Morphological and chemical analysis of indoor airborne microplastics: implications for human health in Ahvaz, Iran.

Airborne microplastics (AMPs) present significant health risks indoors due to prolonged exposure. This study evaluates AMP concentration, types, and health impacts in residential, office, and commercial settings in Ahvaz, Iran, during winter and summer. The annual inhaled AMP dose was calculated based on typical occupancy patterns. AMP particles were collected from 30 locations using active sampling at 5 L/min for 8 h. Raman spectroscopy identified polymers, and SEM-EDX analysis examined surface morphology and elemental composition. The inhaled dose was estimated using MP concentrations and typical indoor exposure times. The highest AMP concentrations were in offices during winter (up to 48 MPs/m³), moderate in residential areas, and lowest in commercial settings. Predominant AMPs were spherules (67.2% in winter, 69.3% in summer), with black/gray particles being most common. Smaller particles (< 250 µm) were more frequent in summer. Identified polymers included polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The estimated annual inhaled AMP dose was 2,952 MPs/kg/year, mainly from residential, followed by offices and commercial spaces. Results underscore the need for policies to reduce indoor AMP pollution, improve ventilation, and manage exposure risks, especially in high-occupancy areas like offices. Future research should focus on advanced chemical analyses and size-specific dose assessments to better evaluate health risks from inhaled microplastics.