Indoor pools may contribute to high asthma rates
Children who live in regions with more indoor swimming pools are more likely to have asthma, a new European study shows.
The findings support the “pool chlorine hypothesis,” which proposes that exposure to this toxic chemical and its byproducts may play at least some role in the development of the disease, Drs. Alfred Bernard and M. Nickmilder of the Catholic University of Louvain in Brussels conclude.
Recent studies have linked frequent pool visits to a greater risk of asthma, especially among young children, the researchers note in their report, published in Occupational and Environmental Medicine. And chlorine gas in the indoor pool environment has become “one of the most concentrated air pollutants to which children are exposed,” they add.
To investigate whether the number of indoor pools per person could help explain the variation in asthma rates across Europe, the researchers analyzed data from the International Study of Asthma and Allergies in Childhood, which included 189,150 children aged 13 to 14 examined at 69 centers in 21 countries, as well as 94,549 children aged 6 to 7. The researchers compared the prevalence of wheezing and asthma to the number of indoor swimming pools per 100,000 people in each country.
Swimming pool prevalence varied from none in Estonia, Georgia and Uzbekistan to as many as six per 100,000 people in the UK. There was an average of one pool per 50,000 people in Western Europe compared with one pool for 300,000 people in Eastern Europe.
Because wealthier countries would be expected to have more swimming pools, the researchers controlled for each country’s gross domestic product.
Even after this adjustment, the researchers found that the prevalence of asthma rose with the number of swimming pools per person across the continent and in both age groups studied. The relationship was stronger in the older children.
“The discovery that this chlorine-laden atmosphere can be deleterious to the lungs of young children exercising in it is not surprising,” Bernard and Nickmilder write. They call for more research into whether the high rates of exposure to indoor swimming pools in developed nations contribute to the “asthma epidemic” in children.
SOURCE: Occupational and Environmental Medicine, July 18, 2006.
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