Air microbial quality in certain public buildings, Egypt: A comparative study

Özet

This study aims to determine microbiological air quality in public buildings: libraries, faculties, schools, childdaycare centers and hospitals and its association with microclimatic conditions, particulate matter (PM) andventilation type. Airborne bacteria and fungi were collected using Andersen two-stage sampler, it divides particlesinto coarse (≥7 μm) and fine (< 2.5 μm) size ranges. Bacterial and fungal concentrations ranged between0 ‒ 105 CFU/m3 and 0–103 CFU/m3, respectively. The 95th percentile values were 3399 CFU/m3 for environmentalbacteria; 2299 CFU/m3 for mesophilic bacteria and 513 CFU/m3 for fungi. The Global Index of MicrobialContamination (GIMC/m3) exceeded 2000 CFU/m3 in hospitals' admission rooms and educational buildings.Index of Mesophilic Bacterial Contamination (IMC) achieved the greatest value in the faculty of specific education(F.SE), indicating overcrowding and hypoventilation. Fine particle fraction ranged within 2–41% forbacteria and 47–94% for fungi. Bacillus subtilis and Bacillus atrophaeus were the common bacterial species.Aspergillus, Alternaria, Penicillium and Cladosporium were the common fungal types. The secondary and tertiaryfungal colonizers were detected in low counts. Agreement ratios showed that, outdoor air was the main contributorof indoor fungal flora, and accumulated dust was important contributor of fungal and bacterial flora inschools and faculties. Indoor/outdoor (I/O) ratios of PM concentrations exceeded 1 in ∼37% of the publicbuildings. Temperature negatively affected bacterial culturability while, relative humidity and PM supportedfungal culturability in indoor environment. However¸ PM positively affected bacterial culturability and temperaturenegatively affected bacterial and fungal curturability in outdoor environment.