Settleable Dust and Bioburden in Portuguese Dwellings.

Monitoring campaigns in several buildings have shown that occupants exposed to contaminated indoor air generally exhibit diverse health symptoms. This study intends to assess settleable dust loading rates and bioburden in Portuguese dwellings by passive sampling onto quartz fiber filters and electrostatic dust cloths (EDCs), respectively. Settled dust collected by EDCs was analyzed by culture-based methods (including azole-resistance screening) and qPCR, targeting four different toxigenic sections (, , and ). Dust loading rates and bioburden showed higher variability in the summer season. In both seasons, sp. was the one with the highest prevalence (59.1% winter; 58.1% summer), followed by sp. in winter (13.0%). Fungal contamination increased in the winter period, while bacterial counts decreased. sections and , detected in voriconazole supplemented media, and sections and , detected by molecular tools, were found in the winter samples. This study reinforces the importance of applying: (a) Passive sampling methods in campaigns in dwellings; (b) two different culture media (MEA and DG18) to assess fungi; (c) in parallel, molecular tools targeting the most suitable indicators of fungal contamination; and (d) azole resistance screening to unveil azole resistance detection in fungal species.