NEW YORK (Reuters Health) — Children who go to swimming pools on a regular basis may be at risk for developing hay fever in adulthood, German researchers report.Dr. Y. Kohlhammer, from the GSF-National Research Center for Environment and Health in Neuherberg, and colleagues speculate that the chlorination by-products at swimming pools may damage the lining of the lungs, allowing closer contact to allergens and increasing the risk of hay fever.

They surveyed 2,606 adults between 35 and 74 years of age. Personal interviews and questionnaires were used to gather detailed information about medical history and swimming pool attendance.

Subjects who attended a chlorinated swimming pool three to 11 times each year at school age were 74 percent more likely to develop hay fever than those who never attended a pool at school age, the findings indicate.

Recent exposure to a chlorinated swimming pool also increased the risk of hay fever. Subjects who reported exposure to a pool more than once a week for the last 12 months were 32 percent more likely to have hay fever than non-exposed individuals.