The health impacts associated with exposure to elevated concentrations of fine particulate matter (PM 2.5 ) are well recognised. There is a substantial number of studies characterising PM 2.5 concentrations outdoors, as well as in homes within low- and middle-income countries. In high-income countries (HICs), there is a sizeable literature on indoor PM 2.5 relating to smoking, but the evidence on exposure to PM 2.5 generated f...