Indoor Microplastics: A Comprehensive Review and Bibliometric Analysis

Abstract The global scale of concern regarding indoor microplastic (MP) pollution is increasing and considering the amount of time people spend indoors. Indoor MP contamination can directly affect the human population through indoor dust and air exposure. This review summarized recent research progress on pretreatments, quality control, filter membranes, identification, keywords used, publication record, and authors' contribution. Comparatively, dust and deposition samples exhibit higher MPs concentrations than indoor air samples. Fiber-shaped MPs are commonly detected indoors, although fragments and films are also present. The color and types of MPs display variability, with polypropylene, polyethylene, polyethylene terephthalate, and polystyrene identified as the dominant MPs. Indoor environments generally demonstrate higher concentrations of MPs than outdoor environments, and MPs in the lower size range (1–100 µm) are typically more abundant. Among the reviewed articles, 45.24% conducted pretreatment on their samples, while 16.67% did not undergo any pretreatment. The predominant filter utilized in most studies was the Whatman Glass microfiber filter (41.67%), and MPs were predominantly characterized using µ-FTIR (19.23%). Within the examined literature, 17 articles incorporated blank samples into their research, while 8 articles did not include blank samples. Notably, most studies (23) did not integrate blank results into their samples. A significant increase in published articles has been observed since 2020, with an annual growth rate exceeding 10%. Bibliometric analysis of the literature review identified 35 authors who have contributed relevant material on indoor MPs. The keyword microplastics had the highest frequency, followed by fibers.