It is now understood that emissions from traditional cook stoves pose a threat bigger than previously thought. The newest health data from WHO estimates that 4.3 million people die annually from household air pollution caused by cooking with biomass and coal. It is the greatest health risk in the world after high blood pressure, and alcohol. More people are dying from the incremental, ongoing inhalation of smoke from fires they ignite in their homes than from malaria, tuberculosis and HIVAIDS combined.