covers (hard to get, but ask around) when new. Then put the ordinary covers on top, and wash these regularly.

Allergens in Food
Anyone with true food allergy or coeliac disease needs to be very careful about avoiding certain foods. The information given here is aimed mainly at such people, rather than those with food intolerance (see p. 74), who can usually tolerate small amounts of their offending foods. However, some of the basic information given here is relevant to those with food intolerance as well.
There are different levels of sensitivity even among those with true food allergy. The ‘exquisitely sensitive’ can react to unbelievably minute traces of the food, and for them life is especially difficult. The same is true of some coelicacs, who can be affected by the tiniest quantity of gluten.
These people are a small minority. The level of vigilance required of such people will not be necessary for most people reading this book, so don’t get things out of proportion. While it is vital to be sensible about avoiding your problem food, it is also important not to become over-anxious.
Buying basic ingredients
Cooking for yourself is the safest way to eat for those with true food allergy and coeliac disease. There are relatively few hazards, but do beware of well-meaning assistants in health-food shops who try to sell you some exotic package of grain or flour – spelt or kamut or triticale, for example – reassuring
you that it is ‘definitely not wheat’. Be well informed about the different forms of your problem food and the names under which it is sold (see pp. 172-5).
Oils made from foods such as corn or peanut sometimes cause concern. Ordinary refined oils have been so thoroughly processed that they actually contain no allergenic proteins, so you can safely use these. Bottles of gourmet walnut oil and almond oil are a different story however, and should be avoided if you have nut allergies. Sesame oil is not purified either and can provoke serious reactions. With any oil, if you are unsure how safe it might be, go by the smell. Oils that smell or taste like the food from which they are made could well contain allergens.
Those with allergy to tuna can usually eat tinned tuna because the processing makes it safe. The allergens in fresh fruit and vegetables are generally inactivated by cooking too, so jams and tinned fruits tend to be safe – but test very cautiously. Cooking does not have much effect on other food allergens, apart from eggs. In rare cases, cooking can create allergens (see box on p. 186).
If you share your kitchen with others, and are highly sensitive, check that all cooking utensils are truly clean before use. Coeliac should watch out for breadcrumbs in the butter dish, jam or toaster. Where small children are allergic to a food, it may be best to keep the culprit out of the house entirely.
Genetic engineering and food allergy
Many people with food allergies are very concerned about the possibility that genetic engineering could introduce allergens from one plant species into another. This concern seems to be shared by government officials and those in the food industry, who are being extremely vigilant and cautious at present. As long as this attitude continues, there should be little danger to food allergy sufferers.
Finding food in funny places
If you are suffering some inexplicable reactions to non-food items, it might, just possibly, be a food reaction. Some latex gloves contain the milk protein casein, for example, added as a manufacturing aid.
Buying packaged foods
There are several different issues here:
• the need to read labels carefully for allergenic ingredients described by unfamiliar names (see p. 172)
• errors in the packaging used (see pp. 174-5)
• contamination by minute traces of a food substance due to processing machinery not being cleaned adequately. Cartons of fruit drink have occasionally been contaminated with traces of milk because the same production lines were used for packaging milk drinks. Tofu desserts made in ice-cream factories can also become contaminated with milk. These tiny traces of a food will only affect the most highly sensitive individuals, but contamination by nuts can involve large pieces and affect anyone with nut allergy (see p. 174).
• foodstuffs which are used as part of the production process
and leave a tiny residue in the finished item (see p. 174).
Be very cautious indeed about ready-made food that is unlabelled, such as that from bakeries and home-made stalls. Egg is frequently used as a glaze on baked products, nuts may lurk within, and milk or wheat can turn up in the most unlikely places.
Restaurants, cafes and takeaways
The majority of fatal and near-fatal incidents involving people with true food allergy are due to restaurants, cafeterias and canteens. Takeaways can also be a problem except in the case of the large chains such as McDonald’s, where ingredients are standardised. It is alarming that highly allergenic foods (e.g. peanut) are sometimes used – yet far from obvious – in recipes and sandwich fillings where they would simply not be expected. Anyone with peanut or shellfish allergy should be ultra-cautious about Chinese, Thai or Malaysian cooking – but those with milk allergy should find a haven here, because milk is not part of these culinary traditions.
The simplest solution is to eat very plainly when you go out –steak and salad, for example. Steer clear of casseroles and thick soups, where you can’t see what’s in it (the occasional chef throws in peanut butter to thicken the mix…). Food wrapped in pastry is best avoided for the same reason. Desserts and cakes are risky for anyone with nut, egg or milk allergy.
You must insist on accurate information about the food before you taste it. If the counter staff, the waiter or the waitress
is unsure of the ingredients, ask them to check with the chef, or with the label on pre-packaged food. Be persistent and never eat anything unless you are sure. Make eye contact with the person concerned, and learn to be a good judge of character. Your life could depend on telling the difference between the waiter who knows the facts about the food and the waiter who is being blandly reassuring for the sake of a quiet life.
It is a great mistake to pick out the pieces of offending food – kiwi fruit from a fruit salad for example – and eat the rest. There is often enough allergen left behind to cause anaphylaxis in the highly allergic individual.
Those who are extremely sensitive to the offending food must also consider the problem of contamination in the kitchen. Grills and fryers in restaurants and canteens can become contaminated with fish allergens or nut allergens (e.g. from nut cutlets) and these can be transferred to fried potatoes or other foods, provoking anaphylaxis in the highly allergic individual. One person with fish allergy died in this way. Sesame seeds can also contaminate equipment, work-surfaces or bakery counters.
Parties and buffets
Milk, egg, shellfish or nut allergies can make it especially hazardous to eat buffet or party food. Regard everything with suspicion. Cocktail snacks with nuts or peanut paste hidden inside are a particular problem.
When fish allergy isn’t fish allergy
Anisakis is a parasitic worm that infests fish and can sometimes survive the
cooking process to infect humans. The worms are easily thrown off by the human immune system, but the body is primed to make IgE antibodies should
it ever encounter Anisakis again. Another meal of parasitised fish – even if the Anisakis worms are all dead this time, and only the allergens remain
will provoke a massive IgE-mediated reaction, leading to anaphylactic shock. This problem is usually misdiagnosed as allergy to fish itself.
Other inconsistent reactions to food can be due to contaminants such as antibiotics, preservatives, other food additives or (especially in the case of shellfish) naturally occuring toxins.

Moulds and Other Fungi

The air around us is full of bits and pieces that are mostly too small to be seen without a microscope - pollen grains, mould spores, fragments from plants, fibres from clothing, specks of ash from smoke, skin flakes and diesel particles. Of these, mould spores are by far the most abundant.
Except in very dry climates, there are more mould spores in the air than anything else. In Britain the record count is over 160,000 spores per cubic metre of air, compared to a record pollen count of only 2800 grains per cubic metre. Luckily, mould spores are not particularly allergenic or even more people would be suffering as a result of inhaling such huge quantities of them.
Spores are produced by moulds and other fungi, and they are to the fungus what seeds are to a plant – they can grow into new fungi. Doctors generally speak just of ‘mould allergy’ because moulds are the most common offenders, but larger fungi – mushrooms and toadstools – also produce allergenic spores. For example, a bracket fungus called Ganoderma, that infests dead trees and produces spores prolifically in mid-June, has been found to affect 16% of asthmatics in one part of New Zealand. Bracket fungi occur all over the world, but until recently no one had suspected them of causing allergic reactions, so the extent to which they cause allergies has not been investigated. The same is true of other large fungi.
Yeasts (single-celled fungi) are also found in the air, and it is possible –though this has not been investigated – that people with an allergy to yeast in food would also react to inhaled yeasts.
Indoors and out
Mould spores are a particular nuisance because they can be produced both indoors and out. There are different species of mould in different places, and you may be lucky and only react to one or two uncommon species. But many moulds grow in a very wide range of situations, both indoors and outdoors. There are also cross-reactions (see p. 14) between some of the moulds, unfortunately, which means that people generally react to a great number of different moulds. You will probably need to reduce mould growth inside your home as well as avoiding mould-rich places outside. Changes to your garden that eliminate havens for moulds, such as leaf piles, may also be helpful.
Moulds may only be growing in one part of a house – the cellar perhaps – but can be carried all around the house on air currents.
The size of the allergen particles
Most mould spores are between 2 and 10 microns in size. A few species have spores that are smaller than 2 microns.
(A micron is one thousandth of a millimetre.) Some people with mould allergy may be protected by an ordinary dust mask (see p. 109), but most will probably need a better-quality mask.
Avoiding outdoor moulds
Moulds live in the soil, and grow on any decaying plant matter, such as dead leaves, dying plants, fallen trees, hay and straw. Spore counts are highest in the autumn. A thick covering of snow reduces the numbers of mould spores in the air dramatically. Once the snow melts in spring, moulds flourish on the plants killed by the cold, so spore counts soon rise again.
The effect of the weather on spore release is very complex. Some moulds like to release their spores when it is dry and windy, but others favour fog, mist or dew. Rainfall washes a lot of spores out of the air, but it stimulates the release of some small spores.
A few pollen information services also give current mould-spore counts, but predicting spore counts for the following day is well-nigh impossible.
Drastic avoidance measures, for those who are severely sensitive, include moving to a desert or semi-arid area where there are far fewer mould spores in the air.
Listed below are the mould-rich situations and activities which could provoke your allergy symptoms. If they do, you should avoid them, or wear a mask that will prevent the spores being inhaled (see box on p. 120).
Places
• Near fields of cereal crops in late summer, because of moulds growing on the cereal leaves. Symptoms are likely at harvest time, when combine harvesters disperse the spores.
• In forests and old orchards, in gardens with compost heaps or piles of dead leaves, and in greenhouses.
• Near springs, waterfalls, and other damp, shady places.
Times
• During late summer and autumn, when moulds flourish outdoors on fallen leaves and fruit.
• Following the first frost of autumn, which triggers spore release by fungi in the soil.
Activities
• Disturbing compost heaps, damp straw or hay, piles of grass clippings or heaps of fallen leaves, all of which are absolutely full of moulds.
• Collecting up fallen leaves or fruit.
• Watering the garden because mould spores are released when water hits the dry soil.
• Mowing grass, if the clippings were not cleared up after the last mowing. Unless the weather is very dry, the clippings tend to go mouldy.
• Removing dead leaves or flowers from plants.
A dangerous mould allergy
Anyone with asthma who also has allergy to the mould Alternaria should –with their doctor’s agreement – increase their dose of preventer inhaler (e.g. steroid or cromoglycate) during the spore-producing season. Research shows that severe near-fatal asthma attacks often occur during the Alternaria spore season among those allergic to this mould.
Spore release by Alternaria usually occurs in the summer or autumn, but the timing varies from one part of the world to another, so check with your doctor or a local pollen/spore monitoring service. Alternaria can live outdoors in soil, and on seeds and plants. Indoors, it is a denizen of window frames, carpets and textiles.
Indoor moulds
These are the indoor situations that can be difficult for mould-sensitive people. You should either avoid these, wear a mask, or tackle the problem at source – for example, by reducing dampness (see p. 119).
Places
• Buildings that are damp, because moisture encourages mould growth. Never sleep in a room which has mould growing on the walls or window-panes. In addition to damp houses – now very common – you may encounter moulds in old churches and church halls.
• Buildings that are near lakes, rivers or the sea, because of the dampness of the air. Rooms with humidifiers.
• Bathrooms and shower rooms, unless well ventilated, owing to the steam and condensation.
• Rooms that are generally left unheated, and are therefore colder than the rest of the house, as these tend to suffer from condensation.
• Buildings with dry rot or wet rot. Not all mould-sensitive people react to the spores of these dreaded timber-rotting fungi, but some do.
• Buildings where old timbers are being removed, as this stirs up huge numbers of spores.
• Buildings where central heating has recently been installed, as the warmer temperatures in the building stimulates the existing moulds to release their spores.
• Buildings with lots of indoor plants. There are moulds you cannot see growing on the surface of the soil around a potted plant.
• Cellars and basements. Conservatories can also be full of moulds if not well maintained.
• Antique shops, farms, mills, holiday cottages.
On the first day of Christmas…
Christmas trees usually have moulds (which you can’t see) growing on the needles. When the tree is brought indoors, the warmth encourages these moulds to shed their spores.
Times
• During the winter, when there are usually more moulds growing indoors due to condensation.
Activities
• Handling clothes, curtains or furnishings that smell mildewy: they may be dry now but they will still be full of mould spores.
• Handling vegetables or fruit that have been stored a long
time, or in damp conditions (e.g. in plastic wrapping). Note
that this can include mushrooms – they often have white
moulds growing on them, which can be quite inconspicuous. If looking around your house for moulds, bear in mind that they vary a great deal in colour. Bread, vegetables, cheese and other foods that are past their best grow green, grey or white moulds, often furry, and these are the ones most people are familiar with. But the black stuff on the walls of bathrooms and in the door seals of refrigerators is also mould. In some situations it takes a practised eye to spot this type of mould – around window frames for example, or in the patterns of bathroom-window glass, it can easily be mistaken for ordinary dirt. On shower curtains and cubicles you may find pinkish-red moulds as well as these black kinds. Garden plants and crops can have bright orange moulds (called ‘rusts’) on their leaves, as well as the more familiar grey or black kinds.
Combating indoor moulds
The crucial task here is to reduce dampness and condensation in the house – see p. 119 for the details – as this encourages mould growth on all kinds of surfaces, including walls, ceilings, windows, bathroom tiles, shower curtains, and even carpets. Once you have reduced the humidity, then you can have a big clean-up and remove the spores that have been left by moulds.
If your allergy symptoms are very bad, and you need some immediate relief, then you could get someone to clean away the mould growth and spores first, then tackle the damp problem, then repeat the cleaning operation. Obviously, this is less efficient, but it may be the best approach if you are severely affected.
Note that the cleaning will, in itself, stir up a massive but unseen cloud of spores, so the allergy sufferer should not be at home during this work (see p. 109).
Cleaning away moulds and stopping regrowth
There are two aspects to this task:
• a one-off effort to clear the accumulation of mould growth and old mould spores – trillions of them are probably lying around your house – since these spores are the cause of the allergic reaction
• an ongoing effort to prevent the regrowth of moulds in problem areas such as the bathroom.
Get rid of any furniture that smells ‘mildewy’: it is packed with old mould spores. Fabric items that have this smell should be washed thoroughly. Old clothing, books and newspapers may also be a source of mould spores.
Any carpets or other porous materials (e.g. ceiling tiles, wall panels) that have ever been soaked by flood or storm waters should be disposed of now – and, unless everything can be dried within 24 hours, this should be always be done if there is water penetration in the future. Research shows that such materials quickly become infested with moulds. Check above the flood line, as water can seep upwards through the walls or panelling.
On fridges and freezers, clean out the rubber seals around the doors, going into all the crevices to get out the black mould that lives there. Also clean out the drip-pans of fridges, freezers and dehumidifiers. Keep shower heads and air conditioning equipment (including the filters) very clean. This all needs to be done regularly from now on.
Clean off all the mould growing around windows, or on walls and ceilings, tiles or other surfaces. Alcohol (e.g, white spirit or surgical spirit) kills it very effectively, without the use of water, and it takes a long time to grow back again. You could, alternatively, wash down the walls with a mix of one part bleach to two parts water. (But note that chlorine fumes may be irritating to the airways of those with rhinitis or asthma.) Special anti-mould sprays are also available, but try them out cautiously as they too may be irritants. Do not brush mould growth off with a dry cloth, as this simply disperses the spores. In the future, keep an eye out for new mould growth, and remove it promptly.
Buy a new shower curtain and replace it regularly, or clean it thoroughly with an anti-mould spray.
Can foods and mould spores cross-react?
Some people with mould allergy appear to be affected by eating mushrooms, or foods that contain yeasts or other fungi, e.g. certain well-ripened cheeses, dried fruit, soy sauce and vinegar. There has been little scientific investigation of these claims.
No cause for concern
The drug penicillin – which can cause severe allergic reactions – comes from the Penicillium mould. Fortunately, there appears to be no cross-reaction between the drug and the spores of Penicillium.
Cut down on the number of houseplants, and find a new home for any that need constant moisture. With the remaining plants, take off dying leaves and flowers promptly, and remove the top layer of soil occasionally, replacing it with fresh soil or – even better – sand or grit. Pot-pourri should also be evicted, as it can be full of mould spores.
Use vegetables and fruit promptly, and do not allow bread to go stale, or jam to go mouldy.
What to do if these measures fail
Where there is an invincible damp problem, a really powerful dehumidifier used during the day in bedrooms, and at night in the sitting room, will kill off most moulds and defeat their efforts to regrow. Close all the doors and windows in the room where the dehumidifier is operating, and shut off air vents. Note that air conditioning will also reduce the humidity of the air, but not as much.
Keeping mould spores out of the airways
Ordinary house dust can contain a lot of mould spores. The allergic individual should not dust, vacuum clean, sweep floors or make beds until the anti-mould measures have begun to bite. Ideally the allergic person should go out while housework is done, and the house should be thoroughly aired before their return. If this is impossible, then wearing a good mask all the time is essential. A special vacuum cleaner that retains allergens, or vents them outside. may be helpful in addition to the mask.
Even though you have cut down on moisture and condensation, and tackled mould growth, there could still be a lot of mould spores around, especially in an old house, one that has been very damp in the past, or one that is close to water. If symptoms persist, then think about hiring or buying a high-quality HEPA air filter (see p. 108) to take mould spores out of the air.
Do not use fans or fan heaters, as these churn up mould spores from the floor and other surfaces.
Beating athlete’s foot
Allergenic fungi can grow on your body, as well as in your house (see pp. 16-17). If athlete’s foot is playing a part in your allergies, it is vital to treat the infection thoroughly with drugs, because the fungus grows deep into the skin and can quickly stage a come-back if not completely destroyed. You should also be careful not to reinfect yourself:
• always dry your feet very thoroughly, especially between the toes; kitchen roll does a better job than towels, and can be discarded, reducing the risk of re-infection
• wear cotton socks and shoes made of leather or canvas, which allow sweat to evaporate; only wear trainers or gumboots, or any other footwear that makes your feet feel sweaty, when you really need to
• when your feet get wet, change your socks and shoes promptly
• launder all towels and bath mats at high temperatures when you start the course of anti-fungal drugs, and again when you complete it
• never share towels, bath mats, socks, sandals or shoes
• wear flip-flops at the swimming pool or sauna, and in changing rooms; if any other member of the household has athlete’s foot, take the same precautions in the bathroom at home – and make sure they seek treatment.
Occasionally athlete’s foot is a misdiagnosis for atopic eczema of the feet, which is a common problem among allergy-prone children (see box on p. 45). If the skin between the toes is not affected, it’s unlikely to be athlete’s foot and more likely to be eczema.