In Lower Normandy and Upper Normandy, the number of reported cases of CO poisoning decreased between 2013 and 2014 (Lower Normandy: n=28 in 2013, n=14 in 2014, Upper Normandy: n=30 in 2013, n=23 in 2014). The number of people poisoned also decreased in both regions between 2013 and 2014 (Lower Normandy: n=68 in 2013, n=30 in 2014, Upper Normandy: n=63 in 2013, n=53 in 2014). In Lower Normandy, the proportion of people hospitalized or referred to a hyperbaric chamber among poisoning cases remained stable between 2013 and 2014. In Upper Normandy, the proportion of people hospitalized among poisoning cases decreased (40% in 2013 versus 31% in 2014). The proportion of people referred to a hyperbaric chamber, however, increased (6% in 2013 versus 26% in 2014).In 2014, as in 2013, the majority of cases occurred in the home, whether in Lower Normandy or Upper Normandy (71% and 91%, respectively, for 2014).In 2014, the primary source of poisoning was a boiler/water heater system in both Lower Normandy and Upper Normandy (75% and 50%, respectively). The same observation was reported in 2013. However, regional differences in terms of fuel were noted. In Lower Normandy, the fuels most commonly used in 2014 to operate boilers and water heaters were heating oil (44%) and city gas (44%). In Upper Normandy, it was city gas (88%).Considering all connected appliances (boiler/water heater, open fireplace, closed fireplace/insert, wood stove/radiator), the most commonly used fuel in Lower Normandy after heating oil (33%) and city gas (33%) was wood (25%). The use of a wood-burning stove/heater or an open wood-burning fireplace is a characteristic observed in rural areas. In Upper Normandy, wood (28%) was the most commonly used fuel after city gas (61%) for operating connected appliances.In 2014, considering all identified sources of poisoning (connected and unconnected appliances), the factors contributing to poisoning were primarily inadequate ventilation or poor airflow. For unconnected appliances, these factors included inadequate ventilation and improper use of the appliance. The same observations were reported in 2013.