Associations between children's upper respiratory tract mycobiome, school air mycobiome, and surrounding greenness

Fungal spores are ubiquitous in the air, shaped by landscape and climate, and are known contributors to respiratory allergy in children. However, the contribution of airborne fungi to the upper respiratory tract (URT) mycobiome in children remains poorly understood, as does the influence of natural landscape on this exposure. This study investigated associations between children's URT mycobiome, the school air mycobiome, and surrounding greenness. Two study waves were conducted one year apart at 44 schools around Taiwan. Each wave included passive air sampling across classrooms to characterize school-wide fungal exposure, along with nasal and oropharyngeal swab collection from 78 boys. Fungal genus abundance was estimated using high-throughput sequencing and quantitative PCR targeting the ITS2 region, with URT data normalized to human DNA content. Greenness was estimated using the normalized difference vegetation index within a 10-km buffer around each school. Pearson correlation and linear mixed-effect models were used to examine associations. Cladosporium and Malassezia were the most abundant genera in nasal and oral samples. Nasal abundance of Cladosporium was positively associated with its school air abundance, and similar associations were observed for Bjerkandera, Curvularia, Phlebia, Scopuloides, Sertulicium, Sporobolomyces, Wallemia, and Xylodon. Oropharyngeal abundances of Cladosporium and Malassezia were more strongly associated with nasal than airborne abundances. Greenness surrounding schools was positively associated with the airborne abundance of Bjerkandera, Scopuloides, Sertulicium, Sporobolomyces, and Xylodon. These findings suggest that the air and nasal mycobiomes may be related and that natural landscape may influence children's respiratory fungal exposure.