Worldwide, approximately three billion people cook their food using biomass fuels such as wood, charcoal, crop residues, and animal dung. The emissions produced by these smoky fires lead to four million premature deaths annually and large environmental consequences. While the negative effects of biomass burning have spurred much research into designing less polluting cookstoves, researchers need a knowledge-base to draw from when making design decisions. However, previous research has measured these emissions relatively far away from the source, not exploring how the design modifications affect the actual combustion. In this study, the emissions from an improved cookstove, the Berkeley-Darfur Stove, and single blocks of wood are examined in-situ using laser extinction. The pollutant production, measured by the opacity or soot volume fraction, was compared between the two systems to gain a deeper understanding of combustion in the stove while providing initial steps towards a non-intrusive sampling system for pollutant production in cookstove combustion chambers.Kathleen M. Lask, Paul R. Medwell, Cristian H. Birzer, Ashok J. Gadgilhttp://cfe.uwa.edu.au/news/acs2013http://www.anz-combustioninstitute.org