Never use unvented combustion appliances, such as barbecues, cook stoves, fondues, butane camping lanterns, propane or kerosene heaters, and lamps inside your house. They burn up available oxygen. They produce Co2 (carbon dioxide) and other combustion gases and fumes. Some produce huge quantities of colorless, odorless, and deadly carbon monoxide. Sterno cookers, fondues, and charcoal-burning devices are especially dangerous. Room ventilation won't get rid of fumes from unvented appliances. Use portable propane cook stoves, heaters, and lamps outside only. There is a very real risk of fire, explosion, asphyxiation, or poisoning from fumes.