Globally, about 50% of all households and 90% of rural households use solid fuels (coal and biomass) as the main domestic source of energy, thus exposing approximately 50% of the world population-close to 3 billion people-to the harmful effects of these combustion products. There is strong evidence that acute respiratory infections in children and chronic obstructive pulmonary disease in women are associated with indoor biomass smoke. Lung cancer in women has been clearly associated with household coal use. Other conditions such as chronic obstructive pulmonary disease in men and tuberculosis could be also associated but evidence is scarce. According to estimates of the World Health Organization, more than 1.6 million deaths and over 38.5 million disability-adjusted life-years can be attributable to indoor smoke from solid fuels affecting mainly children and women. Interventions to suppress or reduce indoor exposure include behavior changes, improvements of household ventilation, improvements of stoves, and, outstandingly, transitions to better and cleaner fuels. These changes face personal and local beliefs and economic and sociocultural conditions. In addition, selection of fuels should consider cost, sustainability, and protection of the environment. Consequently, complex solutions need to be locally adapted, and involve the commitment and active participation of governments, scientific societies, nongovernmental organizations, and the general community.