A huge effort is put into the science of nanoparticles and their production. In many cases it is unavoidable that nanoparticles are released into the environment, either during the production processes or during the use of a product made from these particles. It is also realized that combustion processes like traffic and power plants release nanoparticles into the atmosphere. However it is not known how nanoparticles interact with the human body, especially upon inhalation. At the same time research activities are devoted to understand how nano-sized medicine particles can be used to administer medicines via inhalation. In any case it is absolutely necessary to know how the nanoparticles interfere with the inhalation system, how they deposit and affect on the human system. Three main themes are discussed: Nanoparticle sources and production Nanoparticle inhalation and deposition Toxicological and medical consequences of nanoparticles Each theme is covered comprehensively, starting at nano-quantum effects up to technical and medical applications such as measuring equipment and inhalation instrumentation. This book brings together all sub-disciplines in the field related to aerosol nanoparticles. Each chapter is written by a world expert, giving the state of the art information and challenging open questions. The last chapter summarizes in an interdisciplinary way what is already known and what still is ahead of us.