Emerging risk assessment in areas affected by the Valencia DANA flood: Microplastics and pathogens in sediment and dust

This study aims to quantify the concentration and characterize the morphology of microplastics (MPs) and microbial contaminants in sediment and dust samples from areas affected by the “DANA”, an Isolated High-Level Depression or cold drop. The floods caused by the DANA on October 29 th , 2024, resulted in significant damage across several regions in eastern Spain, transporting sediments and (emerging)-contaminants to urban, agricultural, and aquatic ecosystems. Samples were collected from the main affected municipalities. MPs were identified using Raman spectroscopy, while microbial contaminants were analyzed through ISO-standard culture methods, plaque assays for coliphages, and RT-qPCR for enteric viruses. The results of this study showed that dust samples contained twice the concentration of MPs per gram compared to sediment samples, primarily composed of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), rubber (SBR) and polyethylene terephthalate (PET). Morphological analysis revealed a prevalence of fragments over fibres and films, with smaller particle sizes in the dust samples, increasing their potential for dispersion and inhalation. The presence of microbial contaminants in dust was low. In contrast, the sediments were identified as key reservoirs of pathogenic microorganisms, including Salmonella spp ., Escherichia coli , and human enteric viruses, which may lead to prolonged environmental persistence and increased risks to ecosystems and human health. These results confirm that flood events can redistribute MPs and pathogens differently across sludge and dust, representing a critical pathway for human exposure. These findings underline the urgent need for control and mitigation strategies to limit the environmental dispersal of these contaminants. Given their potential impacts on ecosystems, soil quality, and human health, further research is required to evaluate the long-term consequences of microplastics and associated pollutants in the affected regions. • Valencia floods raised MPs and pathogen contamination in dust posing inhalation risks • Automated confocal micro-Raman detected microplastics down to 0.8 μm • Polyethylene, polypropylene and polystyrene dominated; <100 μm MPs were 75% • Sediments acted as reservoirs of Salmonella, E. coli and enteric viruses • RotaV genomes indicate inhalable particles may pose risks in dry windy periods