Humans are potentially exposed to microplastics through food, drink, and air. The first two pathways have received quite some scientific attention, while little is known about the latter. We address the exposure of humans to indoor airborne microplastics using a Breathing Thermal Manikin. Three apartments were investigated, and samples analysed through FPA-µFTIR-Imaging spectroscopy followed by automatic analyses down to 11 µm particle size. All samples were contaminated with microplastics, with concentrations between 1.7 and 16.2 particles m⁻³. Synthetic fragments and fibres accounted, on average, for 4% of the total identified particles, while nonsynthetic particles of protein and cellulose constituted 91% and 4%, respectively. Polyester was the predominant synthetic polymer in all samples (81%), followed by polyethylene (5%), and nylon (3%). Microplastics were typically of smaller size than nonsynthetic particles. As the identified microplastics can be inhaled, these results highlight the potential direct human exposure to microplastic contamination via indoor air.

Microplastics (MP) are ubiquitous within the environment, but the approaches to analysis of this contaminant are currently quite diverse, with a number of analytical methods available. The comparability of results is hindered as even for a single analytical method such as Fourier transform infrared spectroscopy (FT-IR) the different instruments currently available do not allow a harmonized analysis. To overcome this limitation, a new free of charge software tool, allowing the systematic identification of MP in the environment (siMPle) was developed. This software tool allows a rapid and harmonized analysis of MP across FT-IR systems from different manufacturers (Bruker Hyperion 3000, Agilent Cary 620/670, PerkinElmer Spotlight 400, and Thermo Fischer Scientific Nicolet iN10). Using the same database and the automated analysis pipeline in siMPle, MP were identified in samples that were analyzed with instruments with different detector systems as well as optical resolutions and the results discussed.

Urban and highway surfaces discharge polluted runoff during storm events. To mitigate environmental risks, stormwater retention ponds are commonly constructed to treat the runoff water. This study is the first to quantify the retention of microplastics in the sediments of such ponds. It applied state-of-art FTIR-methods to analyse the composition, size, shape, and mass of microplastics in the range 10-2000 μm. Seven ponds serving four land uses were investigated, and the results are related to catchment characteristics, sediment organic matter content, and hydraulic loading. We have not found a correlation between the microplastics abundance, polymer composition, size distribution and the land use in the catchment, as well as the sediment organic matter content. Both the highest (127,986 items kg-1; 28,732 μg kg-1) and the lowest (1511 items kg-1; 115 μg kg-1) accumulation of microplastics were found in the sediments of ponds serving industrial areas. There was, however, a correlation to the hydraulic loading of the ponds, where the sediments of the highest-loaded ponds held the most microplastics. This study shows that sediments in stormwater retention ponds can trap some of the microplastics and prevent them from being transported downstream. These systems need to be considered when assessing the fate of microplastics from urban and highway areas.

In this paper, we evaluate the performance of a disc filter that retains microplastic (MP) particles from treated wastewater. A focal plane array-based Fourier transform infrared imaging technique enabled MP quantification and an in-house-built software (MPhunter) facilitated automatic analysis of the obtained infrared spectra. The disc filter retained 89.7% of particles, and 75.6% of their mass. This removal efficiency is comparable to removal rates reported by previous studies. However, the presence of an unexpectedly large number of MP particles whose size substantially exceeded the pore size of the disc filter suggests that particles could either bypass or pass through the filter mesh, somewhat diminishing the performance of the filter. The concentration of MPs in the effluent was 3 MP/L, corresponding to an estimated mass concentration of 0.31 µg/L. The annual MP discharge from the studied WWTP after the disc filter was estimated to be 1.1 kg in 2017. It was hence not a significant contributor to MP emissions in Denmark. Although the operation of the disc filter seems to have been disturbed, it nonetheless achieved a high MP removal rate. Therefore, we conclude that it is a suitable technology to decrease the concentration of discharged MPs in wastewater effluents.