Carbon Monoxide Poisoning in Limousin Carbon monoxide (CO) is an invisible, odorless, and non-irritating gas produced by the incomplete combustion of carbon-containing materials, most often due to poor ventilation combined with malfunctioning heating or hot water systems, or the improper use of internal combustion engines. Inhalation of CO, followed by its entry into the bloodstream, blocks the transport of oxygen to the tissues, which can lead to death within minutes. The fight against CO poisoning became a priority in 2004 under the National Health and Environment Plan and the Public Health Act, leading to strengthened prevention and regulation, as well as the establishment in 2005 of a surveillance system coordinated by the French Institute for Public Health Surveillance (InVS). The objectives of the surveillance system are: - to prevent poisoning and recurrence through risk management, particularly in the home; - to monitor, at the national and local levels, trends in the incidence of poisoning, describe the characteristics of victims, and analyze the circumstances and etiological factors of poisoning in order to develop prevention measures. Therefore, any suspected or confirmed CO poisoning—whether accidental or intentional—occurring at home, in a public access building (ERP), in the workplace, or related to the use of a combustion engine must be reported to the focal point of the Regional Health Agency (ARS). The ARS or municipal health and hygiene services are then responsible for investigating the incident and implementing corrective and preventive measures. The InVS is responsible for the epidemiological analysis of the collected data. In 2013, 14 cases of CO poisoning were reported and selected for epidemiological analysis in Limousin. According to information gathered during reporting, 32 people were involved in these incidents. One person died. In 86% of the incidents, the poisoning occurred in the victims’ homes, and the appliance involved was most often a boiler. While CO poisoning can be serious, preventing it is simple. Prevention relies in particular on the maintenance of combustion-based heating and hot water appliances by a qualified professional, on ventilating the home, and on the proper use of combustion appliances.