We investigated element composition ratios in two sets of sequentially collected airborne particulate matter (PM) samples obtained through the automatic sampler of the Atmospheric Environmental Regional Observation System (AEROS). A series of micro-PIXE analyses and imaging were performed on a PTFE (Polytetrafluoroethylene) membrane tape filter corresponding to two hourly time slots through a high-concentration air pollution event from 26th to 27th March 2020 sampled at Ota, Japan (36.290° N, 139.381° E) by utilizing an external 3 MeV proton microprobe. Latent variables of sequentially collected PM samples were analyzed by the non-linear least square method and classified by those clustering driven by house-made data analysis software. Micro-PIXE imaging effectively confirmed the presence of large elemental agglomerations on the PTFE membrane tape filter of AEROS that often appeared as outliners in data analysis.