Atmospheric deposition of anthropogenic microfibers in different indoor environments of Chennai, India

Microplastics, particularly microplastic fibers, are one of the emerging pollutants of concern. However, recent studies emphasized the predominance of artificial and natural microfibers over microplastic fibers. Despite this, research focusing on all types of microfibers, commonly grouped as anthropogenic microfibers (MFs) remains limited, especially in residential indoor environments. Therefore, this study explored the indoor MFs deposition in the residential homes of Chennai, India, a first such study in the country. Additionally, workplaces, including offices, laboratories, and hostel rooms, were examined. Bedrooms (16,736 ± 7,263 MF/m²/day) and student hostels (5,572 ± 2,898 MF/m²/day) recorded highest contamination in respective categories, and this could be attributed to the abundance of textile products in both the rooms. MFs<500 μm dominated in both residential (78.8 %) and workplace (65.9 %) samples. The observed diameter of MFs (2.02–36.4 μm) indicate their potential to penetrate human lungs. μ-FTIR analysis revealed the distribution of semi-synthetic (48.2 %), natural (29.3 %) and synthetic (22.5 %) MFs, underscoring the need to consider all categories of MFs. Further classification revealed textiles (rayon - 94.5 ± 6.40 %, cotton - 68.1 ± 6.12 %, and polyethylene terephthalate (PET) - 48.1 ± 11.5 %) as a significant source of contamination. The detection of black rubber/latex MFs indicates additional contributions from road dust. Surface morphological analysis further highlighted the primary role of indoor/local sources in MFs contamination. Overall, the study emphasizes the need to monitor all categories of MFs and calls for comprehensive investigations into the impact of various sources on indoor MFs contamination.