A Review of Atmospheric Microplastics: Sources, Characteristics, and Detection Method

Microplastics (MPs) are ubiquitous in the atmosphere, with an average lifetime of 1 week to several weeks. They originate from various sources, including direct emissions from industrial activities, fragmentation of larger plastic debris, and transport from terrestrial and aquatic environments. Atmospheric MPs (AMPs) have been reported to play vital impacts on human health, climate forcing, and air quality. It could absorb and release harmful chemicals, potentially affecting human health through ingestion or inhalation. Additionally, it could contribute to the absorption and scattering of solar radiation, potentially altering the Earth's radiation balance. However, there is great uncertainty about their health and climate effects, mainly due to MPs undergoing complex physical, chemical, or biological aging in the atmosphere, which results in great changes in their chemical composition and morphonology. Therefore, the transformation mechanisms of AMPs are still poorly understood, hampering our ability to model responses to changes in AMPs.This review summarizes the current knowledge on AMPs, focusing on their sources, characteristics, and detection methods. The variety of the detection techniques used to measure and characterize the AMPs present in literature makes it complex to compare the results. In addition, previous studies were mainly focused on fiber plastics in atmospheric deposition samples, whereas only few studies have been found in the literature about the identification of other types of plastics. We highlight the challenges associated with assessing the distribution, abundance, and composition of AMPs and discuss the need for standardized sampling and analytical protocols.