Carbon Monoxide poisoning Carbon Monoxide (CO) is a toxic gas that is odourless and colourless, meaning that is almost impossible to identify without a proper detector. According to the Department of Health, carbon monoxide poisoning in the home causes approximately 50 deaths a year in the UK, and up to 4,000 medical visits. Carbon monoxide is produced when fuel is not burnt properly, so appliances such as boilers, gas fires and cookers, can be high risk within the home. It is therefore strongly recommended to get these fuel-burning appliances checked regularly by a registered engineer, and have a CO alarm placed close by. Unfortunately, cases of CO poisoning continue to rise, and there is still a profound lack of understanding of the gas.