Airborne Nanoparticles and Human Health: Toxicological Insights with a Focus on Inhalation Exposure and Mechanisms of Toxicity During Pregnancy

Air pollution, particularly from airborne particulate matter (PM), is a major global health challenge and a leading cause of premature death. In this perspective, we provide an overview of human exposure routes to airborne PM and engineered nanoparticles, their subsequent translocation across biological barriers, and their biological effects within barrier tissues and beyond with a focus on the pulmonary and placental barrier. Emphasis is placed on direct versus indirect toxicity mechanisms in the absence of barrier crossing as well as on the 'Trojan Horse effect' that can enhance toxicity. Based on the current state of research, we outline critical knowledge gaps and highlight selected research efforts with Swiss participation that seeks to address these challenges. Collectively, these efforts will contribute to advancing risk assessment frameworks, informing regulatory policy, and ultimately reducing the global health burden of particle exposure.