Every breath you take: High concentration of breathable microplastics in indoor environments

The widespread presence of microplastics (MPs) in the air and their potential impact on human health underscore the pressing need to develop robust methods for quantifying their presence, particularly in the breathable fraction (1 μm in four indoor environments (a meeting room, a workshop, and two apartments) under different levels of human activity. The indoor airborne MP concentration spanned between 58 and 684 MPs per cubic meter (MP m−3) (median 212 MP m−3, MPs/non-plastic ratio 0–1.6%), depending not only on the type and level of human activity, but also on the surface area and air circulation of the investigated locations. Additionally, we assessed in the same environments the filtration performance of a type IIR surgical facemask, which could overall retain 85.4 ± 3.9% of the MPs. We furthermore estimated a human MP intake from indoor air of 3415 ± 2881 MPs day−1 (mostly poly-amide MPs), which could be decreased to 283 ± 317 MPs day−1 using the surgical facemask. However, for the breathable fraction of MPs (1–5 μm), the efficiency of the surgical mask was reduced to 57.6%. [Display omitted] •Airborne MPs >1 μm were quantified in four indoor locations with μRaman.•Effect of human activity and surgical facemask was investigated.•MP concentration was 58–684 MP m−3 (median 212 MP m−3).•Only 57.6% of the 1–5 μm MP was filtered out by the surgical facemask.•Estimated MP intake: 3415 MPs day−1 (283 MPs day−1 with facemask).