The traditional method of cooking in some third world countries is on a three stone cooking fire. It is the cheapest stove to produce, requiring only three suitable stones of the same height on which a cooking pot can be balanced over a fire. However, this cooking method also has many problems:
* Smoke is vented into the home, instead of outdoors, causing health problems. According to the World Health Organization, "Every year, indoor air pollution is responsible for the death of 1.6 million people - that's one death every 20 seconds."
* Fuel is wasted, as heat is allowed to escape into the open air. This requires more labor on the part of the user to gather fuel and results in faster deforestation (if wood is the fuel being used).
* Only one cooking pot can be used at a time.
* The use of an open fire creates a risk of burns and scalds. Especially when the stove is used indoors, cramped conditions make adults and particularly children susceptible to falling or stepping into the fire and receiving burns. Additionally, accidental spills of boiling water may result in scalding, and blowing on the fire to supply oxygen may discharge burning embers and cause eye injuries.
Read about Improved stoves and other measures