Airborne particles when inhaled, can lead to pathological changes in the respiratory tract. Therefore, toxicological studies on the effects of inhalable fibers and particles involve an assessment of the histopathological alterations in the trachea, lungs and the upper respiratory tract. The pathology of particle and fibre toxicology depends on the exposure source, duration, concentration and individual predisposition. Particles such as combustion-derived particles, engineered nanoparticles, ultrafine particles, silica, asbestos, etc. can induce an inflammatory response. There may be long term effects of chronic particle exposure, such as allergic airway inflammation, chronic obstructive pulmonary disease, fibrosis or neoplasms. The extent of tissue damage and pulmonary inflammation can be addressed and studied via pulmonary histopathology as well as diverse histopathological inflammatory parameters. This book unfolds the innovative aspects of particle and fibre toxicology which will be crucial for the progress of this field in the future. It will also provide interesting topics for research which interested readers can take up. It attempts to assist those with a goal of delving into toxicology.