The dawn of a new air pollutant: inhalable microplastics as emerging vectors of hazardous contaminants and their implications for human health.

This study presents the first comprehensive research on inhalable microplastics (iMPs, <10 μm), a notorious subset of airborne microplastics (AMPs). To identify human health risk, ambient iMPs concentrations were assessed at human breathing height across the markets of four major Indian cities. With winter evening being the highest iMPs concentration, in Kolkata (14.23 µg/m3), followed by Delhi (14.18 µg/m3), linked to the highest footfalls, use of synthetic clothing, and poor waste management. Coastal cities (Chennai: 4 µg/m3, and Mumbai: 2.65 µg/m3) showed lower levels, likely due to improved air circulation, less winter, and reduced apparel, confirmed by Principal Component Analysis. Py-GC-MS quantified 11 polymers, with PET (Polyester) from textiles as the most abundant, followed by PE and SBR from single-use plastics, packaging, vehicles, and footwear. Urban areas in India show an average iMPs concentration of 8.8 µg/m3, translating to a lifetime lung load of ∼2.9 g/person. Furthermore, this investigation highlights the risks of iMPs-associated tracers such as diethyl phthalates and lead. This pioneering research is the first-ever study to explore AMPs carrier capabilities for ultrafine particulate matter, PTEs, POPs, PPCPs, and microbes. During peak exposure periods like autumn festivals, AMPs harbored diverse microbial communities, including pathogenic (Aspergillus fumigatus) and new strains of bacteria/fungi with antibiotic resistance and virulence factor genes. This suggests that microbes carried by iMPs possess enhanced pathogenicity and resistance against broad-spectrum drugs like tetracycline and are more likely to be multidrug-resistant. Cross-referencing toxicological databases revealed that exposure to AMPs-linked modern-day contaminants elevates the risk of cancer, gastrointestinal, endocrine, breast, and respiratory diseases.