Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Indoor biomass smoke exposure from inefficient burning of solid fuels may be the leading preventable cause among women in lesser developed countries. Although considerable evidence of an association between biomass smoke exposures and COPD has been demonstrated in observational studies, major limitations are that exposure assessment has been typically by self-report and no longitudinal studies that allow quantification of the effect of biomass smoke on the rate of decline in lung function have been conducted. Moreover, there are no studies of the efficacy of advanced biomass combustion stoves to slow the rate of decline in lung function in biomass smoke-exposed women as exist for smoking cessation. To address these data gaps, we propose to take advantage of the unique opportunity to build on the infrastructure of two UK-funded studies in Malawi, an advanced stove intervention trial to prevent childhood pneumonia (the Cooking and Pneumonia Study or CAPS) and a Burden of Lung Disease protocol Adult Lung Health Study (ALHS) which is being conducted in some of the same villages as CAPS. We plan to follow 2000 adults with spirometry, respiratory questionnaire administration, and personal biomass smoke exposure monitoring on an annual basis over a 6-year period. Our hypothesis is that greater biomass smoke exposure is associated with more rapid decline in lung function and more frequent respiratory symptoms. To test this hypothesis, we will be applying for R01 funding to conduct a prospective cohort study with the following specific aims: 1) to test the efficacy of the stove intervention to reduce the annual decline in lung function and incidence of respiratory symptoms; and 2) to establish the relationship between exposure to biomass smoke constituents (carbon monoxide, fine particulate matter, and black carbon) using personal monitoring data and rate of decline in lung function. For this 1-year R56 proposal, we plan to conduct personal monitoring on all 2000 subjects to be enrolled in the ALHS. The knowledge to be gained is critical to prevention efforts to reduce risk of COPD in the developing world.