Posts Tagged ‘irritants’

No single factor lies behind the allergy epidemic — the causes are many and various (see p. 20). What this means for parents interested in allergy prevention is that there is no

single measure which will ensure that your children do not develop allergies. Instead there are a great many different things that can be done, each of which reduces the risk to

some extent. The more of these you do, the lower the risk becomes.
Avoiding allergens
Starting before the birth is best, if you want to reduce allergen exposure for your child (see p. 240). But if you have missed the boat with that one, don’t despair – there is

still a lot to be gained by reducing allergen exposure at a later stage.
If you are ridding your home of allergens after the child’s birth, bear in mind that things will get worse before they get better– there will be a temporary surge in airborne

allergen as a result of the clean-up operation, and you will need to protect the child from this. The best strategy is for the child to be away for a few days while the work is

done, especially if you are taking out carpets, furniture or mattresses. Remember to protect yourself as well, if you are allergy-prone (see p. 109).
One of the most important steps you can take to reduce allergen levels is improve the natural ventilation of your home. This lowers the humidity (assuming you don’t live in an

extremely humid climate), which helps combat both moulds and dust mites. Ventilation also flushes out allergens in the air, especially cat, dog and mould allergens. Half the

problem with modern houses is that the airtight seals around doors and windows, introduced to conserve heat and save energy, turn the indoor air into a rich stew of allergens

and irritants.
House-dust mite
Avoiding high levels of house-dust mite in the home is one of the most valuable things you can do to reduce the risk of allergies in your child. Not only is house-dust mite a

powerful allergen in its own right, it may also act as an agent provocateur as far as the immune system is concerned (see p. 12), and may help to initiate allergic reactions to

other potential allergens – such as those from pets or indoor moulds.
Even if you do nothing else to protect your new baby from mite allergen, at least buy a new mattress and pillow for the cot, with ready-fitted allergen-proof covers. Do the same

for the portable crib, if you have one. Choose anti-mite products that are designed for babies and are guaranteed safe – there is a risk of suffocation with some loose covers

sold for older children and adults (see p. 245).
You may want to eliminate house-dust mite from your own bed as well as the baby’s, because there will probably be times when you take the baby into bed with you for a feed or a

cuddle – and times when, as a toddler, he or she just barges in! It is good to know that your child is still breathing air free from dust-mite allergen in these circumstances.
Deal with your own bed as soon as you can. Some doctors believe that lowering your exposure to dust mite during pregnancy may reduce the risk of sensitising your baby before

birth (see p. 241).
When taking anti-mite measures with your own bed, make sure that there is no risk of suffocation to the baby from the allergen-proof materials used. Microporous membranes based

on plastic could, if sucked onto the baby’s face during sleep, cause suffocation. Loose covers on duvets are worrying in this respect. Buy a new duvet with a built-in

allergen-proof cover, for preference, or a duvet that can be laundered at 60°C or above.
All the other measures for combating dust mites, described on pp. 114-17, will help to protect your child. Buy a good anti-allergen vacuum cleaner if you possibly can, and keep

your baby out of the room while vacuuming if you can’t (open the windows too). Make sure the baby only has new soft toys, preferably washable ones (see p. 116).
It is also an excellent idea to reduce dust-mite levels in the carpets and soft furnishings (see p. 117), because children tend to have very close contact with these in their

early years. A crawling baby, motoring enthusiastically around the sitting room floor, is stirring up the stockpile of dust-mite allergen that is found in any carpet, and

inhaling it in full measure. An adult walking around the same room has a far lower exposure, because dust-mite allergen, being relatively heavy, stays near the ground.
The best option is to go for non-carpet flooring, which doesn’t encourage dust mites. Parents tend to worry about the hardness of this, for a baby or toddler. In fact babies are

far more robust than we generally believe, and a hard floor is no problem for a small child who has never known the luxury of carpeting.
If you really hate the idea of your baby having anything other than carpet to play on, the next best option is to get new carpet, so that you start with zero dust mites. You

must then prevent dust-mite numbers from building up too much, by means of good ventilation, or with the use of a powerful dehumidifier (see p. 117).
Although the first year is the most vulnerable time for your baby, you mustn’t let your guard drop too much as time passes. The moment when a toddler moves from a cot to a ‘big

bed’ is sometimes the beginning of allergy symptoms because, after carefully protecting their child from dust mites in infancy, parents then put him or her into a bed with a

used mattress. This sudden exposure to a high dose of
dust-mite allergen can be the start of asthma. Get a new mattress if you can, and put allergen-proof covers on it. Alternatively, put allergen-proof covers on the existing

mattress.
Moulds
Mould spores are another potent allergen, and you should avoid bringing up a vulnerable child in a damp house if you can, because moulds will be growing there in abundance. Some

new research suggests that heavy exposure to mould allergens in childhood makes allergies in general much more likely. Even in a house that is not obviously damp, it is a good

plan to reduce indoor humidity (see p. 119). Carpets and furnishings that are full of mould spores (see p. 122) should be replaced.
Pets
What about pet allergens – should you find another home for your cat or dog when you are expecting a baby? This is a difficult question because the latest research shows that

pets are a double-edged sword as far as allergies are concerned.
A baby with allergic tendencies who is born into a house with a resident cat or dog is more likely to show allergic reactions to cats or dogs some years later. On the other

hand, there is research showing that having a pet in the house reduces the risk of allergies overall, especially for a child with no brothers or sisters. This is probably

because the pet boosts household levels of endotoxin (see p. 21), and generally makes the environment less hygienic for the child, fulfilling the same anti-allergy role as

brothers and sisters would in the early life of a child (see p. 246).
If you are planning to give your child the kind of grubby childhood that seems to protect against allergy (see p. 246), the additional protection provided by a pet is probably

unnecessary. Or, you could view your pet as having both pros and cons, and decide to keep it, while implementing all the other anti-allergy measures described here. If you do

this, ensure that the house is well ventilated (so pet allergens don’t build up to very high levels) and keep the pet out of the child’s bedroom so that he or she is not

breathing huge amounts of pet allergen while asleep. You could also wash the pet regularly (see p. 125) to reduce allergen levels.
If your child begins to show any signs of allergy to the pet, you must then find it another home.
Avoiding irritants
As well as increasing ventilation and eliminating cigarette smoke from the home completely, it may be worth evicting certain specific items that produce irritant gases.
The main ones are:
•    gas cookers (if you can’t afford to switch to an electric cooker, at least improve the ventilation in your kitchen as much as possible)
•    easy-clean plastic wall coverings and flooring
•    materials such as chipboard and MDF, which give off formaldehyde.
The evidence regarding the possible role of these in increasing the risk of allergies and asthma is described on pp. 128-9. In addition, although there is no evidence on this

point, common sense would suggest getting rid of any plastic or lacquered items that have a powerful smell.
Generally speaking, although traffic pollution can act as an irritant, it seems to play a lesser role in causing allergies and asthma than most people imagine. However, it may

sometimes play a part, especially if there are high levels of diesel fumes in the air (see p. 131).
Infections - friend or foe?
A large group of Italian military cadets were recently studied by doctors interested in the causes of allergy. By taking blood samples and testing them for antibodies to common

infections, the doctors could see what diseases the men had been exposed to early in life. At the same time, the young conscripts were assessed for allergies.
Allergies were least frequent among the young men with antibodies against three common infections that are dispersed via food and faeces – Hepatitis A, Toxoplasma gondii and

Helicobacter pylori. Only one in twelve of the cadets in this group had allergies.
Among the men with no antibodies against any of these infections, the rate of allergy was nearly three times as high – one in five of these cadets had allergies.
The doctors who carried out this experiment believe that these three infections are not necessarily important in themselves, but that they identify individuals who were ‘reared

in an environment that provides a higher exposure to many other orofecal or foodborne microbes’. In other words, they grew up in the kind of household where washing your hands

before meals wasn’t considered too important.
This study adds to the growing body of evidence (see p. 21) which shows that an over-clean environment during childhood encourages the development of an allergic disposition.
Those with lower rates of allergy include:
•    children raised on farms with livestock. The more exposure the children have to farm animals, the less the likelihood of them developing allergies.
•    children from homes with high levels of bacterial endotoxin in the household dust (see p. 21)
•    children who have fewer baths, and wash their hands less often (see p. 21)
•    children with brothers and sisters, especially those with older siblings. Some of the protection here may be due to the impact of the mother’s hormones and immune system

on the foetus in the womb: these effects change with successive pregnancies. But close contact with older siblings, and thus exposure to more microbes, probably plays a part.
•    children who go into kindergarten, nursery school or day care with other children at an early age – this is only valuable for children without brothers and sisters
•    children with pets at home – the benefits are much more pronounced for children without brothers and sisters.
The Italian study is especially important because, for the first time, it gives detailed information about the kinds of infections that make a difference in allergy prevention.

The military cadets were also checked for antibodies to measles, mumps, rubella, chickenpox and herpes. None of these infections gives protection against allergies – only

infections carried in food and faeces do.
Exactly what practical use you make of these discoveries is up to you. For most of us, the importance of hygiene was so firmly instilled during our own childhood that it is

quite hard to suddenly become more relaxed about it. But do let your children play in the garden, if you have one, and don’t worry so much about how dirty they get. Encourage

them to do some gardening – medical researchers believe that harmless bacteria in the soil may be particularly important in educating the immune system away from allergies (see

p. 21). Let them play with pets, as long as the animals are not carrying harmful parasitic worms (talk to your vet about whether pets should be treated for parasites). Ease up

or, hand-washing and, if this is your first baby, make sure he or she plays with other children as early in life as possible.
A few chest infections do seem to increase the risk of asthma, notably Respiratory Syncytial Virus (RSV). If this Infects babies, it provokes an IgE-reaction (see box on p. 12)

which may encourage the development of allergies. Unfortunately, there is very little you can do to protect your child from this common virus, but it makes sense not to take the

baby to a hospital for unnecessary trips (visiting relatives, for example) because RSV infections are often picked up in hospital.
Taking care with antibiotics
The possible role of antibiotics in making allergies more likely to develop is an exceedingly controversial topic. Before making any practical decisions in this respect, you

must consult your doctor. Never go against your doctor’s advice, if he or she thinks that antibiotics are necessary.
Several different studies have now produced evidence of a link between antibiotic use before the age of one or two, and the later development of allergies, asthma or both. The

best of these studies was carried out by doctors in Oxford, who followed 1900 children up to the age of sixteen. Among children at risk of allergy (because their mothers had

allergies) taking antibiotics before the age of two was linked with an increase in the rate of allergy from 32% to 54%. The more courses of antibiotics a child received, the

greater the risk.
The type of infection for which the drugs were prescribed was not important, as far as the risk of allergy was concerned, but the type of antibiotic did make a difference.

Broad-spectrum antibiotics, which kill a wide range of bacteria, were more risky –suggesting that the depletion of friendly bacteria in the gut (see p. 204) could be responsible

for increasing the allergy risk. Penicillins seemed less likely to promote allergies than erythromycin or cephalosporins.
This research is not widely known, as yet. And because there is a widespread assumption that giving an antibiotic can do no harm, even if it is unnecessary, antibiotics are

sometimes prescribed when they serve no purpose. In particular, antibiotics are often given for virus infections, especially in childhood, despite the fact that antibiotics are

of no value whatever against viruses. Research shows that doctors are sometimes responding to pressure from anxious parents when they prescribe antibiotics – it is difficult for

some parents to accept that a virus infection cannot easily be treated and just has to ‘run its course’. (Although there are drugs that combat viruses, these are expensive and

produce unpleasant side effects – they are reserved for very serious virus infections such as hepatitis.)
Obviously. when a child needs antibiotics to deal with a serious infection there can be no question about giving them. This is why you should always follow your doctor’s advice.

But it is also worth asking the doctor the following questions before giving antibiotics to your child:
•    are you sure that this is a bacterial infection, and not a virus infection?
•    would it be possible to do tests and check that it is a bacterial infection, before prescribing antibiotics?
•    what is the chance of the child overcoming the infection without antibiotics?
•    would it be dangerous to wait and see if the infection clears up naturally?
Vaccination
The same Oxford research team that investigated antibiotics (see left) also looked at the question of vaccination and allergy. They found a link between vaccination for

pertussis (whooping cough) and increases in asthma, eczema and hayfever. However the increases were not large, and a study from Sweden found that whooping cough vaccination did

not have any effect on rates of allergy and asthma. And researchers in Ethiopia have found that whooping cough vaccination actually reduces the risk of allergy in their country.
This is clearly a complex issue. The contradictory results from different parts of the world suggest that the ‘big picture’ is what counts here – the overall combination of

childhood infections, antibiotic treatment and exposure to harmless bacteria such as those in the soil or from animals. Depending on this big picture, vaccination against

whooping cough may push the allergy risk one way or the other.
There are many other arguments both for and against vaccination and, given our current state of ignorance about the possible effect on allergy, these other considerations are

probably more relevant. Discuss the matter in detail with your doctor before making a decision.

Doctors in Japan recently tried a very simple experiment in allergy prevention. They chose babies suffering from atopic eczema who were allergic to foods, but not allergic to

house-dust mite. Dividing the babies into two groups, the doctors put special allergen-proof covers, designed to protect against house-dust mite (see p. 115), on the mattresses

of all the babies in the first group. Babies in the second group were given ordinary cotton covers.
When the babies were one year old, they were tested again for allergy to house-dust mite. Two out of three children in the second group now gave a positive skin test to

house-dust mite.
By comparison, only one in three of the children from the first group gave a positive skin test. In other words, using the anti-allergy covers for these high-risk children had

cut by half the number who developed an allergic reaction to dust mite.
As this experiment shows, even if a child has already developed allergies, it is not too late to bring protective measures into play. Indeed, an allergy problem in infancy, such

as atopic eczema, can be seen as a warning sign to parents, telling them that they should reduce the child’s exposure to allergens as much as possible.
As well as reducing dust-mite levels, you should minimise your child’s exposure to moulds at home by limiting indoor humidity (see p. 119) and cleaning up any existing mould

growth (see pp. 122-3). This will lessen the chance of mould allergy developing.
Try to avoid staying, even temporarily, in any house that is damp or has old carpets and mattresses. When you are moving house, or carrying out any kind of renovation work,

remember that this will stir up a lot of dust-mite and mould allergens. Protect your child by arranging for a stay away from home.
This pro-active approach should not just apply to airborne
allergens, but also to food, in the opinion of some experts. They
suggest that any child with a true allergy to cow’s milk or egg
should not be given peanuts, tree nuts, fish or shellfish until three
years of age, to avoid sensitisation to these potent food allergens.
Pets are a more difficult issue, with both pros and cons as
regards allergy-prone children (see p. 245). If you decide to keep
your cat or dog, always ventilate the house well, and wash the animal regularly if you can (see p. 125). Be alert for your child developing an allergic reaction to your pet –

don’t turn a blind eye to the symptoms, as parents sometimes do because they are reluctant to accept that the child has become allergic to the family’s much-loved pet. If your

child does develop an allergy to the pet, the best option is to find the animal another home as quickly as possible (see p. 124).
Breast-fed babies with atopic eczema
Although breast-feeding is a good way of protecting children against atopic eczema, it is no guarantee. Sometimes babies become sensitised to food, in spite of being breast-fed,

and then they may react to traces of that same food, eaten by the mother and coming through in her breast milk.
Skin-prick tests (see p. 91) may help to identify the foods responsible for the eczema. Otherwise, a simple elimination diet by the mother, as used for colic (see p. 203), may

pinpoint the offending food. Keeping that food out of the mother’s diet will often clear the baby’s eczema.
Sometimes a breast-fed child’s eczema remains severe, despite the elimination of suspect foods from the mother’s diet. In this case, what should be done? New research from Or

Erika Isolauri – a staunch advocate of breast-feeding – suggests that the best option at this point is to stop breast-feeding promptly. Her research team found that breast-fed

children with persistent eczema had a slower growth rate. If these babies are switched to hypoallergenic formula – either an extensively hydrolysed formula or an artificial

amino-acid formula (see box on p.66) – their eczema symptoms usually subside, and their growth picks up.
Is vaccination safe for those with allergies?
The influenza vaccine and a few others (e.g. yellow fever) are grown in eggs and are not usually given to people with egg allergy. Measles vaccine is grown in cells taken from

eggs and may contain a minute trace of egg allergen, but only those who are extremely sensitive will react: there should be resuscitation equipment available for children who

have had anaphylactic reactions to egg and for those with severe asthma as well as egg allergy. Some vaccines come in vials with latex seals that are designed to be pierced by

the needle of the syringe. A different method should be used for latex-allergic patients. Smallpox vaccine (for bio-terrorism threats) is dangerous for children with atopic

eczema.
Never too late?
The role of modern ultra-clean lifestyles in promoting allergies is now well established (see p. 21). If your child already has allergies, it may seem as if these discoveries

have come too late to help —but that is not the case. Some research suggests that the battle for supremacy between Th1 and Th2 cells (see p. 11) — the unseen power struggle

which decides whether a child will be allergy-prone — is not really settled until some time between the ages of five and seven years. So there is still some potential for

intervening right up to this age. Some studies have suggested that the immune system can be pushed away from an allergic disposition at an even later age, right into adulthood,

by exposure to endotoxin, a bacterial product found around livestock and in `lived-in’ homes.
Several research groups are working on vaccination strategies (for example, using extracts of soil bacteria) that might also be able to achieve this. The initial results are

promising and they suggest that these vaccines can even help adults with allergies. Unfortunately, such treatments will not be available for many years. In the meantime, you can

probably reduce your child’s chance of developing new allergies, and perhaps make the existing ones less severe, by easing up on hygiene (see p. 246).
Fresh air and exercise
With the boom in watching TV and videos, and playing on computer games, some modern children hardly go outdoors at all. As far as allergies and asthma are concerned, there are

two big disadvantages to being a juvenile couch potato. For a start, the couch is also home to dust mites in their millions, and secondly the child is not running about and

using his or her lungs to the full. Airways that are never stretched (because the child never gets out of breath) lose their youthful flexibility in time. Once this has

happened, the airways can never be stretched to their full capacity. Some doctors believe that this may make asthma more likely to develop, or help to make it more severe once

it has developed. Inactivity also encourages obesity, which increases the risk of asthma developing.
Getting outside and running around, or engaging in other vigorous exercise, should be encouraged for any child with allergies. Obviously, you should balance this against the

need to protect the child from pollution peaks and (if your child has hayfever) pollen peaks. Children with exercise-induced asthma should use their reliever inhalers to allow

them to take exercise (see p. 41).
Keep the air at home free from irritants such as nitrogen dioxide (see p. 128), formaldehyde, air fresheners, paint, polish and strong-smelling cleaning fluids. These may

encourage new allergies to develop, and can make existing asthma worse.
Medical treatments
Antihistamines may have a preventive role in very young children with allergies. A study of one- to two-year-olds with atopic eczema found that the antihistamine cetirizine,

taken daily for 18 months, halved the chances of the children developing asthma later.
The children who benefited in this study were those with several risk factors for becoming asthmatic. They had moderate to severe atopic eczema, at least one close relative with

allergies, and allergic sensitisation to pollen or house-dust mite, as shown by skin-prick tests (see p. 91).
The cetirizine was taken at fairly low doses and had no bad effects on the children in this study. What is more, it seemed to benefit their skin as well as reducing the risk of

asthma: those taking the drug had less need of high-strength steroid creams. There is some controversy about the validity of these results, so few children with atopic eczema

are receiving antihistamines at present.
No one yet knows if other antihistamines might have the same effect as claimed for cetirizine. Ketotifen, which is an atypical antihistamine (see p. 159), may do so.
Immunotherapy may also have a protective effect. One study, involving children suffering from nasal allergies, found that those given immunotherapy were less likely to develop

asthma (see p. 165). Another study shows that immunotherapy for children with mite allergy halves the risk of their developing new allergic reactions to other allergens.

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.

Steroid inhalers
Most asthmatics nowadays are given a steroid inhaler at some point, as part of their asthma treatment (see p. 160). It will probably be a low-dose inhaler, and the risks of side effects from this are very small. Even at higher doses, inhaled steroids are relatively safe. Many people are unnecessarily afraid of inhaled steroids and refuse to use them until their asthma becomes really incapacitating. It is important not to delay using an inhaled steroid for too long, as this could cause permanent damage to the airways: inflammation eventually thickens the airway wall, leaving it less flexible and therefore less capable of widening.
For side effects of inhaled steroids see p. 145, and for common brand names see p. 147.
Steroid tablets
These are usually a treatment of last resort. But when you need them you need them – and if your asthma has got badly out of control, they can, quite literally, be a life-saver. On the other hand, if there are any other means by which you can tackle your asthma, so that you do not need steroid tablets again in the future –avoiding allergens and irritants, for example, or using other preventer treatments – those means should definitely be taken.
For side effects of steroid tablets see pp. 141-3, and for common brand names see p. 147.
Cromoglycate-type drugs
For asthma, these drugs are taken by inhalation only. They work by blocking the allergic reaction (see p. 148), and are therefore a type of preventer drug.
Cromoglycate-type drugs are usually inhaled four times a day, although your doctor may recommend more frequent inhalations to begin with. Once your asthma is well controlled, you may be able to reduce the dosing regime to three times a day, or possibly twice a day: ask your doctor’s advice about this.
Should you decide to stop taking these drugs at some point, talk to your doctor first. It is generally best to reduce the dose gradually, over a period of 7-10 days. Some asthmatics need to introduce (or reintroduce) steroids at this time, to maintain control of the airway inflammation.
Side effects
When inhaled, cromoglycate-type drugs can produce short-lived irritation in the throat, which may lead to coughing. This sometimes develops into temporary bronchospasm, causing you to wheeze, but this is really only a minor side effect – it does not indicate that the drug is making your asthma worse.
Asthmatics are sometimes advised to use a short-acting
beta-2 reliever (such as Ventolin) before their cromoglycate inhaler, to overcome this problem. However, this would involve using the beta-2 reliever four times a day, which is no longer considered a good idea (see pp. 153-4). Talk to your doctor again if you have been given this advice.
Inhalers that combine sodium cromoglycate with a short-acting beta-2 reliever (e.g. Aerocrom) are not recommended for the same reason.
A better way around the problem of throat irritation may be to switch to an aerosol inhaler, because the irritation is much less than with dry-powder inhalers. Using a spacer along with the aerosol inhaler (see p. 162) will help even more.
Serious side effects of these drugs are very rare (see p. 149). For common brand names, see p. 148.