Over half the world's population, most from developing countries, use solid fuel for domestic purposes and are exposed to very high concentrations of harmful air pollutants with potential health effects such as respiratory problems, cardiovascular, infant mortality and ocular problems. The evidence also suggests that, although the total percentage of people using solid fuel is coming down, the absolute number is currently increasing. Exposure to smoke from solid fuel burning increases the risk of chronic obstructive pulmonary diseases (COPD) and lung cancer in adults and acute lower respiratory tract infection/pneumonia in children. Despite heterogeneity among different studies the association between COPD and exposure to smoke produced by burning different types of solid fuel is consistent. However, there is strong evidence that while coal burning is a risk for lung cancer, exposure to other biomass fuel smoke is less so. There is some evidence that reduction of smoke exposure using improve cook stoves reduces the risk of COPD and possibly acute lower respiratory infection in children so approaches to reduce biomass smoke exposure are likely to result in reductions in the global burden of respiratory disease.