Atmospheric microplastics in PM_2.5 from 2010 to 2024 in Beijing: Type-specific trends and driving factors

Atmospheric microplastics in respirable PM_2.5 (MP_2.5) have attracted widespread attention, yet their characteristics, major sources, and factors influencing their emission remain poorly understood. We present the first long-term (2010-2024) observation of atmospheric MP_2.5 in Beijing, quantified with pyrolysis-gas chromatography / mass spectrometry. Our investigation of type-specific trends and driving factors revealed an overall increasing trend in MP_2.5 concentration, with an average level of 264 ng/m³ and a peak of 417.6 ng/m³ in 2021. The distinct trends of MP_2.5 and PM_2.5 concentrations suggest that their major sources differ, necessitating different regulation measures for each. PVC (polyvinyl chloride), PS (polystyrene), PP (polypropylene), PE (polyethylene), and PA66 (polyamide 66) are the predominant types of MP_2.5, differing markedly from the pattern in dustfall or total suspended particulate matter. PS, PP, and PP correlated positively with express delivery volume and total retail sales of consumer goods, implicating packaging material as a potential major source. PA66 and PVC, which are widely used in disposable medical supplies such as protective suits, responded sensitively to the COVID-19 pandemic. Our findings reveal that socioeconomic activities strongly influence the long-term evolution of MP_2.5 patterns, and provide a scientific basis for related risk assessments.