Having your kids cool off in an outdoor pool during those hot summer months could do more harm than good.
Belgian researchers found swimming in outdoor chlorinated pools appears to increase the odds a child will develop asthma, Reuters reported.
"The more you swim, the higher the risk," said Alfred Bernard, a toxicologist at Catholic University of Louvain in Brussels, in a news release. "What is new in this study is that we looked at outdoor pools for the first time."
Previous studies have linked chlorine and asthma, but this new study debunks the idea that outdoor pools are safer than indoor ones, according to Bernard and his team.
"We see that the risk of the outdoor pool is equal and even higher than indoor pools because children tend to spend longer in outdoor pools and they are more chlorinated," he said.
Asthma is the leading chronic illness in children in the U.S. and the third leading cause of hospitalization among children under the age of 15, according to the American Lung Association. In 2006, nearly 7 millions kids under the age of 18 had asthma.
Worldwide, it’s estimated 300 million people are affected by this chronic illness.