Željko Linšak

Background/Objectives: Heavy metals are environmental hazards that are recognized as neurotoxic agents that may impair olfactory pathways in susceptible individuals. This study aimed to determine the concentrations of cadmium (Cd), arsenic (As), lead (Pb), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), iron (Fe), and mercury (Hg) in the nasal mucosa and secretions of patients diagnosed with nasal septal deviation, nasal polyposis, or chronic rhinosinusitis, and to investigate their associations with olfactory function, nasal airflow, and pathohistological changes in the nasal mucosa. Methods: This prospective study included 97 adult patients who underwent nasal surgery. We used the Smell Diskettes Olfaction Test to assess olfactory function and rhinomanometry to evaluate nasal airflow resistance. Nasal mucosal tissue samples were collected intraoperatively. Heavy metal concentrations were analyzed using inductively coupled plasma mass spectrometry and atomic absorption spectrometry. Results: Preoperative olfactometry scores in patients with olfactory dysfunction differed to those in patients without olfactory dysfunction (3.4 ± 1.3 vs. 4.1 ± 1.2). Inferential analysis of heavy metals and olfactometry revealed that Cr, Fe, and Pb concentrations were negatively associated with olfactory performance before exposure (Cr: β = −0.12, p = 0.018; Fe: β = −0.08, p = 0.009; Pb: β = −0.10, p = 0.048). Rhinomanometry parameters showed positive associations with olfactory function, independently of age, sex, and groups of patients with or without olfactory dysfunction (R1: β = 0.45, p < 0.001; R2: β = 0.30, p = 0.003). Stepwise regression identified Fe, Pb, and Cr as the strongest predictors of olfactory dysfunction. The adverse effects of Fe and Pb exposure were significantly amplified with age. MANOVA revealed significant differences in heavy metal concentrations across pathohistological categories (Wilks’ Lambda = 0.038, p < 0.001). Carcinoma tissue exhibited significantly higher Cr concentrations, whereas precancerous lesions exhibited increased Cd concentrations. Conclusions: Cr, Fe, and Pb accumulation in nasal mucosa secretion is significantly associated with impaired olfactory function and pathohistological changes. Prolonged exposure to environmental heavy metals may affect olfactory function in the elderly population.

Indoor air quality (IAQ) in educational facilities is shaped by a dynamic interplay of microbial, chemical and physical factors, all of which influence health and cognitive performance. This study explored IAQ in university classrooms by combining microbiological, chemical and physical measurements to better understand microbial–chemical interactions in such environments. Samples ( N = 33) were collected from 11 rooms of different sizes, including lecture halls, classrooms and computer labs. Bacteria and moulds were quantified using standard microbiological procedures, while CO₂, O₂, CH₄, temperature, relative humidity and pressure were monitored by portable analysers. MALDI‐TOF MS was applied to identify airborne bacterial and fungal species, providing insight into microbial diversity and sources. The average CO₂ concentration was 906 ppm (range 509–1462 ppm). Although the overall mean was below the recommended 1000 ppm limit, more than half of the monitored rooms recorded CO₂ levels above this threshold. Mean bacterial and mould loads were 572 CFU/m ³ (range 50–1376 CFU/m ³ ) and 130 CFU/m ³ (range 56–260 CFU/m ³ ), respectively. Oxygen remained stable at 20.6 vol.%, while methane concentrations were negligible (mean 2.5 ppm). Relative humidity varied between 25% and 55%. Identified microorganisms were dominated by human‐associated bacteria ( Staphylococcus, Micrococcus ) and environmental fungi ( Cladosporium, Penicillium ), with noticeable differences between occupied and unoccupied rooms. Correlation analysis showed significant positive associations between CO₂ and bacterial load ( ρ = 0.56, p < 0.05), as well as relative humidity and bacterial abundance ( ρ = 0.67, p < 0.05). Species richness was negatively correlated with occupancy ( ρ = –0.77, p < 0.01), indicating microbial homogenisation in crowded conditions. Multiple regression analysis identified CO₂ and relative humidity as significant independent predictors of bacterial load ( p < 0.05). These findings highlight the importance of integrating microbial and physico‐chemical monitoring in IAQ assessments. CO₂ and relative humidity emerged as key controllable indicators, offering practical targets for improving air quality and limiting microbial contamination in educational environments.

Emissions of odorous compounds are major contributors to public opposition when siting waste management facilities. Thus, it is essential to understand how to minimise the concentration of odour-causing chemicals in ambient air surrounding such facilities. Although the concentration of pollutants in the atmosphere is a function of meteorology, there is limited data on the atmospheric parameters that drive ambient air concentrations of odour-causing substances in settlements near waste management facilities. Here, we analysed how temperature, wind direction, wind speed, atmospheric pressure and humidity impact the concentrations of hydrogen sulphide (H₂S) in the ambient air, a potentially toxic chemical and a chief contributor to noxious odours. The relative contribution of each variable was assessed using multivariate statistical analysis applied to an extensive data set of over 7,000 data points collected during 2021. Our results show that all tested atmospheric parameters significantly affected H₂S concentrations in ambient air. Wind direction had the greatest impact on H₂S concentrations, followed by temperature, humidity, atmospheric pressure and wind speed. Specifically, the concentration of H₂S was positively correlated with humidity and atmospheric pressure and had a U-shaped correlation with temperature. Atmospheric variables were able to explain 15% of variation in H₂S concentrations (R² = 15%), indicating the presence of other factors affecting H₂S ambient air concentrations. Our study shows that proper consideration of atmospheric parameters, especially wind direction and temperatures, is of uttermost importance when siting waste management facilities. The conclusions are broadly applicable to odorous compounds near waste management facilities, so adverse effects to human health and the environment can be minimised.

Emerging infectious diseases that we are witnessing in the modern age are among the leading public health concerns. They most often occur in the form of epidemics or pandemics, and they have not been sufficiently researched. Owing to the current coronavirus disease 2019 (COVID-19) pandemic, the World Health Organization has published various recommendations to prevent the spread of this communicable disease, including a recommendation to wear protective facial masks. Therefore, this study aimed to determine the filtration effectiveness of bacteria, yeasts, and molds on three different commonly and commercially available masks used in children’s educational institutions. In addition, the bacterial content of indoor air bioaerosols was identified. The genera Staphylococcus and Micrococcus were dominant in all samples, whereas bacteria of the genera Bacillus, Acinetobacter, and Corynebacterium were identified at a significantly smaller number. Bacterial, yeast, and mold filtering effectiveness increased from the single-layer cloth mask, which proved to be the least effective, to the surgical mask, to the filtering facepiece type 2 (FFP2) mask. Furthermore, surveys are needed to study the effectiveness of protective measures.

The bacterium Legionella pneumophila is a ubiquitous microorganism naturally present in water environments. The actual presence of this opportunistic premise plumbing pathogen in recreational swimming pools and hot tubs in the northwestern part of Croatia has not been investigated. This study aimed to analyze the presence of the opportunistic pathogen L. pneumophila in public swimming pool water in Primorje-Gorski Kotar County (N = 4587) over a four-year period (2018–2021). Additionally, the second aim was to investigate the connection between the presence of L. pneumophila and pool water physicochemical parameters using mathematical predictive models. The presence of L. pneumophila was detected in six pool samples. Five positive samples were found in the water of indoor hot tubs filled with fresh water, and one positive sample in an outdoor recreational saltwater pool. A predictive mathematical model showed the simultaneous influence of chemical parameters dominated by the temperature in saltwater and freshwater pools, as well as the significant influence of free residual chlorine and trihalomethanes. Our results pointed out that keeping all physicochemical parameters in perfect harmony is necessary to reach the best disinfection procedure and to avoid the optimum conditions for L. pneumophila occurrence.

In Croatia, Podravina is a well-known lead-polluted region due to the intensive exploitation of natural gas, a highly developed agricultural industry, and a traffic hub with several heavily traveled roads. It represents a natural environment with a great variety of wildlife, especially hares (Lepus europaeus Pallas), which may serve as an indicator for environmental quality assessment. This study was conducted to estimate the bioaccumulation of lead in hare liver, kidney, muscle, and brain during long-term exposure and its impact on the oxidative status of the organism and to investigate a possible lead exchange ionic mechanism in the brain. In the organs of two hare groups (experimental from polluted area and control from the island of Krk), Ca, Fe, Mg, Na, lead concentrations, and antioxidant enzyme defense system were analyzed. The accumulation of lead was highest in the brain (3.7-fold higher compared to the control group) and lowest in the liver (1.6-fold higher compared to the control group). Kendall-Tau and multiple regression analysis showed that the increased lead content caused a stronger exchange of Ca and Na ions in the brain. We proposed that lead either mobilizes intracellular cation stores or causes competitive displacement of Ca from the binding site in intoxicated cells. A linear predictive model for cell intoxication by lead was proposed, where GPx and SOD were predominantly influenced by long-term lead exposure. The presented results showed that long-term lead exposure in hares negatively affected their oxidative status and caused the strongest toxicity in the brain and muscles, making their survival and/or population vulnerable.

Considering the fact that water is a basic need of every living being, it is important to ensure its safety. In this work, the data on the presence of the opportunistic pathogen P. aeruginosa in drinking water (n = 4171) as well as in pool water (n = 5059) in Primorje-Gorski Kotar County in Croatia in the five-year period (2016–2020) were analysed. In addition, the national criteria were compared with those of neighboring countries and worldwide. The proportion of P. aeruginosa-positive samples was similar for drinking water (3.9%) and pool water (4.6%). The prevalence of this bacterium was most pronounced in the warmer season. P. aeruginosa-positive drinking water samples were mostly collected during building commissioning, while pool samples were from entertainment and spa/hydromassage pools. Outdoor pools showed a higher percentage of positive samples than indoor pools, as well as the pools filled with freshwater rather than seawater. The highest P. aeruginosa load was found in rehabilitation pools. Croatia, Serbia and Montenegro are countries that have included P. aeruginosa in their national regulations as an indicator of the safety of water for human consumption as well as for bottled water, while Slovenia and Bosnia and Herzegovina have limited this requirement to bottled water only. In the case of swimming pool water, this parameter is mandatory in all countries considered in this study.