P OLICY R ESEARCH WORKING P APER 4422 Improving Indoor Air Quality for Poor Families: A Controlled Experiment in Bangladesh Susmita Dasgupta Mainul Huq M. Khaliquzzaman David Wheeler The World Bank Development Research Group Sustainable Rural and Urban Development Team December 2007 WPS4422 Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized