Occurrence, temporal variation, and meteorological drivers of airborne fungal spores in Laoag City, northern Philippines.

Airborne fungal spores are major constituents of atmospheric bioaerosols that influence environmental exposure, ecosystem processes, and respiratory health. Despite their ecological and public health significance, long-term outdoor monitoring data describing their temporal dynamics and relationships with meteorological conditions remain limited in Southeast Asia. This study provides the first aeromycological assessment of airborne fungal spores in Laoag City, Ilocos Norte, northern Philippines, a coastal region influenced by monsoon climatic conditions. Airborne spore concentrations were monitored from March to November 2022, and a total spore index of 190,096 spores m⁻3 was accumulated over 216 sampling days. Six primary spore types were identified, and most atmospheric samples were dominated by Cladosporium and Fusaroid-like spores. Spore concentrations exhibited clear seasonal and diurnal patterns, with most of the cumulative seasonal spore load recorded during the wet season, although the highest daily spore concentrations were observed during the dry season. Peak diurnal concentrations occurred during the early morning hours (00:00-06:00). Statistical analysis revealed significant positive associations with relative humidity and rainfall and significant negative associations with temperature, whereas wind-related variables were not significantly associated with airborne fungal spore concentrations. These findings suggest that temperature, relative humidity, and rainfall contribute to the temporal variation in airborne fungal spore concentrations at the study site. This study provides baseline data on fungal spore abundance and temporal dynamics in northern Philippines that may support future environmental monitoring, agricultural management, and respiratory exposure studies.