Biomass fuels dominate the household energy mix in sub-Saharan Africa. Much of it is used inefficiently in poorly ventilated kitchens resulting in indoor air pollution and consumption of large amounts of wood fuel. Micro-gasification cookstoves can improve fuel use efficiency and reduce indoor air pollution while producing char as a by-product. This study monitored real-time concentrations of carbon monoxide (CO), carbon dioxide (CO2) and fine particulate matter (PM2.5), and amount of firewood used when households were cooking dinner. Twenty-five households used the gasifier cookstove to cook and five repeated the same test with three-stone open fire on a different date. With the gasifier, the average corresponding dinner time CO, CO2, and PM2.5 concentrations were reduced by 57%, 41%, and 79% respectively compared to three-stone open fire. The gasifier had average biomass-to-char conversion efficiency of 16.6%. If the produced char is used as fuel, households could save 32% of fuel compared to use of three-stone open fire and 18% when char is used as biochar, for instance. Adoption of the gasifier can help to reduce the need for firewood collection, hence reducing impacts on the environment while saving on the amount of time and money spent on cooking fuel.