Abstract
<title>Abstract</title> <p>Airborne pollen and fungal spores are important biological components of urban air quality and can contribute to respiratory and allergic diseases. However, information on their spatial variability within urban environments remains limited in Pakistan. This study investigated the spatial and vertical distribution of airborne pollen and fungal spores across six sampling locations within the National University of Sciences and Technology (NUST) campus, Islamabad, during the peak spring season of April 2016. A low-cost portable volumetric sampler was developed and deployed simultaneously at multiple sites, generating 144 samples for microscopic identification and concentration analysis. A total of 33 pollen types and 14 fungal genera were identified. Aspergillus and Alternaria were the dominant fungal taxa across all sites. Bioaerosol concentrations showed substantial spatial variability, with pollen concentrations varying five-fold and fungal concentrations varying three-fold among sites located within approximately 1 km of each other. Land use/land cover (LULC) analysis revealed positive associations between natural vegetation and concentrations of Aspergillus and Alternaria, while barren land was negatively associated with total fungal concentrations. Exploratory statistical and machine-learning analyses indicated that wind direction components were among the major meteorological factors associated with temporal variability in dominant fungal taxa.Bioaerosol concentrations decreased markedly with sampling height. Mean pollen concentrations declined by 77% and fungal concentrations by approximately 60% between ground and rooftop levels. These findings highlight significant intra-urban variation in bioaerosol exposure and demonstrate the importance of local land cover characteristics and sampling height in aerobiological monitoring and exposure assessment.</p>