Sand Quality on Portuguese Blue Flagged Beaches: Fungal and Faecal Contamination Across Two Bathing Seasons

There is growing concern about the quality of sand on beaches, as users tend to spend most of their time on the sand rather than in the water. Numerous pathogenic agents have reportedly been isolated from sand, including bacteria, nematodes and opportunistic fungi. The ability of sand to retain pollutants and facilitate the transmission of pathogens raises public health concerns. We analysed sand-monitoring data from the 2024 and 2025 bathing seasons on Blue Flag beaches to find trends and patterns in total fungal counts, enterococci, and E. coli. The values recorded for microorganisms showed considerable variability, which may reflect the possible combined influence of multiple climatic, environmental, and anthropogenic factors contributing to their presence in beach sand. Our findings suggest that the total fungal count on coastal beaches may be influenced by periods of rainfall, which increases the fungal load in the sand. Values recorded from inland beaches vary considerably between beaches which may reflect the influence of local environmental characteristics, particularly vegetation and beach morphology, although the smaller number of inland samples also makes it difficult to define clear patterns and consistent reference values for this parameter. Bacterial indicators may be particularly influenced by occasional anthropogenic disturbances and contamination events. This study adds significantly to the understanding of the microbiological quality of beach sand, encouraging the integration of sand monitoring into environmental surveillance and management programmes.