Abundances, Characteristics, and Health Risk Assessment of Airborne Microplastics in the Urban Area: A Case Study of Kuala Lumpur, Malaysia

Atmospheric microplastics (MPs) have been attracting attention mainly due to its potential adverse effect on human health resulting from inhalation. This study aims to determine the concentration of MPs in total suspended particles (TSP) and fine particulate matter (PM_2.5) in the ambient air of urban environment of Kuala Lumpur. The concentration and characteristics of MPs collected during different monsoon seasons (Northeast, Intermonsoon, and Southwest) were also determined. A high-volume air sampler was used to collect samples from December 2022 to July 2023. MPs were analyzed for size, shape, and color using a stereo microscope, and their polymer composition was determined using pyrolysis-GC/MS. Health risk assessments were conducted based on established formulas from the World Health Organization (WHO) and the United States Environmental Protection Agency (US EPA). Results showed significantly higher MP concentrations (p<0.05) in TSP compared to PM_2.5 across all seasons, with the highest concentrations (TSP = 13.14 ± 7.57 particles/m³, PM_2.5 = 0.54 ± 0.37 particles/m³) during the Northeast Monsoon. The size of MPs in TSP and PM_2.5 was mostly concentrated in the 0.1 – 0.5 mm group. Most of the MPs in the urban environment are fibre-shaped (PM_2.5: 58.40 ± 10.45%; TSP: 56.07 ± 5.72%) and transparent particles were the most abundant colour found in this area (PM_2.5: 67.27%; TSP: 60.87%). Polymer analysis revealed polyvinyl chloride (PVC) as the most prevalent polymer. HYSPLIT trajectory analysis indicated long-range transport during the Northeast and Intermonsoon periods, while the Southwest Monsoon showed more localized sources. Health risk assessment showed a decreasing exposure to airborne MPs in the following order: adults and adolescents > children > toddlers > infants. This study highlights the seasonal variation of atmospheric MPs in an urban environment and the importance of considering both particle size fractions and meteorological conditions for a comprehensive understanding of MP pollution. The co-occurrence of MPs with PM_2.5 raises significant concerns about potential human health risks. Further research and continuous monitoring are needed to fully understand the long-term implications of inhaling MPs, particularly in densely populated regions.