Global concern over air pollution and particulate matter (PM) is growing. PM2.5 particles less than 2.5 micrometers pose particular health risks. Infrared (IR) imaging can augment standard gravimetric methods used to measure airborne PM2.5. An IR imaging study of PM2.5 samples collected in Seoul, Beijing, and Tokyo found higher overall PM2.5 in Beijing. The IR images also showed differences in chemical composition between sites, indicating no significant cross-border air pollution between areas, especially into Tokyo. IR imaging provides both qualitative identification and quantitative analysis of PM2.5 components in only 5 minutes, faster than alternative methods.