Methods for Determining the Number of Mold Fungi in the Air—Current Trends

Indoor fungal contamination poses significant health concerns due to the diversity and dynamic behaviour of airborne spores. Accurate quantification of indoor fungal bioaerosols remains challenging because of variability in sampling efficiency, particle-size resolution, and analytical approaches. This review critically evaluates commonly used physical sampling methods, including Andersen cascade impactors, Coriolis μ liquid cyclones, sedimentation techniques, and filter-based air sampling, with emphasis on volumetric accuracy, reproducibility, and compatibility with downstream molecular analysis. The processes underlying spore aerosolization in indoor environments and their implications for air quality and occupant exposure are discussed. Indoor fungi such as Aspergillus, Penicillium, Cladosporium, and Rhizopus proliferate under high humidity and inadequate ventilation, particularly within damp materials and HVAC systems. Despite technological advances, significant gaps persist in methodological standardization, harmonization of exposure metrics, and integration of indoor–outdoor fungal dynamics. Such heterogeneity limits cross-study comparability and constrains exposure assessment. By systematically comparing available methods and their optimal applications, this review highlights the need for integrated and standardized strategies to improve fungal bioaerosol quantification and support evidence-based indoor air quality management.