 More common than we think, the Dodge Safety Board suspects that the real number of victims is three to five times as large as assumed. The image of old and poorly maintained appliances as the main source should also be adjusted. In nearly half the cases examined, carbon monoxide poisoning was caused by a modern central heating system. These appliances were usually periodically maintained by an installer. Why are there still hundreds of carbon monoxide poisoning victims each year in the Netherlands? Why has the increased knowledge and the modernization of heating appliances not led to the elimination of carbon monoxide accidents? To answer these questions, in the evening of January 5th, 2012, the police received a report that three girls of 10, 11 and 12 years old had locked themselves in the bathroom of the home of one of them and did not respond. After the bathroom door was forced, two girls were found drowned in the bath. The third girl was taken to hospital in critical condition after carbon monoxide poisoning. Two other inhabitants in the house were also injured. In the utility room on the ground floor, a central heating boiler and gas water heater were placed. These appliances were inspected and maintained three months before the accident. The stormy wind that night disturbed the flow of fumes from the burning heater. Because the flu duct was placed incorrectly, the wind pushed the fumes back. As a result, air recirculated in and around the heater. Recirculation is a common cause of carbon monoxide. The pantry filled with toxic gas. The pantry was connected to the bathroom with a laundry chute. The ventilator in the bathroom sucked up the toxic fumes with the fatal outcome as a result. An accident with carbon monoxide is always a two-stage event. First, the appliance should produce a high concentration of carbon monoxide. This is usually the result of incomplete combustion with too little oxygen or recirculation. Then the resulting carbon monoxide has to be released in a confined space. That does not necessarily have to be the same house as in which the carbon monoxide formed, as is evident from the following occurrence. On December the 25th, 2010, two young people deceased from carbon monoxide poisoning in this flat. The building was recently renovated. The central heating system on the ground floor was new but incorrectly adjusted. Therefore, it produced a large amount of carbon monoxide. It turned out that the flu duct was not properly installed, causing the carbon monoxide to be released through a shaft and ceiling into the upper apartments. Also in the adjacent apartment there was a lethal concentration of carbon monoxide present, but luckily the residents were not at home. This accident demonstrates that even a new installation installed by a certified company can be deadly if the two aforementioned conditions are met. The appliance produces a lot of carbon monoxide and it is subsequently released into a home. The Dutch Safety Board concludes that in nearly half of all cases examined, a central heating boiler is the source of carbon monoxide poisoning. Gas water heaters are responsible for less than a third of the accidents. What is also striking is that these appliances were in most cases recently purchased or periodically serviced by a professional installer with a quality certification. Residents and owners cannot always trust a certified installer to deliver craftsmanship. When the wind pushed the exhaust gases back inside the heater, it did not switch off. The exhaust in the flat was not properly installed, but it went unnoticed. Moreover, the system of heating is not foolproof. The boiler in the flat produced much carbon monoxide because it was incorrectly adjusted, but it continued to function. Carbon monoxide is an extremely poisonous and odourless, tasteless and invisible gas. That means that poisoning often goes unnoticed. The first signs of poisoning appear relatively harmless, but it can cause permanent damage to health or worse. On January 21, 2013, the manager of a holiday park found an elderly permanent resident had died in his home. A doctor and the police observed a natural death. A son of the man came to the house because of the death of his father and remained there overnight. The next day revealed he deceased as well. The officers had been suffering from headaches the evening before but did not link it to carbon monoxide. The fire brigade used measuring equipment to find a lethal dose of carbon monoxide. The central heating boiler caused the poisoning. It was installed three months earlier. The park uses propane for heating, but the appliance was not adjusted accordingly. In addition, the flu duct was installed incorrectly, so it leaked carbon monoxide in the house. After this accident, other heating installations that were placed by the same installer were investigated. Several appliances were found to produce too much carbon monoxide. In this accident, it took a long time for the carbon monoxide poisoning to be recognized. Various people had been exposed to high concentrations. A carbon monoxide detector could possibly have saved lives. These detectors are sold everywhere, for example in hardware stores and household shops. The reliability, however, leaves much to be desired. In a recent study, 10 out of 25 devices failed on one or more disciplines. A properly functioning detector, however, is often the first and only warning of the presence of carbon monoxide. The Dutch Safety Board concludes that residents and house owners generally take their responsibility. They tend to replace their old equipment timely for new and have them serviced regularly by a professional. In addition, installers have the key to safer installations. Professional maintenance work should therefore not be limited to the appliance itself, but executed in conjunction with the building system. Manufacturers are responsible for making installations failsafe and foolproof. The government should set a uniform statutory accrediting scheme for installers. This must prove craftsmanship and safety and thus add to the...