Retired nurse Sue Collins was just beginning the second length of her local pool when her morning swim suddenly became anything but a pleasure.
Two months ago Sue, 69, who has never suffered from asthma or any other breathing problem in the past, suddenly found herself gasping for breath.
‘I felt as if my throat and oesophagus were closing up,’ says the grandmother, who lives near Tewkesbury, Gloucestershire.
‘I hauled myself out on the side and lay there clutching my chest, struggling to breathe. It was terrifying. I thought: “Am I going to have a heart attack? A stroke?”
‘I had felt a little breathless after finishing my swim a couple of weeks before — but this time it was far worse.’
After sitting quietly for a few minutes Sue’s breathing improved and she decided to, as she puts it, ‘not be a wimp’ and get back in.
‘I could feel the same thing happening again. I’m now too nervous to go back — and I used to go swimming three times a week.’
Sue is convinced the problem is related to the indoor swimming baths. ‘I spend half the year in Turkey and swim every day outside in a pool or the sea there and never have this problem,’ she says.
She may be right, because although a trip to the pool is the perfect exercise for many, the chlorine used to keep the water free from germs can trigger problems.
‘Chlorinated environments can make people feel as if they are choking or have difficulty breathing,’ says Dr James Hull, consultant respiratory physician at Royal Brompton Hospital, London.
But in most cases it’s not the chlorine that triggers problems, but the by-products formed when chlorine interacts with other substances — and this is mostly down to people not showering before they enter the pool.
‘This then poisons the water for them and for others,’ says Dr Hull. ‘The chlorine interacts with sweat and urine (and beauty products such as moisturiser) on the skin and forms by-products called chloramines that float above the surface as a gaseous solution that can be inhaled.’
Chloramines are heavier than air so hang over the water where they are easily inhaled. Some believe they may cause lung disorders. A Swedish study in 2013 examining the health of 146 workers at 46 indoor pools found that 17 per cent had airway trouble at work — but no problems at home.
Meanwhile, a paper in the journal Expert Review of Respiratory Medicine in 2012 commented on the ‘high prevalence of airway sensitivity among swimmers’.
The Canadian researchers studied the lungs of competitive swimmers, and found that after training, they had signs of inflammatory changes similar to those in asthmatics. The scientists said that this may be due to chlorine by-products affecting the lining of the airways and ‘possibly contributing to the development of respiratory disease’.
Swimmers are also prone to another condition — exercise-induced laryngeal obstruction (EILO). This leads to symptoms similar to asthma, such as breathlessness or wheezing.
‘It occurs when intense exercise such as swimming causes an abnormal closing of the larynx (or voice box),’ says Dr Hull. This is a physical reaction — not an allergy — in which the vocal cords, the V-shaped band of tissue within the voice box, close, obstructing breathing.
Some people say it only affects them when they are swimming — ‘Why, we don’t know,’ says Dr Hull. It is possible that this, too, is linked to the chloramines.
‘It tends to affect young adolescents — around six to nine per cent of that age group have this condition — although it can affect people in their 60s and 70s, too.
‘It may be that they don’t know they have the issues until they take up vigorous exercise at this point of their life.
‘But the problem, especially for affected youngsters, is that it gets mistaken for asthma and so they spend years on inhalers that do nothing to help their symptoms.’
Dr Hull has developed a tool that can accurately diagnose EILO in swimmers. ‘Although we can normally induce symptoms on a treadmill, some people say it only occurs in the pool,’ he explains.
‘The tool comprises a camera, half the width of a pencil, attached to a flexible tube that goes up the nose and takes pictures of the voice box to see if it closes during swimming.’
EILO can be helped with physiotherapy to control the voice box — though it may sometimes require surgery.
Dr Hull urges anyone with symptoms like Sue’s to get checked. He says: ‘In older people there is a chance that breathlessness when exercising could be related to something unconnected with swimming such as heart disease.’
Avoiding indoor pools or finding one that is well ventilated may help. And everyone should shower before swimming. As Dr Hull says: ‘People need to remember that showering isn’t just for them. It is for the greater good.’