The toxicology of particles is an absorbing area of research in which to work and when we conceived this book, we wanted to capture some of the fascination that we feel about our profession. We are well-pleased with the result—everyone we invited to write a chapter agreed and almost everyone delivered a manuscript—a remarkable outcome in this time of conflicting deadlines. It is difficult to keep up with the sheer quantity of data that accumulates on particle toxicology. This has resulted in pol