The Universidad Peruana Cayetano Heredia applied for the supplement in order to conduct a community-based feasibility trial in which they will install improved cook stoves with a chimney in 40 rural households of women aged 35 to 45 years in some areas of Kenya, Peru and Nepal. . All households will have a baseline observational period of 4 months in which they will collect outcome, environmental, and behavioral data longitudinally. Thereafter, 20 households will be randomly assigned to receive a commercially-available, improved cook stove with a chimney or a locally-constructed improved cook stove with a chimney. They will collect behavioral, compliance, outcome and exposure data longitudinally for 4 months. Exposure assessments will include particulate matter and carbon monoxide. Respiratory outcome assessment will include spirometry, carboxyhemoglobin, exhaled nitric oxide and diffusing capacity of the lung for carbon monoxide. At the end of 4 the month period, households that received the Envirofit improved cook stoves will have their cook stoves switched with the locally-constructed improved cook stoves and vice versa, and all households will be followed for another 4 months. At the end of the year, all participants will be asked which cook stove they prefer and will be asked to provide information on preferences, practices, and use patterns that influenced their final choice. These studies will be conducted as a collaboration between the Peru and Kenya COes and the Nepal Nutrition Intervention Project-Sarlahi.