Real-time concentrations of particulate matter 2.5 μm in diameter or smaller (PM2.5) inside of a 0.5 m3 chamber generated from Experiment 1 (A), Experiment 2 (B), Experiment 3 (C), and Experiment 4 (D). Arrows indicate the times when the JUUL pod was removed and reinserted during each 10-puff bout. For Experiment 1, the pod was inserted into the JUUL device before the first puff and all 10 puffs were generated from the device. For Experiment 2, the pod was also removed and reinserted between puffs five and six. For Experiment 3, the pod was removed and reinserted after puffs two, four, six, and eight. For Experiment 4, the pod was removed and reinserted after every puff.