Environmental pollution by microplastics is recognized as a global issue, Although previous studies have focused primarily on marine environments, increasing evidence indicates that microplastic particles are also present in the atmosphere and may circulate widely through atmospheric transport, In this study, we developed an analytical method for airborne microplastics by optimizing pretreatment procedures and applying micro-Fourier transform infrared attenuated total reflectance imaging (µFTIR-ATR imaging), This approach enabled the identification and quantification of microplastic particles down to the ca, 2 µm scale, which had been difficult to detect conventionally, A key feature of this method is its ability to integrate polymer identification, particle size and shape characterization, and surface degradation assessment, The method was applied to diverse environmental samples, including aerodynamic size-segregated atmospheric aerosols, cloud water, rainwater, snow, wild bird lung tissue, plant leaf surfaces, forest soil, seawater, and freshwater, These applications revealed that sub-100 µm environmental microplastics are widely distributed across various media, including the atmosphere, This technique provides a fundamental analytical platform for understanding the sources, transport, transformation, deposition, inhalation exposure, climate effects, and ecological risks of airborne microplastics, It also represents an important step toward the standardization of observation methods and the establishment of long-term monitoring networks,