Indoor air pollutant levels in urban and rural areas of developing countries are much higher than ambient air pollutant levels in urban areas of developed and even of developing countries. Health effects due to indoor air pollution are, however, much less studied than in developed countries. Therefore, this paper summarises the information available on indoor air pollutant levels in developing countries. The evidence on the health impacts is presented and discussed. Starting from ongoing work on the global disease burden from air pollution at the World Health Organization (WHO) estimates of particle pollution induced mortality and morbidity are reported.