Assessment of exposure to fungal aerosol in the lecture rooms of schools in the Lesser Poland region

Abstract

The paper presents an assessment of the mycological air quality in classrooms of school buildings located in Lesser Poland. In 10 schools, 5 sampling points were designated: 4 indoors and 1 as an "outdoor background". A 6-stage Andersen impactor was used to collect fungal aerosol samples. During sampling, dust measurements were made (using the DustTrak II dust meter) as well as temperature and relative humidity. The predominant genera of fungi were determined by the MALDI-TOF MS method. The results indicated no statistically significant differences in indoor air fungal concentrations among the tested locations (p>0.05). The highest concentrations were observed in large classrooms (max. 2,678 CFU∙m-3), however, these differences were not statistically significant across different types of school rooms (Kruskal-Wallis test: p>0.05). All rooms exhibited similar levels of fungal aerosol contamination. Relative air humidity had a significant influence on the number of microorganisms. The most frequently isolated fungi belonged to Cladosporium, Penicillium, and Aspergillus genera. Fungal aerosol concentrations in the tested classrooms did not exceed proposed limit values for this type of indoor environment. The results suggest that natural ventilation in classrooms is insufficient to ensure adequate microbiological quality of indoor air.