Mitigating indoor air quality risks from Cladosporium sphaerospermum-induced biodeterioration of oil-based paints using silver and zinc oxide nanoparticles

Abstract Indoor air quality is significantly compromised by the biodeterioration of building materials, such as oil-based paints, which facilitates the release of fungal bioaerosols posing health risks to occupants. This study examines the role of Cladosporium sphaerospermum as a key airborne contaminant in paint degradation and evaluates metal nanoparticles as antimicrobial additives to mitigate associated bioaerosol emissions. Cladosporium sphaerospermum was isolated from deteriorated oil-based paint samples and identified via phenotypic and genotypic analyses. Microscopic evaluations, including stereomicroscopy, light microscopy, and scanning electron microscopy (SEM), confirmed its primary involvement in paint degradation through surface invasion and colonization. The fungus displayed robust lipase and urease activities, with specific activities of 43.2 and 824 units per milligram protein, respectively, indicating enzymatic breakdown of paint components. Indoor air quality assessments identified C. sphaerospermum as the predominant bioaerosol in environments with degraded paint, accounting for 69.8% of the total fungal count (128 CFU/m 3 ), followed by Aspergillus niger at 11.7%. Incorporation of silver nanoparticles (Ag-NPs; 3–60 nm particle size) and zinc oxide nanoparticles (ZnO-NPs; 18.2 nm particle size) into oil-based paints markedly improved resistance to fungal deterioration in vivo, relative to controls. These results underscore Ag-NPs and ZnO-NPs as effective additives for enhancing paint longevity and reducing fungal bioaerosol contamination in indoor settings, particularly from C. sphaerospermum and related dematiaceous fungi.