Research has revealed that there are more airborne microplastics (AMPs) in indoor air than outdoors. People spend more than 90% of their time in indoor environments; hence it is prudent to characterize AMPs to better understand human exposure levels through inhalation. In addition, individuals spend their time in different locations, conducting various activities with varying inhalation rates, all of which can affect their actual AMP exposure. This study used an active sampling method to collect AMPs in selected Southeast Queensland indoor locations where people spend most of their time. Among the sites chosen, a childcare centre had the highest MP concentration (2.25 ± 0.38 particles/m3), while the lowest MP concentration was observed inside a vehicle (0.20 ± 0.14 particles/m3). The most commonly identified AMPs were fibers (98%) with lengths ranging from 71 to 4950 µm, and polyethylene terephthalate was the dominant polymer type. Scenario-specific activity levels were used to calculate an average annual human exposure to AMPs. The highest calculated exposure level of 3187 ± 594 particles/year was observed among males aged 18 to 64. Females aged 5 to 17 had the lowest calculated exposure level of 1928 ± 549. This study is the first to report AMPs in indoor locations where people spend most of their time. More detailed inhalation exposure studies on AMPs should be conducted in the future, considering individual susceptibility and industrial, acute, and chronic exposure levels.
Keywords: Airborne Microplastics; Australia; Human exposure; Indoor air