Determination of hygroscopic growth of aerosol particles under physiologically relevant conditions

• Hygroscopic growth of liquid particles generated by consumer products was evaluated • Measurements were performed using a humidified mouth-trachea mechanistic model • Hygroscopic growth was mainly influenced by the main components PG, VG, and nicotine • Trace amounts of flavorings and/or acids in liquids did not change particle growth • Hygroscopic growth could increase particle deposition in the lower airways Particle size is a key parameter determining the deposition region in the human airways. We evaluated the hygroscopic growth of liquid particles generated by consumer products while they are transported from ambient conditions to the human respiratory system with high relative humidity. The measurements were performed using a humidified mouth-trachea mechanistic model. The results showed that the hygroscopic growth of the particles was mainly influenced by the content of the main liquid components (propylene glycol, vegetable glycerol, and nicotine). In contrast, the trace amounts of flavorings and/or acids in the liquids did not change particle growth. Growth factors increased with increasing residence time and relative humidity. The results for the liquid particles generated by the test consumer products indicate that particle growth in the human respiratory system could increase their deposition in the lower airways.