The study by the Belgian researchers of the Catholic University of Louvain, which appears in Occupational and Environmental Medicine, has found that the rates of childhood asthma and wheezing rose by around 2-3% for every indoor swimming pool per 100,000 people. The researchers were of the opinion that the exposure to chlorine, which is used worldwide, could probably be the key cause.
The researchers explained that there should be a thorough evaluation on the long-term effects of chlorine by-products on the respiratory health of the children, and that the pools should be properly ventilated with the levels of chlorine by-products regulated. The researchers had published a report three years back, wherein they produced proof on the production of harmful fumes by the chlorine present in swimming pools that react with the sweat or urine, damaging the lungs.
Their study found that children who regularly swam in the indoor pools built up large quantities of proteins that caused damage to cells in the lungs. The researchers reported their findings in the current study on 190,000 children of 13 to 14 year olds from across 21 countries analysing the rates of wheezing, asthma, hay fever, allergic rhinitis and atopic eczema, reported in a study of almost 190,000 13 and 14-year-olds from 21 countries across Europe.
They had then compared the rates they obtained with the number of indoor chlorinated swimming pools per 100,000 of the population in each of the countries. They explained that the number of indoor pools varied by a factor of 20 between Eastern and Western Europe, ranging from one pool for every 50,000 people in Western Europe to one for every 300,000 people in Eastern Europe.
The results of the study showed that, even after taking to account the factors like, wealth, climate, and altitude, there still seemed to exist the probability of a strong link between asthma and related disorders and potential access to swimming pools. They found that the rate of wheezing rose by 3.39% for every additional indoor chlorinated swimming pool, while the rate of asthma rose by 2.73%.
The researchers claimed, based on their study that the rise of asthma in Western Europe could to a certain extent be credited to the increasing exposure of children to the by-products of chlorine in the air and water of indoor swimming pools.
Meanwhile a spokesperson for the charity Asthma UK said, "Swimming is an excellent form of exercise for children with asthma as the warm humid air in the swimming pool is less likely to trigger asthma symptoms." She also said, "We do recognise, however, that the chemicals present in heavily chlorinated pools may be important in making the airways more irritable and further research is needed to understand this association."