Researchers from the Catholic University of Louvain in Brussels studied nearly 190,000 teenagers from 21 European countries, analyzing rates of asthma, hay fever, wheezing and other allergies. That information was then compared with the number of indoor chlorinated swimming pools per 100,000 people.
Lead researcher Professor Alfred Bernard said that the rate of asthma rose by 2.73 percent for every extra indoor swimming pool per 100,000 people in a country, while the wheezing rate rose by 3.39 percent.
The UK has the most swimming pools with about five per 100,000 people, while Eastern European countries only had one per 300,000. Eastern European countries also had much lower rates of asthma.
The study concluded that increases in asthma in Western Europe and the UK -- where Scotland leads the world in asthma cases for 13- and 14-year-olds -- could at least partly be attributed to the byproducts of chlorine in the air and water in indoor pools.
According to Professor Bernard, there should hardly be any chlorine smell in a properly ventilated pool, but since ventilation can be expensive, many public pools do not ventilate. This can cause increased problems for asthmatic children, for whom swimming is recommended as a good form of exercise.
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