Researchers from the Catholic University of Louvain in
Belgium set out to study whether exposure to nitrogen trichloride in indoor
chlorinated pools may affect the respiratory epithelium of children and
increase the risk of some lung diseases such as asthma. Health problems of
swimmers in indoor pools at such facilities as health clubs and competition
pools have traditionally been attributed to the chlorine in the water.
The researchers found an increased incidence of asthma in
children who swam regularly in chlorinated pools. In some cases the damage was
equivalent to that found in heavy smokers. Even people working at the sides of
pools such as lifeguards and instructors were found to be at risk. The recent
scientific study links chlorine byproducts in indoor swimming pools to a rise
in childhood asthma.1
The study claims that regular attendance at chlorinated
pools by young children is associated with an exposure-dependent increase in
lung epithelium permeability and an increase in the risk of asthma development,
particularly when associated with other risk factors. Researchers concluded
that "the increasing exposure of children to chlorination products in
indoor pools might be an important cause of the rising incidence of childhood
asthma and allergic diseases. Although there are various types of chemicals,
nitrogen trichloride is the most common and the type that researchers believe
may be the cause of the asthma development.
The researchers believe that symptoms are caused by
chloramines, particularly trichloramines, which are formed when chlorine reacts
with sweat or urine in the pool water. Trichloramines evaporate easily into the
air and, like mono and dichloramines, are powerful irritants that are
responsible for the unpleasant smells and eye irritation often felt by visitors
and staff at indoor pools.
The study reports that the amount of chloramines present in
the air depends on factors such as swimmers' personal hygiene and how often the
water is changed.
The study's authors recommended that pool operators should
try to reduce the levels of chloramine-laden air from pool surroundings.
Methods suggested include better ventilation, improved hygiene practices by
bathers themselves such as showering before swimming and the regular renewal of
pool water. They also suggested that operators should seriously consider
alternatives to chlorine-based disinfection.
While chlorine is used to ensure that the water is
disinfected, other treatment methods should be considered. For instance,
ultraviolet (UV) water treatment can provide an effective way of reducing those
chloramines from pool water. UV systems can destroy these compounds, resulting
in improved air around the pool.
UV dechloranation inactivates microorganisms, particularly
chlorine-resistant ones, present in pool water. This means that the amount of
chlorine necessary for general disinfection also can be significantly reduced.
The primary action of UV is to kill bacteria, viruses, molds
and their spores, thus reducing the risk of transmission of stomach, skin and
respiratory tract infections to bathers. UV has an important secondary action:
it initiates photochemical and photo-oxidation reactions which destroy
chloramines, a range of compounds responsible for unpleasant smells in pools.
This is particularly important for indoor pools where features such as water
slides and waves give a greater surface area for the release of chloramines
into the air.
The overall result is a cleaner, healthier environment with none
of the unpleasant side effects commonly associated with chlorination. A
reduction in chlorine usage also can mean significant financial savings for
pool operators.
While further research into the effects of chloramines is
needed, pool managers with any doubts about the long-term health effects of
their current disinfection regime can be offered ultraviolet as an alternative
to current chlorination practices.
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