Abstract:
Objective To investigate the pollution of Legionella pneumophila in three types of public places in a city in Central-South China in 2023, and to analyze the health risks.
Methods In July 2023, a targeted non-random sampling method was used to collect samples from centralized air conditioning water, indoor air, and surface of public facility objects in three types of public spaces in a city in Central-South China. Legionella pneumophila in the cooling water and condensate water of centralized air conditioning was determined using the culture method, while fluorescent quantitative PCR was applied for indoor air and object surface samples. The Fisher's exact test was employed to evaluate the associations between water sample types, public space types, and health risk levels.
Results In this study, 24 samples from centralized air conditioning water systems, 213 samples of indoor air, and 282 public facility object surface samples were collected. The culture assay showed that the overall positive rate was 37.5% for centralized air conditioning water samples, 55.6% (5/9) for the cooling water samples, and 26.7% (4/15) for the condensate water samples. For centralized air conditioning water samples, the positive rate was 27.3% (3/11) in subway stations, 66.7% (6/9) in hotels, and 0% (0/4) in train stations. In risk assessment, the high-risk rate was 55.6% (5/9) for cooling water, 20.0% (3/15) for condensate water, 27.3% (3/11) for subway water, and 55.6% (5/9) for hotel water. Fluorescence quantitative PCR showed that the positive rates of samples from indoor air and object surface in public places were 0%, and the medium and high risk rates were 0%.
Conclusion In three types of public places, subways and hotels showed relatively high positive rates of Legionella pneumophila. Both cooling water and condensate water showed high positive rates.