INEGI study identifies measures to mitigate risks associated with the indoor environment of public pools

An INEGI team drew the current picture of the quality of the indoor environment in indoor pools in northern Portugal. Standards are being met, but there are concentrations of pollutants which, in case of continued exposure, may pose health risks.

Swimming, water polo or water aerobics are sports with more and more practitioners, from the baby who begins to acclimate to the water to the elderly who want to stay active. Therefore, growing concerns about the health conditions of water and ambient air, as well as safety, in indoor pools are justified.

It was in this context that INEGI proposed an air quality audit to 21 indoor swimming pools in the northern region of Portugal with the objective of “collecting data that enables the characterization of the existing situation and the development of a set of recommendations, namely to ensure the application of good practices in public indoor pools”, explains INEGI’s researcher Marta Gabriel, who was part of the team that developed the study.

One of the main measures imposed by legislation to ensure public health is water disinfection to prevent infections caused by microorganisms. However, chlorine-based disinfectants are likely to react with organic and inorganic material in the water, typically introduced by the physiological secretions (urine, saliva and perspiration) of pool users, leading to the formation of disinfection by-products. Accidentally ingested water, inhaled or absorbed through direct skin contact, these by-products can have harmful health effects.

The HEBE project - Health, Comfort and Energy in the Built Environment, in which 17 municipalities and 2 sports entities participated, assessed the current exposure to disinfection by-products in the ambient air, in terms of the Quality of the Interior Environment and Health.


The case study conducted in an Olympic swimming pool assessed the exposure to which a competitive swim team - young swimmers and their coaches - is subject in the long term. It concluded that, even if the pool meets the requirements of the current regulation, disinfection by-products can reach airborne concentrations that may pose serious health risks to athletes. "The estimated average risk of cancer, although low, was higher than the upper limit defined as negligible, suggesting that we adopt strategies to mitigate the risk associated with disinfection by-products in these environments", explains the researcher.

The overall study found that, overall, the 21 audited pools were in good condition in terms of World Health Organization “guide values” and national legislation, although it reveals that there are cases where poorer ventilation conditions induce higher concentrations disinfection by-products, which should be avoided.

The work carried out also showed that, during periods of high inflow to the pool, there is a greater transfer of disinfection by-products from water to air, which indicates that exposure may potentially be increased during these periods”, Marta Gabriel said. "These results suggest that the possibility of reinforcing the fresh air flow should be envisaged during the day(s) when a high influx of users is expected at the pool," she adds.

“The findings support the need to develop public health strategies and policies to mitigate the risks associated with the indoor environment of public pools. In particular, through measures that minimize exposure to disinfection by-products and control the levels of these compounds in indoor air”, concludes the researcher.

Over the past three years, the HEBE project has involved close cooperation with the Faculty of Medicine of the University of Porto (FMUP) and the Institute of Public Health of the University of Porto (ISPUP), and has been scientifically coordinated by Eduardo de Oliveira Fernandes, former INEGI researcher and Emeritus Professor at the University of Porto. The project was funded under the Northern 2020, Portugal 2020 and European Regional Development Fund (ERDF) programs.

Universidade do Porto
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