Which means that, on average, three pupils in every classroom will have asthma. Yet a survey carried out in 1999 found that 42 per cent of local education authorities in England and Wales did not have an asthma policy.
So have things changed? Many children still complain that their teachers don't know what to do when they have an attack, and many teachers claim they are not properly trained to spot the tell-tale signs.
On the rise
In the UK, asthma is the most common long-term condition among children.
More than one million young people under the age of 16, around one in 10, are known to have asthma, and there may be more who remain undiagnosed.
Every 18 minutes, a child is admitted to hospital because of asthma, and around 25 under-16s die every year during an attack. Children can start showing symptoms between the ages of five and seven, but most cases are diagnosed between the ages of seven and 10. Many sufferers "grow out" of asthma by the time they reach their teens, but around a quarter of those diagnosed as children will be stuck with the condition for life. Some adults are so hampered that they are registered disabled.
All Greek to me
Despite being so widespread, there's still little agreement as to exactly what asthma is. The ancient Greeks knew about the condition - Hippocrates named it after the Greek words for "difficult breathing" - but there has been remarkably little progress since. Not only does asthma vary from person to person, but also from place to place, although developed countries seem to be hardest hit. Research in 1999 found that asthma rates among 13 to 14-year-olds in Sweden and Finland were between 10 and 20 per cent, while those in poorer countries such as Albania and Romania were below 6 per cent. It's not just a straightforward link between asthma and industrialisation, however; in India, there are estimated to be up to 20 million asthmatics, including many in rural areas, and in South America up to 30 per cent of children are affected.
What causes asthma?
The greatest risk factor appears to be genetic, but our understanding of why some children get asthma and some don't is still hazy. Sometimes there is a link to other allergies, and sometimes there isn't. Children whose parents smoke are one and a half times more likely to become asthmatic than those with non-smoking parents, and it is more than twice as common in boys as girls.
Some scientists have even linked the increase in asthma rates to ultra-hygienic modern homes, which could encourage the immune system to overreact to allergens. But it's unlikely that there is a single cause.
It's more likely to be a combination of factors; everything from diet - some people blame dairy products - to breast-feeding. Certainly air pollutants, such as smoking and car fumes, commonly trigger attacks, but what is not clear is whether these just act as irritants, making an already latent condition worse, or whether they actually change the cell structure of the airways and so cause someone to develop asthma.
Asthma affects the system that carries air in and out of the lungs.
Sufferers have inflamed airways, caused by chemicals released from white blood cells which infiltrate their lungs and which make the muscles surrounding the airways twitchy and sensitive. When asthmatics come into contact with a "trigger", these muscles tighten and become narrower. The already sensitive airway lining becomes further inflamed and begins to swell, making it difficult to breathe.
There are many triggers. The most common are colds and viral infections, house-dust mites, pollen, cigarette smoke, furry or feathery animals and air pollution. Not all triggers are external, however: exercise, laughter, excitement and stress can all set someone wheezing. In schools, chemicals used in science and art lessons or in cleaning products, chalk dust, and damp can all exacerbate the problem. Try to keep pollinating plants out of the classroom or playground, and ensure sports fields are mown out of school hours.
The asthma attack
The common signs of an asthma attack are wheezing and shortness of breath, coughing, and a tight feeling in the chest. Children suffering an attack may well be unusually quiet, and have difficulty speaking. Younger children also sometimes complain of tummy ache. Symptoms can vary, from person to person and from time to time, so the best advice is to listen to the child.
Managing Asthma in Schools, a study carried out by the Government's Office of Public Services Reform in 2004, found that many teachers know little about asthma and don't know what to do if someone is wheezing. But even if you are used to dealing with asthma, a full-blown attack can be frightening. The main thing is to stay calm, try to keep the child calm and listen to what they are telling you; if they get stressed or frightened their breathing is only likely to get worse. Don't hug the child, or be tempted to put a reassuring arm round their shoulders. This can be restrictive. And don't make them lie down. Instead, get them to sit up as straight as they can and to lean slightly forward, which should allow as much air as possible into their lungs. Loosen any tight clothing.
The standard dose of an inhaler for an attack is two puffs of the reliever (blue) inhaler immediately. If there is no immediate improvement, make sure they take a puff every minute for five minutes, or until they start to improve.
If the symptoms don't improve after five or 10 minutes, if the child gets too breathless or exhausted to talk, or if their lips are turning blue, then you need to get emergency medical help. Give one puff of the inhaler every minute until the doctor arrives; reliever medicine is safe and there's no need to worry about someone overdosing.
After an attack, whether or not the child needed medical help, it is up to the school to give parents all the details.
The lines of defence
Although the specific symptoms and the triggers that can cause an attack are different among children, most asthma treatments are the same for everyone. Reliever inhalers relax the muscles in the airways, making it easier to breathe. They are essential in treating attacks, and are likely to be the only inhaler needed in school. However, they do not reduce the swelling in the airways and so are usually used in combination with preventer inhalers (usually brown, orange or red). These contain anti-inflammatory corticosteroids, which can act like the natural hormone, cortisol, produced in the body. These drugs calm the swelling and stop the airways being so sensitive. The preventer has to be used regularly to be effective, and is normally taken outside school hours. The same is true for steroid tablets, which may be given to a child who has had a bad attack.
They are usually taken as a three to five-day course, and are most likely to be given at home.
The basic inhalers are usually used with "spacers", a plastic or metal container with a mouthpiece at one end and a slot for the inhaler at the other. These help deliver the medicine more effectively to the lungs, and are especially helpful for younger children. There are also machines called nebulisers, which create a mist of medicine that can then be breathed in through a mask or mouthpiece. But spacers have been shown to work just as well, and it is unlikely that a child will need to use a nebuliser in school. If they do, staff will need to be trained by a health professional.
Some sufferers also use alternative treatments, such as breathing techniques, homeopathy and acupuncture. Asthma UK says more research is needed, and sufferers must continue with their regular asthma medicine, but homeopathy may be helpful if the trigger for asthma can be identified. It says homeopathic immunotherapy has also shown encouraging results.
Research by Asthma UK in 1999 found that 30 per cent of pupils did not have immediate access to their inhalers. "Things are improving, but we still get calls from parents to say inhalers have been locked away," says Patrick Ladbury, children and young people's services manager for Asthma UK. "All children should be allowed free access to their reliever inhaler at all times." Ideally, pupils should carry them, but if children are too young to take care of them, then they should be kept in an accessible and recognisable place. Parents should also be asked to provide a spare inhaler, clearly labelled with the pupil's name, and everyone should be aware of where these are kept. In primary schools, the inhalers should be kept in a visible place in classrooms; Asthma UK recommends storing them in spice racks. For older pupils, it's fine to use a central room, as long as it is never locked and everyone knows exactly where to get their medicine.
It is important to know which reliever belongs to which pupil, and each pupil should also have their own individually labelled spacer.
Asthma can be a complicated condition, with invisible knock-on effects.
Although it's the chronic disease most responsible for days off school, pupils missing lessons is not the only problem. Many also find the condition stops them sleeping, for example, and a run of disturbed nights makes for tired, irritable or badly behaved pupils. PE teachers should be especially aware that exercise can often bring on symptoms: more than 50 per cent of respondents to a 2005 Asthma UK web poll said that their PE teachers did not understand their condition.
But this doesn't mean children with asthma should stay indoors to play on computers. "It's a case of better understanding for both PE staff and parents," says Patrick Ladbury. "Children are being signed off PE when there's no need. There are always alternative ways of taking part, such as refereeing or coaching." PE staff should be aware of potential triggers such as cut grass or cold weather, and should encourage good practice, such as thorough warming up and down. They can be particularly helpful in spotting children with undiagnosed or poorly controlled asthma, and in raising this with parents or the school nurse. Children with asthma may well need extra time to get ready for PE, or indeed for making the changeover between any lessons, since rushing can increase the likelihood of an attack.
But asthmatics can become top-class sportsmen and women. Asthma UK's "out there and active" campaign to promote understanding about exercise and asthma is backed by, among others, athlete Paula Radcliffe and footballer Paul Scholes; both are asthmatics.
Just faking it?
The biggest complaint to come out of the Managing Asthma in Schools survey was that teachers didn't listen to pupils who were having an asthma attack.
Young people said they were rarely asked what they wanted, and sometimes parents were called, or the pupil carted off to hospital, even though they felt able to control the attack. Pupils also said they felt isolated, and many reported a lack of sympathy among school staff who tended to downplay the impact of the disease.
In particular, children complained that they were often thought to be faking an attack to avoid lessons. This was especially true among older pupils; greater allowances seem to be made at primary level. Health professionals point out that it is extremely rare for someone to fake an asthma attack and, if they do, then this should be taken seriously as evidence of other problems, and the pupil referred to a counsellor or clinical psychologist.
Asthma is not just a physical condition; all kinds of emotional and psychological factors are involved. The condition can be particularly problematic for teenagers, not because they are medically more susceptible, but because they are more likely to stop taking inhalers, or to start smoking. Teenage girls can also be concerned about stories of steroids leading to weight gain. To take account of teenage sensitivities, Asthma UK recently launched a website, kickasthma.org.uk, and some health authorities have started offering a texting service where users can text a nurse for discreet advice without blowing their street cred. Cultural factors, as well as age, can also make a difference. Managing Asthma in Schools found that asthma was less likely to be diagnosed among Asian children, even when symptoms were present, and that there was a resistance to inhaled medication among some Asian families.
In the front line
Research by Professor Peter Campion at the University of Hull in 2002 found that children's knowledge of their asthma medication, when and how it should be used, and what effect it might have, was often inadequate. This means that during the day it's often up to the school to get things right.
The role of teachers in this is not straightforward. Guidelines from the Department for Education and Skills and the Scottish Executive both state that administering medicine is not a contractual obligation. Teachers who do give medication should be seen to be doing it as volunteers, and there should possibly be a written agreement with parents to this effect. But a school's "duty of care" means that in an emergency teachers are required to act as "any reasonable prudent parent", which may mean administering medicine. As Professor Campion says: "You can't get away from teachers having to understand asthma, particularly at primary level." A survey conducted in the summer of 2005 by Blue Peter and Asthma UK with almost 18,000 children found that 11 per cent go to their teachers for information about their asthma and more than half would like it dealt with in more depth at school.
Each child should be given a personal asthma action plan by their GP or practice nurse, to be kept at home and used as the basis for a similar card in school, carrying all the basic need-to-know information; Asthma UK has a downloadable model on its website (see resources).
A matter of policy
Having an agreed asthma policy can help. It should cover both the steps to be taken with individual children and more general issues around creating an inclusive and supportive environment; it can stand alone or be incorporated into another school policy, such as health and safety or first aid. It is also worth recognising that pupils with asthma may be more likely to be bullied, and to include the condition in anti-bullying policies. One in 10 respondents to the Blue PeterAsthma UK survey said they had been bullied.
A policy can also outline some of the more tricky legal issues involved with dealing with asthma. Check with your LEA, for example, about guidelines for using private vehicles in an emergency and make sure everyone is aware of guidance (which varies in England, Wales and Scotland) for administering medicines and the indemnity back-up they can expect. The policy needs to be made available to every pupil and parent, not just those directly concerned with asthma. This should raise awareness of the symptoms and help reduce the number of undiagnosed cases.
* Asthma UK (www.asthma.org.uk). Helpline 9am-5pm: 08457 010203. Young person's advice: www. asthma.org.ukkickasthmaindexindex.php. Asthma UK provides advice to schools on developing a policy. It also runs holidays for young people with asthma.
* www.teachernet.gov.ukmedical includes DfES guidelines on dealing with asthma.The DfES's "Managing medicines in schools and early years settings"
article can also be downloaded here. The Welsh Assembly is working on updating guidelines (www.wales.gov.uk). For guidance on administering medicines in Scottish schools, visit www.scotland.
Did you know?
* About one in 10 under-16s has asthma. Many more may remain undiagnosed.
About 25 of them die every year during an attack
* It is more than twice as common in boys
* It's the chronic disease most responsible for days off school
* Developed countries seem to be hardest hit. Asthma rates among 13 to 14-year-olds in Sweden and Finland are between 10 and 20 per cent, while those in poorer countries such as Albania and Romania are below 6 per cent
* The most common triggers include colds and viral infections, house-dust mites, pollen, cigarette smoke, furry animals and air pollution
* Chemicals used in science and art lessons or in cleaning products, chalk dust, and damp can exacerbate the problem
* In primary schools, inhalers should be kept in a visible place in classrooms; Asthma UK recommends storing them in spice racks
Main text: Steven Hastings
Photographs: Getty, SPL
Additional research: Sarah Jenkins
Next week: Body language