Airborne microplastics: a Trojan horse for respiratory dysfunction and multiorgan damage

Microplastics (MPs), a class of pollutants, have emerged as a global challenge impacting both ecosystems and human health. Over recent decades, extensive research has been conducted to assess their presence across aquatic, terrestrial, and atmospheric environments. The pervasive accumulation of MPs, resulting from both excessive plastic consumption and inefficient waste management, has established ingestion (via the food chain) and inhalation (via ambient air) as primary routes of human exposure. While numerous studies have investigated the effects of ingested MPs, research on inhaled particles and their respiratory system impacts remains comparatively limited. Owing to their diminutive size, with MPs ranging from 1 μm to 5 mm and Nanoplastics (NPs) being smaller than 1 μm, they can penetrate bronchioles and pulmonary alveoli, eliciting both localized effects (e.g., inflammatory responses, oxidative stress) and systemic consequences. Notably, studies demonstrate that MPs can traverse the Blood-Brain Barrier (BBB), inducing neurotoxic effects. This review provides an overview of MPs' environmental impact and their documented effects on major human organs and tissues, with a focused analysis on the respiratory system. Specifically, we evaluate epidemiological studies and in vitro experimental models employed to elucidate the mechanisms by which MPs may contribute to chronic respiratory disease pathogenesis.