This book evaluates methodologies in epidemiologic and related studies for obtaining measurements of exposure to environmental tobacco smoke (ETS). The book is divided into three parts. The first part discusses physicochemical and toxicological studies of environmental tobacco smoke, including physicochemical nature of smoke and in vivo and in vitro assays of smoke. The second part discusses assessing exposures to environmental tobacco smoke, focusing on the external environment, questionnaires, exposure-dose relationship, and biological markers. The third part discusses possible health effects associated with exposure to ETS. These effects include the following: (1) sensory reactions; (2) lung function and respiratory symptoms; (3) lung cancer; (4) cancers other than lung; (5) cardiovascular system; and (6) special considerations in children. Appendixes discuss guidelines for public and occupational chemical exposures to materials that are also found in ETS, a method of combining data from studies of ETS exposure and lung cancer, adjustments to epidemiological estimates of excess lung cancer in persons exposed to ETS, and risk assessment for exposure to ETS and lung cancer. (ABL)