What you need to know Carbon monoxide (CO) is an odourless, colourless, tasteless and invisible gas that occurs through combustion, or the process of burning. Excessive amounts of CO will form when there isn’t proper ventilation or an adequate air supply. Most often, exposure to carbon monoxide occurs indoors. Any appliance that burns fuel can cause CO build-up, including fireplaces, gas stoves, water heaters, furnaces, grills, generators or car engines. CO poisoning can happen to anyone but some people are more susceptible than others. Elderly, infants and those with heart or respiratory...