Screening-level human health risk assessment of Pseudomonas aeruginosa in municipal chlorinated swimming pools using routine monitoring data

Pseudomonas aeruginosa is an opportunistic waterborne pathogen that can persist in inadequately controlled swimming pool systems and cause contact-associated infections. This study applied a screening-level quantitative microbial risk assessment (QMRA) framework to estimate event-level infection risk associated with P. aeruginosa exposure in four municipal chlorinated swimming pools in Patras, Greece, using routine microbiological and physicochemical monitoring data collected between 2022 and 2024. P. aeruginosa concentrations were analysed under alternative non-detect treatment scenarios, and infection probabilities were estimated using an exponential dose-response model, with sensitivity analysis across one order of magnitude in the dose-response parameter. Quantified detections occurred in three of the four pools, with the highest detection frequency observed in the PEAK swimming pool. Across all pools and scenarios, estimated event-level infection probabilities remained below the commonly used 10−4 benchmark, although occasional higher concentrations and correlations with microbial indicators highlighted the value of routine monitoring. The findings suggest that QMRA can support the interpretation of pool monitoring data by translating microbiological results into risk-based public health information, while also identifying priorities for improved exposure assessment and future operational monitoring.