Airborne infectious diseases remain a major global health threat. The primary vector for their transmission is coarse and fine droplets, known as bioaerosols, exhaled from infected individuals during natural respiratory maneuvers, such as breathing, coughing and sneezing. Unfortunately, our current knowledge of the mechanisms by which these exhaled bioaerosols are formed in the lungs is in its infancy. In particular, progress in this field has been hindered by the complex structure of the respiratory fluid and the resulting lack of understanding of the biophysical properties of the fluid. 2011 All Rights Reserved Graduate College ii To my beloved parents, Azzam Hamed and Bahia Nazer, and my brothers, Raed, Rami and Fadi for their continuous support and patience iii ACKNOWLEDGMENTS I would like to thank my advisor Dr. Jennifer Fiegel for her unconditional support and help from the initial to the final level. This work would not have been possible without her. I have gained tremendous knowledge and experience from interacting with her and being part of her research group. I also would like to thank my committee members, Drs. ) for their help, fun time and scientific discussions. I have learned a lot from the intellectual exchanges and laboratory meetings we had, in addition to the interesting conversations about life and science. I am also greatly thankful for the undergraduate students, Laura Northrup, Alexander Benson and Kyle Merrill, who helped me in this work and gave me the opportunity to guide them. In addition, I would like to thank my colleague Mohammed Saleh who helped me in analyzing the results of the bioaerosol study. His effort is appreciated. I express my love and heartfelt gratitude to my parents, despite being thousands of miles away; their love, understanding, patience and support were essential throughout this challenging process. I am heartily thankful to my brothers Raed, Rami and Fadi who supported me, believed in me and provided me with strength throughout these years. Finally, I would like to show my gratitude to all my friends with whom I shared an enjoyable time during these years. iv ABSTRACT Airborne infectious diseases remain a major global health threat. The primary vector for their transmission is coarse and fine droplets, known as bioaerosols, exhaled from infected individuals during natural respiratory maneuvers, such as breathing, coughing and sneezing. Unfortunately, our current knowledge of the mechanisms bywhich these exhaled bioaerosols are formed in the lungs is in its infancy. In particular, progress in this field has been hindered by the complex structure of the respiratory fluid and the resulting lack of understanding of the biophysical properties of the fluid.