More than three billion people still use wood, animal dung and coal to fuel the fires and stoves that cook their meals and heat their houses. By using this method, toxic and carcinogenic fumes, such as benzene and toluene, accumulate in poorly-ventilated dwellings. According to the World Health Organization, 4.3 million people a year die prematurely from illnesses caused by the use of solid fuels. Fuel derived from biochar, i.e. biobriquettes, does not emit these harmful fumes and can therefore be used as a safe and cheap replacement for traditionally-used fuels.