Stay in the swim

It is just what parents needed: another health scare. For years, parents of asthmatic children have been told that swimming is one of the best forms of exercise they can take. Now, a new study suggests that chlorine used to disinfect indoor swimming pools could be behind the surge in childhood asthma.

The suggestion, from Belgian researchers who carried out the study, is that chlorine may react with sweat and urine in the water, releasing into the air a powerful irritant, nitrogen trichloride.

Dr Alfred Barnard, of the Catholic University of Louvain in Brussels, says this gas is then inhaled by swimmers and also spectators sitting around the pool - and may affect the cell barriers that protect the lungs.

The Brussels group say exposure to the gas could increase the risk of children developing asthma - although they admit that more research needs to be done.

So should you stop your children from going swimming? Absolutely not, say health experts.

Dr Alan Hunter, consultant in respiratory medicine at York Hospital, says the Belgian researchers conclusions are "very contentious". He has encountered the "very occasional" asthma patient who had been upset by chlorine in water, he says.

"But that really is uncommon. Most asthmatics should be encouraged to take exercise - and swimming is an excellent form of exercise for most asthmatics. It makes them use their lungs. It makes them breathe and maintain good lung function."

Exercise also improves fitness generally, he points out - a big health benefit in itself. "If your body is fit, and your muscles are fit, then whatever level of lung function you've got, you can do more."

York GP Dr Sarah Bottom, of the Jorvik Medical Practice, agrees. She concedes that asthma is on the increase, but insists the jury is still out about the cause. There are many theories, of which the Belgian research is just the latest.

What is not in doubt is the huge benefits to health of regular exercise, she says - and swimming is one of the best forms of exercise.

Dr Bottom adds that a generation of youngsters is growing without getting enough exercise, leading to health complications such as obesity and diabetes.

"So I would not discourage anybody from swimming," she says. "It is excellent exercise."

The National Asthma Campaign, which provides advice and information about asthma, confirms that the new study is "interesting".

"Exposure of any child to a chemical which may damage the airways is clearly a matter of concern and requires further investigation," says its chief medical adviser, Professor Martyn Partridge.

Nevertheless, the Belgian research is far from conclusive. "Great care must be taken in interpreting such associations between chlorine and asthma and it is unlikely that swimming, at least by itself, could really be the cause for the increase in asthma," says Prof Partridge.

The charity's advice remains that swimming is a "healthy form of activity for children with asthma and parents should not keep their children away from the pool".

It is a view echoed by Bob Lancaster, manager of the Selby Abbey Leisure Centre, which has a popular indoor pool.

He points out that chlorine has been used to disinfect water in pools for many years, and says it is therefore unlikely that there is a direct link between chlorine levels and increasing rates of asthma. If anything, modern methods and improved ventilation should reduce the risk to asthmatics.

He is also unconvinced by the Belgian researchers' recommendations that alternative methods of disinfecting water should be tried. Chlorine will always be necessary, because of its immediate effect in killing any water-borne bacteria.

So what do parents think?

Jayne Dwyer's ten-year-old daughter Rosie suffers from asthma and she is a firm believer in swimming. It is one of the few forms of exercise Rosie can take that does not risk provoking an attack, says Jayne.

Rosie is a member of the York Asthmatic Swim Group, which meets every Friday evening at Archbishop Holgate's School for swimming lessons and sessions.

Jayne, of Holgate, York, says that with other forms of exercise there is always the risk of Rosie suffering an attack. "Running around the park or playing field does affect her," she says. "At this time of year it's pollen - but even the exercise itself can bring on an attack.

"But when she goes swimming, it is really nice. She is exercising and you can see the benefits of that, and yet it is almost as though asthma is not an issue.

"She has never had an attack after swimming."

Linda Nicholson, secretary of the York Asthmatic Swim Group, says Rosie is not alone.

Linda's daughter, Sarah, has mild asthma and has been swimming regularly since she was seven - she is now 22.

"We've never had any problem with her or with other children," says Linda. "But there are many benefits. Swimming opens up their airwaves and helps them with their breathing. Many parents who come say how much better their children are for having a swim.

"We just hope this does not put parents off. Swimming is a healthy activity."

If you are concerned about asthma, the National Asthma Campaign can provide advice and information. Call the Asthma Helpline on 0845 701 0203.

The York Asthmatic Swim Group runs sessions and swimming lessons every Friday evening at Archbishop Holgate's School from 7.30pm to 8.30pm.

Parents are welcome to swim in the pool during lessons. Call Linda Nicholson on 01904 430339 for more information.

Updated: 10:01 Monday, June 02, 2003