This study presents a novel and efficient method for analyzing inhalable airborne microplastics (AMPs) in ambient PM 10 aerosols. Although many studies have been conducted on MPs in a variety of environments, the physicochemical characteristics of AMPs of inhalable size (<10 μm) in ambient PM 10 are poorly understood because of the lack of suitable analytical methods. The method employed in this study combines fluorescence microscopy, Raman microspectrometry (RMS), and scanning electron microscopy/energy-dispersive X-ray spectrometry (SEM/EDX) for an efficient and reliable investigation of inhalable AMPs, which constitute a small portion of ambient PM 10 aerosol particles. Fluorescence microscopy and staining are used to select particles with high MP potential from ambient urban PM 10 aerosols. The combination of RMS and SEM/EDX then allows for a detailed characterization of these particles on a single-particle basis. The results of the study show that ∼0.008% of the particles collected using a PM 10 sampler had high MP potential, corresponding to ∼800 particles/m 3 . Among the stained particles of <10 μm, 27% were determined to be plastic, while the remaining 73% were found to be from tire/road wear. The number of inhalable AMPs was estimated to be 192 (±127) particles/m 3 . This study provides an important insight into the characteristics of inhalable AMPs in ambient PM 10 aerosols that are particularly critical in respect of human health and climate change. The authors highlight that the use of a single fluorescence staining method can overestimate the number of inhalable AMPs in ambient air by including tire/road wear particles. To the best of their knowledge, this is the first study to demonstrate the morphological and spectroscopic characteristics of the same individual inhalable AMPs.

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In this work, two single particle analytical techniques such as a quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-Z particle EPMA, and attenuated total reflectance Fourier transform-Infrared (ATR-FTIR) imaging were applied in combination for the characterization and distinction of six standard asbestos and one non-asbestos Mg-silicate minerals of micrometer size. Asbestos fibers have been reported as a natural carcinogen which causes some serious illness like mesothelioma, asbestosis, and lung cancer. Atmospheric aerosols are heterogeneous mixtures and airborne asbestos fibers would be present due to their extensive industrial uses for various purposes. The fibers could also be airborne from natural and anthropogenic sources. As different asbestos fibers have different carcinogenic properties, it is important to determine different types of individual asbestos and non-asbestos Mg-silicate mineral particles and their sources for the public health management. In our previous works, the speciation of individual aerosol particles was performed by the combined use of the two single-particle analytical techniques, which demonstrated that the combined use of the two analytical techniques is powerful for detailed characterization of externally heterogeneous aerosol particle samples and has great potential for characterization of atmospheric aerosols. In this work, it is demonstrated that the identification and differentiation of asbestiform and non-asbestiform Mg-silicate mineral particles is clearly performed using the two single particle analytical techniques in combination than using either technique individually. Especially, anthophyllite and talc can be differentiated using this analytical approach, which has not been easy up until now.