Airborne Ultrafine Particles: Real-life Exposure Patterns, Epidemiological Evidence and Regulatory Responses in Switzerland and Beyond

Ultrafine particles (UFP) exhibit large spatial and temporal contrasts, and distinct physicochemical properties that enable deep lung penetration and systemic translocation, posing potential health risks. Despite mechanistic evidence from toxicological studies, large-scale epidemiological evidence remains limited due to sparse monitoring and complex exposure assessment. Switzerland has contributed substantially to UFP research through measurement campaigns, mobile monitoring, and modelling studies, which improved understanding of spatial and temporal exposure contrasts. Emerging findings suggest associations between long-term UFP exposure and cardiovascular indicators, though epidemiological evidence for short-term associations with mortality and morbidity remains weak. Ongoing Swiss and European projects aim to refine high-resolution spatiotemporal models, assess population-level health impacts, and inform future air quality standards and regulatory frameworks for UFPs.