Asthma PrevalenceNumber of people ever told by a health professional that they
Results from a new study support a growing body of research that suggests a link between chlorinated pools and asthma. Also, for the first time it extends that link to all respiratory allergies.
The findings — published in September in an online edition of
the journal Pediatrics — show that teenagers who
swam in chlorinated pools (indoors or outdoors) faced a
significantly greater risk of having asthma. They had more than
eight times greater risk of asthma than teens who frequented pools
with copper-silver disinfecting systems.
“With this new study, our previous research and that of
others, and the results from our ongoing studies based on lung
injury biomarkers, there is now very little doubt that the
irritating effects of chlorine and its byproducts can promote the
development of allergic diseases in sensitive subjects,” said
study author Dr. Alfred Bernard, a professor of toxicology and
research director at Catholic
University of Louvain in Brussels, Belgium. “For
recreational swimmers such as those examined in our study …
it is a question of excessive levels of chlorine in the water or in
the air just above water surface, and of some genetic
The study included 847 Belgian adolescents ages of 13-18.
Researchers compared the health of the majority of the group, 773
teens who swam in chlorinated pools, with a “control”
group of 114 teens, who swam mostly in aquatics facilities
sanitized with copper-silver systems. The odds of asthma or
respiratory allergies increased with longer exposure.
Bernard said this study is significant for several reasons,
including “the fact that for the first time we had access to
a reference population [swimmers in the copper-silver pool] who had
almost never attended chlorinated swimming pools, and the fact that
for the first time we considered the total chlorinated pool
attendance, combining the attendance at indoor and outdoor
pools.” Also, the sample population of teens was larger than
in previous research.
But not everyone is ready to accept the hypothesis that chlorine
causes respiratory problems as a fact.
“The new study by Bernard et al. should be evaluated
carefully along with other data on pools and respiratory
health,” cautioned Jeffery Sloan, senior director, water and
sustainability at the Chlorine Chemistry Division of the American
Chemistry Council. “Other research has not shown a
consistent association, much less a conclusive link between
chlorinated pools and childhood asthma.”
Sloan added that proper disinfection is essential to maintain
healthy water and that “in well-managed swimming pools,
chlorination byproducts are expected to pose little risk to