Dynamic airborne mycobiome in the metropolitan city transit system is driven by seasonality and station type

Respiratory infections and allergic reactions caused by airborne fungi have received considerable public attention; however, fungal communities remain poorly investigated. This research performed the first year-long investigation of airborne mycobiome in the world's largest subway system. We found that the fungal diversity peaks in autumn and at stations with higher PM2.5 levels. Intercity hubs exhibit the highest diversity of pathogenic fungi and the least seasonal fluctuation. Suburban stations revealed a reduced diversity of human pathogens but an elevated presence of plant pathogens. Core fungal taxa in subways include both common soil fungi (e.g., <i>Alternaria</i> and <i>Cladosporium</i>) and potential plant and human pathogens (e.g., <i>Phoma</i>, <i>Fusarium</i>, and <i>Rhinocladiella</i>) that pose potential health risks. These results are crucial for infection prevention and public health management in city transit systems.