Swimming Pools

Chlorine chemistry does a great job in keeping our swimming pools safe and healthy. Learn here more about some aspects of swimming pool safety that have recently been discussed.

◊ Scientific review of swimming pool related health implications now available

January 2017

Active chlorine solutions have a wide range of applications most famously in swimming pools. This use harnesses the powerful oxidizing properties of these solutions, but a small part of the active chlorine that isnt used for the disinfection, can take part inreactions which create halogenated organic by-products (also called disinfection by-products or DBPs).

The health implications of these by-products have been of particular interest to toxicologists, health professionals and regulators. This was initially because of concerns that they may include, or be similar to, some carcinogenic or asthma causing molecules.

Euro Chlor has published a document, written by an independent chemist, Mr John Pickup, that reviews the scientific research on the health implications of the relevant by-products formed during such uses of active chlorine solutions as a biocide. 

The dossier draws conclusions consistent with the World Health Organisation who continue to emphasise that standards of protection of water must not be compromised because of concerns about potential risks from disinfection by-products. It also agrees that, with correct management and use of these essential biocides, such DBP formation can be effectively minimised.

The new Science Dossier collates the findings of more than 140 recent scientific studies. It is available to be downloaded here.

◊ Video on swimming pool safety

October 2013

SwimmingPoolSafetyYou prefer a perfectly clean and healthy swimming pool above just a swimming pool and you want to manage it safely? Watch the video that the Chlorine Institute in the US has issued.

It gives an overview of the best practices to ensure that your pool is professionally and safely managed.

Belgian scientists confirm; chlorine still preferred pool disinfection agent

February 2013

When, mid-February 2013, a newspaper cited one of the Belgian Ministers of Environment: "Chlorine should be banned from our swimming pools", the scientific world reacted fiercely. The Walloon regional Minister of Environment replied that he had been quoted incorrectly. He admits that he is working on some new legislation for swimming pool management but denies that it comprises a ban on chlorine as pool disinfectant. What he meant was that he "wishes" in the future swimming pools "would not use chlorine anymore. Alternatives would be acceptable if they are shown to be as effective as chlorine".

Immediately, the Belgian Superior Health Council, an esteemed scientific advisory board for the federal government, repeated its core statements on the use of chlorine in swimming pools:

  • Chlorine is acknowledged as today's best pool disinfectant agent
  • Good pool management must keep chlorine exposure low and below the limits
  • Adequate ventilation must prevent the formed accumulation of chloramines
  • Swimmers' hygiene should be optimised by having a soapy shower before swimming and by avoiding contamination by body substances
  • The long-term effects of alternative disinfection methods should be carefully studied before putting them in place.

Contact: Marleen Pauwels, Science Manager, tel. +32 2 67672 47. Ask your questions to Marleen via the Euro Chlor contact form.

Swimming in chlorinated swimming pools still highly recommended for children above the age of 1

March 2012

"Babies (0-12 months): discouraged; swimming above 1 year: encouraged". This was the clear message of the Belgian Superior Health Council when its chair, Prof. Kirsch-Volders, presented the latest report (on 8 March 2012) on health risks related to swimming in chlorinated pools.

The Belgian Superior Health Council considers that below the age of 1 year, the risks for infection might not weigh up against the potential benefits of the swimming exercise Due to their hyper-reactive mucosa and immature lungs, babies more easily catch infections. Swimming pools constitute an environment with high water temperatures and a combination of low-concentration disinfection by-products and potential bacterial contamination. Therefore the Superior Health Council considers that below the age of 1 year, the risks for infection might not weigh up against the potential benefits of the swimming exercise for that particular age group.

Above the age of 1, however, swimming in chlorinated pools is certainly recommended. About the alleged link between swimming in chlorinated pools and asthma or other adverse health effects, Prof. Kirsch-Volders states that this has never been scientifically proven and she emphasizes that chlorine still is the first choice disinfectant, but that it needs to be combined with sound pool management and clear hygienic standards.

As the former Council's Report (see below) did not focus on other health effects and on babies below 1 year, the Minister of Public health requested a follow-up. The appointed international expert group starts by emphasizing that efficient disinfection of swimming pools is indispensable to avoid infection by micro-organisms. To date, chlorine is considered most adequate in performing this task.

High hygiene standards crucial

A disadvantage however, as is the case with all other disinfection methods, is that it reacts with biological material such as sweat or urine and may form potentially harmful by-products. These by-products are responsible for the typical chlorine smell of the pool. Maintaining high hygiene standards (showering with soap before going into the pool, washing hands after toilet visits) in pools is crucial to avoid the formation of these by-products.

That is why the Superior Health Council emphasizes the importance of good pool management, not only involving adequate ventilation, but also providing clean and easily accessible shower and toilet facilities, diaper changing areas, etc. The Council regrets the non-existence of such harmonized standards and advocates a more severe inspection system with regular water and air quality measurements. The experts advise installing these measures at the national, but also at the international level.

Euro Chlor welcomes the Superior Health Council's report and shares its views on the issue. Euro Chlor actively contributes to develop the science on possible impacts and best practices of disinfection by-products.

Read here the new full Health Council's report on this matter (In English, PDF document)

Relationship between swimming pool attendance and childhood asthma not confirmed

February 2011

The Belgian Superior Health Council recently issued its scientific opinion on papers published by a team of Belgian researchers (Bernard et al.) linking the attendance of chlorinated swimming pools to some respiratory risks, mainly to asthma. The conclusion was that the papers did not provide sufficient evidence to make this link.

The Health Council, upon request of the Belgian Minister of Public Health, reexamined the full set of publications done by a Belgian research team. The experts identified many flaws in the performed study descriptions and noted that the obtained results were not confirmed by other researchers.Swimming in a chlorinated swimming pool is a healthy activity. Photo courtesy of Commune of Overijse (Belgium)

In reaction to the publications issued by the Belgian team since 2002, Euro Chlor and the World Chlorine Council (WCC) have organized several international scientific workshops specifically dealing with the safe use of chlorine in swimming pools. Another aim was to identify the key issues as well as the major data gaps and research priorities in the field. The associations came to the same overall conclusion as the Superior Health Council: the Bernard et al. papers did not provide sufficient evidence to link chlorinated swimming pools with asthma.

Nevertheless, the Belgian expert group stated that, although this relationship between swimming pool attendance and childhood asthma had not been confirmed, it could not yet be excluded.

As this official document was prepared by neutral and renowned scientific experts in the fields of pneumology, toxicology and child pneumology, it was considered of high value by the Euro Chlor Health WG. Only being available in French and Dutch, the Recommendations' section was translated into English for wider use.

Read here the English translation of the Council's recommendations (PDF document)
Lees hier het oorspronkelijke rapport in het Nederlands (PDF document)
Lisez ici le rapport initial en français (document PDF)

Euro Chlor follow up  -  Publications

The Euro Chlor Health WG will continue to closely follow up the chlorinated swimming pool issue. For 2012, a meta-analysis on health effects from swimming in adults and children was commissioned to the University of Utrecht (WCC project) and the compilation of a new Science Dossier on the health effects of disinfection by-products is now available.

Read the Euro Chlor FOCS publication (2009) on Chlorinated swimming pools and respiratory health. 


Marleen Pauwels, Science and Regulatory Affairs Director, tel. +32 2 676 72 47.  Ask your questions to Marleen via the Euro Chlor contact form.