Investigation of indoor microplastics in settled indoor house dust in single‐person residential buildings in Japan

Microplastics, defined as plastic particles smaller than 5 mm, are widely spread in aquatic, terrestrial, and atmospheric environments, which is a marked environmental concern. However, research on indoor microplastic pollution remains limited, particularly in Japan. Therefore, the aim of this study was to investigate the shape and composition of microplastics in house dust from single‐person households in four regions of Japan, including Tohoku, Kanto, Chubu, and Kansai. Micro‐Fourier‐transform infrared spectroscopy, a technique that combines infrared spectroscopy with optical microscopy was used, allowing a detailed analysis by obtaining the specific interference patterns and absorption spectra of the materials. The influence of building structure, flooring, and wall materials on microplastic composition in indoor environments was also investigated. This study addresses crucial knowledge gaps regarding the extent, forms, and sources of indoor microplastics. These findings contribute to the development of targeted measures to mitigate indoor microplastic exposure, support efforts to improve indoor air quality, and protect public health.