Characteristics and influencing factors of airborne microplastics in nail salons

Airborne microplastic particles (MPs) are emerging contaminants. Although some studies have investigated the characteristics of indoor MPs in homes or offices, information regarding MPs in nail salons with potentially higher MP pollution is unavailable. In this study, we collected indoor and outdoor air samples from nail salons to analyze the concentrations, physical characteristics, and polymers of MPs and further assessed the exposure through inhalation and influencing factors. Our data displayed that the average indoor MP concentration was 46 ± 55 MPs/m3. The estimated average annual exposure to indoor MPs was 67,567 ± 81,782 MPs/year. The predominant shape and size of indoor MPs were fragment and <50 μm, respectively. The predominant polymer in indoor air was acrylic (27%), followed by rubber (21%), and polyurethane (13%). Air conditioner, nail treatment, ceiling and flooring with plastic materials, and number of occupants were factors affecting indoor MP concentrations. We concluded that MP pollution was more severe in nail salons and the physical characteristics and polymer compositions differed between nail salons and other indoor spaces reported in other studies. Air conditioner usage induced higher MP emission, and higher MP concentrations were observed in nail salons with plastic ceiling and flooring or more occupants.