Abstract

Background: Water is essential in air conditioning processes, where it is used for cooling or heating. Its longer retention in the tanks and pipes of air conditioning devices can lead to physical and chemical changes that favor the appearance and reproduction of Legionella spp. This pathogen causes diseases that arise from inhalation of contaminated aerosol. The research was conducted in the Federation of Bosnia and Herzegovina, Bosnia and Herzegovina during 2023-2024. and included 30 public facilities where 54 water samples were collected from air conditioning devices. Objective: The main goal of the research was to determine the presence of Legionella spp. in water from air conditioning devices, and to examine correlation of physical and chemical parameters (temperature, residual chlorine, ph value, iron, zinc and copper) with the pathogen presence. An additional goal of the research was to examine the relationship between the physical and chemical parameters of water. Methods: The research was conducted at the territory of the Federation of Bosnia and Herzegovina (FBiH), Bosnia and Herzegovina (BiH) in the period 2023-2024. The samples were analysed in an authorized laboratory in Sarajevo, using standard microbiological and chemical methods. The water of the air conditioning units was analysed for presence of L. spp., the detection of the bacteria and the determination of the relationship between the examined physical and chemical factors and the settlement of pathogens in the air conditioning units. Results: Legionella spp. was isolated in 7 (13%) of 54 analysed samples. A correlation between higher temperature, lower residual chlorine, and higher concentrations of iron and copper with the bacteria appearance was established. Among the analysed parameters, several significant mutually positive correlations were recorded. Out of a total of 54 analysed samples from air conditioning devices, L. spp. was isolated in seven. The results showed that there is a relation between higher temperature and lower concentration of residual chlorine, as well as higher concentrations of Fe and Cu, with the occurrence of L. spp. in air conditioning devices. No statistically significant association between the presence of bacteria and Zn concentration or water pH was confirmed. By analysing the mutual relations between the tested physical and chemical parameters, the relation of Fe with Zn and Cu, and Zn with Cu and Ph value was determined. The limitation of this study refers to the fact that during the testing the so-called dead pipes in the system was not detected nor present, nor was there a test for the presence of biofilm inside the installation. Conclusion: The results indicate the importance of regular monitoring of water parameters in air conditioning devices in order to reduce the risk of Legionella spp. colonization and to improve preventive measures in public health and air conditioning engineering.

Key words: Bacteria, pH value, residual chlorine, temperature, heavy metals.