The goal of this clinical trial is to evaluate the independent and synergistic effects of liquefied petroleum gas (LPG) substitution and improved ventilation on household air pollution (HAP) reduction and cardiopulmonary health. The main questions it aims to answer are: 1. Does LPG substitution or improved ventilation reduce HAP and improve cardiopulmonary health? 2. Would the combined intervention of LPG substitution and improved ventilation outperform single interventions? 3. What is the cost-effectiveness of such interventions, and are they sustainable? Participants will be randomized in 4 groups: A: Solid fuel + no ventilation facilities group (150 households): Continued use of solid fuels without ventilation facilities, with a one-time financial compensation provided post-intervention; B: Liquefied petroleum gas (LPG) + no ventilation facilities group (150 households): Provided with LPG stoves and instructed to use them for cooking, with regular LPG supply during the intervention period; C: Solid fuel + ventilation facilities group (150 households): Maintained solid fuel usage habits while provided with ventilation facilities and instructed to use them during cooking, with electricity costs compensated during the intervention; D: LPG + ventilation facilities group (150 households): Provided with both LPG stoves and ventilation facilities, instructed to use both during cooking, with regular LPG supply and electricity cost compensation throughout the intervention period.