Purpose of Review: Micro/nanoplastics (MNPs), as emerging pollutants, have attracted increasing attention due to their potential adverse effects on human health, ecosystems, and climate. The rapid, turbulent, and large-scale nature of atmospheric transport facilitates both horizontal and vertical movement of MNPs over long distances within a short time, largely independent of topographical constraints, thereby accelerating their global cycle and exacerbating their impacts. Despite growing interest, our understanding of the atmospheric lifecycle of MNPs remains limited. This review aims to synthesise recent advances in understanding the atmospheric lifecycle of MNPs, including their emission sources, long-range transport characteristics, and driving mechanisms. It also evaluates the key sources of uncertainty—particularly those related to emission flux estimates—and provides corresponding recommendations for future research. Recent Findings: Current research on the atmospheric processes of MNPs primarily relies on a combination of observational data and numerical modelling. Two major uncertainties in atmospheric micro/nanoplastic (AMNP) emissions persist: the wide variability in marine emission estimates, which span four orders of magnitude, and the unresolved question of whether terrestrial or marine sources are the dominant contributors to AMNP emissions. Furthermore, this review highlights critical factors driving these uncertainties, including limited data availability, inconsistencies in observational methodologies, oversimplified simulations, and gaps in understanding atmospheric cycling mechanisms. Additionally, variations in the particle size ranges targeted by different observational and modelling studies hinder cross-comparisons and model evaluations, representing another important source of uncertainty. Summary: AMNP research is constrained by multiple uncertainties that hinder a comprehensive understanding of their emissions, transport, and fate. To address these issues, we call for establishing a global network of standardised observations, improving sampling and simulation practices, and incorporating artificial intelligence. These strategies will enhance our understanding of the complete atmospheric cycle of MNPs, paving the way for more effective environmental management and better-informed policy decisions.

Airborne micro- and nanoplastic (AMNP) pollution is ubiquitous in the environment, and its abundance and persistence in the atmosphere have raised global concern. Transport and the changing interface of micro- and nanoplastics play an essential role in linking their sources and sinks within the planetary system. In this study, an airborne micro- and nanoplastic measurement campaign was conducted using our newly developed active samplers to investigate the unique sources and interface changes of AMNPs in Hong Kong. These include tyre wear from take-off and landing operations at Hong Kong International Airport (HKIA). Two distinct sampling sites from Tung Chung for airport-related AMNPs were selected. Seasonal measurements were arranged to capture both seasonal and event-based variations in AMNP concentrations. All collected samples underwent Micro-FTIR and PY-GC-MS analyses to determine the physical properties (e.g., size, shape, morphology) and chemical composition of AMNPs, and were subsequently applied to source and receptor analyses. To the best of our knowledge, this is the first survey of atmospheric AMNPs in Hong Kong, providing essential information on background AMNP levels.

Micro/nanoplastics (MNPs), as emerging pollutants, have attracted increasing attention due to their potential adverse effects on human health, ecosystems, and climate. The rapid, turbulent, and large-scale nature of atmospheric transport facilitates both horizontal and vertical movement of MNPs over long distances within a short time, largely independent of topographical constraints, thereby accelerating their global cycle and exacerbating their impacts. Research on the atmospheric life cycle of MNPs primarily relies on a combination of observations and numerical modelling, yet emission estimates remain the major source of uncertainty, posing substantial challenges for lifecycle assessment. This review synthesises findings from atmospheric observations and numerical modelling studies conducted over the past five years to examine the sources and long-range transport dynamics of MNPs, as well as the key factors influencing their transport, while also quantifying uncertainties in emission flux estimates. Two major uncertainties persist: the wide variability in marine emission estimates, which span four orders of magnitude, and the unresolved question of whether terrestrial or marine sources are the dominant contributors to atmospheric micro/nanoplastic emissions. Furthermore, this review highlights critical factors driving these uncertainties, including limited data availability, inconsistencies in observational methodologies, oversimplified simulations, and gaps in understanding atmospheric cycling mechanisms. Additionally, variations in the particle size ranges targeted by different observational and modelling studies hinder cross-comparisons and model evaluations, representing another important source of uncertainty. To address these issues, we call for establishing a global network of standardised observations, improving sampling and simulation practices, and incorporating artificial intelligence. These strategies will enhance our understanding of the complete atmospheric cycle of MNPs, paving the way for more effective environmental management and better-informed policy decisions.