Microplastics in settled dust from university indoor environments: Puerto Colombia, Colombia†

Microplastics (MPs), plastic particles ranging from 1 μm to 5 mm, are contaminants of concern due to their adverse effects on human health. Interest in analyzing their presence in settled dust from indoor environments has increased. However, available data remain limited. This study analyzes the presence of MPs in deposited dust from three indoor university environments: a laboratory, a classroom, and a conference room in Puerto Colombia, Colombia, using a stereomicroscope for quantification and physical analysis and micro-Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (μATR-FT-IR) for chemical characterization. Our findings revealed the highest mean abundance of anthropogenic microparticles and MPs in the laboratory (2070 microparticles per g – 1635 MPs per g), followed by the classroom (1141 microparticles per g – 949 MPs per g) and the conference room (955 microparticles per g – 803 MPs per g). No correlations were found between microparticle abundance and temperature or relative humidity. Fibers were predominant, and most particles fell within the size of 501–1000 μm, with polyethylene terephthalate (PET; 12.2%), polypropylene (PP; 17%), and polyester (32.7%) being the most common polymers across all analyzed samples. μATR-FT-IR analysis also revealed multi-component polymers and weathering on the MPs. Notably, the estimated daily intake (EDI) of MPs was higher among teenagers (mean EDI: 0.47 microparticles per kg – bw per day) than adults, suggesting that dust is a critical exposure pathway. This study calls for increased research on MPs in indoor spaces. It focuses on their transport mechanism and its relationship with climate variables. It also focuses on multi-component and weathered MPs to better understand their dispersion and interaction with the human body and environment.