Microplastics in indoor dust at Dhaka city: unveiling the unseen contaminants within our homes

Indoor environments, considered sanctuaries from external pollutants, are increasingly recognized as reservoirs for microplastics (MP). This research employed a comprehensive approach, combining dust sampling from diverse indoor spaces, density separation method, and microscopic observation to quantify and characterize microplastic particles. This is the first initial study worldwide that incorporated MP identification in indoor dust from different indoor environments along with factor analysis, health, and ecological risk assessment. The average MP concentration in the indoor environment was 4333.18 ± 353.85 MP/g. The MP distribution pattern was in institutional areas < residential areas < industrial areas < and commercial areas. Black color, fiber, <0.5 mm size was the dominant color, morphology, and size, respectively, among the detected MP from the studied samples. In addition, the polymer types of the MP were detected by Fourier Transform-Infrared (FT-IR) spectroscopy, and ten types of polymers were detected while PET was in high abundance. Population number, architectural features of habitat, human activities, urban topography, and particle residence time were determined as responsible factors for MP abundance in indoor areas. The estimated daily intake (EDI) value via ingestion was higher than the inhalation of MP. Infants are highly susceptible to MP exposures. According to Polymer Hazard Index (PLI) and Polymer Hazard Index (PHI) values, the exposure risk was in the minor and extreme risk categories.