The purpose of the WHO Manual for the Public Health Management of Chemical Incidents is to provide a comprehensive overview of the principles and roles of public health in the management of chemical incidents and emergencies. While this information is provided for each phase of the emergency cycle, including prevention, planning and preparedness, detection and alert, response and recovery, it is recognized that the management of chemical incidents and emergencies requires a multi-disciplinary and multi-sectoral approach and that the health sector may play an influencing, complementary or a leadership role at various stages of the management process. The target audience includes public health and environmental professionals, as well as any other person involved in the management of chemical incidents. WHO and all those involved in the development of the publication hope that the publication will have wide application, especially in developing countries and countries with economies in transition, and that in the future the health sector will be better prepared to acknowledge and fulfill its roles and responsibilities in the management of chemical incidents and emergencies, thereby contributing to the prevention and mitigation of their health consequences. The publication is also available in French: http://apps.who.int/iris/bitstream/handle/10665/246117/9789242598148-fre.pdf?sequence=1 and in Spanish: http://apps.who.int/iris/bitstream/handle/10665/246118/9789243598147-spa.pdf?sequence=1