Assessing airborne microplastics in urban indoor environments using PM2.5 air exchange rate and polymer characterization for respiratory health risk evaluation

Sivasankari  Sivalingam; Nithya  Sivasamy; Meenachi  Loganathan; Anand  Rajendran; Shivashankar  Ravikumar; Venkatesh  Narayanan

doi:10.18502/japh.v11i2.21874

Sivasankari Sivalingam Department of Information Technology, Erode Sengunthar Engineering College, Tamilnadu, India
Nithya Sivasamy Department of Artificial Intelligence and Data Science, Dr Mahalingam College of Engineering and Technology, Tamilandu, India
Meenachi Loganathan Department of Information Technology, Dr Mahalingam College of Engineering and Technology, Tamilandu, India
Anand Rajendran Department of Aeronautical Engineering, Nehru Institute of Technology, Tamilnadu, India
Shivashankar Ravikumar Department of Mechanical Engineering, Sree Sakthi Engineering College, Tamilnadu, India
Venkatesh Narayanan Department of Aerospace Engineering, SNS College of Technology, Tamilnadu, India

DOI: https://doi.org/10.18502/japh.v11i2.21874

Keywords: Microplastics; Polymer; Fourier transform infrared spectroscopy (FTIR); Scanning electron microscopy (SEM); Sampling; Ventilation; Particulate matter (PM2.5)

Abstract

Introduction: Airborne microplastics have recently emerged as indoor air pollutants in urban environments due to extensive use of synthetic textiles, furnishings, and plastic-based materials. Continuous inhalation exposure may pose respiratory health risks, particularly in densely occupied spaces with poor ventilation. This study quantifies airborne microplastic concentrations in urban indoor environments and evaluates mitigation strategies based on ventilation improvement and material management.

Materials and methods: Air sampling was conducted in residential rooms, classrooms, and office spaces using low-volume active air samplers fitted with quartz microfiber filters (flow rate 16.7 L/min; duration 8 h). Microplastics were identified and counted using optical microscopy, while polymer types were confirmed through Fourier Transform Infra-Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) analysis. Environmental parameters including PM2.5 concentration, Air Exchange Rate (AER), relative humidity, temperature, and occupancy density were simultaneously recorded. Respiratory exposure risk was estimated using inhalation dose and Hazard Quotient (HQ) calculations.

Results: Microplastics were detected in all indoor environments, with mean concentrations of 600 particles/m3 in residences, 1050 in offices, and 1180 in classrooms. Fibers dominated (68%), mainly polyester and polypropylene. Higher concentrations were associated with low ventilation (AER 0.4 h−1), high occupancy density (0.85 persons/m2), and elevated PM2.5 levels (>45 μg/m3). Estimated inhalation exposure ranged from 2.1 to 3.8 particles/kg/day, and HQ exceeded the safe threshold (1.32) in poorly ventilated classrooms. Increasing AER to 1.2 h−1 reduced concentrations by 39%, replacing synthetic textiles lowered fiber proportion to 41%, and reducing occupancy to 0.55 persons/m2 decreased inhalation dose to 2.1 particles/kg/day and HQ to 0.78.

Conclusion: Airborne microplastics are prevalent in indoor environments and may contribute to respiratory health risks, especially under low ventilation and occupancy. Enhancing ventilation, indoor materials, and occupancy reduce concentrations and risks, underscoring importance of indoor air management strategies.