It’s estimated that more than 2 billion people use polluting stoves - with severe consequences for their health. The World Health Organisation says 3.2 million people die each year as a result of the household air pollution they cause. Ruth Alexander finds out why this problem – which also harms the environment – is so difficult to solve. She speaks to Dr Fatih Birol of the International Energy Agency in Paris; Sophie Odupoy from Koko Networks in Kenya; Naramath Lucas Kariongi from the Rural Communities Support Organisation in Tanzania; and Dr Mike Clifford of Nottingham University’s engineering department in the UK. If you would like to get in touch with the show, please email: thefoodchain@bbc.co.uk. Producers: Hannah Bewley and Rumella Dasgupta. (Picture: a clay stove with a wood fire lit. Credit: BBC)