Analysis of the correlation between particulate matter and microplastics according to particle size

Indoor air quality (IAQ) is a critical determinant of occupants' health and comfort, as has become a fundamental factor influencing health and comfort. While particulate matter (PM) is a well-established IAQ metric, often monitored in real-time, airborne microplastics (MP) are an emerging pollutant of concern. The quantification of MPs is significantly more complex, requiring time-intensive, filter-based sampling followed by offline spectroscopic analysis for particle identification. This procedural complexity prevents real-time exposure assessment. Therefore, this study investigates the correlation between PM and MP concentrations to establish a basis for estimating real-time MP exposure using readily available PM data. The concentrations and correlations of particulate matter (PM) and microplastics (MP) were analyzed according to indoor space usage and occupant presence in a residential building. Airborne particles were actively collected in a living room, bedroom, and kitchen, classified into PMio and PM2.5 size fractions, and analyzed using p-Raman spectroscopy. The results showed that when occupants were present, particulate matter and microplastics smaller than 10 p m exhibited similar spatial variation trends; however, the dominant influencing factors differed. Microplastic concentrations were relatively high in the living room and bedroom, where fibrous and plastic products were abundant. In contrast, although PM concentrations were elevated in the kitchen due to cooking activities, microplastic concentrations were low, and microplastics smaller than 2.5 pm were not detected. When occupants were absent, overall concentrations of both particulate matter and microplastics decreased, and microplastics smaller than 2.5 pm were detected only in the living room. These findings indicate that while microplastics partially follow trends similar to particulate matter in indoor environments, they are more sensitive to occupant activity and the distribution of plastic products.