Transboundary pollution is a recognized problem in Southeast Asia, with pollution sources including rapid economic growth, industrialization, an increase in the global demand of natural resources, and biomass burning. Transboundary pollution was investigated for Lao People’s Democratic Republic, the only landlocked country in Southeast Asia. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was adopted to evaluate the pollution trajectory from potential sources for the provinces of Bokeo (hotspot for aerosol optical depth [AOD] levels at provincial level during study period) and Saravane (hotspot for ultraviolet aerosol index [UVAI] values during rainy season during study period) in the north and south, respectively.