실내 수영장 내 부유세균과 응축수 미생물의 분포 및 특성 = The Distribution and Characteristics of Airborne and Condensate Bacteria in Indoor Swimming Pools

다국어 초록 (Multilingual Abstract)

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다국어 초록 (Multilingual Abstract)

Background: Indoor swimming pools are high-humidity environments where user activity and condensation-derived wet surfaces may increase microbial persistence and exposure both in indoor air and on surfaces.
Objectives: To characterize culturable bacteria in airborne and condensate samples, this study compared bacterial load, richness, and genus composition and explored differences by ventilation and disinfection methods.
Methods: Four indoor pools (A~D) in the South Korean city of Gwangju were surveyed five times from November 2024 to October 2025. Airborne bacteria were collected by impaction (250 L), and condensate was sampled by swabbing a 10×10 cm area. Culturable concentrations were expressed as CFU/m3. Isolates were identified to the genus level using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).
Results: Mean relative humidity differed among pools (A, 86.5%; D, 68.4%). Airborne bacterial loads ranged from 20 to 378 CFU/m3. They peaked in pool A in June 2025 (378 CFU/m3). Airborne richness increased from June to October. Condensate richness was lower overall, but increased in October in some pools. In total, 58 genera were identified (43 airborne; 35 condensate). In airborne samples, Staphylococcus was frequent, Bacillus contributed more in pools A and B, and Micrococcus contributed more in pools C and D. In condensate, Cupriavidus predominated in pool A, while Pseudomonas and Staphylococcus predominated in pools B~D. Total bacterial counts were weakly associated with relative humidity (R2=0.189). Ventilation/disinfection methods were associated with shifts in Sphingomonas , Staphylococcus , and Bacillus. Principal component analysis (PCA) separated pools by genus composition, explaining 72.4% of the variance.
Conclusions: Airborne and condensate bacteria showed distinct, pool-specific characteristics. Management should extend beyond water disinfection to include humidity/condensation control, optimized ventilation, and hygiene for wet surfaces and HVAC-associated areas.