Movie S1.

The deposition process of inhaled PM2.5 particles in target area of alveolar region. The time interval of each frame in the video is 30 seconds. The left part of video includes both green and red channels to present the fluorescent particles and the tissue structure of target alveolar region. The fluorescent particles in this part are shown as yellow dots. The right part of video includes only red channel. The fluorescent particles are shown as red dots and used for particle counting.