Asthma affects over five million people in the UK and 1.4 million of them are children. On World Asthma Day, Christen Pears finds out what it's like to live with asthma and why the number of sufferers continues to rise.

"HAVING asthma is like breathing through a straw," says former shipwright Fred Harrison. "Your chest tightens up, it inflames your tubes, you get full of mucus and it hurts to breathe."

The 60 year old, who lives in Redcar, is vice chairman of Teesside Asthma Group - a support organisation for people with asthma and their carers. His wife, as well as his son and daughter, also suffer from the condition.

"To be honest, we don't really know why we all have asthma. I gradually began to suffer from it 15 years ago. It may be something to do with my job. After I worked at the docks, I was an ambulance man for British Steel and both of those were what I call "dirty jobs". But my wife has had it since she was a little girl. It may be hereditary or it may be caused by other factors like pollution. No-one really knows."

The Harrison family are among the growing numbers of people afflicted by asthma. World Asthma Day today is intended to raise awareness about the condition, as well as boosting funding for research. Recent studies have revealed a frightening increase in the number of asthma sufferers in this country. The latest figures suggest 5.1 million people - one in 13 adults and one in eight children - have the condition, an increase of 1.7 million in the past two years. And these figures don't even include the thousands of people who are unaware they have mild asthma.

The condition can be fatal. Charlotte Coleman, the actress who played Hugh Grant's madcap flatmate in Four Weddings and a Funeral, died after an attack last November, aged just 33.

But most sufferers are able to control their condition using inhaled steroid medication and other drugs, without hospital treatment.

Rugby star Austin Healey has had asthma since he was a child, and fronts the Tackle Your Asthma campaign to urge young people not to let it hold them back. He says: "So many people simply put up with it getting in the way of living life to the full, with 6 per cent accepting that there are things they cannot do."

Professor Martyn Partridge, chief medical advisor of the National Asthma Campaign, believes that everyone with asthma should be able to control their own condition through regular self-medication - the problem, he says, is that often they don't get the right advice.

"Only three per cent of asthma sufferers in the UK are given a self-medication plan when diagnosed compared with 48 per cent in Australia. The National Asthma Campaign is trying to raise awareness so that more people can bring their condition under control."

When someone has asthma, the walls of the bronchioles - the tiny airways in the lungs - swell and produce mucus, which causes breathing difficulties. The bands of muscle around the outside of the bronchioles also tighten, adding to the blockage of air.

The bronchioles are more sensitive than normal to various triggers ranging from dust mites and cat fur to stress and anxiety. This causes coughing, chest tightness, wheezing and shortness of breath.

The triggers vary from one sufferer to another. Some only develop symptoms after a cold, in others exercise brings on breathlessness and it may be worse on cold, dry days. Peanuts, milk and fizzy or alcoholic drinks may make some people cough and wheeze but usually it is something breathed in rather than food or drink that is more likely to bring on an attack.

Despite extensive research it is still not known what causes asthma, yet several theories have been suggested. The increasing number of asthmatics in Western countries has led to the hygiene hypothesis - the idea that the immune system of the newborn child needs to be challenged in order to develop a balanced immune response.

It is suggested that the cleanliness of modern Western society and the reduced exposure to childhood infections, mean that the immune system fails to mature properly and overreacts to allergens or other triggers.

Other theories blame the diet with an over-dependence on convenience foods and a reduced intake of protective antioxidants such as vitamins A, C and E.

Dr Neil Leitch, respiratory consultant at the University Hospital of North Tees in Stockton, says: "There has been a definite increase in the number of people suffering from asthma over the last 10 to 20 years. It has been suggested it could be down to more awareness of the condition and improved diagnosis. This is certainly a factor but, on the whole, it seems as if more people now have asthma."

Asthma can develop at any point in a person's life although it most commonly develops in children.

"There have been lots of major studies into the causes of asthma over the last few years but we are still unsure as to the right answer. It's unlikely to be genetic as the number of sufferers has increased so rapidly and it is not necessarily down to outside agents either.

"Pollutants in the atmosphere have actually decreased rather than increased recently, although household dust mites and passive smoking are known to be major factors.

"It is more likely to be due to a change in susceptibility. People have looked at changes in our diets, our intake of fruit and vegetables and certain fruity acids. No-one has come up with a definite answer and researchers are still exploring all these avenues."

While there is still no cure, asthma can be effectively controlled through drugs. Most asthma treatments are given by inhalers. Reliever inhalers relax the muscles and help the airways to open up, while preventive inhalers, often steroid-based, treat the inflammation and swelling and also provide some protection for the airways.

According to figures, more than half of all people with asthma believe that their condition imposes restrictions on how they lead their lives and nearly one third avoid physical activity because they think their asthma would worsen.

But Mr Harrison says it shouldn't restrict what sufferers can do, as long as they have their condition under control: "Asthma attacks vary from person to person. They can last a few minutes or a few hours but the main thing for someone with asthma is to get it under control. A lot of people believe there are things you can't do, like sport or playing a musical instrument, but if you get it under control, it's not a problem.

"My son took up old time dancing when he was at university and then they discovered he has asthma. People told him he wouldn't be able to do it any more but he proved them wrong. My daughter suffers too and she plays the saxophone. It isn't very pleasant to have asthma but you can live with it and you can still have a very full life."

* For more information about asthma, call the Asthma Helpline on 0845 7010203 or visit the National Asthma Campaign website at www.asthma.org.uk.

* Teesside Asthma Group can be contacted on (01642) 481280.